orphans and wallet files

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.16)
 
-project(miniboinc
+project(skalacoin
     VERSION 0.1.0
     LANGUAGES C CXX
 )
@@ -10,6 +10,7 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 set(CMAKE_C_EXTENSIONS OFF)
 
 find_package(Threads REQUIRED)
+include(FetchContent)
 
 # OpenSSL
 find_package(OpenSSL QUIET)
@@ -28,51 +29,154 @@ if(NOT OpenSSL_FOUND)
     find_package(OpenSSL REQUIRED)
 endif()
 
+# libcurl (required by autolykos2 vendored code)
+find_package(CURL QUIET)
+if(NOT CURL_FOUND)
+    message(STATUS "libcurl not found on system; attempting to fetch/build via FetchContent")
+    FetchContent_Declare(
+        curl
+        GIT_REPOSITORY https://github.com/curl/curl.git
+        GIT_TAG curl-8_4_0
+        GIT_SHALLOW TRUE
+    )
+    # Try to make it available (this will add_subdirectory if curl provides CMake)
+    FetchContent_MakeAvailable(curl)
+endif()
+
 # secp256k1 (Bitcoin Core library)
 find_package(PkgConfig QUIET)
 if(PkgConfig_FOUND)
     pkg_check_modules(SECP256K1 QUIET IMPORTED_TARGET libsecp256k1)
 endif()
 
+# Try pkg-config / system first, then fall back to find_*(). If still not found
+# attempt to fetch and build a bundled copy of libsecp256k1 using FetchContent.
 if(NOT SECP256K1_FOUND)
     find_path(SECP256K1_INCLUDE_DIR NAMES secp256k1.h)
     find_library(SECP256K1_LIBRARY NAMES secp256k1)
-    if(NOT SECP256K1_INCLUDE_DIR OR NOT SECP256K1_LIBRARY)
-        message(FATAL_ERROR "secp256k1 not found. Install with: brew install secp256k1")
+    if(SECP256K1_INCLUDE_DIR AND SECP256K1_LIBRARY)
+        set(SECP256K1_FOUND TRUE)
     endif()
 endif()
 
-# RandomX
-set(RANDOMX_ROOT "" CACHE PATH "Root directory of a RandomX installation")
-set(RANDOMX_USING_FETCHCONTENT OFF)
-if(PkgConfig_FOUND)
-    pkg_check_modules(RANDOMX QUIET IMPORTED_TARGET randomx)
+if(NOT SECP256K1_FOUND)
+    message(STATUS "secp256k1 not found on system; fetching and building a vendored copy")
+    include(FetchContent)
+    FetchContent_Declare(
+        secp256k1
+        GIT_REPOSITORY https://github.com/bitcoin-core/secp256k1.git
+        GIT_TAG master
+        GIT_SHALLOW TRUE
+    )
+    FetchContent_GetProperties(secp256k1)
+    if(NOT secp256k1_POPULATED)
+        FetchContent_Populate(secp256k1)
+        # Prefer a CMake build if present
+        if(EXISTS "${secp256k1_SOURCE_DIR}/CMakeLists.txt")
+            add_subdirectory(${secp256k1_SOURCE_DIR} ${secp256k1_BINARY_DIR})
+            if(TARGET secp256k1)
+                set(SECP256K1_FOUND TRUE)
+                set(SECP256K1_TARGET secp256k1)
+            elseif(TARGET libsecp256k1)
+                set(SECP256K1_FOUND TRUE)
+                set(SECP256K1_TARGET libsecp256k1)
+            endif()
+        else()
+            # Fall back to the autotools build path. Install into a private prefix
+            set(SECP256K1_INSTALL_DIR "${CMAKE_BINARY_DIR}/_deps/secp256k1/install")
+            file(MAKE_DIRECTORY ${SECP256K1_INSTALL_DIR})
+            execute_process(COMMAND ./autogen.sh
+                WORKING_DIRECTORY ${secp256k1_SOURCE_DIR}
+                RESULT_VARIABLE _secp_autogen_result
+                OUTPUT_QUIET ERROR_QUIET)
+            if(NOT _secp_autogen_result EQUAL 0)
+                message(FATAL_ERROR "Failed to run autogen.sh for secp256k1")
+            endif()
+            execute_process(COMMAND ./configure --enable-module-ecdh --enable-experimental --prefix=${SECP256K1_INSTALL_DIR}
+                WORKING_DIRECTORY ${secp256k1_SOURCE_DIR}
+                RESULT_VARIABLE _secp_configure_result
+                OUTPUT_QUIET ERROR_QUIET)
+            if(NOT _secp_configure_result EQUAL 0)
+                message(FATAL_ERROR "Failed to configure secp256k1")
+            endif()
+            execute_process(COMMAND make
+                WORKING_DIRECTORY ${secp256k1_SOURCE_DIR}
+                RESULT_VARIABLE _secp_make_result
+                OUTPUT_QUIET ERROR_QUIET)
+            if(NOT _secp_make_result EQUAL 0)
+                message(FATAL_ERROR "Failed to build secp256k1")
+            endif()
+            execute_process(COMMAND make install
+                WORKING_DIRECTORY ${secp256k1_SOURCE_DIR}
+                RESULT_VARIABLE _secp_make_install_result
+                OUTPUT_QUIET ERROR_QUIET)
+            set(SECP256K1_INCLUDE_DIR ${SECP256K1_INSTALL_DIR}/include)
+            set(SECP256K1_LIBRARY ${SECP256K1_INSTALL_DIR}/lib/libsecp256k1.a)
+            if(EXISTS ${SECP256K1_LIBRARY})
+                set(SECP256K1_FOUND TRUE)
+            endif()
+        endif()
+    endif()
 endif()
 
-if(NOT RANDOMX_FOUND)
-    find_path(RANDOMX_INCLUDE_DIR
-        NAMES randomx.h
-        HINTS ${RANDOMX_ROOT}
-        PATH_SUFFIXES include
+# Autolykos2 CPU reference backend (optional)
+option(SKALACOIN_ENABLE_AUTOLYKOS2_REF "Enable Autolykos2 CPU reference backend" ON)
+set(SKALACOIN_AUTOLYKOS2_REF_AVAILABLE OFF)
+
+if(SKALACOIN_ENABLE_AUTOLYKOS2_REF)
+    FetchContent_Declare(
+        autolykos2_ref_src
+        GIT_REPOSITORY https://github.com/mhssamadani/Autolykos2_NV_Miner.git
+        GIT_TAG main
+        GIT_SHALLOW TRUE
     )
-    find_library(RANDOMX_LIBRARY
-        NAMES randomx
-        HINTS ${RANDOMX_ROOT}
-        PATH_SUFFIXES lib
+    FetchContent_MakeAvailable(autolykos2_ref_src)
+
+    set(AUTOLYKOS2_REF_BASE ${autolykos2_ref_src_SOURCE_DIR}/secp256k1)
+    set(AUTOLYKOS2_REF_SOURCES
+        ${AUTOLYKOS2_REF_BASE}/src/cpuAutolykos.cc
+        ${AUTOLYKOS2_REF_BASE}/src/conversion.cc
+        ${AUTOLYKOS2_REF_BASE}/src/cryptography.cc
+        ${AUTOLYKOS2_REF_BASE}/src/definitions.cc
+        ${AUTOLYKOS2_REF_BASE}/src/easylogging++.cc
+        ${AUTOLYKOS2_REF_BASE}/src/jsmn.c
+        ${PROJECT_SOURCE_DIR}/src/autolykos2/easylogging_init.cpp
+        ${PROJECT_SOURCE_DIR}/src/autolykos2/autolykos2_ref_wrapper.cpp
     )
 
-    if(NOT RANDOMX_INCLUDE_DIR OR NOT RANDOMX_LIBRARY)
-        include(FetchContent)
-        FetchContent_Declare(
-            randomx_src
-            GIT_REPOSITORY https://github.com/tevador/RandomX.git
-            GIT_TAG master
-            GIT_SHALLOW TRUE
+    add_library(autolykos2_ref STATIC ${AUTOLYKOS2_REF_SOURCES})
+    target_include_directories(autolykos2_ref PRIVATE ${AUTOLYKOS2_REF_BASE}/include)
+    # Upstream source uses `malloc/free/exit/EXIT_FAILURE` without including
+    # stdlib headers in some C++ translation units. AppleClang can compile this,
+    # while Linux Clang fails. Force-include stdlib.h for C++ in this vendored lib.
+    if(CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU")
+        target_compile_options(autolykos2_ref PRIVATE
+            $<$<COMPILE_LANGUAGE:CXX>:-include>
+            $<$<COMPILE_LANGUAGE:CXX>:stdlib.h>
+        )
+    elseif(MSVC)
+        target_compile_options(autolykos2_ref PRIVATE
+            $<$<COMPILE_LANGUAGE:CXX>:/FIstdlib.h>
         )
-        FetchContent_MakeAvailable(randomx_src)
-        set(RANDOMX_USING_FETCHCONTENT ON)
-        set(RANDOMX_INCLUDE_DIR ${randomx_src_SOURCE_DIR}/src)
     endif()
+    if(TARGET CURL::libcurl)
+        target_link_libraries(autolykos2_ref PRIVATE
+            ${CMAKE_THREAD_LIBS_INIT}
+            OpenSSL::SSL
+            OpenSSL::Crypto
+            CURL::libcurl
+        )
+    elseif(DEFINED CURL_LIBRARIES AND CURL_LIBRARIES)
+        target_link_libraries(autolykos2_ref PRIVATE
+            ${CMAKE_THREAD_LIBS_INIT}
+            OpenSSL::SSL
+            OpenSSL::Crypto
+            ${CURL_LIBRARIES}
+        )
+    else()
+        message(FATAL_ERROR "autolykos2_ref requires libcurl (curl/curl.h). Install libcurl devel package or allow FetchContent to build it.")
+    endif()
+    set(SKALACOIN_AUTOLYKOS2_REF_AVAILABLE ON)
 endif()
 
 # ---------------------------------------------------------
@@ -98,21 +202,19 @@ target_link_libraries(node PRIVATE
     OpenSSL::Crypto
 )
 
-if(SECP256K1_FOUND)
+if(TARGET PkgConfig::SECP256K1)
     target_link_libraries(node PRIVATE PkgConfig::SECP256K1)
-else()
+elseif(DEFINED SECP256K1_TARGET AND TARGET ${SECP256K1_TARGET})
+    target_link_libraries(node PRIVATE ${SECP256K1_TARGET})
+elseif(SECP256K1_FOUND AND SECP256K1_LIBRARY)
     target_include_directories(node PRIVATE ${SECP256K1_INCLUDE_DIR})
     target_link_libraries(node PRIVATE ${SECP256K1_LIBRARY})
+else()
+    message(FATAL_ERROR "secp256k1 not found and no vendored target available. Install libsecp256k1 or enable FetchContent builds.")
 endif()
 
-if(RANDOMX_FOUND)
-    target_link_libraries(node PRIVATE PkgConfig::RANDOMX)
-elseif(RANDOMX_USING_FETCHCONTENT)
-    target_link_libraries(node PRIVATE randomx)
-    target_include_directories(node PRIVATE ${RANDOMX_INCLUDE_DIR})
-else()
-    target_include_directories(node PRIVATE ${RANDOMX_INCLUDE_DIR})
-    target_link_libraries(node PRIVATE ${RANDOMX_LIBRARY})
+if(SKALACOIN_AUTOLYKOS2_REF_AVAILABLE)
+    target_link_libraries(node PRIVATE autolykos2_ref)
 endif()
 
 target_include_directories(node PRIVATE 
@@ -126,5 +228,7 @@ target_compile_options(node PRIVATE
 )
 target_compile_definitions(node PRIVATE
     CHAIN_DATA_DIR="${CMAKE_BINARY_DIR}/chain_data"
+    $<$<BOOL:${SKALACOIN_AUTOLYKOS2_REF_AVAILABLE}>:SKALACOIN_AUTOLYKOS2_REF_AVAILABLE>
+    $<$<BOOL:1>:_POSIX_C_SOURCE=200809L>
 )
-set_target_properties(node PROPERTIES OUTPUT_NAME "minicoin_node")
+set_target_properties(node PROPERTIES OUTPUT_NAME "skalacoin_node")

LICENSE

@@ -0,0 +1,504 @@
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.]
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+Licenses are intended to guarantee your freedom to share and change
+free software--to make sure the software is free for all its users.
+
+  This license, the Lesser General Public License, applies to some
+specially designated software packages--typically libraries--of the
+Free Software Foundation and other authors who decide to use it.  You
+can use it too, but we suggest you first think carefully about whether
+this license or the ordinary General Public License is the better
+strategy to use in any particular case, based on the explanations below.
+
+  When we speak of free software, we are referring to freedom of use,
+not price.  Our General Public Licenses are designed to make sure that
+you have the freedom to distribute copies of free software (and charge
+for this service if you wish); that you receive source code or can get
+it if you want it; that you can change the software and use pieces of
+it in new free programs; and that you are informed that you can do
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+
+  To protect your rights, we need to make restrictions that forbid
+distributors to deny you these rights or to ask you to surrender these
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+
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+library, and (2) we offer you this license, which gives you legal
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+  When a program is linked with a library, whether statically or using
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+General Public License therefore permits such linking only if the
+entire combination fits its criteria of freedom.  The Lesser General
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+  We call this license the "Lesser" General Public License because it
+does Less to protect the user's freedom than the ordinary General
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+
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+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
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+    USA
+
+Also add information on how to contact you by electronic and paper mail.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the library, if
+necessary.  Here is a sample; alter the names:
+
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+  library `Frob' (a library for tweaking knobs) written by James Random
+  Hacker.
+
+  <signature of Ty Coon>, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!

README.md

@@ -1,8 +1,20 @@
-# MiniCoin
+# Skalacoin
 
-Basic blockchain currency implementation in C, for educational purposes. Not intended for production use.
+Privacy coin made in C. One day hopefully with a purpose beyond "educational" :)
+
+Some notes for me right now:
 
 cmake:
 ```bash
 cmake .. -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_FLAGS="-fsanitize=address -fno-omit-frame-pointer" -DCMAKE_CXX_FLAGS="-fsanitize=address -fno-omit-frame-pointer" -DCMAKE_EXE_LINKER_FLAGS="-fsanitize=address"
 ```
+
+Build with clang/clang++ (I don't want to deal with the gcc/MSVC shenangans right now)
+
+Use:
+```bash
+./bin/skalacoin_node <-mine>
+```
+
+Main Hashing Algorithm: SHA256d (double SHA256) for now.
+Proof-of-Work Algorithm: Autolykos2

TODO.txt

@@ -1,2 +1,25 @@
+TODO:
+Make transactions private. A bit more work, but it's a challenge worth taking on.
+I want to make an "optional privacy" system, where the TX can be public or private. Of course private TXs need more bytes, so the fees (although low) will be higher for them.
+I need to figure out a way to make the privacy work without a UTXO system, and instead, with a "Balance Sheet" approach.
+
+Move the Networking Code to support win32 as well, as I'm just doing POSIX right now
+Maybe move the node system to an async event loop instead of spawning threads.
+
+A potential race could occur if the P2P node receives a new block, or flushes a new block to disk while the user is running a full verify.
+
+Maybe think about how block broadcasting works. Instead of unsolicited broadcasting, maybe only advertise a new height and have peers request the block if they want it. This would reduce bandwidth usage, but it also means that blocks won't propagate as fast, which could lead to more orphaned blocks. It's a tradeoff.
+
+Check if Block FullVerify is actually verifying fully (not missing any conditions).
+
+A loophole in the reorg penalty system could potentially exist where someone broadcasts blocks one-at-a-time. Determine a solution to this.
+
+TO TEST:
+Implement Horizen's "Reorg Penalty" system to make it harder for the young chain to be attacked by a powerful miner.
+
+DONE:
+I want to move away from the Monero emission. I want to do something a bit radical for cryptocurrency, but I feel like it's necessary to make it more like money:
+a constant inflation rate of 1.5% per year. It's lower than fiat (USD is ~2.8% per year), and it additionally doesn't fluctuate during crisis. It's constant.
+
 Move to a GPU algo. RandomX is a good candidate, but CPU mining is not that attractive to anyone but people who actually want to support the project.
-It won't incentivize people who want to profit, which let's be fair, is the majority of miners.
+Sadly, CPUs won't incentivize people who want to profit, which let's be fair, is the majority of miners.

include/autolykos2/autolykos2.h

@@ -0,0 +1,72 @@
+#ifndef SKALACOIN_AUTOLYKOS2_H
+#define SKALACOIN_AUTOLYKOS2_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <constants.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct Autolykos2Context Autolykos2Context;
+
+extern uint64_t autolykos2_sleepBetweenHashOperationsMicroseconds;
+
+Autolykos2Context* Autolykos2_Create(void);
+void Autolykos2_Destroy(Autolykos2Context* ctx);
+
+bool Autolykos2_DagAllocate(Autolykos2Context* ctx, size_t bytes);
+bool Autolykos2_DagAppend(Autolykos2Context* ctx, const uint8_t* data, size_t len);
+bool Autolykos2_DagGenerate(Autolykos2Context* ctx, const uint8_t seed32[32]);
+void Autolykos2_DagClear(Autolykos2Context* ctx);
+size_t Autolykos2_DagSize(const Autolykos2Context* ctx);
+
+bool Autolykos2_Hash(
+	Autolykos2Context* ctx,
+	const uint8_t* message,
+	size_t messageLen,
+	uint64_t nonce,
+	uint64_t height,
+	uint8_t outHash[32]
+);
+
+bool Autolykos2_LightHash(const uint8_t* seed, blockchain_t* chain, uint64_t nonce, uint8_t* out);
+bool Autolykos2_LightHashAtHeight(
+	const uint8_t seed32[32],
+	const uint8_t* message,
+	size_t messageLen,
+	uint64_t nonce,
+	uint64_t height,
+	size_t dagBytes,
+	uint8_t out[32]
+);
+
+bool Autolykos2_CheckTarget(
+	Autolykos2Context* ctx,
+	const uint8_t message32[32],
+	uint64_t nonce,
+	uint64_t height,
+	const uint8_t target32[32],
+	uint8_t outHash[32]
+);
+
+bool Autolykos2_FindNonceSingleCore(
+	Autolykos2Context* ctx,
+	const uint8_t message32[32],
+	uint64_t height,
+	const uint8_t target32[32],
+	uint64_t startNonce,
+	uint64_t maxIterations,
+	uint64_t* outNonce,
+	uint8_t outHash[32]
+);
+
+void Autolykos2_SetSleepBetweenHashOperations(uint64_t sleepMicroseconds);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

include/balance_sheet.h

@@ -2,10 +2,31 @@
 #define BALANCE_SHEET_H
 
 #include <stdint.h>
+#include <dynarr.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <khash/khash.h>
+#include <crypto/crypto.h>
+#include <string.h>
+#include <utils.h>
+#include <uint256.h>
 
 typedef struct {
     uint8_t address[32]; // For now just the SHA-256 of the public key; allows representation in different encodings (base58, bech32, etc) without changing the underlying data structure
-    uint64_t balance;
+    uint256_t balance;
+    // TODO: Additional things
 } balance_sheet_entry_t;
 
+KHASH_INIT(balance_sheet_map_m, key32_t, balance_sheet_entry_t, 1, hash_key32, eq_key32)
+extern khash_t(balance_sheet_map_m)* sheetMap;
+
+void BalanceSheet_Init();
+int BalanceSheet_Insert(balance_sheet_entry_t entry);
+bool BalanceSheet_Lookup(uint8_t* address, balance_sheet_entry_t* out);
+bool BalanceSheet_SaveToFile(const char* outPath);
+bool BalanceSheet_LoadFromFile(const char* inPath); 
+void BalanceSheet_Print();
+void BalanceSheet_Destroy();
+
 #endif

include/blake2/blake2.h

@@ -0,0 +1,14 @@
+#ifndef SKALACOIN_BLAKE2_H
+#define SKALACOIN_BLAKE2_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define SKALACOIN_BLAKE2B_OUTBYTES 64
+#define SKALACOIN_BLAKE2S_OUTBYTES 32
+
+bool Blake2b_Hash(const uint8_t* input, size_t inputLen, uint8_t* out, size_t outLen);
+bool Blake2s_Hash(const uint8_t* input, size_t inputLen, uint8_t* out, size_t outLen);
+
+#endif

include/block/block.h

@@ -7,9 +7,9 @@
 #include <block/transaction.h>
 #include <stdbool.h>
 #include <string.h>
-#include <randomx/librx_wrapper.h>
 #include <stdlib.h>
 
+#pragma pack(push, 1) // Ensure no padding for consistent file storage
 typedef struct {
     uint64_t blockNumber;
     uint64_t timestamp;
@@ -20,21 +20,28 @@ typedef struct {
     uint8_t version;
     uint8_t reserved[3];       // 3 bytes (Explicit padding for 8-byte alignment)
 } block_header_t;
+#pragma pack(pop)
 
 typedef struct {
     block_header_t header;
-    DynArr* transactions; // Array of signed_transaction_t
+    DynArr* transactions; // Array of signed_transaction_t, NOTE: Potentially move to a hashmap at some point for quick lookups.
 } block_t;
 
 block_t* Block_Create();
 void Block_CalculateHash(const block_t* block, uint8_t* outHash);
 void Block_CalculateMerkleRoot(const block_t* block, uint8_t* outHash);
-void Block_CalculateRandomXHash(const block_t* block, uint8_t* outHash);
+void Block_CalculateAutolykos2Hash(const block_t* block, uint8_t* outHash);
+bool Block_RebuildAutolykos2Dag(size_t dagBytes, const uint8_t seed32[32]);
 void Block_AddTransaction(block_t* block, signed_transaction_t* tx);
 void Block_RemoveTransaction(block_t* block, uint8_t* txHash);
 bool Block_HasValidProofOfWork(const block_t* block);
 bool Block_AllTransactionsValid(const block_t* block);
+bool Block_IsFullyValid(const block_t* block);
+void Block_ShutdownPowContext(void);
 void Block_Destroy(block_t* block);
 void Block_Print(const block_t* block);
+void Block_ShortPrint(const block_t* block);
+// Deep-copy a block (allocates a new `block_t*`). Caller must call `Block_Destroy`.
+block_t* Block_Copy(const block_t* src);
 
 #endif

include/block/chain.h

@@ -7,8 +7,9 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <string.h>
-#include <constants.h>
 #include <uint256.h>
+#include <storage/block_table.h>
+#include <balance_sheet.h>
 
 typedef struct {
     DynArr* blocks;
@@ -23,8 +24,19 @@ size_t Chain_Size(blockchain_t* chain);
 bool Chain_IsValid(blockchain_t* chain);
 void Chain_Wipe(blockchain_t* chain);
 
+// Roll back the chain to `height` (exclusive): after this call, Chain_Size(chain) == height
+// Returns true on success.
+bool Chain_RollbackToHeight(blockchain_t* chain, size_t height);
+
+// Retrieve a deep copy of the block at `index`. Caller must free with `Block_Destroy`.
+bool Chain_GetBlockCopy(blockchain_t* chain, size_t index, block_t** outCopy);
+
 // I/O
-bool Chain_SaveToFile(blockchain_t* chain, const char* dirpath, uint256_t currentSupply);
-bool Chain_LoadFromFile(blockchain_t* chain, const char* dirpath, uint256_t* outCurrentSupply);
+bool Chain_SaveToFile(blockchain_t* chain, const char* dirpath, uint256_t currentSupply, uint64_t currentReward);
+bool Chain_LoadFromFile(blockchain_t* chain, const char* dirpath, uint256_t* outCurrentSupply, uint32_t* outDifficultyTarget, uint64_t* outCurrentReward, uint8_t* outLastSavedHash, bool loadTransactions);
+bool Chain_LoadBlockFromFile(const char* dirpath, uint64_t blockNumber, bool loadTransactions, block_t** outBlock, size_t* outTxCount);
+
+// Difficulty
+uint32_t Chain_ComputeNextTarget(blockchain_t* chain, uint32_t currentTarget);
 
 #endif

include/block/transaction.h

@@ -20,19 +20,30 @@ static inline bool Address_IsCoinbase(const uint8_t address[32]) {
     return true;
 }
 
-// 178 bytes total for v1
+// 160 bytes total for v1
+#pragma pack(push, 1) // Ensure no padding for consistent file storage
 typedef struct {
-    uint8_t version;
-    uint8_t senderAddress[32];
-    uint8_t recipientAddress[32];
-    uint64_t amount;
     uint64_t fee; // Rewarded to the miner; can be zero, but the miner may choose to ignore transactions with very low fees
-    uint8_t compressedPublicKey[33];
+    uint64_t amount1;
+    uint64_t amount2;
+    // Only one "input" sender address
+    uint8_t senderAddress[32];
+    // The "main" recepient address and amount. This is the only required output, and is used for calculating the transaction hash and signature.
+    uint8_t recipientAddress1[32];
+    // The "extra" recepient address and amount. This can safely be NULL/0 if not used and has multiple uses:
+    // - Sending zero: parital spend, sender keeps coins on the same address
+    // - Sending to a different address: normal spend, sender's coins move to a new address, e.g. change address
+    // - Private Transactions: Can nullify the whole original stealth address input (sender) and send change to a new stealth address (recipient 2) to obfuscate the transaction graph.
+    // Note that coinbase will have this as NULL/0 (for now, but we could have multiple payouts in the future)
+    uint8_t recipientAddress2[32];
     // Timestamp is dictated by the block
+    uint8_t compressedPublicKey[33];
+    uint8_t version;
+    uint8_t reserved[6]; // 6 bytes (Explicit padding for 8-byte alignment)
 } transaction_t;
+#pragma pack(pop)
 
 typedef struct {
-    uint8_t txHash[32];
     uint8_t signature[64]; // Signature of the hash
 } transaction_sig_t;
 
@@ -41,6 +52,7 @@ typedef struct {
     transaction_sig_t signature;
 } signed_transaction_t;
 
+void Transaction_Init(signed_transaction_t* tx);
 void Transaction_CalculateHash(const signed_transaction_t* tx, uint8_t* outHash);
 void Transaction_Sign(signed_transaction_t* tx, const uint8_t* privateKey);
 bool Transaction_Verify(const signed_transaction_t* tx);

include/constants.h

@@ -4,43 +4,244 @@
 #include <stdint.h>
 #include <uint256.h>
 #include <stdbool.h>
+#include <block/chain.h>
+#include <block/block.h>
 
+#include <runtime_state.h>
+
+// Nets
+#define MAX_CONS 32 // Some baseline for now
+#define LISTEN_PORT 9393
+#define ECHO_PEERS 1 // If non-zero, automatically attempt to connect back to any inbound peers (helps form bidirectional peering)
+#define TCP_THREAD_STACK_SIZE (512 * 1024) // 512 KB. We could get away with like 128 KB since it's mostly just recv bufs, but it's good having some breathing room.
+                                           // This is also for client threads. The server has the default (~8 MB on POSIX).
+
+// Economics
 #define DECIMALS 1000000000000ULL
-#define DIFFICULTY_ADJUSTMENT_INTERVAL 960 // Every 960 blocks (roughly every 24 hours with a 90 second block time)
+#define DIFFICULTY_ADJUSTMENT_INTERVAL 3840 // Every 3840 blocks (roughly every 4 days with a 90 second block time)
                                            // Max adjustment per is x2. So if blocks are coming in too fast, the difficulty will at most double every 24 hours, and vice versa if they're coming in too slow.
-#define RANDOMX_KEY_ROTATION_INTERVAL 6720 // 1 week at 90s block time
 #define TARGET_BLOCK_TIME 90 // Target block time in seconds
+//#define INITIAL_DIFFICULTY 0x1f0c1422 // Default compact target used by Autolykos2 PoW (This is ridiculously low)
+#define INITIAL_DIFFICULTY 0x1f1b7c51 // This takes 90s on my machine with a single thread, good for testing
+
+// Sync / Reorg tuning constants
+// Timeouts and retry/backoff behavior for block fetches during sync (milliseconds)
+static const uint64_t SYNC_REQUEST_TIMEOUT_MS = 5000ULL; // 5s
+static const int MAX_SYNC_RETRIES = 4; // retry attempts per block fetch
+static const uint64_t SYNC_BACKOFF_BASE_MS = 200ULL; // base backoff in ms (exponential)
+// Parallelism
+static const int MAX_PARALLEL_FETCHES = 8; // concurrent block fetches during windowed sync
+// Heuristic: if peer is this many blocks ahead, treat as initial sync
+static const uint64_t INITIAL_SYNC_HEIGHT_DIFF = 50ULL;
+
+// Reorg penalty configuration (used to penalize peers reporting higher heights but with delayed work)
+static const uint64_t REORG_PENALTY_GRACE_BLOCKS = 3ULL; // allow small reorgs without penalty
+static const double REORG_PENALTY_FACTOR = 1.0; // base scaling factor (theta)
+static const double REORG_PENALTY_EXPONENT = 2.0; // exponent p in penalty ~ B^p
+static const double REORG_PENALTY_REF_BLOCK_TIME = 150.0; // reference block time in seconds used by original scheme
+
+// Reward schedule acceleration: 1 means normal-speed progression.
+#define EMISSION_ACCELERATION_FACTOR 1ULL
+
+// Phase-one target horizon: emit ~2^64-1 atomic units by this many blocks at x1.
+#define PHASE1_TARGET_BLOCKS 3000000ULL
+
+// Inflation is expressed in tenths of a percent to preserve integer math.
+#define INFLATION_PERCENTAGE_PER_EPOCH_TENTHS 15ULL // 1.5%
+
+// Monero-style main emission: reward = (MONEY_SUPPLY - generated) >> speed factor.
+// Keep this at 20 to match the canonical curve shape against a 2^64 atomic supply cap.
+#define MONERO_EMISSION_SPEED_FACTOR 20U
+
+// Future Autolykos2 constants:
+#define EPOCH_LENGTH 350000 // ~1 year at 90s
+#define DAG_BASE_GROWTH (1ULL << 30) // 1 GB per epoch, adjusted by acceleration
+//#define DAG_BASE_SIZE (6ULL << 30) // 6 GB, adjusted per cycle based off DAG_BASE_GROWTH
+#define DAG_BASE_SIZE (1ULL << 30) // TEMPORARY FOR TESTING
+// Swings - calculated as MIN(percentage, absolute GB) to prevent absurd swings from low hashrate or very large DAG growth
+#define DAG_MAX_UP_SWING_PERCENTAGE 1.15 // 15%
+#define DAG_MAX_DOWN_SWING_PERCENTAGE 0.90 // 10%
+#define DAG_MAX_UP_SWING_GB (2ULL << 30) // 2 GB
+#define DAG_MAX_DOWN_SWING_GB (1ULL << 30) // 1 GB
+#define DAG_GENESIS_SEED 0x00 // Genesis seed is zeroes, every epoch's seed is the hash of the previous block, therefore unpredictable until the block is mined
+
+/**
+ * Each epoch has 2 phases, connected logarithmically:
+ * - Phase 1: Aggressive DAG growth (target is ~75% of the max cap) to kick out any ASICs, 30k blocks (roughly 1 month)
+ * - Phase 2: Stable DAG growth (target is the max cap) to provide a stable environment for GPU miners, 320k blocks (roughly 11 months)
+**/
+
 static const uint64_t M_CAP = 18446744073709551615ULL; // Max uint64
-static const uint64_t TAIL_EMISSION = DECIMALS; // Emission floor is 1.0 coins per block
+static const uint64_t TAIL_EMISSION = 750000000000ULL; // 0.75 coins per block floor
 // No max supply. Instead of halving, it'll follow a more gradual, Monero-like emission curve.
 
-static uint256_t currentSupply = {{0, 0, 0, 0}}; // Global variable to track total supply; updated with each block mined
+// Phase 3: update once per effective epoch and keep a fixed per-block reward for that epoch.
+static inline uint64_t GetInflationRateReward(uint256_t currentSupply, blockchain_t* chain) {
+    if (!chain || !chain->blocks) { return 0x00; } // Invalid
+    size_t height = Chain_Size(chain);
+    const uint64_t effectiveEpochLength =
+        (EPOCH_LENGTH / EMISSION_ACCELERATION_FACTOR) > 0
+            ? (EPOCH_LENGTH / EMISSION_ACCELERATION_FACTOR)
+            : 1;
 
-static inline uint64_t CalculateBlockReward(uint256_t currentSupply, uint64_t height) {
-    // Inclusive of block 0
-    (void)height;
+    if (height == 0) {
+        currentReward = TAIL_EMISSION;
+        return currentReward;
+    }
+    
+    if (height % effectiveEpochLength == 0) {
+        // inflationPerBlock = currentSupply * 1.5% / effectiveEpochLength
+        // = currentSupply * 15 / (1000 * effectiveEpochLength)
+        uint256_t multiplied = uint256_from_u64(0);
+        for (uint64_t i = 0; i < INFLATION_PERCENTAGE_PER_EPOCH_TENTHS; ++i) {
+            uint256_add(&multiplied, &currentSupply);
+        }
+
+        uint64_t divisor = 1000ULL * effectiveEpochLength;
+        uint256_t quotient = {{0, 0, 0, 0}};
+        unsigned __int128 remainder = 0;
+
+        // Work from the most significant limb to the least
+        for (int i = 3; i >= 0; i--) {
+            unsigned __int128 current = (remainder << 64) | multiplied.limbs[i];
+            quotient.limbs[i] = (uint64_t)(current / divisor);
+            remainder = current % divisor;
+        }
+
+        uint64_t inflationPerBlock = quotient.limbs[0];
+        currentReward = (inflationPerBlock > TAIL_EMISSION) ? inflationPerBlock : TAIL_EMISSION;
+        return currentReward;
+    }
+
+    return (currentReward > TAIL_EMISSION) ? currentReward : TAIL_EMISSION;
+}
+
+static inline uint64_t CalculateBlockReward(uint256_t currentSupply, blockchain_t* chain) {
+    if (!chain || !chain->blocks) { return 0x00; } // Invalid
+
+    const uint64_t effectivePhase1Blocks =
+        (PHASE1_TARGET_BLOCKS / EMISSION_ACCELERATION_FACTOR) > 0
+            ? (PHASE1_TARGET_BLOCKS / EMISSION_ACCELERATION_FACTOR)
+            : 1;
+    const uint64_t height = (uint64_t)Chain_Size(chain);
+
+    // After the phase-one target horizon, only floor/inflation schedule applies.
+    if (height >= effectivePhase1Blocks) {
+        return GetInflationRateReward(currentSupply, chain);
+    }
 
     if (currentSupply.limbs[1] > 0 || 
         currentSupply.limbs[2] > 0 || 
         currentSupply.limbs[3] > 0 || 
-        currentSupply.limbs[0] >= M_CAP) {
-        return TAIL_EMISSION;
+        currentSupply.limbs[0] >= M_CAP)
+    {
+        // Post-Monero phase with unlimited supply: floor/inflation schedule only.
+        return GetInflationRateReward(currentSupply, chain);
     }
 
-    uint64_t supply_64 = currentSupply.limbs[0];
+    const uint64_t generated = currentSupply.limbs[0];
+    const uint64_t remaining = M_CAP - generated;
 
-    // Formula: ((M - Supply) >> 20) * 181 / 256
-    // Use 128-bit intermediate to avoid overflow while preserving integer math.
-    __uint128_t rewardWide = (((__uint128_t)(M_CAP - supply_64) >> 20) * 181u) >> 8;
-    uint64_t reward = (rewardWide > UINT64_MAX) ? UINT64_MAX : (uint64_t)rewardWide;
-    // At a block time of ~90s and a floor of 1.0 coins, this will make a curve of ~8.5 years
+    // Monero-style base curve against ~2^64 atomic-unit terminal supply.
+    uint64_t reward = remaining >> MONERO_EMISSION_SPEED_FACTOR;
 
-    // Check if the calculated reward has fallen below the floor
-    if (reward < TAIL_EMISSION) {
-        return TAIL_EMISSION;
+    // Acceleration preserves curve shape while reaching the floor sooner in block-height terms.
+    if (EMISSION_ACCELERATION_FACTOR > 1ULL && reward > 0ULL) {
+        __uint128_t accelerated = (__uint128_t)reward * (__uint128_t)EMISSION_ACCELERATION_FACTOR;
+        reward = (accelerated > (__uint128_t)remaining) ? remaining : (uint64_t)accelerated;
     }
 
-    return reward;
+    // Retarget phase one to finish by PHASE1_TARGET_BLOCKS (x1), while keeping
+    // Monero-style behavior as the preferred curve when it is already sufficient.
+    const uint64_t blocksLeft = effectivePhase1Blocks - height;
+    const uint64_t minRewardToFinish = (remaining + blocksLeft - 1ULL) / blocksLeft; // ceil(remaining / blocksLeft)
+    if (reward < minRewardToFinish) {
+        reward = minRewardToFinish;
+    }
+    if (reward > remaining) {
+        reward = remaining;
+    }
+
+    // Phase 1 until Monero reward goes below the floor.
+    if (reward > TAIL_EMISSION) {
+        return reward;
+    }
+
+    // Phase 2 + 3: floor and epoch inflation updates.
+    return GetInflationRateReward(currentSupply, chain);
+}
+
+// Hashing DAG
+#include <math.h>
+static inline size_t CalculateTargetDAGSize(blockchain_t* chain) {
+    // Base size plus (base growth * difficulty factor), adjusted by acceleration
+    if (!chain || !chain->blocks) { return 0; } // Invalid
+    uint64_t height = (uint64_t)Chain_Size(chain);
+    
+    if (height < EPOCH_LENGTH) {
+        return DAG_BASE_SIZE;
+    }
+
+    // Get the height - EPOCH_LENGTH block and the last block;
+    block_t* lastBlock = NULL;
+    block_t* epochStartBlock = NULL;
+    if (!Chain_GetBlockCopy(chain, Chain_Size(chain) - 1, &lastBlock) || !lastBlock) {
+        if (lastBlock) Block_Destroy(lastBlock);
+        return 0;
+    }
+    if (!Chain_GetBlockCopy(chain, (size_t)(Chain_Size(chain) - 1 - EPOCH_LENGTH), &epochStartBlock) || !epochStartBlock) {
+        Block_Destroy(lastBlock);
+        if (epochStartBlock) Block_Destroy(epochStartBlock);
+        return 0;
+    }
+
+    int64_t difficultyDelta = (int64_t)epochStartBlock->header.difficultyTarget - (int64_t)lastBlock->header.difficultyTarget;
+    int64_t growth = (DAG_BASE_GROWTH * difficultyDelta); // Can be negative if difficulty has decreased, which is why we use int64_t
+
+    // Clamp
+    if (growth > 0) {
+        // Difficulty increased -> Clamp the UPWARD swing
+        int64_t maxUp = (int64_t)((DAG_BASE_SIZE * 15) / 100); // 15%
+        if (growth > maxUp) growth = maxUp;
+        if (growth > (int64_t)DAG_MAX_UP_SWING_GB) growth = DAG_MAX_UP_SWING_GB;
+    } else {
+        // Difficulty decreased -> Clamp the DOWNWARD swing
+        int64_t maxDown = (int64_t)((DAG_BASE_SIZE * 10) / 100); // 10%
+        if (-growth > maxDown) growth = -maxDown;
+        if (-growth > (int64_t)DAG_MAX_DOWN_SWING_GB) growth = -(int64_t)DAG_MAX_DOWN_SWING_GB;
+    }
+    
+    int64_t targetSize = (int64_t)DAG_BASE_SIZE + growth;
+    if (targetSize <= 0) {
+        Block_Destroy(lastBlock);
+        Block_Destroy(epochStartBlock);
+        return 0;
+    }
+
+    size_t out = (size_t)targetSize;
+    Block_Destroy(lastBlock);
+    Block_Destroy(epochStartBlock);
+    return out;
+}
+
+static inline void GetNextDAGSeed(blockchain_t* chain, uint8_t outSeed[32]) {
+    if (!chain || !chain->blocks || !outSeed) { return; } // Invalid
+    uint64_t height = (uint64_t)Chain_Size(chain);
+
+    if (height < EPOCH_LENGTH) {
+        memset(outSeed, DAG_GENESIS_SEED, 32);
+        return;
+    }
+
+    block_t* prevBlock = NULL;
+    if (!Chain_GetBlockCopy(chain, Chain_Size(chain) - 1, &prevBlock) || !prevBlock) {
+        memset(outSeed, 0x00, 32); // Fallback to zeroes if we can't get the previous block for some reason; The caller should treat this as an error if height >= EPOCH_LENGTH
+        if (prevBlock) Block_Destroy(prevBlock);
+        return;
+    }
+
+    Block_CalculateHash(prevBlock, outSeed);
+    Block_Destroy(prevBlock);
 }
 
 #endif

include/crypto/crypto.h

@@ -9,5 +9,6 @@
 
 bool Crypto_VerifySignature(const uint8_t* data, size_t len, const uint8_t* signature, const uint8_t* publicKey);
 void Crypto_SignData(const uint8_t* data, size_t len, const uint8_t* privateKey, uint8_t* outSignature);
+void to_hex(const uint8_t *in, char *out);
 
 #endif

include/dynarr.h

@@ -55,6 +55,9 @@ size_t DynArr_capacity(DynArr* p);
 
 void DynArr_destroy(DynArr* p);
 
+// Note: Make sure to not overread or overwrite
+void* DynArr_c_arr(DynArr* p);
+
 #define DYNARR_CREATE(T, initialCapacity) DynArr_create(sizeof(T), initialCapacity)
 
 #endif

include/khash/khash.h

@@ -0,0 +1,627 @@
+/* The MIT License
+
+   Copyright (c) 2008, 2009, 2011 by Attractive Chaos <attractor@live.co.uk>
+
+   Permission is hereby granted, free of charge, to any person obtaining
+   a copy of this software and associated documentation files (the
+   "Software"), to deal in the Software without restriction, including
+   without limitation the rights to use, copy, modify, merge, publish,
+   distribute, sublicense, and/or sell copies of the Software, and to
+   permit persons to whom the Software is furnished to do so, subject to
+   the following conditions:
+
+   The above copyright notice and this permission notice shall be
+   included in all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+   BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+   SOFTWARE.
+*/
+
+/*
+  An example:
+
+#include "khash.h"
+KHASH_MAP_INIT_INT(32, char)
+int main() {
+	int ret, is_missing;
+	khiter_t k;
+	khash_t(32) *h = kh_init(32);
+	k = kh_put(32, h, 5, &ret);
+	kh_value(h, k) = 10;
+	k = kh_get(32, h, 10);
+	is_missing = (k == kh_end(h));
+	k = kh_get(32, h, 5);
+	kh_del(32, h, k);
+	for (k = kh_begin(h); k != kh_end(h); ++k)
+		if (kh_exist(h, k)) kh_value(h, k) = 1;
+	kh_destroy(32, h);
+	return 0;
+}
+*/
+
+/*
+  2013-05-02 (0.2.8):
+
+	* Use quadratic probing. When the capacity is power of 2, stepping function
+	  i*(i+1)/2 guarantees to traverse each bucket. It is better than double
+	  hashing on cache performance and is more robust than linear probing.
+
+	  In theory, double hashing should be more robust than quadratic probing.
+	  However, my implementation is probably not for large hash tables, because
+	  the second hash function is closely tied to the first hash function,
+	  which reduce the effectiveness of double hashing.
+
+	Reference: http://research.cs.vt.edu/AVresearch/hashing/quadratic.php
+
+  2011-12-29 (0.2.7):
+
+    * Minor code clean up; no actual effect.
+
+  2011-09-16 (0.2.6):
+
+	* The capacity is a power of 2. This seems to dramatically improve the
+	  speed for simple keys. Thank Zilong Tan for the suggestion. Reference:
+
+	   - http://code.google.com/p/ulib/
+	   - http://nothings.org/computer/judy/
+
+	* Allow to optionally use linear probing which usually has better
+	  performance for random input. Double hashing is still the default as it
+	  is more robust to certain non-random input.
+
+	* Added Wang's integer hash function (not used by default). This hash
+	  function is more robust to certain non-random input.
+
+  2011-02-14 (0.2.5):
+
+    * Allow to declare global functions.
+
+  2009-09-26 (0.2.4):
+
+    * Improve portability
+
+  2008-09-19 (0.2.3):
+
+	* Corrected the example
+	* Improved interfaces
+
+  2008-09-11 (0.2.2):
+
+	* Improved speed a little in kh_put()
+
+  2008-09-10 (0.2.1):
+
+	* Added kh_clear()
+	* Fixed a compiling error
+
+  2008-09-02 (0.2.0):
+
+	* Changed to token concatenation which increases flexibility.
+
+  2008-08-31 (0.1.2):
+
+	* Fixed a bug in kh_get(), which has not been tested previously.
+
+  2008-08-31 (0.1.1):
+
+	* Added destructor
+*/
+
+
+#ifndef __AC_KHASH_H
+#define __AC_KHASH_H
+
+/*!
+  @header
+
+  Generic hash table library.
+ */
+
+#define AC_VERSION_KHASH_H "0.2.8"
+
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+/* compiler specific configuration */
+
+#if UINT_MAX == 0xffffffffu
+typedef unsigned int khint32_t;
+#elif ULONG_MAX == 0xffffffffu
+typedef unsigned long khint32_t;
+#endif
+
+#if ULONG_MAX == ULLONG_MAX
+typedef unsigned long khint64_t;
+#else
+typedef unsigned long long khint64_t;
+#endif
+
+#ifndef kh_inline
+#ifdef _MSC_VER
+#define kh_inline __inline
+#else
+#define kh_inline inline
+#endif
+#endif /* kh_inline */
+
+#ifndef klib_unused
+#if (defined __clang__ && __clang_major__ >= 3) || (defined __GNUC__ && __GNUC__ >= 3)
+#define klib_unused __attribute__ ((__unused__))
+#else
+#define klib_unused
+#endif
+#endif /* klib_unused */
+
+typedef khint32_t khint_t;
+typedef khint_t khiter_t;
+
+#define __ac_isempty(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&2)
+#define __ac_isdel(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&1)
+#define __ac_iseither(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&3)
+#define __ac_set_isdel_false(flag, i) (flag[i>>4]&=~(1ul<<((i&0xfU)<<1)))
+#define __ac_set_isempty_false(flag, i) (flag[i>>4]&=~(2ul<<((i&0xfU)<<1)))
+#define __ac_set_isboth_false(flag, i) (flag[i>>4]&=~(3ul<<((i&0xfU)<<1)))
+#define __ac_set_isdel_true(flag, i) (flag[i>>4]|=1ul<<((i&0xfU)<<1))
+
+#define __ac_fsize(m) ((m) < 16? 1 : (m)>>4)
+
+#ifndef kroundup32
+#define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))
+#endif
+
+#ifndef kcalloc
+#define kcalloc(N,Z) calloc(N,Z)
+#endif
+#ifndef kmalloc
+#define kmalloc(Z) malloc(Z)
+#endif
+#ifndef krealloc
+#define krealloc(P,Z) realloc(P,Z)
+#endif
+#ifndef kfree
+#define kfree(P) free(P)
+#endif
+
+static const double __ac_HASH_UPPER = 0.77;
+
+#define __KHASH_TYPE(name, khkey_t, khval_t) \
+	typedef struct kh_##name##_s { \
+		khint_t n_buckets, size, n_occupied, upper_bound; \
+		khint32_t *flags; \
+		khkey_t *keys; \
+		khval_t *vals; \
+	} kh_##name##_t;
+
+#define __KHASH_PROTOTYPES(name, khkey_t, khval_t)	 					\
+	extern kh_##name##_t *kh_init_##name(void);							\
+	extern void kh_destroy_##name(kh_##name##_t *h);					\
+	extern void kh_clear_##name(kh_##name##_t *h);						\
+	extern khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key); 	\
+	extern int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets); \
+	extern khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret); \
+	extern void kh_del_##name(kh_##name##_t *h, khint_t x);
+
+#define __KHASH_IMPL(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
+	SCOPE kh_##name##_t *kh_init_##name(void) {							\
+		return (kh_##name##_t*)kcalloc(1, sizeof(kh_##name##_t));		\
+	}																	\
+	SCOPE void kh_destroy_##name(kh_##name##_t *h)						\
+	{																	\
+		if (h) {														\
+			kfree((void *)h->keys); kfree(h->flags);					\
+			kfree((void *)h->vals);										\
+			kfree(h);													\
+		}																\
+	}																	\
+	SCOPE void kh_clear_##name(kh_##name##_t *h)						\
+	{																	\
+		if (h && h->flags) {											\
+			memset(h->flags, 0xaa, __ac_fsize(h->n_buckets) * sizeof(khint32_t)); \
+			h->size = h->n_occupied = 0;								\
+		}																\
+	}																	\
+	SCOPE khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key) 	\
+	{																	\
+		if (h->n_buckets) {												\
+			khint_t k, i, last, mask, step = 0; \
+			mask = h->n_buckets - 1;									\
+			k = __hash_func(key); i = k & mask;							\
+			last = i; \
+			while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
+				i = (i + (++step)) & mask; \
+				if (i == last) return h->n_buckets;						\
+			}															\
+			return __ac_iseither(h->flags, i)? h->n_buckets : i;		\
+		} else return 0;												\
+	}																	\
+	SCOPE int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets) \
+	{ /* This function uses 0.25*n_buckets bytes of working space instead of [sizeof(key_t+val_t)+.25]*n_buckets. */ \
+		khint32_t *new_flags = 0;										\
+		khint_t j = 1;													\
+		{																\
+			kroundup32(new_n_buckets); 									\
+			if (new_n_buckets < 4) new_n_buckets = 4;					\
+			if (h->size >= (khint_t)(new_n_buckets * __ac_HASH_UPPER + 0.5)) j = 0;	/* requested size is too small */ \
+			else { /* hash table size to be changed (shrink or expand); rehash */ \
+				new_flags = (khint32_t*)kmalloc(__ac_fsize(new_n_buckets) * sizeof(khint32_t));	\
+				if (!new_flags) return -1;								\
+				memset(new_flags, 0xaa, __ac_fsize(new_n_buckets) * sizeof(khint32_t)); \
+				if (h->n_buckets < new_n_buckets) {	/* expand */		\
+					khkey_t *new_keys = (khkey_t*)krealloc((void *)h->keys, new_n_buckets * sizeof(khkey_t)); \
+					if (!new_keys) { kfree(new_flags); return -1; }		\
+					h->keys = new_keys;									\
+					if (kh_is_map) {									\
+						khval_t *new_vals = (khval_t*)krealloc((void *)h->vals, new_n_buckets * sizeof(khval_t)); \
+						if (!new_vals) { kfree(new_flags); return -1; }	\
+						h->vals = new_vals;								\
+					}													\
+				} /* otherwise shrink */								\
+			}															\
+		}																\
+		if (j) { /* rehashing is needed */								\
+			for (j = 0; j != h->n_buckets; ++j) {						\
+				if (__ac_iseither(h->flags, j) == 0) {					\
+					khkey_t key = h->keys[j];							\
+					khval_t val;										\
+					khint_t new_mask;									\
+					new_mask = new_n_buckets - 1; 						\
+					if (kh_is_map) val = h->vals[j];					\
+					__ac_set_isdel_true(h->flags, j);					\
+					while (1) { /* kick-out process; sort of like in Cuckoo hashing */ \
+						khint_t k, i, step = 0; \
+						k = __hash_func(key);							\
+						i = k & new_mask;								\
+						while (!__ac_isempty(new_flags, i)) i = (i + (++step)) & new_mask; \
+						__ac_set_isempty_false(new_flags, i);			\
+						if (i < h->n_buckets && __ac_iseither(h->flags, i) == 0) { /* kick out the existing element */ \
+							{ khkey_t tmp = h->keys[i]; h->keys[i] = key; key = tmp; } \
+							if (kh_is_map) { khval_t tmp = h->vals[i]; h->vals[i] = val; val = tmp; } \
+							__ac_set_isdel_true(h->flags, i); /* mark it as deleted in the old hash table */ \
+						} else { /* write the element and jump out of the loop */ \
+							h->keys[i] = key;							\
+							if (kh_is_map) h->vals[i] = val;			\
+							break;										\
+						}												\
+					}													\
+				}														\
+			}															\
+			if (h->n_buckets > new_n_buckets) { /* shrink the hash table */ \
+				h->keys = (khkey_t*)krealloc((void *)h->keys, new_n_buckets * sizeof(khkey_t)); \
+				if (kh_is_map) h->vals = (khval_t*)krealloc((void *)h->vals, new_n_buckets * sizeof(khval_t)); \
+			}															\
+			kfree(h->flags); /* free the working space */				\
+			h->flags = new_flags;										\
+			h->n_buckets = new_n_buckets;								\
+			h->n_occupied = h->size;									\
+			h->upper_bound = (khint_t)(h->n_buckets * __ac_HASH_UPPER + 0.5); \
+		}																\
+		return 0;														\
+	}																	\
+	SCOPE khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret) \
+	{																	\
+		khint_t x;														\
+		if (h->n_occupied >= h->upper_bound) { /* update the hash table */ \
+			if (h->n_buckets > (h->size<<1)) {							\
+				if (kh_resize_##name(h, h->n_buckets - 1) < 0) { /* clear "deleted" elements */ \
+					*ret = -1; return h->n_buckets;						\
+				}														\
+			} else if (kh_resize_##name(h, h->n_buckets + 1) < 0) { /* expand the hash table */ \
+				*ret = -1; return h->n_buckets;							\
+			}															\
+		} /* TODO: to implement automatically shrinking; resize() already support shrinking */ \
+		{																\
+			khint_t k, i, site, last, mask = h->n_buckets - 1, step = 0; \
+			x = site = h->n_buckets; k = __hash_func(key); i = k & mask; \
+			if (__ac_isempty(h->flags, i)) x = i; /* for speed up */	\
+			else {														\
+				last = i; \
+				while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
+					if (__ac_isdel(h->flags, i)) site = i;				\
+					i = (i + (++step)) & mask; \
+					if (i == last) { x = site; break; }					\
+				}														\
+				if (x == h->n_buckets) {								\
+					if (__ac_isempty(h->flags, i) && site != h->n_buckets) x = site; \
+					else x = i;											\
+				}														\
+			}															\
+		}																\
+		if (__ac_isempty(h->flags, x)) { /* not present at all */		\
+			h->keys[x] = key;											\
+			__ac_set_isboth_false(h->flags, x);							\
+			++h->size; ++h->n_occupied;									\
+			*ret = 1;													\
+		} else if (__ac_isdel(h->flags, x)) { /* deleted */				\
+			h->keys[x] = key;											\
+			__ac_set_isboth_false(h->flags, x);							\
+			++h->size;													\
+			*ret = 2;													\
+		} else *ret = 0; /* Don't touch h->keys[x] if present and not deleted */ \
+		return x;														\
+	}																	\
+	SCOPE void kh_del_##name(kh_##name##_t *h, khint_t x)				\
+	{																	\
+		if (x != h->n_buckets && !__ac_iseither(h->flags, x)) {			\
+			__ac_set_isdel_true(h->flags, x);							\
+			--h->size;													\
+		}																\
+	}
+
+#define KHASH_DECLARE(name, khkey_t, khval_t)		 					\
+	__KHASH_TYPE(name, khkey_t, khval_t) 								\
+	__KHASH_PROTOTYPES(name, khkey_t, khval_t)
+
+#define KHASH_INIT2(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
+	__KHASH_TYPE(name, khkey_t, khval_t) 								\
+	__KHASH_IMPL(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal)
+
+#define KHASH_INIT(name, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
+	KHASH_INIT2(name, static kh_inline klib_unused, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal)
+
+/* --- BEGIN OF HASH FUNCTIONS --- */
+
+/*! @function
+  @abstract     Integer hash function
+  @param  key   The integer [khint32_t]
+  @return       The hash value [khint_t]
+ */
+#define kh_int_hash_func(key) (khint32_t)(key)
+/*! @function
+  @abstract     Integer comparison function
+ */
+#define kh_int_hash_equal(a, b) ((a) == (b))
+/*! @function
+  @abstract     64-bit integer hash function
+  @param  key   The integer [khint64_t]
+  @return       The hash value [khint_t]
+ */
+#define kh_int64_hash_func(key) (khint32_t)((key)>>33^(key)^(key)<<11)
+/*! @function
+  @abstract     64-bit integer comparison function
+ */
+#define kh_int64_hash_equal(a, b) ((a) == (b))
+/*! @function
+  @abstract     const char* hash function
+  @param  s     Pointer to a null terminated string
+  @return       The hash value
+ */
+static kh_inline khint_t __ac_X31_hash_string(const char *s)
+{
+	khint_t h = (khint_t)*s;
+	if (h) for (++s ; *s; ++s) h = (h << 5) - h + (khint_t)*s;
+	return h;
+}
+/*! @function
+  @abstract     Another interface to const char* hash function
+  @param  key   Pointer to a null terminated string [const char*]
+  @return       The hash value [khint_t]
+ */
+#define kh_str_hash_func(key) __ac_X31_hash_string(key)
+/*! @function
+  @abstract     Const char* comparison function
+ */
+#define kh_str_hash_equal(a, b) (strcmp(a, b) == 0)
+
+static kh_inline khint_t __ac_Wang_hash(khint_t key)
+{
+    key += ~(key << 15);
+    key ^=  (key >> 10);
+    key +=  (key << 3);
+    key ^=  (key >> 6);
+    key += ~(key << 11);
+    key ^=  (key >> 16);
+    return key;
+}
+#define kh_int_hash_func2(key) __ac_Wang_hash((khint_t)key)
+
+/* --- END OF HASH FUNCTIONS --- */
+
+/* Other convenient macros... */
+
+/*!
+  @abstract Type of the hash table.
+  @param  name  Name of the hash table [symbol]
+ */
+#define khash_t(name) kh_##name##_t
+
+/*! @function
+  @abstract     Initiate a hash table.
+  @param  name  Name of the hash table [symbol]
+  @return       Pointer to the hash table [khash_t(name)*]
+ */
+#define kh_init(name) kh_init_##name()
+
+/*! @function
+  @abstract     Destroy a hash table.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+ */
+#define kh_destroy(name, h) kh_destroy_##name(h)
+
+/*! @function
+  @abstract     Reset a hash table without deallocating memory.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+ */
+#define kh_clear(name, h) kh_clear_##name(h)
+
+/*! @function
+  @abstract     Resize a hash table.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  s     New size [khint_t]
+ */
+#define kh_resize(name, h, s) kh_resize_##name(h, s)
+
+/*! @function
+  @abstract     Insert a key to the hash table.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  k     Key [type of keys]
+  @param  r     Extra return code: -1 if the operation failed;
+                0 if the key is present in the hash table;
+                1 if the bucket is empty (never used); 2 if the element in
+				the bucket has been deleted [int*]
+  @return       Iterator to the inserted element [khint_t]
+ */
+#define kh_put(name, h, k, r) kh_put_##name(h, k, r)
+
+/*! @function
+  @abstract     Retrieve a key from the hash table.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  k     Key [type of keys]
+  @return       Iterator to the found element, or kh_end(h) if the element is absent [khint_t]
+ */
+#define kh_get(name, h, k) kh_get_##name(h, k)
+
+/*! @function
+  @abstract     Remove a key from the hash table.
+  @param  name  Name of the hash table [symbol]
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  k     Iterator to the element to be deleted [khint_t]
+ */
+#define kh_del(name, h, k) kh_del_##name(h, k)
+
+/*! @function
+  @abstract     Test whether a bucket contains data.
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  x     Iterator to the bucket [khint_t]
+  @return       1 if containing data; 0 otherwise [int]
+ */
+#define kh_exist(h, x) (!__ac_iseither((h)->flags, (x)))
+
+/*! @function
+  @abstract     Get key given an iterator
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  x     Iterator to the bucket [khint_t]
+  @return       Key [type of keys]
+ */
+#define kh_key(h, x) ((h)->keys[x])
+
+/*! @function
+  @abstract     Get value given an iterator
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  x     Iterator to the bucket [khint_t]
+  @return       Value [type of values]
+  @discussion   For hash sets, calling this results in segfault.
+ */
+#define kh_val(h, x) ((h)->vals[x])
+
+/*! @function
+  @abstract     Alias of kh_val()
+ */
+#define kh_value(h, x) ((h)->vals[x])
+
+/*! @function
+  @abstract     Get the start iterator
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @return       The start iterator [khint_t]
+ */
+#define kh_begin(h) (khint_t)(0)
+
+/*! @function
+  @abstract     Get the end iterator
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @return       The end iterator [khint_t]
+ */
+#define kh_end(h) ((h)->n_buckets)
+
+/*! @function
+  @abstract     Get the number of elements in the hash table
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @return       Number of elements in the hash table [khint_t]
+ */
+#define kh_size(h) ((h)->size)
+
+/*! @function
+  @abstract     Get the number of buckets in the hash table
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @return       Number of buckets in the hash table [khint_t]
+ */
+#define kh_n_buckets(h) ((h)->n_buckets)
+
+/*! @function
+  @abstract     Iterate over the entries in the hash table
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  kvar  Variable to which key will be assigned
+  @param  vvar  Variable to which value will be assigned
+  @param  code  Block of code to execute
+ */
+#define kh_foreach(h, kvar, vvar, code) { khint_t __i;		\
+	for (__i = kh_begin(h); __i != kh_end(h); ++__i) {		\
+		if (!kh_exist(h,__i)) continue;						\
+		(kvar) = kh_key(h,__i);								\
+		(vvar) = kh_val(h,__i);								\
+		code;												\
+	} }
+
+/*! @function
+  @abstract     Iterate over the values in the hash table
+  @param  h     Pointer to the hash table [khash_t(name)*]
+  @param  vvar  Variable to which value will be assigned
+  @param  code  Block of code to execute
+ */
+#define kh_foreach_value(h, vvar, code) { khint_t __i;		\
+	for (__i = kh_begin(h); __i != kh_end(h); ++__i) {		\
+		if (!kh_exist(h,__i)) continue;						\
+		(vvar) = kh_val(h,__i);								\
+		code;												\
+	} }
+
+/* More convenient interfaces */
+
+/*! @function
+  @abstract     Instantiate a hash set containing integer keys
+  @param  name  Name of the hash table [symbol]
+ */
+#define KHASH_SET_INIT_INT(name)										\
+	KHASH_INIT(name, khint32_t, char, 0, kh_int_hash_func, kh_int_hash_equal)
+
+/*! @function
+  @abstract     Instantiate a hash map containing integer keys
+  @param  name  Name of the hash table [symbol]
+  @param  khval_t  Type of values [type]
+ */
+#define KHASH_MAP_INIT_INT(name, khval_t)								\
+	KHASH_INIT(name, khint32_t, khval_t, 1, kh_int_hash_func, kh_int_hash_equal)
+
+/*! @function
+  @abstract     Instantiate a hash set containing 64-bit integer keys
+  @param  name  Name of the hash table [symbol]
+ */
+#define KHASH_SET_INIT_INT64(name)										\
+	KHASH_INIT(name, khint64_t, char, 0, kh_int64_hash_func, kh_int64_hash_equal)
+
+/*! @function
+  @abstract     Instantiate a hash map containing 64-bit integer keys
+  @param  name  Name of the hash table [symbol]
+  @param  khval_t  Type of values [type]
+ */
+#define KHASH_MAP_INIT_INT64(name, khval_t)								\
+	KHASH_INIT(name, khint64_t, khval_t, 1, kh_int64_hash_func, kh_int64_hash_equal)
+
+typedef const char *kh_cstr_t;
+/*! @function
+  @abstract     Instantiate a hash map containing const char* keys
+  @param  name  Name of the hash table [symbol]
+ */
+#define KHASH_SET_INIT_STR(name)										\
+	KHASH_INIT(name, kh_cstr_t, char, 0, kh_str_hash_func, kh_str_hash_equal)
+
+/*! @function
+  @abstract     Instantiate a hash map containing const char* keys
+  @param  name  Name of the hash table [symbol]
+  @param  khval_t  Type of values [type]
+ */
+#define KHASH_MAP_INIT_STR(name, khval_t)								\
+	KHASH_INIT(name, kh_cstr_t, khval_t, 1, kh_str_hash_func, kh_str_hash_equal)
+
+#endif /* __AC_KHASH_H */

include/nets/fetch_scheduler.h

@@ -0,0 +1,10 @@
+#ifndef FETCH_SCHEDULER_H
+#define FETCH_SCHEDULER_H
+
+#include <stdint.h>
+
+// Compute penalty in blocks for a delayed/heavy reorg reported by a peer.
+// Returns the number of penalty blocks to subtract from the peer's advertised work.
+uint64_t FetchScheduler_ComputeReorgPenaltyBlocks(uint64_t delayBlocks);
+
+#endif

include/nets/net_node.h

@@ -0,0 +1,73 @@
+#ifndef NET_NODE_H
+#define NET_NODE_H
+
+#ifndef _WIN32
+// POSIX
+#include <tcpd/tcpconnection.h>
+#include <tcpd/tcpclient.h>
+#include <tcpd/tcpserver.h>
+#endif
+
+#include <constants.h>
+#include <packettype.h>
+
+#include <stddef.h>
+
+#include <dynarr.h>
+#include <dynset.h>
+
+#include <pthread.h>
+
+#include <block/block.h>
+#include <block/chain.h>
+#include <block/transaction.h>
+
+typedef struct {
+    tcp_server_t* server;
+    tcp_client_t outboundClients[MAX_CONS];
+    size_t outboundCount;
+    // Dedup cache for recently seen block hashes (canonical 32-byte hash)
+    DynSet* seenBlocks;
+    // Protects seenBlocks
+    pthread_mutex_t seenLock;
+    // Protects outboundClients snapshots and peerBlockHeight writes
+    pthread_mutex_t outboundLock;
+    void (*on_connect)(tcp_connection_t* conn, void* user);
+    void (*on_data)(tcp_connection_t* conn, const unsigned char* data, size_t len, void* user);
+    void (*on_disconnect)(tcp_connection_t* conn, void* user);
+    void* callbackUser;
+    // Maintenance thread for periodic tasks (orphan attach, pruning, metrics)
+    pthread_t maintenanceThread;
+    volatile int maintenanceRunning;
+    int maintenanceIntervalMs;
+} net_node_t;
+
+net_node_t* Node_Create();
+void Node_Destroy(net_node_t* node);
+
+void Node_SetCallbacks(
+    net_node_t* node,
+    void (*on_connect)(tcp_connection_t* conn, void* user),
+    void (*on_data)(tcp_connection_t* conn, const unsigned char* data, size_t len, void* user),
+    void (*on_disconnect)(tcp_connection_t* conn, void* user),
+    void* user
+);
+
+int Node_ConnectPeer(net_node_t* node, const char* ip, unsigned short port);
+int Node_ConnectStartupPeers(net_node_t* node, const char** ips, const unsigned short* ports, size_t peersCount);
+
+int Node_SendPacket(net_node_t* node, tcp_connection_t* conn, packet_type_t packetType, const void* payload, size_t payloadLen);
+
+// Helpers for outbound peer selection and block broadcast
+int Node_GetBestOutboundPeer(net_node_t* node, tcp_connection_t** outConn, uint64_t* outHeight);
+void Node_BroadcastChainRange(net_node_t* node, size_t startHeightInclusive, tcp_connection_t* sourceConn);
+
+// Callback logic
+void Node_Server_OnConnect(tcp_connection_t* client);
+void Node_Server_OnData(tcp_connection_t* client);
+void Node_Server_OnDisconnect(tcp_connection_t* client);
+void Node_Client_OnConnect(tcp_connection_t* client);
+void Node_Client_OnData(tcp_connection_t* client);
+void Node_Client_OnDisconnect(tcp_connection_t* client);
+
+#endif

include/nets/orphan_pool.h

@@ -0,0 +1,20 @@
+#ifndef ORPHAN_POOL_H
+#define ORPHAN_POOL_H
+
+#include <stdint.h>
+#include <block/block.h>
+#include <block/chain.h>
+
+// Initialize/destroy the global orphan pool
+void OrphanPool_Init(void);
+void OrphanPool_Destroy(void);
+
+// Insert an orphan block into the pool. Ownership of `block` is transferred to the pool.
+// `height` is the block number from the header.
+void OrphanPool_Insert(block_t* block, uint64_t height);
+
+// Attempt to attach any orphans whose parents now exist in `chain`.
+// Returns the number of blocks successfully attached.
+size_t OrphanPool_AttemptAttach(blockchain_t* chain);
+
+#endif

include/packettype.h

@@ -1,18 +1,24 @@
 #ifndef PACKETTYPE_H
 #define PACKETTYPE_H
 
+#include <stdint.h>
+
 typedef enum {
     PACKET_TYPE_NONE = 0,
-    PACKET_TYPE_HELLO = 1,
-    PACKET_TYPE_TASK_ASSIGN = 2,
-    PACKET_TYPE_TASK_RESULT = 3,
-    PACKET_TYPE_STATUS_UPDATE = 4,
-    PACKET_TYPE_CLIENT_CAPABILITIES = 5,
-    PACKET_TYPE_TASK_REQUEST = 6,
-    PACKET_TYPE_MISSING_INFO = 7,
-    PACKET_TYPE_ACKNOWLEDGE = 8,
-    PACKET_TYPE_TASK_REJECT = 9,
-    PACKET_TYPE_TASK_NONE_AVAILABLE = 10
-} PacketType;
+    PACKET_TYPE_HELLO = 1, // Hello, let's connect! Here's who I am, and what I have!
+    PACKET_TYPE_ACK_HELLO = 2, // I received your hello, here's who I am and what I have (response to hello)
+    PACKET_TYPE_FETCH_BLOCK = 3, // I want a Block
+    PACKET_TYPE_BLOCK_DATA = 4, // Here's a Block (response to fetch) - I don't care what you do with it, but you wanted it, so here it is!
+    PACKET_TYPE_BROADCAST_BLOCK = 5, // Here's a new Block I want to share with the network (unsolicited - e.g. just mined it)
+    PACKET_TYPE_ACK_BLOCK = 6, // I have received your block, here's what I did with it (response to broadcast)
+    PACKET_TYPE_BROADCAST_TX = 7, // Here's a new transaction I want to share with the network
+    PACKET_TYPE_ACK_TX = 8, // I have received your transaction, here's what I did with it (response to broadcast)
+    PACKET_TYPE_ERROR = 9, // Something went wrong with the packet you sent me, here's an error message (can be response to any packet)
+    PACKET_TYPE_MAX = 10
+} packet_type_t;
+
+static inline int PacketType_IsValid(uint8_t packetType) {
+    return packetType > PACKET_TYPE_NONE && packetType < PACKET_TYPE_MAX;
+}
 
 #endif

include/randomx/librx_wrapper.h

@@ -1,21 +0,0 @@
-#ifndef LIBRX_WRAPPER_H
-#define LIBRX_WRAPPER_H
-
-#include <stddef.h>
-#include <stdint.h>
-#include <randomx.h>
-#include <stdbool.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-bool RandomX_Init(const char* key, bool preferFullMemory);
-void RandomX_Destroy();
-void RandomX_CalculateHash(const uint8_t* input, size_t inputLen, uint8_t* output);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif

include/runtime_state.h

@@ -0,0 +1,25 @@
+#ifndef RUNTIME_STATE_H
+#define RUNTIME_STATE_H
+
+#include <stdint.h>
+
+#include <uint256.h>
+
+#include <block/chain.h>
+#include <pthread.h>
+
+extern uint64_t currentBlockHeight;
+extern blockchain_t* currentChain;
+extern uint256_t currentSupply;
+extern uint64_t currentReward;
+extern uint32_t difficultyTarget;
+extern const char* chainDataDir;
+extern unsigned short listenPort;
+extern bool echoPeersEnabled;
+extern bool forceOrphanReorgEnabled;
+
+// Global synchronization primitives for runtime state
+extern pthread_rwlock_t chainLock; // protects chain structure and related mutations
+extern pthread_mutex_t balanceSheetLock; // protects balance sheet map
+
+#endif

include/storage/block_table.h

@@ -0,0 +1,13 @@
+#ifndef BLOCK_TABLE_H
+#define BLOCK_TABLE_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+    uint64_t blockNumber;
+    uint64_t byteNumber;
+    uint64_t blockSize;
+} block_table_entry_t;
+
+#endif

include/tcpd/tcpclient.h

@@ -1,29 +1,36 @@
 #ifndef TCPCLIENT_H
 #define TCPCLIENT_H
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
 #include <arpa/inet.h>
-#include <pthread.h>
+#include <stddef.h>
 #include <stdint.h>
-#include <dynarr.h>
 
-#define MTU 1500
+#include <constants.h>
+#include <tcpd/tcpconnection.h>
 
-struct TcpClient {
-    int clientFd;
-    struct sockaddr_in clientAddr;
-    uint32_t clientId;
+typedef struct {
+    tcp_connection_t* connection;
+    void (*on_connect)(tcp_connection_t* conn);
+    void (*on_data)(tcp_connection_t* conn);
+    void (*on_disconnect)(tcp_connection_t* conn);
+    void* owner;
+    uint64_t peerBlockHeight;
+} tcp_client_t;
 
-    unsigned char dataBuf[MTU];
-    ssize_t dataBufLen;
-    void (*on_data)(struct TcpClient* client);
-    void (*on_disconnect)(struct TcpClient* client);
+int TcpClient_Init(tcp_client_t* client);
+void TcpClient_Destroy(tcp_client_t* client);
 
-    pthread_t clientThread;
-};
+int TcpClient_Connect(
+    tcp_client_t* client,
+    const char* peerIp,
+    unsigned short peerPort,
+    void (*on_connect)(tcp_connection_t* conn),
+    void (*on_data)(tcp_connection_t* conn),
+    void (*on_disconnect)(tcp_connection_t* conn),
+    void* owner
+);
 
-typedef struct TcpClient TcpClient;
+int TcpClient_Send(tcp_client_t* client, const void* data, size_t len);
+void TcpClient_Disconnect(tcp_client_t* client);
 
 #endif

include/tcpd/tcpconnection.h

@@ -0,0 +1,64 @@
+#ifndef TCPCONNECTION_H
+#define TCPCONNECTION_H
+
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define TCP_IO_BUFFER_SIZE 1500
+#define TCP_FRAME_HEADER_SIZE 4U
+#define TCP_MAX_FRAME_PAYLOAD (1024U * 1024U)
+
+typedef enum {
+    TCP_CONNECTION_ROLE_INBOUND = 0,
+    TCP_CONNECTION_ROLE_OUTBOUND = 1
+} tcp_connection_role_t;
+
+typedef struct tcp_connection_t tcp_connection_t;
+
+struct tcp_connection_t {
+    int sockFd;
+    struct sockaddr_in peerAddr;
+    uint32_t connectionId;
+    tcp_connection_role_t role;
+
+    pthread_t ioThread;
+    pthread_mutex_t sendLock;
+    pthread_mutex_t stateLock;
+
+    bool closing;
+    bool disconnectedNotified;
+
+    unsigned char* dataBuf;
+    size_t dataBufLen;
+    size_t dataBufCap;
+
+    unsigned char headerBuf[TCP_FRAME_HEADER_SIZE];
+    size_t headerBytesRead;
+    uint32_t expectedPayloadLen;
+    unsigned char* frameBuf;
+    size_t frameBytesRead;
+
+    void (*on_data)(tcp_connection_t* conn);
+    void (*on_disconnect)(tcp_connection_t* conn);
+    void* owner;
+};
+
+int TcpConnection_Init(tcp_connection_t* conn, int sockFd, const struct sockaddr_in* peerAddr, tcp_connection_role_t role);
+void TcpConnection_Destroy(tcp_connection_t* conn);
+
+int TcpConnection_SetDataBuffer(tcp_connection_t* conn, const unsigned char* data, size_t len);
+
+void TcpConnection_ResetFramingState(tcp_connection_t* conn);
+int TcpConnection_FeedFramedData(tcp_connection_t* conn, const unsigned char* input, size_t inputLen);
+
+int TcpConnection_SendRaw(int sockFd, const void* data, size_t len);
+int TcpConnection_SendFramed(tcp_connection_t* conn, const void* payload, size_t payloadLen);
+
+void TcpConnection_RequestClose(tcp_connection_t* conn);
+void TcpConnection_MarkDisconnectNotified(tcp_connection_t* conn);
+bool TcpConnection_IsDisconnectNotified(tcp_connection_t* conn);
+
+#endif

include/tcpd/tcpserver.h

@@ -1,56 +1,53 @@
 #ifndef TCPSERVER_H
 #define TCPSERVER_H
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
 #include <arpa/inet.h>
-#include <stdlib.h>
 #include <pthread.h>
-#include <stdint.h>
+#include <stddef.h>
+#include <constants.h>
 
-#include <tcpd/tcpclient.h>
-#include <numgen.h>
-#include <dynarr.h>
+#include <tcpd/tcpconnection.h>
 
 typedef struct {
     int sockFd;
     struct sockaddr_in addr;
     int opt;
+    int isRunning;
+    void* owner;
 
     // Called before the client thread runs
-    void (*on_connect)(TcpClient* client);
+    void (*on_connect)(tcp_connection_t* client);
     // Called when data is received
-    void (*on_data)(TcpClient* client);
+    void (*on_data)(tcp_connection_t* client);
     // Called before the socket and client thread are killed; Do NOT free client manually
-    void (*on_disconnect)(TcpClient* client);
+    void (*on_disconnect)(tcp_connection_t* client);
 
     // max clients
-    size_t clients;
-    TcpClient** clientsArrPtr;
+    size_t maxClients;
+    tcp_connection_t** clientsArrPtr;
+    pthread_mutex_t clientsMutex;
 
     pthread_t svrThread;
-} TcpServer;
+} tcp_server_t;
 
 struct tcpclient_thread_args {
-    TcpClient* clientPtr;
-    TcpServer* serverPtr;
+    tcp_connection_t* clientPtr;
+    tcp_server_t* serverPtr;
 };
 
 typedef struct tcpclient_thread_args tcpclient_thread_args;
 
-TcpServer* TcpServer_Create();
-void TcpServer_Destroy(TcpServer* ptr);
+tcp_server_t* TcpServer_Create();
+void TcpServer_Destroy(tcp_server_t* ptr);
 
-void TcpServer_Init(TcpServer* ptr, unsigned short port, const char* addr);
-void TcpServer_Start(TcpServer* ptr, int maxcons);
-void TcpServer_Stop(TcpServer* ptr);
-void TcpServer_Send(TcpServer* ptr, TcpClient* cli, void* data, size_t len);
-void Generic_SendSocket(int sock, void* data, size_t len);
-void TcpServer_Disconnect(TcpServer* ptr, TcpClient* cli);
-void TcpServer_KillClient(TcpServer* ptr, TcpClient* cli);
+void TcpServer_Init(tcp_server_t* ptr, unsigned short port, const char* addr);
+void TcpServer_Start(tcp_server_t* ptr, int maxcons);
+void TcpServer_Stop(tcp_server_t* ptr);
+int TcpServer_Send(tcp_server_t* ptr, tcp_connection_t* cli, const void* data, size_t len);
+void Generic_SendSocket(int sock, const void* data, size_t len);
+void TcpServer_Disconnect(tcp_server_t* ptr, tcp_connection_t* cli);
+void TcpServer_KillClient(tcp_server_t* ptr, tcp_connection_t* cli);
 
-size_t Generic_FindClientInArrayByPtr(TcpClient** arr, TcpClient* ptr, size_t len);
+size_t Generic_FindClientInArrayByPtr(tcp_connection_t** arr, tcp_connection_t* ptr, size_t len);
 
 #endif

include/txmempool.h

@@ -0,0 +1,19 @@
+#ifndef TXMEMPOOL_H
+#define TXMEMPOOL_H
+
+#include <block/transaction.h>
+#include <khash/khash.h>
+#include <utils.h>
+#include <uint256.h>
+
+KHASH_INIT(tx_mempool_map_m, key32_t, signed_transaction_t, 1, hash_key32, eq_key32)
+extern khash_t(tx_mempool_map_m)* txMempool;
+
+void TxMempool_Init();
+// Assumed that the transation was confirmed to be valid
+int TxMempool_Insert(signed_transaction_t tx);
+bool TxMempool_Lookup(uint8_t* txHash, signed_transaction_t* out);
+void TxMempool_Print();
+void TxMempool_Destroy();
+
+#endif

include/uint256.h

@@ -55,4 +55,94 @@ static inline bool uint256_add(uint256_t* a, const uint256_t* b) {
     return carry > 0;
 }
 
+static inline bool uint256_subtract_u64(uint256_t* balance, uint64_t amount) {
+    if (!balance) {
+        return false;
+    }
+
+    if (balance->limbs[0] >= amount) {
+        balance->limbs[0] -= amount;
+        return false;
+    }
+
+    uint64_t borrow = amount - balance->limbs[0];
+    balance->limbs[0] = UINT64_MAX - borrow + 1ULL;
+
+    for (int i = 1; i < 4; ++i) {
+        if (balance->limbs[i] > 0) {
+            balance->limbs[i]--;
+            return false;
+        }
+
+        balance->limbs[i] = UINT64_MAX;
+    }
+
+    return true; // underflow past 256 bits
+}
+
+static inline bool uint256_subtract(uint256_t* a, const uint256_t* b) {
+    // Check if a < b to prevent underflow
+    for (int i = 3; i >= 0; i--) {
+        if (a->limbs[i] > b->limbs[i]) break;
+        if (a->limbs[i] < b->limbs[i]) return false; // Underflow
+    }
+
+    uint64_t borrow = 0;
+    for (int i = 0; i < 4; i++) {
+        uint64_t old_a = a->limbs[i];
+        a->limbs[i] -= b->limbs[i] + borrow;
+
+        // Detect borrow: if we subtracted more than we had, or we were at zero and had a borrow
+        if (borrow) {
+            borrow = (a->limbs[i] >= old_a);
+        } else {
+            borrow = (a->limbs[i] > old_a);
+        }
+    }
+    return true;
+}
+
+/**
+ * Compares two uint256_t values in a greater-than manner.
+ * Returns [-1, 0, 1] if a > b, a < b, or a == b respectively.
+**/
+static inline int uint256_cmp(const uint256_t* a, const uint256_t* b) {
+    for (int i = 3; i >= 0; i--) {
+        if (a->limbs[i] > b->limbs[i]) return 1;
+        if (a->limbs[i] < b->limbs[i]) return -1;
+    }
+    return 0;
+}
+
+static inline void uint256_serialize(const uint256_t* value, char* out) {
+    if (!value || !out) {
+        return;
+    }
+
+    // Convert into string of decimal digits for easier readability; max 78 digits for 256 bits
+    char digits[80];
+    size_t digitCount = 0;
+    uint256_t tmp = *value;
+    while (tmp.limbs[0] != 0 || tmp.limbs[1] != 0 || tmp.limbs[2] != 0 || tmp.limbs[3] != 0) {
+        uint64_t remainder = 0;
+        for (int i = 3; i >= 0; --i) {
+            __uint128_t cur = ((__uint128_t)remainder << 64) | tmp.limbs[i];
+            tmp.limbs[i] = (uint64_t)(cur / 10u);
+            remainder = (uint64_t)(cur % 10u);
+        }
+
+        if (digitCount < sizeof(digits) - 1) {
+            digits[digitCount++] = (char)('0' + remainder);
+        } else {
+            break;
+        }
+    }
+    digits[digitCount] = '\0';
+
+    for (size_t i = 0; i < digitCount; ++i) {
+        out[i] = digits[digitCount - 1 - i];
+    }
+    out[digitCount] = '\0';
+}
+
 #endif

include/utils.h

@@ -0,0 +1,349 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <crypto/crypto.h>
+#include <uint256.h>
+#include <time.h>
+
+typedef struct {
+    uint8_t bytes[32];
+} key32_t;
+
+static inline uint32_t hash_key32(key32_t k) {
+    uint32_t hash = 2166136261u;
+    for (int i = 0; i < 32; i++) {
+        hash ^= k.bytes[i];
+        hash *= 16777619;
+    }
+    return hash;
+}
+
+static inline int eq_key32(key32_t a, key32_t b) {
+    return memcmp(a.bytes, b.bytes, 32) == 0;
+}
+
+static inline uint64_t get_current_time_ms(void) {
+    struct timespec spec;
+    if (clock_gettime(CLOCK_REALTIME, &spec) == -1) {
+        return 0; // Handle error
+    }
+    // Convert seconds to milliseconds and add nanoseconds converted to milliseconds
+    return (spec.tv_sec * 1000) + (spec.tv_nsec / 1000000);
+}
+
+static inline void sleep_for_microseconds(uint64_t microseconds) {
+    struct timespec req;
+    req.tv_sec = (time_t)(microseconds / 1000000ULL);
+    req.tv_nsec = (long)((microseconds % 1000000ULL) * 1000ULL);
+    while (nanosleep(&req, &req) == -1) {
+        continue;
+    }
+}
+
+static inline void sleep_for_milliseconds(uint64_t milliseconds) {
+    sleep_for_microseconds(milliseconds * 1000ULL);
+}
+
+static inline void AddressToHexString(const uint8_t address[32], char out[65]) {
+    if (!address || !out) {
+        return;
+    }
+    to_hex(address, out);
+}
+
+static inline void AddressFromCompressedPubkey(const uint8_t compressedPubkey[33], uint8_t outAddress[32]) {
+    if (!compressedPubkey || !outAddress) {
+        return;
+    }
+
+    SHA256(compressedPubkey, 33, outAddress);
+}
+
+static inline void PrintHexBytes(const uint8_t* bytes, size_t length) {
+    if (!bytes) {
+        return;
+    }
+
+    for (size_t i = 0; i < length; ++i) {
+        printf("%02x", bytes[i]);
+    }
+}
+
+static inline int CompareHashToTarget(const uint8_t hash[32], const uint8_t target[32]) {
+    if (!hash || !target) {
+        return 1;
+    }
+
+    for (size_t i = 0; i < 32; ++i) {
+        if (hash[i] < target[i]) {
+            return -1;
+        }
+        if (hash[i] > target[i]) {
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static inline bool DecodeCompactTarget(uint32_t nBits, uint8_t target[32]) {
+    if (!target) {
+        return false;
+    }
+
+    memset(target, 0, 32);
+
+    uint32_t exponent = nBits >> 24;
+    uint32_t mantissa = nBits & 0x007fffff;
+    bool negative = (nBits & 0x00800000) != 0;
+
+    if (negative || mantissa == 0) {
+        return false;
+    }
+
+    if (exponent <= 3) {
+        mantissa >>= 8 * (3 - exponent);
+        target[29] = (uint8_t)((mantissa >> 16) & 0xffu);
+        target[30] = (uint8_t)((mantissa >> 8) & 0xffu);
+        target[31] = (uint8_t)(mantissa & 0xffu);
+    } else {
+        uint32_t byteIndex = exponent - 3;
+        if (byteIndex > 29) {
+            return false;
+        }
+
+        target[32 - byteIndex - 3] = (uint8_t)((mantissa >> 16) & 0xffu);
+        target[32 - byteIndex - 2] = (uint8_t)((mantissa >> 8) & 0xffu);
+        target[32 - byteIndex - 1] = (uint8_t)(mantissa & 0xffu);
+    }
+
+    return true;
+}
+
+static inline bool GenerateTestMinerIdentity(uint8_t privateKey[32], uint8_t compressedPubkey[33], uint8_t address[32]) {
+    if (!privateKey || !compressedPubkey || !address) {
+        return false;
+    }
+
+    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    if (!ctx) {
+        return false;
+    }
+
+    uint8_t seed[64];
+    secp256k1_pubkey pubkey;
+
+    for (uint64_t counter = 0; counter < 1024; ++counter) {
+        const char* base = "skalacoin-test-miner-key";
+        size_t baseLen = strlen(base);
+        memcpy(seed, base, baseLen);
+        memcpy(seed + baseLen, &counter, sizeof(counter));
+        SHA256(seed, baseLen + sizeof(counter), privateKey);
+
+        if (!secp256k1_ec_seckey_verify(ctx, privateKey)) {
+            continue;
+        }
+
+        if (!secp256k1_ec_pubkey_create(ctx, &pubkey, privateKey)) {
+            continue;
+        }
+
+        size_t pubLen = 33;
+        if (!secp256k1_ec_pubkey_serialize(ctx, compressedPubkey, &pubLen, &pubkey, SECP256K1_EC_COMPRESSED) || pubLen != 33) {
+            continue;
+        }
+
+        AddressFromCompressedPubkey(compressedPubkey, address);
+        secp256k1_context_destroy(ctx);
+        return true;
+    }
+
+    secp256k1_context_destroy(ctx);
+    return false;
+}
+
+static inline bool GenerateRandomTestAddress(uint8_t outAddress[32], uint8_t outPrivateKey[32], uint8_t outCompressedPubkey[33]) {
+    if (!outAddress) {
+        return false;
+    }
+
+    uint8_t privateKey[32];
+    uint8_t compressedPubkey[33];
+    secp256k1_pubkey pubkey;
+
+    secp256k1_context* ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    if (!ctx) {
+        return false;
+    }
+
+    for (size_t attempt = 0; attempt < 4096; ++attempt) {
+        for (size_t i = 0; i < sizeof(privateKey); ++i) {
+            privateKey[i] = (uint8_t)(rand() & 0xFF);
+        }
+
+        if (!secp256k1_ec_seckey_verify(ctx, privateKey)) {
+            continue;
+        }
+
+        if (!secp256k1_ec_pubkey_create(ctx, &pubkey, privateKey)) {
+            continue;
+        }
+
+        size_t pubLen = sizeof(compressedPubkey);
+        if (!secp256k1_ec_pubkey_serialize(ctx, compressedPubkey, &pubLen, &pubkey, SECP256K1_EC_COMPRESSED) || pubLen != 33) {
+            continue;
+        }
+
+        AddressFromCompressedPubkey(compressedPubkey, outAddress);
+        if (outPrivateKey) {
+            memcpy(outPrivateKey, privateKey, 32);
+        }
+        if (outCompressedPubkey) {
+            memcpy(outCompressedPubkey, compressedPubkey, 33);
+        }
+        secp256k1_context_destroy(ctx);
+        return true;
+    }
+
+    secp256k1_context_destroy(ctx);
+
+    return false;
+}
+
+static inline bool ParseHexAddress32(const char* in, uint8_t outAddress[32]) {
+    if (!in || !outAddress) {
+        return false;
+    }
+
+    const char* p = in;
+    if (p[0] == '0' && (p[1] == 'x' || p[1] == 'X')) {
+        p += 2;
+    }
+
+    if (strlen(p) != 64) {
+        return false;
+    }
+
+    for (size_t i = 0; i < 32; ++i) {
+        char hi = p[i * 2];
+        char lo = p[i * 2 + 1];
+        int hiVal = (hi >= '0' && hi <= '9') ? (hi - '0') :
+                    (hi >= 'a' && hi <= 'f') ? (10 + hi - 'a') :
+                    (hi >= 'A' && hi <= 'F') ? (10 + hi - 'A') : -1;
+        int loVal = (lo >= '0' && lo <= '9') ? (lo - '0') :
+                    (lo >= 'a' && lo <= 'f') ? (10 + lo - 'a') :
+                    (lo >= 'A' && lo <= 'F') ? (10 + lo - 'A') : -1;
+
+        if (hiVal < 0 || loVal < 0) {
+            return false;
+        }
+
+        outAddress[i] = (uint8_t)((hiVal << 4) | loVal);
+    }
+
+    return true;
+}
+
+static inline bool IsValidIPv4(const char* ip) {
+    if (!ip || *ip == '\0') {
+        return false;
+    }
+
+    int octetCount = 0;
+    const char* p = ip;
+
+    while (*p != '\0') {
+        if (octetCount >= 4) {
+            return false;
+        }
+
+        if (*p < '0' || *p > '9') {
+            return false;
+        }
+
+        unsigned int value = 0;
+        int digits = 0;
+        while (*p >= '0' && *p <= '9') {
+            value = (value * 10u) + (unsigned int)(*p - '0');
+            if (value > 255u) {
+                return false;
+            }
+            ++digits;
+            if (digits > 3) {
+                return false;
+            }
+            ++p;
+        }
+
+        if (digits == 0) {
+            return false;
+        }
+
+        ++octetCount;
+        if (octetCount < 4) {
+            if (*p != '.') {
+                return false;
+            }
+            ++p;
+            if (*p == '\0') {
+                return false;
+            }
+        }
+    }
+
+    return octetCount == 4;
+}
+
+static inline void Uint256ToDecimal(const uint256_t* value, char* out, size_t outSize) {
+    if (!value || !out || outSize == 0) {
+        return;
+    }
+
+    uint64_t tmp[4] = {
+        value->limbs[0],
+        value->limbs[1],
+        value->limbs[2],
+        value->limbs[3]
+    };
+
+    if (tmp[0] == 0 && tmp[1] == 0 && tmp[2] == 0 && tmp[3] == 0) {
+        if (outSize >= 2) {
+            out[0] = '0';
+            out[1] = '\0';
+        } else {
+            out[0] = '\0';
+        }
+        return;
+    }
+
+    char digits[80];
+    size_t digitCount = 0;
+
+    while (tmp[0] != 0 || tmp[1] != 0 || tmp[2] != 0 || tmp[3] != 0) {
+        uint64_t remainder = 0;
+        for (int i = 3; i >= 0; --i) {
+            __uint128_t cur = ((__uint128_t)remainder << 64) | tmp[i];
+            tmp[i] = (uint64_t)(cur / 10u);
+            remainder = (uint64_t)(cur % 10u);
+        }
+
+        if (digitCount < sizeof(digits) - 1) {
+            digits[digitCount++] = (char)('0' + remainder);
+        } else {
+            break;
+        }
+    }
+
+    size_t writeLen = (digitCount < (outSize - 1)) ? digitCount : (outSize - 1);
+    for (size_t i = 0; i < writeLen; ++i) {
+        out[i] = digits[digitCount - 1 - i];
+    }
+    out[writeLen] = '\0';
+}
+
+#endif

src/autolykos2/autolykos2.c

@@ -0,0 +1,535 @@
+#include <autolykos2/autolykos2.h>
+
+#include "../../include/blake2/blake2.h"
+
+#include <stdlib.h>
+#include <string.h>
+#if defined(_WIN32) || defined(_WIN64)
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
+uint64_t autolykos2_sleepBetweenHashOperationsMicroseconds = 0;
+
+typedef struct {
+    uint8_t* buf;
+    size_t cap;
+    size_t len;
+} dag_buffer_t;
+
+struct Autolykos2Context {
+    dag_buffer_t dag;
+    void* backend;
+};
+
+#ifdef SKALACOIN_AUTOLYKOS2_REF_AVAILABLE
+extern void* skalacoin_autolykos2_ref_create(void);
+extern void skalacoin_autolykos2_ref_destroy(void* handle);
+extern bool skalacoin_autolykos2_ref_check_target(
+    void* handle,
+    const uint8_t message32[32],
+    uint64_t nonce,
+    uint32_t height,
+    const uint8_t target32[32]
+);
+#endif
+
+static bool Autolykos2_FallbackHash(
+    const uint8_t seed32[32],
+    const uint8_t* message,
+    size_t messageLen,
+    uint64_t nonce,
+    uint64_t height,
+    uint8_t outHash[32]
+) {
+    if (!seed32 || !outHash) {
+        return false;
+    }
+
+    uint8_t nonceBytes[8];
+    uint8_t heightBytes[8];
+    memcpy(nonceBytes, &nonce, sizeof(nonceBytes));
+    memcpy(heightBytes, &height, sizeof(heightBytes));
+
+    const size_t totalLen = 32 + messageLen + sizeof(nonceBytes) + sizeof(heightBytes);
+    uint8_t* material = (uint8_t*)malloc(totalLen == 0 ? 1 : totalLen);
+    if (!material) {
+        return false;
+    }
+
+    size_t off = 0;
+    memcpy(material + off, seed32, 32);
+    off += 32;
+    if (messageLen > 0) {
+        memcpy(material + off, message, messageLen);
+        off += messageLen;
+    }
+    memcpy(material + off, nonceBytes, sizeof(nonceBytes));
+    off += sizeof(nonceBytes);
+    memcpy(material + off, heightBytes, sizeof(heightBytes));
+
+    const bool ok = Blake2b_Hash(material, totalLen, outHash, 32);
+    free(material);
+    return ok;
+}
+
+static int Cmp256BE(const uint8_t a[32], const uint8_t b[32]) {
+    for (size_t i = 0; i < 32; ++i) {
+        if (a[i] < b[i]) return -1;
+        if (a[i] > b[i]) return 1;
+    }
+    return 0;
+}
+
+static void WriteU64LE(uint64_t v, uint8_t out[8]) {
+    out[0] = (uint8_t)(v & 0xffu);
+    out[1] = (uint8_t)((v >> 8) & 0xffu);
+    out[2] = (uint8_t)((v >> 16) & 0xffu);
+    out[3] = (uint8_t)((v >> 24) & 0xffu);
+    out[4] = (uint8_t)((v >> 32) & 0xffu);
+    out[5] = (uint8_t)((v >> 40) & 0xffu);
+    out[6] = (uint8_t)((v >> 48) & 0xffu);
+    out[7] = (uint8_t)((v >> 56) & 0xffu);
+}
+
+static void WriteU32LE(uint32_t v, uint8_t out[4]) {
+    out[0] = (uint8_t)(v & 0xffu);
+    out[1] = (uint8_t)((v >> 8) & 0xffu);
+    out[2] = (uint8_t)((v >> 16) & 0xffu);
+    out[3] = (uint8_t)((v >> 24) & 0xffu);
+}
+
+static bool DeriveSeedFromMessage(const uint8_t* message, size_t messageLen, uint8_t outSeed[32]) {
+    if (!message || !outSeed) {
+        return false;
+    }
+
+    return Blake2b_Hash(message, messageLen, outSeed, 32);
+}
+
+static bool ComputeLaneIndex(
+    const uint8_t seed32[32],
+    uint64_t nonce,
+    uint64_t height,
+    uint32_t round,
+    uint32_t laneCount,
+    uint32_t* outLane
+) {
+    if (!seed32 || !outLane || laneCount == 0) {
+        return false;
+    }
+
+    uint8_t input[32 + 8 + 8 + 4];
+    uint8_t digest[32];
+    uint8_t nonceBytes[8];
+    uint8_t heightBytes[8];
+    uint8_t roundBytes[4];
+
+    WriteU64LE(nonce, nonceBytes);
+    WriteU64LE(height, heightBytes);
+    WriteU32LE(round, roundBytes);
+
+    memcpy(input, seed32, 32);
+    memcpy(input + 32, nonceBytes, sizeof(nonceBytes));
+    memcpy(input + 40, heightBytes, sizeof(heightBytes));
+    memcpy(input + 48, roundBytes, sizeof(roundBytes));
+
+    if (!Blake2b_Hash(input, sizeof(input), digest, sizeof(digest))) {
+        return false;
+    }
+
+    uint32_t raw =
+        ((uint32_t)digest[0]) |
+        ((uint32_t)digest[1] << 8) |
+        ((uint32_t)digest[2] << 16) |
+        ((uint32_t)digest[3] << 24);
+    *outLane = raw % laneCount;
+    return true;
+}
+
+static bool ReadDagLaneFromContext(const Autolykos2Context* ctx, uint32_t laneIndex, uint8_t outLane[32]) {
+    if (!ctx || !ctx->dag.buf || !outLane) {
+        return false;
+    }
+
+    const size_t offset = (size_t)laneIndex * 32u;
+    if (ctx->dag.len < offset + 32u) {
+        return false;
+    }
+
+    memcpy(outLane, ctx->dag.buf + offset, 32);
+    return true;
+}
+
+static bool ReadDagLaneFromSeed(const uint8_t seed32[32], uint32_t laneIndex, uint8_t outLane[32]) {
+    if (!seed32 || !outLane) {
+        return false;
+    }
+
+    const uint64_t counter = (uint64_t)laneIndex / 2u;
+    const bool upperHalf = (laneIndex & 1u) != 0u;
+    uint8_t input[32 + 8];
+    uint8_t digest[64];
+    uint8_t counterBytes[8];
+
+    WriteU64LE(counter, counterBytes);
+    memcpy(input, seed32, 32);
+    memcpy(input + 32, counterBytes, sizeof(counterBytes));
+
+    if (!Blake2b_Hash(input, sizeof(input), digest, sizeof(digest))) {
+        return false;
+    }
+
+    memcpy(outLane, digest + (upperHalf ? 32 : 0), 32);
+    return true;
+}
+
+static bool Autolykos2_HashCore(
+    const uint8_t messageSeed32[32],
+    const uint8_t dagSeed32[32],
+    const uint8_t* message,
+    size_t messageLen,
+    uint64_t nonce,
+    uint64_t height,
+    uint32_t laneCount,
+    const Autolykos2Context* ctx,
+    bool useContextDag,
+    uint8_t outHash[32]
+) {
+    if (!messageSeed32 || !message || !outHash || laneCount == 0) {
+        return false;
+    }
+
+    uint8_t acc[32];
+    memset(acc, 0, sizeof(acc));
+
+    for (uint32_t round = 0; round < 32; ++round) {
+        uint32_t laneIndex = 0;
+        uint8_t lane[32];
+
+        if (!ComputeLaneIndex(messageSeed32, nonce, height, round, laneCount, &laneIndex)) {
+            return false;
+        }
+
+        if (useContextDag) {
+            if (!ReadDagLaneFromContext(ctx, laneIndex, lane)) {
+                return false;
+            }
+        } else {
+            if (!ReadDagLaneFromSeed(dagSeed32 ? dagSeed32 : messageSeed32, laneIndex, lane)) {
+                return false;
+            }
+        }
+
+        for (size_t i = 0; i < 32; ++i) {
+            acc[i] ^= lane[i];
+        }
+    }
+
+    uint8_t baseHash[32];
+    uint8_t accHash[32];
+    if (!Autolykos2_FallbackHash(messageSeed32, message, messageLen, nonce, height, baseHash)) {
+        return false;
+    }
+    if (!Blake2b_Hash(acc, sizeof(acc), accHash, sizeof(accHash))) {
+        return false;
+    }
+
+    uint8_t finalInput[32 + 32 + 8 + 8];
+    uint8_t nonceBytes[8];
+    uint8_t heightBytes[8];
+    WriteU64LE(nonce, nonceBytes);
+    WriteU64LE(height, heightBytes);
+
+    memcpy(finalInput, baseHash, 32);
+    memcpy(finalInput + 32, accHash, 32);
+    memcpy(finalInput + 64, nonceBytes, 8);
+    memcpy(finalInput + 72, heightBytes, 8);
+    bool ok = Blake2b_Hash(finalInput, sizeof(finalInput), outHash, 32);
+
+    // Throttle between hash operations if configured (applies to all hash paths).
+    if (autolykos2_sleepBetweenHashOperationsMicroseconds > 0) {
+#if defined(_WIN32) || defined(_WIN64)
+        DWORD ms = (DWORD)((autolykos2_sleepBetweenHashOperationsMicroseconds + 999) / 1000);
+        Sleep(ms);
+#else
+        sleep_for_microseconds(autolykos2_sleepBetweenHashOperationsMicroseconds);
+#endif
+    }
+
+    return ok;
+}
+
+Autolykos2Context* Autolykos2_Create(void) {
+    Autolykos2Context* ctx = (Autolykos2Context*)calloc(1, sizeof(Autolykos2Context));
+    if (!ctx) {
+        return NULL;
+    }
+
+#ifdef SKALACOIN_AUTOLYKOS2_REF_AVAILABLE
+    ctx->backend = skalacoin_autolykos2_ref_create();
+#endif
+
+    return ctx;
+}
+
+void Autolykos2_Destroy(Autolykos2Context* ctx) {
+    if (!ctx) {
+        return;
+    }
+
+#ifdef SKALACOIN_AUTOLYKOS2_REF_AVAILABLE
+    if (ctx->backend) {
+        skalacoin_autolykos2_ref_destroy(ctx->backend);
+        ctx->backend = NULL;
+    }
+#endif
+
+    free(ctx->dag.buf);
+    free(ctx);
+}
+
+bool Autolykos2_DagAllocate(Autolykos2Context* ctx, size_t bytes) {
+    if (!ctx) {
+        return false;
+    }
+
+    uint8_t* newBuf = (uint8_t*)realloc(ctx->dag.buf, bytes == 0 ? 1 : bytes);
+    if (!newBuf) {
+        return false;
+    }
+
+    ctx->dag.buf = newBuf;
+    ctx->dag.cap = bytes;
+    if (ctx->dag.len > bytes) {
+        ctx->dag.len = bytes;
+    }
+    if (bytes > 0) {
+        memset(ctx->dag.buf, 0, bytes);
+    }
+    return true;
+}
+
+bool Autolykos2_DagAppend(Autolykos2Context* ctx, const uint8_t* data, size_t len) {
+    if (!ctx || !data || len == 0) {
+        return false;
+    }
+
+    if (ctx->dag.len + len > ctx->dag.cap) {
+        return false;
+    }
+
+    memcpy(ctx->dag.buf + ctx->dag.len, data, len);
+    ctx->dag.len += len;
+    return true;
+}
+
+bool Autolykos2_DagGenerate(Autolykos2Context* ctx, const uint8_t seed32[32]) {
+    if (!ctx || !seed32 || !ctx->dag.buf || ctx->dag.cap == 0) {
+        return false;
+    }
+
+    uint8_t input[32 + 8];
+    uint8_t digest[64];
+    size_t offset = 0;
+    uint64_t counter = 0;
+
+    while (offset < ctx->dag.cap) {
+        WriteU64LE(counter, input + 32);
+        memcpy(input, seed32, 32);
+
+        if (!Blake2b_Hash(input, sizeof(input), digest, sizeof(digest))) {
+            return false;
+        }
+
+        size_t chunk = ctx->dag.cap - offset;
+        if (chunk > sizeof(digest)) {
+            chunk = sizeof(digest);
+        }
+
+        memcpy(ctx->dag.buf + offset, digest, chunk);
+        offset += chunk;
+        ++counter;
+    }
+
+    ctx->dag.len = ctx->dag.cap;
+    return true;
+}
+
+void Autolykos2_DagClear(Autolykos2Context* ctx) {
+    if (!ctx || !ctx->dag.buf) {
+        return;
+    }
+    memset(ctx->dag.buf, 0, ctx->dag.cap);
+    ctx->dag.len = 0;
+}
+
+size_t Autolykos2_DagSize(const Autolykos2Context* ctx) {
+    return ctx ? ctx->dag.len : 0;
+}
+
+bool Autolykos2_Hash(
+    Autolykos2Context* ctx,
+    const uint8_t* message,
+    size_t messageLen,
+    uint64_t nonce,
+    uint64_t height,
+    uint8_t outHash[32]
+) {
+    if (!ctx || !message || !outHash) {
+        return false;
+    }
+
+    if (!ctx->dag.buf || ctx->dag.len < 32 || (ctx->dag.len % 32) != 0) {
+        return false;
+    }
+
+    uint8_t seed32[32];
+    if (!DeriveSeedFromMessage(message, messageLen, seed32)) {
+        return false;
+    }
+
+    const size_t laneCount64 = ctx->dag.len / 32u;
+    if (laneCount64 == 0 || laneCount64 > UINT32_MAX) {
+        return false;
+    }
+
+    return Autolykos2_HashCore(
+        seed32,
+        NULL,
+        message,
+        messageLen,
+        nonce,
+        height,
+        (uint32_t)laneCount64,
+        ctx,
+        true,
+        outHash
+    );
+}
+
+bool Autolykos2_LightHash(const uint8_t* seed, blockchain_t* chain, uint64_t nonce, uint8_t* out) {
+    if (!seed || !chain || !out) {
+        return false;
+    }
+
+    const uint64_t height = (uint64_t)Chain_Size(chain);
+    const size_t dagBytes = CalculateTargetDAGSize(chain);
+    if (dagBytes < 32 || (dagBytes % 32) != 0) {
+        return false;
+    }
+
+    const size_t laneCount64 = dagBytes / 32u;
+    if (laneCount64 == 0 || laneCount64 > UINT32_MAX) {
+        return false;
+    }
+
+    // Light path derives the needed DAG lanes from seed on-demand, no large DAG allocation required.
+    return Autolykos2_HashCore(
+        seed,
+        seed,
+        seed,
+        32,
+        nonce,
+        height,
+        (uint32_t)laneCount64,
+        NULL,
+        false,
+        out
+    );
+}
+
+bool Autolykos2_LightHashAtHeight(
+    const uint8_t seed32[32],
+    const uint8_t* message,
+    size_t messageLen,
+    uint64_t nonce,
+    uint64_t height,
+    size_t dagBytes,
+    uint8_t out[32]
+) {
+    if (!seed32 || !message || !out || dagBytes < 32 || (dagBytes % 32) != 0) {
+        return false;
+    }
+
+    const size_t laneCount64 = dagBytes / 32u;
+    if (laneCount64 == 0 || laneCount64 > UINT32_MAX) {
+        return false;
+    }
+
+    uint8_t messageSeed32[32];
+    if (!DeriveSeedFromMessage(message, messageLen, messageSeed32)) {
+        return false;
+    }
+
+    return Autolykos2_HashCore(
+        messageSeed32,
+        seed32,
+        message,
+        messageLen,
+        nonce,
+        height,
+        (uint32_t)laneCount64,
+        NULL,
+        false,
+        out
+    );
+}
+
+bool Autolykos2_CheckTarget(
+    Autolykos2Context* ctx,
+    const uint8_t message32[32],
+    uint64_t nonce,
+    uint64_t height,
+    const uint8_t target32[32],
+    uint8_t outHash[32]
+) {
+    if (!ctx || !message32 || !target32 || !outHash) {
+        return false;
+    }
+
+#ifdef SKALACOIN_AUTOLYKOS2_REF_AVAILABLE
+    if (ctx->backend) {
+        const bool ok = skalacoin_autolykos2_ref_check_target(ctx->backend, message32, nonce, height, target32);
+        if (Autolykos2_Hash(ctx, message32, 32, nonce, height, outHash)) {
+            return ok;
+        }
+        return false;
+    }
+#endif
+
+    if (!Autolykos2_Hash(ctx, message32, 32, nonce, height, outHash)) {
+        return false;
+    }
+    return Cmp256BE(outHash, target32) <= 0;
+}
+
+bool Autolykos2_FindNonceSingleCore(
+    Autolykos2Context* ctx,
+    const uint8_t message32[32],
+    uint64_t height,
+    const uint8_t target32[32],
+    uint64_t startNonce,
+    uint64_t maxIterations,
+    uint64_t* outNonce,
+    uint8_t outHash[32]
+) {
+    if (!ctx || !message32 || !target32 || !outNonce || !outHash) {
+        return false;
+    }
+
+    uint64_t nonce = startNonce;
+    for (uint64_t i = 0; i < maxIterations; ++i, ++nonce) {
+        if (Autolykos2_CheckTarget(ctx, message32, nonce, height, target32, outHash)) {
+            *outNonce = nonce;
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void Autolykos2_SetSleepBetweenHashOperations(uint64_t sleepMicroseconds) {
+    autolykos2_sleepBetweenHashOperationsMicroseconds = sleepMicroseconds;
+}

src/autolykos2/autolykos2_ref_wrapper.cpp

@@ -0,0 +1,86 @@
+#include <cstdint>
+#include <cstring>
+
+#include <cpuAutolykos.h>
+#include <definitions.h>
+
+// Reference implementation dependency from request.cc. We provide it locally
+// to avoid pulling the network/request stack.
+uint32_t calcN(uint32_t Hblock) {
+    uint32_t headerHeight = 0;
+    ((uint8_t*)&headerHeight)[0] = ((uint8_t*)&Hblock)[3];
+    ((uint8_t*)&headerHeight)[1] = ((uint8_t*)&Hblock)[2];
+    ((uint8_t*)&headerHeight)[2] = ((uint8_t*)&Hblock)[1];
+    ((uint8_t*)&headerHeight)[3] = ((uint8_t*)&Hblock)[0];
+
+    uint32_t newN = INIT_N_LEN;
+    if (headerHeight < IncreaseStart) {
+        newN = INIT_N_LEN;
+    } else if (headerHeight >= IncreaseEnd) {
+        newN = MAX_N_LEN;
+    } else {
+        uint32_t itersNumber = (headerHeight - IncreaseStart) / IncreasePeriodForN + 1;
+        for (uint32_t i = 0; i < itersNumber; i++) {
+            newN = newN / 100 * 105;
+        }
+    }
+
+    return newN;
+}
+
+struct skalacoin_autolykos2_ref_handle {
+    AutolykosAlg* alg;
+};
+
+extern "C" void* skalacoin_autolykos2_ref_create(void) {
+    skalacoin_autolykos2_ref_handle* h = new skalacoin_autolykos2_ref_handle();
+    h->alg = new AutolykosAlg();
+    return h;
+}
+
+extern "C" void skalacoin_autolykos2_ref_destroy(void* handle) {
+    if (!handle) {
+        return;
+    }
+
+    auto* h = static_cast<skalacoin_autolykos2_ref_handle*>(handle);
+    delete h->alg;
+    delete h;
+}
+
+extern "C" bool skalacoin_autolykos2_ref_check_target(
+    void* handle,
+    const uint8_t message32[32],
+    uint64_t nonce,
+    uint32_t height,
+    const uint8_t target32[32]
+) {
+    if (!handle || !message32 || !target32) {
+        return false;
+    }
+
+    auto* h = static_cast<skalacoin_autolykos2_ref_handle*>(handle);
+    if (!h->alg) {
+        return false;
+    }
+
+    uint8_t nonceBytes[8];
+    uint8_t heightBytes[4];
+    std::memcpy(nonceBytes, &nonce, sizeof(nonceBytes));
+
+    // RunAlg expects height bytes; keep deterministic network order.
+    heightBytes[0] = static_cast<uint8_t>((height >> 24) & 0xffu);
+    heightBytes[1] = static_cast<uint8_t>((height >> 16) & 0xffu);
+    heightBytes[2] = static_cast<uint8_t>((height >> 8) & 0xffu);
+    heightBytes[3] = static_cast<uint8_t>(height & 0xffu);
+
+    uint8_t poolBound[32];
+    std::memcpy(poolBound, target32, sizeof(poolBound));
+
+    return h->alg->RunAlg(
+        const_cast<uint8_t*>(message32),
+        nonceBytes,
+        poolBound,
+        heightBytes
+    );
+}

src/autolykos2/easylogging_init.cpp

@@ -0,0 +1,3 @@
+#include <easylogging++.h>
+
+INITIALIZE_EASYLOGGINGPP

src/balance_sheet.c

@@ -0,0 +1,145 @@
+#include <balance_sheet.h>
+#include <pthread.h>
+
+khash_t(balance_sheet_map_m)* sheetMap = NULL;
+static pthread_mutex_t g_sheetLock;
+
+static int BalanceSheet_InsertLocked(balance_sheet_entry_t entry) {
+    if (!sheetMap) {
+        return -1;
+    }
+
+    key32_t key;
+    memcpy(key.bytes, entry.address, 32);
+
+    int ret = 0;
+    khiter_t k = kh_put(balance_sheet_map_m, sheetMap, key, &ret);
+    if (k == kh_end(sheetMap)) {
+        return -1;
+    }
+
+    kh_value(sheetMap, k) = entry;
+    return ret;
+}
+
+void BalanceSheet_Init() {
+    sheetMap = kh_init(balance_sheet_map_m);
+    pthread_mutex_init(&g_sheetLock, NULL);
+}
+
+int BalanceSheet_Insert(balance_sheet_entry_t entry) {
+    if (!sheetMap) { return -1; }
+
+    pthread_mutex_lock(&g_sheetLock);
+    int ret = BalanceSheet_InsertLocked(entry);
+    pthread_mutex_unlock(&g_sheetLock);
+    return ret;
+}
+
+bool BalanceSheet_Lookup(uint8_t* address, balance_sheet_entry_t* out) {
+    if (!address || !out) { return false; }
+
+    pthread_mutex_lock(&g_sheetLock);
+    key32_t key;
+    memcpy(key.bytes, address, 32);
+
+    khiter_t k = kh_get(balance_sheet_map_m, sheetMap, key);
+    if (k != kh_end(sheetMap)) {
+        balance_sheet_entry_t entry = kh_value(sheetMap, k);
+        memcpy(out, &entry, sizeof(balance_sheet_entry_t));
+        pthread_mutex_unlock(&g_sheetLock);
+        return true;
+    }
+
+    pthread_mutex_unlock(&g_sheetLock);
+    return false;
+}
+
+bool BalanceSheet_SaveToFile(const char* outPath) {
+    if (!sheetMap) { return false; }
+
+    pthread_mutex_lock(&g_sheetLock);
+    char outFile[512];
+    strcpy(outFile, outPath);
+    strcat(outFile, "/balance_sheet.data");
+    FILE* file = fopen(outFile, "wb");
+    if (!file) {
+        pthread_mutex_unlock(&g_sheetLock);
+        return false;
+    }
+
+    khiter_t k;
+    for (k = kh_begin(sheetMap); k != kh_end(sheetMap); ++k) {
+        if (kh_exist(sheetMap, k)) {
+            balance_sheet_entry_t entry = kh_val(sheetMap, k);
+            if (fwrite(&entry, sizeof(balance_sheet_entry_t), 1, file) != 1) {
+                fclose(file);
+                pthread_mutex_unlock(&g_sheetLock);
+                return false;
+            }
+        }
+    }
+
+    fclose(file);
+    pthread_mutex_unlock(&g_sheetLock);
+    return true;
+}
+
+bool BalanceSheet_LoadFromFile(const char* inPath) {
+    if (!sheetMap) { return false; }
+
+    pthread_mutex_lock(&g_sheetLock);
+    char inFile[512];
+    strcpy(inFile, inPath);
+    strcat(inFile, "/balance_sheet.data");
+    FILE* file = fopen(inFile, "rb");
+    if (!file) {
+        pthread_mutex_unlock(&g_sheetLock);
+        return false;
+    }
+
+    balance_sheet_entry_t entry;
+    while (fread(&entry, sizeof(balance_sheet_entry_t), 1, file) == 1) {
+        if (BalanceSheet_InsertLocked(entry) < 0) {
+            fclose(file);
+            pthread_mutex_unlock(&g_sheetLock);
+            return false;
+        }
+    }
+
+    fclose(file);
+    pthread_mutex_unlock(&g_sheetLock);
+    return true;
+}
+
+void BalanceSheet_Print() {
+    if (!sheetMap) { return; }
+
+    pthread_mutex_lock(&g_sheetLock);
+    // Iterate through every entry
+    khiter_t k;
+    for (k = kh_begin(sheetMap); k != kh_end(sheetMap); ++k) {
+        if (kh_exist(sheetMap, k)) {
+            key32_t key = kh_key(sheetMap, k);
+            balance_sheet_entry_t val = kh_val(sheetMap, k);
+
+            char balanceStr[80];
+            uint256_serialize(&val.balance, balanceStr);
+
+            char addrHex[65];
+            AddressToHexString(key.bytes, addrHex);
+
+            // Print full address
+            printf("Address %s: balance=%s pebble(s)\n",
+                addrHex,
+                balanceStr);
+        }
+    }
+    pthread_mutex_unlock(&g_sheetLock);
+}
+
+void BalanceSheet_Destroy() {
+    kh_destroy(balance_sheet_map_m, sheetMap);
+    sheetMap = NULL;
+    pthread_mutex_destroy(&g_sheetLock);
+}

src/blake2/blake2.c

@@ -0,0 +1,50 @@
+#include <blake2/blake2.h>
+
+#include <openssl/evp.h>
+#include <string.h>
+
+static bool Blake2_HashInternal(
+    const EVP_MD* md,
+    size_t maxDigestLen,
+    const uint8_t* input,
+    size_t inputLen,
+    uint8_t* out,
+    size_t outLen
+) {
+    if (!md || !out || outLen == 0 || outLen > maxDigestLen) {
+        return false;
+    }
+
+    uint8_t digest[EVP_MAX_MD_SIZE];
+    unsigned int digestLen = 0;
+
+    EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+    if (!ctx) {
+        return false;
+    }
+
+    bool ok = EVP_DigestInit_ex(ctx, md, NULL) == 1;
+    if (ok && inputLen > 0) {
+        ok = EVP_DigestUpdate(ctx, input, inputLen) == 1;
+    }
+    if (ok) {
+        ok = EVP_DigestFinal_ex(ctx, digest, &digestLen) == 1;
+    }
+
+    EVP_MD_CTX_free(ctx);
+
+    if (!ok || digestLen < outLen) {
+        return false;
+    }
+
+    memcpy(out, digest, outLen);
+    return true;
+}
+
+bool Blake2b_Hash(const uint8_t* input, size_t inputLen, uint8_t* out, size_t outLen) {
+    return Blake2_HashInternal(EVP_blake2b512(), SKALACOIN_BLAKE2B_OUTBYTES, input, inputLen, out, outLen);
+}
+
+bool Blake2s_Hash(const uint8_t* input, size_t inputLen, uint8_t* out, size_t outLen) {
+    return Blake2_HashInternal(EVP_blake2s256(), SKALACOIN_BLAKE2S_OUTBYTES, input, inputLen, out, outLen);
+}

src/block/block.c

@@ -1,6 +1,47 @@
 #include <block/block.h>
+#include <autolykos2/autolykos2.h>
+#include <utils.h>
 #include <stdlib.h>
 
+static Autolykos2Context* g_autolykos2Ctx = NULL;
+
+static Autolykos2Context* GetAutolykos2Ctx(void) {
+    if (!g_autolykos2Ctx) {
+        g_autolykos2Ctx = Autolykos2_Create();
+        if (!g_autolykos2Ctx) {
+            fprintf(stderr, "Failed to create Autolykos2 context\n");
+            exit(1);
+        }
+        Autolykos2_DagAllocate(g_autolykos2Ctx, DAG_BASE_SIZE);
+    }
+    return g_autolykos2Ctx;
+}
+
+void Block_ShutdownPowContext(void) {
+    if (g_autolykos2Ctx) {
+        Autolykos2_Destroy(g_autolykos2Ctx);
+        g_autolykos2Ctx = NULL;
+    }
+}
+
+bool Block_RebuildAutolykos2Dag(size_t dagBytes, const uint8_t seed32[32]) {
+    if (!seed32 || dagBytes == 0) {
+        return false;
+    }
+
+    Autolykos2Context* ctx = GetAutolykos2Ctx();
+    if (!ctx) {
+        return false;
+    }
+
+    Autolykos2_DagClear(ctx);
+    if (!Autolykos2_DagAllocate(ctx, dagBytes)) {
+        return false;
+    }
+
+    return Autolykos2_DagGenerate(ctx, seed32);
+}
+
 block_t* Block_Create() {
     block_t* block = (block_t*)malloc(sizeof(block_t));
     if (!block) {
@@ -12,6 +53,10 @@ block_t* Block_Create() {
         free(block);
         return NULL;
     }
+    
+    // Zero out padding
+    memset(block->header.reserved, 0, sizeof(block->header.reserved));
+
     return block;
 }
 
@@ -41,88 +86,75 @@ void Block_CalculateMerkleRoot(const block_t* block, uint8_t* outHash) {
         return;
     }
 
-    // TODO: Make this not shit
-    DynArr* hashes1 = DynArr_create(sizeof(uint8_t) * 32, 1);
-    DynArr* hashes2 = DynArr_create(sizeof(uint8_t) * 32, 1);
-    if (!hashes1 || !hashes2) {
-        if (hashes1) DynArr_destroy(hashes1);
-        if (hashes2) DynArr_destroy(hashes2);
+    uint8_t* current = (uint8_t*)malloc(txCount * 32u);
+    uint8_t* next = (uint8_t*)malloc(txCount * 32u);
+    if (!current || !next) {
+        free(current);
+        free(next);
+        memset(outHash, 0, 32);
         return;
     }
 
-    // Handle the transactions
-    for (size_t i = 0; i < txCount - 1; i++) {
+    for (size_t i = 0; i < txCount; ++i) {
         signed_transaction_t* tx = (signed_transaction_t*)DynArr_at(block->transactions, i);
-        signed_transaction_t* txNext = (signed_transaction_t*)DynArr_at(block->transactions, i + 1);
-        uint8_t buf1[32] = {0}; uint8_t buf2[32] = {0}; // Zeroed out
-
-        // Unless if by some miracle the hash just so happens to be all zeros,
-        // I think we can safely assume that a 1 : 2^256 chance will NEVER be hit
-        Transaction_CalculateHash(tx, buf1);
-        Transaction_CalculateHash(txNext, buf2);
-
-        // Concat the two hashes
-        uint8_t dataInBuffer[64] = {0};
-        uint8_t* nextStart = dataInBuffer;
-        nextStart += 32;
-        memcpy(dataInBuffer, buf1, 32);
-        if (txNext) { memcpy(nextStart, buf2, 32); }
-
-        // Double hash that tx set
-        uint8_t outHash[32];
-        SHA256((const unsigned char*)dataInBuffer, 64, outHash);
-        SHA256(outHash, 32, outHash);
-
-        // Copy to the hashes dynarr
-        DynArr_push_back(hashes1, outHash);
+        if (!tx) {
+            free(current);
+            free(next);
+            memset(outHash, 0, 32);
+            return;
+        }
+        Transaction_CalculateHash(tx, current + (i * 32u));
     }
 
-    // Move to hashing the existing ones until only one remains
-    do {
-        for (size_t i = 0; i < DynArr_size(hashes1) - 1; i++) {
-            uint8_t* hash1 = (uint8_t*)DynArr_at(hashes1, i); uint8_t* hash2 = (uint8_t*)DynArr_at(hashes1, i + 1);
+    size_t levelCount = txCount;
+    while (levelCount > 1) {
+        size_t nextCount = 0;
+        for (size_t i = 0; i < levelCount; i += 2) {
+            const uint8_t* left = current + (i * 32u);
+            const uint8_t* right = (i + 1 < levelCount) ? current + ((i + 1) * 32u) : left;
 
-            // Concat the two hashes
-            uint8_t dataInBuffer[64] = {0};
-            uint8_t* nextStart = dataInBuffer;
-            nextStart += 32;
-            memcpy(dataInBuffer, hash1, 32);
-            memcpy(nextStart, hash2, 32);
+            uint8_t dataInBuffer[64];
+            memcpy(dataInBuffer, left, 32);
+            memcpy(dataInBuffer + 32, right, 32);
 
-            // Double hash that tx set
-            uint8_t outHash[32];
-            SHA256((const unsigned char*)dataInBuffer, 64, outHash);
-            SHA256(outHash, 32, outHash);
-
-            DynArr_push_back(hashes2, outHash);
+            SHA256((const unsigned char*)dataInBuffer, 64, next + (nextCount * 32u));
+            SHA256(next + (nextCount * 32u), 32, next + (nextCount * 32u));
+            ++nextCount;
         }
 
-        DynArr_erase(hashes1);
-        for (size_t i = 0; i < DynArr_size(hashes2); i++) {
-            DynArr_push_back(hashes1, (uint8_t*)DynArr_at(hashes2, i));
-        }
-        DynArr_erase(hashes2);
-    } while (DynArr_size(hashes1) > 1);
-
-    // Final Merkle
-    uint8_t* merkle = (uint8_t*)DynArr_at(hashes1, 0);
-    if (merkle) {
-        memcpy(outHash, merkle, 32);
-    } else {
-        memset(outHash, 0, 32);
+        uint8_t* swap = current;
+        current = next;
+        next = swap;
+        levelCount = nextCount;
     }
 
-    DynArr_destroy(hashes1);
-    DynArr_destroy(hashes2);
+    memcpy(outHash, current, 32);
+    free(current);
+    free(next);
 }
 
-void Block_CalculateRandomXHash(const block_t* block, uint8_t* outHash) {
+void Block_CalculateAutolykos2Hash(const block_t* block, uint8_t* outHash) {
     if (!block || !outHash) {
         return;
     }
 
-    // PoW hash is also computed from the header only.
-    RandomX_CalculateHash((const uint8_t*)&block->header, sizeof(block_header_t), outHash);
+    // PoW hash is computed from the block header, while canonical block hash remains SHA256.
+    Autolykos2Context* ctx = GetAutolykos2Ctx();
+    if (!ctx) {
+        memset(outHash, 0, 32);
+        return;
+    }
+
+    if (!Autolykos2_Hash(
+        ctx,
+        (const uint8_t*)&block->header,
+        sizeof(block_header_t),
+        block->header.nonce,
+        (uint32_t)block->header.blockNumber,
+        outHash
+    )) {
+        memset(outHash, 0, 32);
+    }
 }
 
 void Block_AddTransaction(block_t* block, signed_transaction_t* tx) {
@@ -140,7 +172,9 @@ void Block_RemoveTransaction(block_t* block, uint8_t* txHash) {
 
     for (size_t i = 0; i < DynArr_size(block->transactions); i++) {
         signed_transaction_t* currentTx = (signed_transaction_t*)DynArr_at(block->transactions, i);
-        if (memcmp(currentTx->signature.txHash, txHash, 32) == 0) {
+        uint8_t currentTxHash[32];
+        Transaction_CalculateHash(currentTx, currentTxHash);
+        if (memcmp(currentTxHash, txHash, 32) == 0) {
             DynArr_remove(block->transactions, i);
             return;
         }
@@ -155,39 +189,6 @@ static int Uint256_CompareBE(const uint8_t a[32], const uint8_t b[32]) {
     return 0;
 }
 
-static bool DecodeCompactTarget(uint32_t nBits, uint8_t target[32]) {
-    memset(target, 0, 32);
-
-    uint32_t exponent = nBits >> 24;
-    uint32_t mantissa = nBits & 0x007fffff;  // ignore sign bit for now
-    bool negative = (nBits & 0x00800000) != 0;
-
-    if (negative || mantissa == 0) {
-        return false;
-    }
-
-    // Compute: target = mantissa * 256^(exponent - 3)
-    if (exponent <= 3) {
-        mantissa >>= 8 * (3 - exponent);
-
-        target[29] = (mantissa >> 16) & 0xff;
-        target[30] = (mantissa >> 8) & 0xff;
-        target[31] = mantissa & 0xff;
-    } else {
-        uint32_t byte_index = exponent - 3;  // number of zero-bytes appended on right
-
-        if (byte_index > 29) {
-            return false; // overflow 256 bits
-        }
-
-        target[32 - byte_index - 3] = (mantissa >> 16) & 0xff;
-        target[32 - byte_index - 2] = (mantissa >> 8) & 0xff;
-        target[32 - byte_index - 1] = mantissa & 0xff;
-    }
-
-    return true;
-}
-
 bool Block_HasValidProofOfWork(const block_t* block) {
     if (!block) {
         return false;
@@ -199,7 +200,7 @@ bool Block_HasValidProofOfWork(const block_t* block) {
     }
 
     uint8_t hash[32];
-    Block_CalculateRandomXHash(block, hash);
+    Block_CalculateAutolykos2Hash(block, hash);
 
     return Uint256_CompareBE(hash, target) <= 0;
 }
@@ -230,6 +231,17 @@ bool Block_AllTransactionsValid(const block_t* block) {
     return true && hasCoinbase && DynArr_size(block->transactions) > 0; // Every block must have at least one transaction (the coinbase)
 }
 
+bool Block_IsFullyValid(const block_t* block) {
+    bool merkleValid = false;
+    uint8_t calculatedMerkleRoot[32];
+    if (block && block->transactions) {
+        Block_CalculateMerkleRoot(block, calculatedMerkleRoot);
+        merkleValid = (memcmp(calculatedMerkleRoot, block->header.merkleRoot, 32) == 0);
+    }
+
+    return Block_HasValidProofOfWork(block) && Block_AllTransactionsValid(block) && DynArr_size(block->transactions) > 0 && merkleValid;
+}
+
 void Block_Destroy(block_t* block) {
     if (!block) return;
     DynArr_destroy(block->transactions);
@@ -239,9 +251,9 @@ void Block_Destroy(block_t* block) {
 void Block_Print(const block_t* block) {
     if (!block) return;
 
-    printf("Block #%llu\n", block->header.blockNumber);
-    printf("Timestamp: %llu\n", block->header.timestamp);
-    printf("Nonce: %llu\n", block->header.nonce);
+    printf("Block #%llu\n", (unsigned long long)block->header.blockNumber);
+    printf("Timestamp: %llu\n", (unsigned long long)block->header.timestamp);
+    printf("Nonce: %llu\n", (unsigned long long)block->header.nonce);
     printf("Difficulty Target: 0x%08x\n", block->header.difficultyTarget);
     printf("Version: %u\n", block->header.version);
     printf("Previous Hash: ");
@@ -259,10 +271,62 @@ void Block_Print(const block_t* block) {
         for (size_t i = 0; i < DynArr_size(block->transactions); i++) {
             signed_transaction_t* tx = (signed_transaction_t*)DynArr_at(block->transactions, i);
             if (tx) {
-                printf("  Tx #%zu: %llu -> %llu, fee %llu\n", i, tx->transaction.amount, tx->transaction.fee, tx->transaction.amount + tx->transaction.fee);
+                printf("  Tx #%zu: 1: %llu -> %02x%02x...%02x%02x, fee %llu\n           2: %llu -> %02x%02x...%02x%02x, fee %llu\n", 
+                    i,
+                    (unsigned long long)tx->transaction.amount1,
+                    tx->transaction.recipientAddress1[0], tx->transaction.recipientAddress1[1], tx->transaction.recipientAddress1[30], tx->transaction.recipientAddress1[31],
+                    (unsigned long long)tx->transaction.fee,
+                    (unsigned long long)tx->transaction.amount2,
+                    tx->transaction.recipientAddress2[0], tx->transaction.recipientAddress2[1], tx->transaction.recipientAddress2[30], tx->transaction.recipientAddress2[31],
+                    (unsigned long long)tx->transaction.fee);
             }
         }
     } else {
         printf("No transactions (or none loaded)\n");
     }
 }
+
+void Block_ShortPrint(const block_t* block) {
+    if (!block) return;
+
+    printf("Block #%llu: Timestamp %llu, Nonce %llu, DiffTarget 0x%08x, Version %u, PrevHash %02x%02x...%02x%02x, MerkleRoot %02x%02x...%02x%02x, TxCount %zu\n",
+        (unsigned long long)block->header.blockNumber,
+        (unsigned long long)block->header.timestamp,
+        (unsigned long long)block->header.nonce,
+        block->header.difficultyTarget,
+        block->header.version,
+        block->header.prevHash[0], block->header.prevHash[1], block->header.prevHash[30], block->header.prevHash[31],
+        block->header.merkleRoot[0], block->header.merkleRoot[1], block->header.merkleRoot[30], block->header.merkleRoot[31],
+        block->transactions ? DynArr_size(block->transactions) : 0);
+}
+
+block_t* Block_Copy(const block_t* src) {
+    if (!src) return NULL;
+    block_t* dst = (block_t*)malloc(sizeof(block_t));
+    if (!dst) return NULL;
+    dst->header = src->header;
+    if (src->transactions) {
+        size_t txCount = DynArr_size(src->transactions);
+        dst->transactions = DYNARR_CREATE(signed_transaction_t, txCount == 0 ? 1 : txCount);
+        if (!dst->transactions) {
+            free(dst);
+            return NULL;
+        }
+        for (size_t i = 0; i < txCount; ++i) {
+            signed_transaction_t* tx = (signed_transaction_t*)DynArr_at(src->transactions, i);
+            if (!tx) {
+                DynArr_destroy(dst->transactions);
+                free(dst);
+                return NULL;
+            }
+            if (!DynArr_push_back(dst->transactions, tx)) {
+                DynArr_destroy(dst->transactions);
+                free(dst);
+                return NULL;
+            }
+        }
+    } else {
+        dst->transactions = NULL;
+    }
+    return dst;
+}

src/block/transaction.c

@@ -1,6 +1,14 @@
 #include <block/transaction.h>
 #include <string.h>
 
+void Transaction_Init(signed_transaction_t* tx) {
+    if (!tx) { return; }
+    // Zero out everything
+    memset(tx, 0, sizeof(signed_transaction_t));
+
+    // NOTE: Other things might be added here
+}
+
 void Transaction_CalculateHash(const signed_transaction_t* tx, uint8_t* outHash) {
     if (!tx || !outHash) {
         return;
@@ -18,10 +26,11 @@ void Transaction_Sign(signed_transaction_t* tx, const uint8_t* privateKey) {
         return;
     }
 
-    Transaction_CalculateHash(tx, tx->signature.txHash);
+    uint8_t txHash[32];
+    Transaction_CalculateHash(tx, txHash);
     Crypto_SignData(
-        (const uint8_t*)&tx->transaction,
-        sizeof(transaction_t),
+        txHash,
+        32,
         privateKey,
         tx->signature.signature
     );
@@ -43,11 +52,11 @@ bool Transaction_Verify(const signed_transaction_t* tx) {
         return false; // Sender address does not match public key
     }
 
-    if (tx->transaction.amount == 0) {
+    if (tx->transaction.amount1 == 0) {
         return false; // Zero-amount transactions are not valid
     }
 
-    if (tx->transaction.fee > tx->transaction.amount) {
+    if (tx->transaction.fee > tx->transaction.amount1) {
         return false; // Fee cannot exceed amount
     }
 
@@ -55,21 +64,28 @@ bool Transaction_Verify(const signed_transaction_t* tx) {
         return false; // Unsupported version
     }
 
-    if (Address_IsCoinbase(tx->transaction.recipientAddress)) {
+    if (Address_IsCoinbase(tx->transaction.recipientAddress1) || Address_IsCoinbase(tx->transaction.recipientAddress2)) {
         return false; // Cannot send to coinbase address
     }
 
+    // Balance checks are stateful and are handled when a block is added to the chain.
+    // Transaction_Verify only checks transaction structure, addresses, and signature material.
+
+    if (tx->transaction.amount2 == 0) {
+        // If amount2 is zero, address2 must be all zeros
+        uint8_t zeroAddress[32] = {0};
+        if (memcmp(tx->transaction.recipientAddress2, zeroAddress, 32) != 0) {
+            return false; // amount2 is zero but address2 is not zeroed
+        }
+    }
+
     uint8_t txHash[32];
     Transaction_CalculateHash(tx, txHash);
 
-    if (memcmp(txHash, tx->signature.txHash, 32) != 0) {
-        return false; // Hash does not match signature hash
-    }
-
     // If all checks pass, verify the signature
     return Crypto_VerifySignature(
-        (const uint8_t*)&tx->transaction,
-        sizeof(transaction_t),
+        txHash,
+        32,
         tx->signature.signature,
         tx->transaction.compressedPublicKey
     );

src/crypto/crypto.c

@@ -75,3 +75,13 @@ void Crypto_SignData(const uint8_t* data, size_t len, const uint8_t* privateKey,
     secp256k1_ecdsa_signature_serialize_compact(ctx, outSignature, &sig);
     secp256k1_context_destroy(ctx);
 }
+
+void to_hex(const uint8_t *in, char *out) {
+    static const char hex[] = "0123456789abcdef";
+
+    for (int i = 0; i < 32; i++) {
+        out[i * 2]     = hex[in[i] >> 4];
+        out[i * 2 + 1] = hex[in[i] & 0x0F];
+    }
+    out[64] = '\0';
+}

src/dynarr.c

@@ -173,3 +173,7 @@ void DynArr_destroy(DynArr* p) {
     free(p->data);
     free(p);
 }
+
+void* DynArr_c_arr(DynArr* p) {
+    return p->data;
+}

src/nets/fetch_scheduler.c

@@ -0,0 +1,24 @@
+#include <nets/fetch_scheduler.h>
+#include <constants.h>
+#include <math.h>
+
+// Note: floating point is used intentionally here for readability and
+// because the final penalty is rounded to whole blocks. This keeps the
+// implementation straightforward while avoiding subtle integer overflow
+// for large exponents. If desired, replace with fixed-point arithmetic.
+uint64_t FetchScheduler_ComputeReorgPenaltyBlocks(uint64_t delayBlocks) {
+    if (delayBlocks <= REORG_PENALTY_GRACE_BLOCKS) {
+        return 0ULL;
+    }
+
+    double B = (double)delayBlocks;
+    double factor = REORG_PENALTY_FACTOR;
+    double exp = REORG_PENALTY_EXPONENT;
+    double timeScale = ((double)TARGET_BLOCK_TIME) / REORG_PENALTY_REF_BLOCK_TIME;
+
+    double raw = factor * pow(B, exp) * timeScale;
+    if (raw < 0.0) raw = 0.0;
+
+    uint64_t penalty = (uint64_t)ceil(raw);
+    return penalty;
+}

src/nets/net_node.c

@@ -0,0 +1,918 @@
+#include <nets/net_node.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <runtime_state.h>
+#include <balance_sheet.h>
+#include <inttypes.h>
+#include <nets/orphan_pool.h>
+#include <inttypes.h>
+#include <pthread.h>
+#include <unistd.h>
+
+static net_node_t* Node_FromConnection(tcp_connection_t* conn) {
+    if (!conn) {
+        return NULL;
+    }
+
+    return (net_node_t*)conn->owner;
+}
+
+static uint64_t Node_GetCurrentBlockHeight(void) {
+    if (currentChain) {
+        return (uint64_t)Chain_Size(currentChain);
+    }
+
+    return currentBlockHeight;
+}
+
+typedef enum {
+    NODE_BLOCK_REJECTED = 0,
+    NODE_BLOCK_ORPHAN_QUEUED = 1,
+    NODE_BLOCK_ACCEPTED = 2
+} node_block_accept_result_t;
+
+static void* Node_MaintenanceThread(void* arg) {
+    net_node_t* n = (net_node_t*)arg;
+    if (!n) return NULL;
+    while (n->maintenanceRunning) {
+        if (currentChain) {
+            size_t attached = OrphanPool_AttemptAttach(currentChain);
+            if (attached > 0) {
+                printf("Maintenance: attached %zu orphan(s)\n", attached);
+                Chain_SaveToFile(currentChain, chainDataDir, currentSupply, currentReward);
+                BalanceSheet_SaveToFile(chainDataDir);
+            }
+        }
+        sleep_for_milliseconds((uint64_t)n->maintenanceIntervalMs);
+    }
+    return NULL;
+}
+
+static int Node_DecodePacket(const tcp_connection_t* conn, packet_type_t* outType, const unsigned char** outPayload, size_t* outPayloadLen) {
+    if (!conn || !outType || !outPayload || !outPayloadLen || conn->dataBufLen < 1 || !conn->dataBuf) {
+        return -1;
+    }
+
+    uint8_t packetType = conn->dataBuf[0];
+    if (!PacketType_IsValid(packetType)) {
+        return -1;
+    }
+
+    *outType = (packet_type_t)packetType;
+    *outPayload = conn->dataBuf + 1;
+    *outPayloadLen = conn->dataBufLen - 1;
+    return 0;
+}
+
+static node_block_accept_result_t Node_ParseAndAcceptBlock(const unsigned char* payload, size_t payloadLen, bool persist) {
+    if (!payload) { return NODE_BLOCK_REJECTED; }
+
+    size_t offset = 0;
+    if (payloadLen < sizeof(uint64_t) + sizeof(block_header_t) + sizeof(uint64_t)) { return NODE_BLOCK_REJECTED; }
+
+    uint64_t blockHeight = 0;
+    memcpy(&blockHeight, payload + offset, sizeof(blockHeight));
+    offset += sizeof(blockHeight);
+
+    block_t* blk = (block_t*)calloc(1, sizeof(block_t));
+    if (!blk) { return NODE_BLOCK_REJECTED; }
+
+    memcpy(&blk->header, payload + offset, sizeof(blk->header));
+    blk->header.blockNumber = blockHeight;
+    offset += sizeof(blk->header);
+
+    uint64_t txCount = 0;
+    memcpy(&txCount, payload + offset, sizeof(txCount));
+    offset += sizeof(txCount);
+
+    blk->transactions = DYNARR_CREATE(signed_transaction_t, txCount == 0 ? 1 : (size_t)txCount);
+    if (!blk->transactions) { free(blk); return NODE_BLOCK_REJECTED; }
+
+    for (uint64_t i = 0; i < txCount; ++i) {
+        if (offset + sizeof(signed_transaction_t) > payloadLen) {
+            DynArr_destroy(blk->transactions);
+            free(blk);
+            return NODE_BLOCK_REJECTED;
+        }
+        signed_transaction_t tx;
+        memcpy(&tx, payload + offset, sizeof(tx));
+        offset += sizeof(tx);
+        if (!DynArr_push_back(blk->transactions, &tx)) {
+            DynArr_destroy(blk->transactions);
+            free(blk);
+            return NODE_BLOCK_REJECTED;
+        }
+    }
+
+    // Validate block
+    if (!Block_IsFullyValid(blk)) {
+        printf("Rejected BLOCK_DATA at height %" PRIu64 " during validation\n", blockHeight);
+        DynArr_destroy(blk->transactions);
+        free(blk);
+        return NODE_BLOCK_REJECTED;
+    }
+
+    if (!currentChain) {
+        printf("Rejected BLOCK_DATA at height %" PRIu64 ": no active chain\n", blockHeight);
+        DynArr_destroy(blk->transactions);
+        free(blk);
+        return NODE_BLOCK_REJECTED;
+    }
+
+    // Temporary debug mode: force network-received blocks through the orphan pool to exercise reorg handling.
+    if (forceOrphanReorgEnabled && blk->header.blockNumber > 0) {
+        OrphanPool_Insert(blk, blockHeight);
+        printf("Forced orphan BLOCK_DATA at height %" PRIu64 "\n", blockHeight);
+        return NODE_BLOCK_ORPHAN_QUEUED;
+    }
+
+    // If parent is missing, insert into orphan pool instead of rejecting immediately.
+    uint64_t chainSize = Chain_Size(currentChain);
+    if (blk->header.blockNumber > chainSize) {
+        // Parent(s) missing; queue as orphan
+        OrphanPool_Insert(blk, blockHeight);
+        printf("Queued orphan BLOCK_DATA at height %" PRIu64 "\n", blockHeight);
+        return NODE_BLOCK_ORPHAN_QUEUED;
+    } else if (blk->header.blockNumber < chainSize) {
+        // Older block than current chain tip: reject
+        printf("Rejected BLOCK_DATA at height %" PRIu64 ": older than current chain\n", blockHeight);
+        DynArr_destroy(blk->transactions);
+        free(blk);
+        return NODE_BLOCK_REJECTED;
+    } else {
+        // blk->header.blockNumber == chainSize -> candidate to append. Ensure prevHash matches current tip.
+        if (chainSize > 0) {
+            block_t* last = NULL;
+            if (!Chain_GetBlockCopy(currentChain, (size_t)(chainSize - 1), &last) || !last) {
+                // Can't verify parent; queue as orphan conservatively
+                OrphanPool_Insert(blk, blockHeight);
+                printf("Queued orphan BLOCK_DATA at height %" PRIu64 " (unable to verify parent)\n", blockHeight);
+                if (last) Block_Destroy(last);
+                return NODE_BLOCK_ORPHAN_QUEUED;
+            }
+            uint8_t lastHash[32];
+            Block_CalculateHash(last, lastHash);
+            if (memcmp(lastHash, blk->header.prevHash, 32) != 0) {
+                // Conflicting block at same height; queue as orphan until resolved by a subsequent extension.
+                OrphanPool_Insert(blk, blockHeight);
+                Block_Destroy(last);
+                printf("Queued conflicting BLOCK_DATA at same height %" PRIu64 " as orphan\n", blockHeight);
+                return NODE_BLOCK_ORPHAN_QUEUED;
+            }
+            Block_Destroy(last);
+        }
+    }
+
+    if (!Chain_AddBlock(currentChain, blk)) {
+        // Chain_AddBlock failed; cleanup
+        printf("Rejected BLOCK_DATA at height %" PRIu64 " during chain add\n", blockHeight);
+        if (blk->transactions) {
+            DynArr_destroy(blk->transactions);
+        }
+        free(blk);
+        return NODE_BLOCK_REJECTED;
+    }
+
+    // Persist on accept if requested
+    if (persist) {
+        Chain_SaveToFile(currentChain, chainDataDir, currentSupply, currentReward);
+        BalanceSheet_SaveToFile(chainDataDir);
+    }
+
+    // Chain_AddBlock copied the block into the chain; free our temporary wrapper but do NOT destroy transactions (they are freed by Chain_SaveToFile when persisted)
+    free(blk);
+    // Attempt to attach any orphans that may now have their parents present.
+    size_t attached = OrphanPool_AttemptAttach(currentChain);
+    if (attached > 0) {
+        printf("Attached %zu orphan(s) after accepting block\n", attached);
+        // Persist after attaching orphans
+        Chain_SaveToFile(currentChain, chainDataDir, currentSupply, currentReward);
+        BalanceSheet_SaveToFile(chainDataDir);
+    }
+    return NODE_BLOCK_ACCEPTED;
+}
+
+static void Node_ForwardConnect(net_node_t* node, tcp_connection_t* conn) {
+    if (node && node->on_connect) {
+        node->on_connect(conn, node->callbackUser);
+    }
+}
+
+static void Node_ForwardDisconnect(net_node_t* node, tcp_connection_t* conn) {
+    if (node && node->on_disconnect) {
+        node->on_disconnect(conn, node->callbackUser);
+    }
+}
+
+static void Node_ForwardData(net_node_t* node, tcp_connection_t* conn, const unsigned char* payload, size_t payloadLen) {
+    if (node && node->on_data) {
+        node->on_data(conn, payload, payloadLen, node->callbackUser);
+    }
+}
+
+net_node_t* Node_Create() {
+    net_node_t* node = (net_node_t*)malloc(sizeof(net_node_t));
+    if (!node) {
+        return NULL;
+    }
+
+    memset(node, 0, sizeof(*node));
+
+    node->server = TcpServer_Create();
+    if (!node->server) {
+        free(node);
+        return NULL;
+    }
+
+    for (size_t i = 0; i < MAX_CONS; ++i) {
+        if (TcpClient_Init(&node->outboundClients[i]) != 0) {
+            Node_Destroy(node);
+            return NULL;
+        }
+    }
+
+    // Initialize outbound lock and seen-block cache
+    pthread_mutex_init(&node->seenLock, NULL);
+    pthread_mutex_init(&node->outboundLock, NULL);
+    node->seenBlocks = DynSet_Create(32); // 32-byte canonical hashes
+
+    TcpServer_Init(node->server, listenPort, "0.0.0.0");
+
+    node->server->owner = node;
+    node->server->on_connect = Node_Server_OnConnect;
+    node->server->on_data = Node_Server_OnData;
+    node->server->on_disconnect = Node_Server_OnDisconnect;
+
+    TcpServer_Start(node->server, MAX_CONS);
+
+    OrphanPool_Init();
+
+    // Start maintenance thread
+    node->maintenanceRunning = 1;
+    node->maintenanceIntervalMs = 1000; // 1s
+    if (pthread_create(&node->maintenanceThread, NULL, Node_MaintenanceThread, node) != 0) {
+        // Failed to start maintenance thread; continue without it
+        node->maintenanceRunning = 0;
+    }
+
+    return node;
+}
+
+void Node_Destroy(net_node_t* node) {
+    if (!node) {
+        return;
+    }
+
+    for (size_t i = 0; i < MAX_CONS; ++i) {
+        TcpClient_Destroy(&node->outboundClients[i]);
+    }
+    node->outboundCount = 0;
+
+    if (node->server) {
+        TcpServer_Stop(node->server);
+        TcpServer_Destroy(node->server);
+    }
+
+    // Stop maintenance thread
+    if (node->maintenanceRunning) {
+        node->maintenanceRunning = 0;
+        pthread_join(node->maintenanceThread, NULL);
+    }
+
+    OrphanPool_Destroy();
+
+    if (node->seenBlocks) {
+        DynSet_Destroy(node->seenBlocks);
+        node->seenBlocks = NULL;
+    }
+    pthread_mutex_destroy(&node->seenLock);
+    pthread_mutex_destroy(&node->outboundLock);
+
+    free(node);
+}
+
+void Node_SetCallbacks(
+    net_node_t* node,
+    void (*on_connect)(tcp_connection_t* conn, void* user),
+    void (*on_data)(tcp_connection_t* conn, const unsigned char* data, size_t len, void* user),
+    void (*on_disconnect)(tcp_connection_t* conn, void* user),
+    void* user
+) {
+    if (!node) {
+        return;
+    }
+
+    node->on_connect = on_connect;
+    node->on_data = on_data;
+    node->on_disconnect = on_disconnect;
+    node->callbackUser = user;
+}
+
+int Node_ConnectPeer(net_node_t* node, const char* ip, unsigned short port) {
+    if (!node || !ip) {
+        return -1;
+    }
+
+    for (size_t i = 0; i < MAX_CONS; ++i) {
+        if (node->outboundClients[i].connection == NULL) {
+            if (TcpClient_Connect(
+                &node->outboundClients[i],
+                ip,
+                port,
+                Node_Client_OnConnect,
+                Node_Client_OnData,
+                Node_Client_OnDisconnect,
+                node
+            ) == 0) {
+                node->outboundCount++;
+                return 0;
+            }
+            return -1;
+        }
+    }
+
+    return -1;
+}
+
+int Node_ConnectStartupPeers(net_node_t* node, const char** ips, const unsigned short* ports, size_t peersCount) {
+    if (!node || !ips || !ports) {
+        return -1;
+    }
+
+    int successes = 0;
+    for (size_t i = 0; i < peersCount; ++i) {
+        if (Node_ConnectPeer(node, ips[i], ports[i]) == 0) {
+            successes++;
+        }
+    }
+
+    return successes;
+}
+
+int Node_SendPacket(net_node_t* node, tcp_connection_t* conn, packet_type_t packetType, const void* payload, size_t payloadLen) {
+    if (!node || !conn || !PacketType_IsValid((uint8_t)packetType) || (!payload && payloadLen > 0)) {
+        return -1;
+    }
+
+    /*
+    if (conn->role == TCP_CONNECTION_ROLE_INBOUND && packetType != PACKET_TYPE_RESPONSE) {
+        return -1;
+    }
+
+    if (conn->role == TCP_CONNECTION_ROLE_OUTBOUND && packetType != PACKET_TYPE_REQUEST) {
+        return -1;
+    }
+    */
+
+    size_t framePayloadLen = payloadLen + 1;
+    unsigned char* framed = (unsigned char*)malloc(framePayloadLen);
+    if (!framed) {
+        return -1;
+    }
+
+    framed[0] = (unsigned char)packetType;
+    if (payloadLen > 0) {
+        memcpy(framed + 1, payload, payloadLen);
+    }
+
+    int rc = TcpConnection_SendFramed(conn, framed, framePayloadLen);
+    free(framed);
+
+    return rc;
+}
+
+void Node_Server_OnConnect(tcp_connection_t* client) {
+    net_node_t* node = Node_FromConnection(client);
+    Node_ForwardConnect(node, client);
+    printf("Inbound node connected: %u\n", client ? client->connectionId : 0U);
+
+    if (echoPeersEnabled && node && client) {
+        // Attempt to create an outbound connection back to the peer's IP on our configured port.
+        // We avoid connecting if we already have an outbound to the same IP.
+        char ipbuf[INET_ADDRSTRLEN];
+        if (inet_ntop(AF_INET, &client->peerAddr.sin_addr, ipbuf, sizeof(ipbuf))) {
+            // Use the configured port as the target port for the peer's listening service.
+            unsigned short targetPort = listenPort;
+
+            int shouldConnect = 1;
+            pthread_mutex_lock(&node->outboundLock);
+            for (size_t i = 0; i < MAX_CONS; ++i) {
+                if (node->outboundClients[i].connection) {
+                    struct in_addr otherAddr = node->outboundClients[i].connection->peerAddr.sin_addr;
+                    if (otherAddr.s_addr == client->peerAddr.sin_addr.s_addr) {
+                        shouldConnect = 0;
+                        break;
+                    }
+                }
+            }
+            pthread_mutex_unlock(&node->outboundLock);
+
+            if (shouldConnect) {
+                // Try to connect; ignore failure silently
+                (void)Node_ConnectPeer(node, ipbuf, targetPort);
+            }
+        }
+    }
+}
+
+void Node_Server_OnData(tcp_connection_t* client) {
+    packet_type_t packetType;
+    const unsigned char* payload = NULL;
+    size_t payloadLen = 0;
+
+    if (!client || Node_DecodePacket(client, &packetType, &payload, &payloadLen) != 0) {
+        return;
+    }
+
+    switch (packetType) {
+        case PACKET_TYPE_HELLO: {
+            // Decode HELLO
+            if (payloadLen < sizeof(uint32_t) + sizeof(uint64_t)) {
+                return;
+            }
+
+            uint32_t protoVersion;
+            uint64_t blockHeight;
+            memcpy(&protoVersion, payload, sizeof(protoVersion));
+            memcpy(&blockHeight, payload + sizeof(protoVersion), sizeof(blockHeight));
+
+            // TODO: Save these somewhere and maybe respond
+            printf("Received HELLO from node %u: protoVersion=%u, blockHeight=%" PRIu64 "\n",
+                client ? client->connectionId : 0U, protoVersion, blockHeight);
+
+            // Craft and send ACK_HELLO
+            uint8_t ackBuf[100];
+            uint8_t* ackData = ackBuf;
+            size_t ackOffset = 0;
+            memcpy(ackData + ackOffset, &protoVersion, sizeof(protoVersion));
+            ackOffset += sizeof(protoVersion);
+            uint64_t currentHeight = Node_GetCurrentBlockHeight();
+            memcpy(ackData + ackOffset, &currentHeight, sizeof(currentHeight));
+            ackOffset += sizeof(currentHeight);
+
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ACK_HELLO, ackData, ackOffset);
+
+            break;
+        }
+        case PACKET_TYPE_ACK_HELLO: {
+            // This is illegal
+            printf("Received unexpected ACK_HELLO packet from node %u\n", client ? client->connectionId : 0U);
+
+            // Send the error and kill the connection
+            const char* msg = "You can't ACK_HELLO me! I'm a server!";
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+            TcpConnection_RequestClose(client);
+            return;
+        }
+        case PACKET_TYPE_FETCH_BLOCK: {
+            // Decode FETCH_BLOCK - payload is the block height as uint64_t
+            if (payloadLen != sizeof(uint64_t)) {
+                return;
+            }
+
+            uint64_t requestedHeight;
+            memcpy(&requestedHeight, payload, sizeof(requestedHeight));
+
+            printf("Received FETCH_BLOCK for height %" PRIu64 " from node %u\n", requestedHeight, client ? client->connectionId : 0U);
+            if (requestedHeight > Node_GetCurrentBlockHeight()) {
+                printf("Requested block height %" PRIu64 " is higher than current height, ignoring\n", requestedHeight);
+
+                // Error the client, but don't kill
+                const char* msg = "Requested block height is higher than my current height!";
+                Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+
+                return;
+            }
+
+            // Find the block (deep-copy it for safe access)
+            block_t* block = NULL;
+            bool loadedFromDisk = false;
+            if (!Chain_GetBlockCopy(currentChain, (size_t)requestedHeight, &block) || !block) {
+                // Try loading from disk directly
+                if (!Chain_LoadBlockFromFile(chainDataDir, requestedHeight, true, &block, NULL) || !block) {
+                    printf("Requested block height %" PRIu64 " not found, ignoring\n", requestedHeight);
+                    const char* msg = "Requested block not found!";
+                    Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+                    return;
+                }
+                loadedFromDisk = true;
+            } else if (!block->transactions) {
+                // In-memory chain may be compacted to headers only after persistence.
+                block_t* fullBlock = NULL;
+                if (Chain_LoadBlockFromFile(chainDataDir, requestedHeight, true, &fullBlock, NULL) && fullBlock) {
+                    Block_Destroy(block);
+                    block = fullBlock;
+                    loadedFromDisk = true;
+                }
+            }
+
+            if (!block || !block->transactions) {
+                printf("Requested block height %" PRIu64 " has no transaction data available\n", requestedHeight);
+                const char* msg = "Requested block missing transactions!";
+                Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+                if (block) {
+                    Block_Destroy(block);
+                }
+                return;
+            }
+
+            if (loadedFromDisk) {
+                printf("Serving block %" PRIu64 " from disk with %zu transaction(s)\n",
+                    requestedHeight,
+                    DynArr_size(block->transactions));
+            }
+
+            // Serialize into a BLOCK_DATA packet [block header][tx count - 8 bytes][transactions...]
+            size_t txCount = block->transactions ? DynArr_size(block->transactions) : 0;
+            size_t blockDataSize = sizeof(uint64_t) + sizeof(block_header_t) + sizeof(uint64_t) + (txCount * sizeof(signed_transaction_t));
+            unsigned char* blockData = (unsigned char*)malloc(blockDataSize);
+            if (!blockData) {
+                // Generic error response
+                printf("Failed to allocate memory for block data response to node %u\n", client ? client->connectionId : 0U);
+                const char* msg = "Generic error for block data!";
+                Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+                Block_Destroy(block);
+                return;
+            }
+
+            size_t offset = 0;
+            // Write height first
+            uint64_t heightLE = requestedHeight;
+            memcpy(blockData + offset, &heightLE, sizeof(heightLE));
+            offset += sizeof(heightLE);
+            memcpy(blockData + offset, &block->header, sizeof(block_header_t));
+            offset += sizeof(block_header_t);
+            uint64_t txCount64 = (uint64_t)txCount;
+            memcpy(blockData + offset, &txCount64, sizeof(txCount64));
+            offset += sizeof(txCount64);
+            if (block->transactions && txCount > 0) {
+                for (size_t ti = 0; ti < txCount; ++ti) {
+                    signed_transaction_t* tx = (signed_transaction_t*)DynArr_at(block->transactions, ti);
+                    memcpy(blockData + offset, tx, sizeof(signed_transaction_t));
+                    offset += sizeof(signed_transaction_t);
+                }
+            }
+
+            // Send the block data
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_BLOCK_DATA, blockData, offset);
+            free(blockData);
+            Block_Destroy(block);
+            break;
+        }
+        case PACKET_TYPE_BLOCK_DATA: {
+            // Server can't receive these!
+            printf("Received unexpected packet type %u from node %u\n", (unsigned int)packetType, client ? client->connectionId : 0U);
+
+            // Send the error and kill the connection
+            const char* msg = "You can't send me BLOCK_DATA! I'm a server!";
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+            TcpConnection_RequestClose(client);
+            return;
+        }
+        case PACKET_TYPE_BROADCAST_BLOCK: {
+            // Accept broadcast blocks from peers and try to append
+            if (payloadLen >= sizeof(uint64_t)) {
+                uint64_t blockHeight = 0;
+                memcpy(&blockHeight, payload, sizeof(blockHeight));
+                node_block_accept_result_t result = Node_ParseAndAcceptBlock(payload, payloadLen, true);
+                if (result == NODE_BLOCK_ACCEPTED) {
+                    printf("Accepted BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                    net_node_t* node = Node_FromConnection(client);
+                    if (node) {
+                        Node_BroadcastChainRange(node, (size_t)blockHeight, client);
+                    }
+                } else if (result == NODE_BLOCK_ORPHAN_QUEUED) {
+                    printf("Queued orphan BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                } else {
+                    printf("Rejected BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                }
+            }
+            break;
+        }
+        case PACKET_TYPE_ACK_BLOCK:
+        case PACKET_TYPE_BROADCAST_TX:
+        case PACKET_TYPE_ACK_TX:
+        case PACKET_TYPE_ERROR: {
+            // Decode the message inside as text
+            char* text = (char*)malloc(payloadLen + 1);
+            if (!text) {
+                return;
+            }
+            memcpy(text, payload, payloadLen);
+            text[payloadLen] = '\0';
+            printf("Received packet type %u from node %u with message: %s\n",
+                (unsigned int)packetType, client ? client->connectionId : 0U, text);
+            free(text);
+            
+            break;
+        }
+        default:
+            return;
+    } 
+
+    net_node_t* node = Node_FromConnection(client);
+    Node_ForwardData(node, client, payload, payloadLen);
+}
+
+void Node_Server_OnDisconnect(tcp_connection_t* client) {
+    net_node_t* node = Node_FromConnection(client);
+    Node_ForwardDisconnect(node, client);
+    printf("Inbound node disconnected: %u\n", client ? client->connectionId : 0U);
+}
+
+void Node_Client_OnConnect(tcp_connection_t* client) {
+    net_node_t* node = Node_FromConnection(client);
+    Node_ForwardConnect(node, client);
+    printf("Outbound node connected: %u\n", client ? client->connectionId : 0U);
+
+    // Construct and send HELLO
+    if (node) {
+        uint8_t buf[100];
+        uint8_t* data = buf;
+        
+        size_t offset = 0;
+        uint32_t protoVersion = 1; // little-endian
+        uint64_t blockHeight = Node_GetCurrentBlockHeight();
+        memcpy((unsigned char*)data + offset, &protoVersion, sizeof(protoVersion)); // This is technically "unsafe", but I honestly just don't give a shit at this point
+        offset += sizeof(protoVersion);
+        memcpy((unsigned char*)data + offset, &blockHeight, sizeof(blockHeight));
+        offset += sizeof(blockHeight);
+
+        Node_SendPacket(node, client, PACKET_TYPE_HELLO, data, offset);
+    }
+}
+
+void Node_Client_OnData(tcp_connection_t* client) {
+    packet_type_t packetType;
+    const unsigned char* payload = NULL;
+    size_t payloadLen = 0;
+
+    if (!client || Node_DecodePacket(client, &packetType, &payload, &payloadLen) != 0) {
+        return;
+    }
+
+    switch (packetType) {
+        case PACKET_TYPE_HELLO: {
+            // This is illegal
+            printf("Received unexpected HELLO packet from node %u\n", client ? client->connectionId : 0U);
+
+            // Send the error and kill the connection
+            const char* msg = "You can't HELLO me! I'm a client!";
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+            TcpConnection_RequestClose(client);
+            return;
+        }
+        case PACKET_TYPE_ACK_HELLO: {
+            // Decode ACK_HELLO
+            if (payloadLen < sizeof(uint32_t) + sizeof(uint64_t)) {
+                return;
+            }
+
+            uint32_t protoVersion;
+            uint64_t blockHeight;
+            memcpy(&protoVersion, payload, sizeof(protoVersion));
+            memcpy(&blockHeight, payload + sizeof(protoVersion), sizeof(blockHeight));
+
+            printf("Received ACK_HELLO from node %u with protoVersion %u and blockHeight %" PRIu64 "\n", client ? client->connectionId : 0U, protoVersion, blockHeight);
+
+            // Store peer-advertised height on matching outbound client
+            net_node_t* node = Node_FromConnection(client);
+            if (node) {
+                pthread_mutex_lock(&node->outboundLock);
+                for (size_t i = 0; i < MAX_CONS; ++i) {
+                    if (node->outboundClients[i].connection == client) {
+                        node->outboundClients[i].peerBlockHeight = blockHeight;
+                        break;
+                    }
+                }
+                pthread_mutex_unlock(&node->outboundLock);
+            }
+            break;
+        }
+        case PACKET_TYPE_FETCH_BLOCK: {
+            // A client can't serve a block!
+            printf("Received unexpected FETCH_BLOCK packet from node %u\n", client ? client->connectionId : 0U);
+
+            // Send the error and kill the connection (this might be too aggressive)
+            const char* msg = "You can't FETCH_BLOCK from me! I'm a client!";
+            Node_SendPacket(Node_FromConnection(client), client, PACKET_TYPE_ERROR, msg, strlen(msg));
+            TcpConnection_RequestClose(client);
+            return;
+        }
+        case PACKET_TYPE_BLOCK_DATA: {
+            if (payloadLen >= sizeof(uint64_t)) {
+                uint64_t blockHeight = 0;
+                memcpy(&blockHeight, payload, sizeof(blockHeight));
+                node_block_accept_result_t result = Node_ParseAndAcceptBlock(payload, payloadLen, true);
+                if (result == NODE_BLOCK_ACCEPTED) {
+                    printf("Accepted BLOCK_DATA from node %u\n", client ? client->connectionId : 0U);
+                    net_node_t* node = Node_FromConnection(client);
+                    if (node) {
+                        // Update peer advertised height
+                        pthread_mutex_lock(&node->outboundLock);
+                        for (size_t i = 0; i < MAX_CONS; ++i) {
+                            if (node->outboundClients[i].connection == client) {
+                                if (node->outboundClients[i].peerBlockHeight < blockHeight) {
+                                    node->outboundClients[i].peerBlockHeight = blockHeight;
+                                }
+                                break;
+                            }
+                        }
+                        pthread_mutex_unlock(&node->outboundLock);
+
+                        Node_BroadcastChainRange(node, (size_t)blockHeight, client);
+                    }
+                } else if (result == NODE_BLOCK_ORPHAN_QUEUED) {
+                    printf("Queued orphan BLOCK_DATA from node %u\n", client ? client->connectionId : 0U);
+                } else {
+                    printf("Rejected BLOCK_DATA from node %u\n", client ? client->connectionId : 0U);
+                }
+            }
+            break;
+        }
+        case PACKET_TYPE_BROADCAST_BLOCK: {
+            if (payloadLen >= sizeof(uint64_t)) {
+                uint64_t blockHeight = 0;
+                memcpy(&blockHeight, payload, sizeof(blockHeight));
+                node_block_accept_result_t result = Node_ParseAndAcceptBlock(payload, payloadLen, true);
+                if (result == NODE_BLOCK_ACCEPTED) {
+                    printf("Accepted BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                    net_node_t* node = Node_FromConnection(client);
+                    if (node) {
+                        // Update peer advertised height
+                        pthread_mutex_lock(&node->outboundLock);
+                        for (size_t i = 0; i < MAX_CONS; ++i) {
+                            if (node->outboundClients[i].connection == client) {
+                                if (node->outboundClients[i].peerBlockHeight < blockHeight) {
+                                    node->outboundClients[i].peerBlockHeight = blockHeight;
+                                }
+                                break;
+                            }
+                        }
+                        pthread_mutex_unlock(&node->outboundLock);
+
+                        Node_BroadcastChainRange(node, (size_t)blockHeight, client);
+                    }
+                } else if (result == NODE_BLOCK_ORPHAN_QUEUED) {
+                    printf("Queued orphan BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                } else {
+                    printf("Rejected BROADCAST_BLOCK from node %u\n", client ? client->connectionId : 0U);
+                }
+            }
+            break;
+        }
+        case PACKET_TYPE_ACK_BLOCK:
+        case PACKET_TYPE_BROADCAST_TX:
+        case PACKET_TYPE_ACK_TX:
+        case PACKET_TYPE_ERROR: {
+            // Decode the message inside as text
+            char* text = (char*)malloc(payloadLen + 1);
+            if (!text) {
+                return;
+            }
+            memcpy(text, payload, payloadLen);
+            text[payloadLen] = '\0';
+            printf("Received packet type %u from node %u with message: %s\n",
+                (unsigned int)packetType, client ? client->connectionId : 0U, text);
+            free(text);
+            
+            break;
+        }
+        default:
+            return;
+    }
+
+    net_node_t* node = Node_FromConnection(client);
+    Node_ForwardData(node, client, payload, payloadLen);
+}
+
+void Node_Client_OnDisconnect(tcp_connection_t* client) {
+    net_node_t* node = Node_FromConnection(client);
+    if (node) {
+        // Clear peer advertised height for this outbound slot
+        pthread_mutex_lock(&node->outboundLock);
+        for (size_t i = 0; i < MAX_CONS; ++i) {
+            if (node->outboundClients[i].connection == client) {
+                node->outboundClients[i].peerBlockHeight = 0;
+                break;
+            }
+        }
+        pthread_mutex_unlock(&node->outboundLock);
+
+        if (node->outboundCount > 0) {
+            node->outboundCount--;
+        }
+    }
+
+    Node_ForwardDisconnect(node, client);
+    printf("Outbound node disconnected: %u\n", client ? client->connectionId : 0U);
+}
+
+int Node_GetBestOutboundPeer(net_node_t* node, tcp_connection_t** outConn, uint64_t* outHeight) {
+    if (!node || !outConn || !outHeight) return -1;
+
+    tcp_connection_t* best = NULL;
+    uint64_t bestH = 0;
+
+    pthread_mutex_lock(&node->outboundLock);
+    for (size_t i = 0; i < MAX_CONS; ++i) {
+        if (node->outboundClients[i].connection) {
+            if (node->outboundClients[i].peerBlockHeight > bestH || best == NULL) {
+                best = node->outboundClients[i].connection;
+                bestH = node->outboundClients[i].peerBlockHeight;
+            }
+        }
+    }
+    pthread_mutex_unlock(&node->outboundLock);
+
+    if (!best) return -1;
+    *outConn = best;
+    *outHeight = bestH;
+    return 0;
+}
+
+void Node_BroadcastChainRange(net_node_t* node, size_t startHeightInclusive, tcp_connection_t* sourceConn) {
+    if (!node || !currentChain) return;
+
+    size_t chainSize = Chain_Size(currentChain);
+    if (startHeightInclusive >= chainSize) return;
+
+    uint32_t sourceIp = 0;
+    if (sourceConn) {
+        sourceIp = sourceConn->peerAddr.sin_addr.s_addr;
+    }
+
+    for (size_t h = startHeightInclusive; h < chainSize; ++h) {
+        block_t* blk = NULL;
+        if (!Chain_GetBlockCopy(currentChain, h, &blk) || !blk) {
+            if (!Chain_LoadBlockFromFile(chainDataDir, h, true, &blk, NULL) || !blk) {
+                continue;
+            }
+        } else if (!blk->transactions) {
+            block_t* full = NULL;
+            if (Chain_LoadBlockFromFile(chainDataDir, h, true, &full, NULL) && full) {
+                Block_Destroy(blk);
+                blk = full;
+            }
+        }
+
+        if (!blk || !blk->transactions) {
+            if (blk) Block_Destroy(blk);
+            continue;
+        }
+
+        unsigned char hash[32];
+        Block_CalculateHash(blk, hash);
+
+        // Dedupe using seenBlocks
+        int seen = 0;
+        pthread_mutex_lock(&node->seenLock);
+        if (DynSet_Contains(node->seenBlocks, hash)) {
+            seen = 1;
+        } else {
+            DynSet_Insert(node->seenBlocks, hash);
+        }
+        pthread_mutex_unlock(&node->seenLock);
+
+        if (seen) {
+            Block_Destroy(blk);
+            continue;
+        }
+
+        // Serialize payload: [uint64_t height][block_header_t][uint64_t txCount][transactions...]
+        size_t txCount = DynArr_size(blk->transactions);
+        size_t payloadLen = sizeof(uint64_t) + sizeof(block_header_t) + sizeof(uint64_t) + (txCount * sizeof(signed_transaction_t));
+        unsigned char* payload = (unsigned char*)malloc(payloadLen);
+        if (!payload) {
+            Block_Destroy(blk);
+            continue;
+        }
+        size_t off = 0;
+        uint64_t h64 = (uint64_t)h;
+        memcpy(payload + off, &h64, sizeof(h64)); off += sizeof(h64);
+        memcpy(payload + off, &blk->header, sizeof(block_header_t)); off += sizeof(block_header_t);
+        uint64_t txCount64 = (uint64_t)txCount;
+        memcpy(payload + off, &txCount64, sizeof(txCount64)); off += sizeof(txCount64);
+        for (size_t ti = 0; ti < txCount; ++ti) {
+            signed_transaction_t* tx = (signed_transaction_t*)DynArr_at(blk->transactions, ti);
+            memcpy(payload + off, tx, sizeof(signed_transaction_t)); off += sizeof(signed_transaction_t);
+        }
+
+        // Snapshot outbound clients and send
+        pthread_mutex_lock(&node->outboundLock);
+        for (size_t i = 0; i < MAX_CONS; ++i) {
+            tcp_connection_t* conn = node->outboundClients[i].connection;
+            if (!conn) continue;
+            if (conn == sourceConn) continue;
+            if (sourceIp != 0 && conn->peerAddr.sin_addr.s_addr == sourceIp) continue;
+            Node_SendPacket(node, conn, PACKET_TYPE_BROADCAST_BLOCK, payload, off);
+        }
+        pthread_mutex_unlock(&node->outboundLock);
+
+        free(payload);
+        Block_Destroy(blk);
+    }
+}

src/nets/orphan_pool.c

@@ -0,0 +1,213 @@
+#include <nets/orphan_pool.h>
+#include <dynarr.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+typedef struct {
+    block_t* block;
+    uint64_t height;
+} orphan_entry_t;
+
+static DynArr* g_orphans = NULL;
+
+void OrphanPool_Init(void) {
+    if (g_orphans) return;
+    g_orphans = DYNARR_CREATE(orphan_entry_t, 16);
+}
+
+void OrphanPool_Destroy(void) {
+    if (!g_orphans) return;
+    size_t n = DynArr_size(g_orphans);
+    for (size_t i = 0; i < n; ++i) {
+        orphan_entry_t* e = (orphan_entry_t*)DynArr_at(g_orphans, i);
+        if (e && e->block) {
+            Block_Destroy(e->block);
+        }
+    }
+    DynArr_destroy(g_orphans);
+    g_orphans = NULL;
+}
+
+void OrphanPool_Insert(block_t* block, uint64_t height) {
+    if (!block) return;
+    if (!g_orphans) OrphanPool_Init();
+    orphan_entry_t e;
+    e.block = block;
+    e.height = height;
+    (void)DynArr_push_back(g_orphans, &e);
+}
+
+static size_t OrphanPool_TryAdoptBranch(blockchain_t* chain, uint64_t forkHeight) {
+    if (!g_orphans || !chain) return 0;
+
+    DynArr* seq = DYNARR_CREATE(block_t*, 8);
+    if (!seq) return 0;
+
+    size_t cursor = forkHeight;
+    while (1) {
+        bool found = false;
+        size_t count = DynArr_size(g_orphans);
+        for (size_t i = 0; i < count; ++i) {
+            orphan_entry_t* entry = (orphan_entry_t*)DynArr_at(g_orphans, i);
+            if (!entry || !entry->block) continue;
+            if (entry->height == cursor) {
+                (void)DynArr_push_back(seq, &entry->block);
+                found = true;
+                break;
+            }
+        }
+        if (!found) break;
+        cursor++;
+    }
+
+    size_t seqCount = DynArr_size(seq);
+    if (seqCount == 0) {
+        DynArr_destroy(seq);
+        return 0;
+    }
+
+    size_t currentTipHeight = Chain_Size(chain) == 0 ? 0 : Chain_Size(chain) - 1;
+    size_t seqTopHeight = forkHeight + seqCount - 1;
+    if (seqTopHeight <= currentTipHeight) {
+        DynArr_destroy(seq);
+        return 0;
+    }
+
+    size_t rollbackHeight = (forkHeight == 0) ? 0 : (forkHeight - 1);
+    if (!Chain_RollbackToHeight(chain, rollbackHeight)) {
+        DynArr_destroy(seq);
+        return 0;
+    }
+
+    size_t attached = 0;
+    for (size_t i = 0; i < seqCount; ++i) {
+        block_t* bptr = *(block_t**)DynArr_at(seq, i);
+        if (!bptr || !Chain_AddBlock(chain, bptr)) {
+            break;
+        }
+
+        size_t count = DynArr_size(g_orphans);
+        for (size_t j = 0; j < count; ++j) {
+            orphan_entry_t* entry = (orphan_entry_t*)DynArr_at(g_orphans, j);
+            if (entry && entry->block == bptr) {
+                DynArr_remove(g_orphans, j);
+                break;
+            }
+        }
+
+        attached++;
+    }
+
+    DynArr_destroy(seq);
+    return attached;
+}
+
+size_t OrphanPool_AttemptAttach(blockchain_t* chain) {
+    if (!g_orphans || !chain) return 0;
+    size_t attached = 0;
+    bool madeProgress = true;
+
+    // Attempt repeatedly while progress is made (to handle chained orphans)
+    while (madeProgress) {
+        madeProgress = false;
+        size_t n = DynArr_size(g_orphans);
+        for (size_t i = 0; i < n; ++i) {
+            orphan_entry_t* e = (orphan_entry_t*)DynArr_at(g_orphans, i);
+            if (!e || !e->block) continue;
+
+            uint64_t parentIndex = (e->height == 0) ? (uint64_t)-1 : (e->height - 1);
+            bool parentExists = false;
+            if (e->height == 0) {
+                // genesis-style block: parent is zero-hash; accept if chain empty
+                parentExists = (Chain_Size(chain) == 0);
+            } else if (parentIndex < Chain_Size(chain)) {
+                block_t* parent = NULL;
+                if (Chain_GetBlockCopy(chain, (size_t)parentIndex, &parent) && parent) {
+                    parentExists = true;
+                    Block_Destroy(parent);
+                } else {
+                    parentExists = false;
+                }
+            }
+
+            if (parentExists) {
+                if (e->height < Chain_Size(chain)) {
+                    block_t* local = NULL;
+                    if (Chain_GetBlockCopy(chain, (size_t)e->height, &local) && local) {
+                        uint8_t localHash[32];
+                        uint8_t orphanHash[32];
+                        Block_CalculateHash(local, localHash);
+                        Block_CalculateHash(e->block, orphanHash);
+                        Block_Destroy(local);
+
+                        if (memcmp(localHash, orphanHash, 32) != 0) {
+                            size_t adopted = OrphanPool_TryAdoptBranch(chain, e->height);
+                            if (adopted > 0) {
+                                attached += adopted;
+                                madeProgress = true;
+                                n = DynArr_size(g_orphans);
+                                i = (size_t)-1;
+                                break;
+                            }
+                        }
+                    } else if (local) {
+                        Block_Destroy(local);
+                    }
+                }
+
+                // Verify that the parent's hash matches the orphan's prevHash before attaching.
+                bool parentMatches = false;
+                if (e->height == 0) {
+                    parentMatches = (Chain_Size(chain) == 0);
+                } else {
+                    block_t* parent = NULL;
+                    if (Chain_GetBlockCopy(chain, (size_t)parentIndex, &parent) && parent) {
+                        uint8_t parentHash[32];
+                        Block_CalculateHash(parent, parentHash);
+                        parentMatches = (memcmp(parentHash, e->block->header.prevHash, 32) == 0);
+                        Block_Destroy(parent);
+                    } else {
+                        parentMatches = false;
+                    }
+                }
+
+                if (!parentMatches) {
+                    // Parent exists but does not match this orphan's prevHash.
+                    size_t adopted = OrphanPool_TryAdoptBranch(chain, e->height);
+                    if (adopted > 0) {
+                        attached += adopted;
+                        madeProgress = true;
+                        n = DynArr_size(g_orphans);
+                        i = (size_t)-1;
+                        break;
+                    }
+
+                    continue;
+                }
+
+                // Try to add to chain
+                if (Chain_AddBlock(chain, e->block)) {
+                    attached++;
+                    madeProgress = true;
+                    // remove this entry
+                    DynArr_remove(g_orphans, i);
+                    // adjust indices
+                    n = DynArr_size(g_orphans);
+                    i = (size_t)-1; // reset outer loop
+                    break;
+                } else {
+                    // Chain_AddBlock rejected it (maybe invalid). Drop it.
+                    Block_Destroy(e->block);
+                    DynArr_remove(g_orphans, i);
+                    n = DynArr_size(g_orphans);
+                    i = (size_t)-1;
+                    madeProgress = true;
+                    break;
+                }
+            }
+        }
+    }
+
+    return attached;
+}

src/randomx/librx_wrapper.c

@@ -1,75 +0,0 @@
-#include <randomx/librx_wrapper.h>
-
-#include <string.h>
-#include <stdio.h>
-#include <stdlib.h>
-
-static randomx_cache* rxCache = NULL;
-static randomx_dataset* rxDataset = NULL;
-static randomx_vm* rxVm = NULL;
-
-bool RandomX_Init(const char* key, bool preferFullMemory) {
-    if (!key || rxCache || rxVm) {
-        return false;
-    }
-
-    const randomx_flags baseFlags = randomx_get_flags() | RANDOMX_FLAG_JIT;
-    randomx_flags vmFlags = baseFlags | RANDOMX_FLAG_FULL_MEM;
-
-    rxCache = randomx_alloc_cache(baseFlags);
-    if (!rxCache) {
-        return false;
-    }
-
-    randomx_init_cache(rxCache, key, strlen(key));
-
-    // Prefer full-memory mode. If dataset allocation fails, fall back to light mode.
-    if (preferFullMemory) {
-        rxDataset = randomx_alloc_dataset(vmFlags);
-        if (rxDataset) {
-            const unsigned long datasetItems = randomx_dataset_item_count();
-            randomx_init_dataset(rxDataset, rxCache, 0, datasetItems);
-            rxVm = randomx_create_vm(vmFlags, NULL, rxDataset);
-            if (rxVm) {
-                printf("RandomX initialized in full-memory mode\n");
-                return true;
-            }
-
-            randomx_release_dataset(rxDataset);
-            rxDataset = NULL;
-        }
-    }
-
-    vmFlags = baseFlags;
-    rxVm = randomx_create_vm(vmFlags, rxCache, NULL);
-    if (!rxVm) {
-        randomx_release_cache(rxCache);
-        rxCache = NULL;
-        return false;
-    }
-
-    printf("RandomX initialized in light mode\n");
-    return true;
-}
-
-void RandomX_Destroy() {
-    if (rxVm) {
-        randomx_destroy_vm(rxVm);
-        rxVm = NULL;
-    }
-    if (rxDataset) {
-        randomx_release_dataset(rxDataset);
-        rxDataset = NULL;
-    }
-    if (rxCache) {
-        randomx_release_cache(rxCache);
-        rxCache = NULL;
-    }
-}
-
-void RandomX_CalculateHash(const uint8_t* input, size_t inputLen, uint8_t* output) {
-    if (!rxVm || !input || !output) {
-        return;
-    }
-    randomx_calculate_hash(rxVm, input, inputLen, output);
-}

src/tcpd/tcpclient.c

@@ -0,0 +1,221 @@
+#ifndef _WIN32
+
+#include <tcpd/tcpclient.h>
+
+#include <errno.h>
+#include <numgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/select.h>
+
+static void* TcpClient_ThreadProc(void* arg) {
+    tcp_client_t* client = (tcp_client_t*)arg;
+    if (!client || !client->connection) {
+        return NULL;
+    }
+
+    tcp_connection_t* conn = client->connection;
+    unsigned char ioBuf[TCP_IO_BUFFER_SIZE];
+
+    while (1) {
+        ssize_t n = recv(conn->sockFd, ioBuf, sizeof(ioBuf), 0);
+        if (n == 0) {
+            break;
+        }
+        if (n < 0) {
+            if (errno == EINTR) {
+                continue;
+            }
+            break;
+        }
+
+        if (TcpConnection_FeedFramedData(conn, ioBuf, (size_t)n) != 0) {
+            break;
+        }
+    }
+
+    if (!TcpConnection_IsDisconnectNotified(conn) && conn->on_disconnect) {
+        TcpConnection_MarkDisconnectNotified(conn);
+        conn->on_disconnect(conn);
+    }
+
+    return NULL;
+}
+
+int TcpClient_Init(tcp_client_t* client) {
+    if (!client) {
+        return -1;
+    }
+
+    memset(client, 0, sizeof(*client));
+    client->connection = NULL;
+    client->peerBlockHeight = 0;
+    return 0;
+}
+
+void TcpClient_Destroy(tcp_client_t* client) {
+    if (!client) {
+        return;
+    }
+
+    TcpClient_Disconnect(client);
+}
+
+int TcpClient_Connect(
+    tcp_client_t* client,
+    const char* peerIp,
+    unsigned short peerPort,
+    void (*on_connect)(tcp_connection_t* conn),
+    void (*on_data)(tcp_connection_t* conn),
+    void (*on_disconnect)(tcp_connection_t* conn),
+    void* owner
+) {
+    if (!client || !peerIp) {
+        return -1;
+    }
+
+    if (client->connection) {
+        return -1;
+    }
+
+    int sockFd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockFd < 0) {
+        return -1;
+    }
+
+    struct sockaddr_in peerAddr;
+    memset(&peerAddr, 0, sizeof(peerAddr));
+    peerAddr.sin_family = AF_INET;
+    peerAddr.sin_port = htons(peerPort);
+
+    if (inet_pton(AF_INET, peerIp, &peerAddr.sin_addr) <= 0) {
+        close(sockFd);
+        return -1;
+    }
+
+    // Use non-blocking connect with a timeout to avoid long blocking in the CLI.
+    int flags = fcntl(sockFd, F_GETFL, 0);
+    if (flags == -1) flags = 0;
+    fcntl(sockFd, F_SETFL, flags | O_NONBLOCK);
+
+    int rc = connect(sockFd, (struct sockaddr*)&peerAddr, sizeof(peerAddr));
+    if (rc < 0) {
+        if (errno != EINPROGRESS) {
+            close(sockFd);
+            return -1;
+        }
+
+        // Wait up to 5 seconds for the socket to become writable (connected)
+        struct timeval tv;
+        tv.tv_sec = 5;
+        tv.tv_usec = 0;
+        fd_set wfds;
+        FD_ZERO(&wfds);
+        FD_SET(sockFd, &wfds);
+        int sel = select(sockFd + 1, NULL, &wfds, NULL, &tv);
+        if (sel <= 0) {
+            // timeout or error
+            if (sel == 0) {
+                errno = ETIMEDOUT;
+            }
+            close(sockFd);
+            return -1;
+        }
+
+        // Check for socket error
+        int so_error = 0;
+        socklen_t len = sizeof(so_error);
+        if (getsockopt(sockFd, SOL_SOCKET, SO_ERROR, &so_error, &len) < 0) {
+            close(sockFd);
+            return -1;
+        }
+        if (so_error != 0) {
+            errno = so_error;
+            close(sockFd);
+            return -1;
+        }
+    }
+
+    // Restore blocking mode
+    fcntl(sockFd, F_SETFL, flags & ~O_NONBLOCK);
+
+    tcp_connection_t* conn = (tcp_connection_t*)malloc(sizeof(*conn));
+    if (!conn) {
+        close(sockFd);
+        return -1;
+    }
+
+    if (TcpConnection_Init(conn, sockFd, &peerAddr, TCP_CONNECTION_ROLE_OUTBOUND) != 0) {
+        free(conn);
+        close(sockFd);
+        return -1;
+    }
+
+    conn->connectionId = random_four_byte();
+    conn->on_data = on_data;
+    conn->on_disconnect = on_disconnect;
+    conn->owner = owner;
+
+    client->connection = conn;
+    client->on_connect = on_connect;
+    client->on_data = on_data;
+    client->on_disconnect = on_disconnect;
+    client->owner = owner;
+
+    if (client->on_connect) {
+        client->on_connect(conn);
+    }
+
+    pthread_attr_t attr;
+    pthread_attr_init(&attr);
+    pthread_attr_setstacksize(&attr, TCP_THREAD_STACK_SIZE);
+
+    if (pthread_create(&conn->ioThread, &attr, TcpClient_ThreadProc, client) != 0) {
+        TcpConnection_Destroy(conn);
+        free(conn);
+        client->connection = NULL;
+        pthread_attr_destroy(&attr);
+        return -1;
+    }
+    pthread_attr_destroy(&attr);
+
+    return 0;
+}
+
+int TcpClient_Send(tcp_client_t* client, const void* data, size_t len) {
+    if (!client || !client->connection) {
+        return -1;
+    }
+
+    return TcpConnection_SendFramed(client->connection, data, len);
+}
+
+void TcpClient_Disconnect(tcp_client_t* client) {
+    if (!client || !client->connection) {
+        return;
+    }
+
+    tcp_connection_t* conn = client->connection;
+
+    TcpConnection_RequestClose(conn);
+
+    if (!pthread_equal(conn->ioThread, pthread_self())) {
+        pthread_join(conn->ioThread, NULL);
+    }
+
+    if (!TcpConnection_IsDisconnectNotified(conn) && conn->on_disconnect) {
+        TcpConnection_MarkDisconnectNotified(conn);
+        conn->on_disconnect(conn);
+    }
+
+    TcpConnection_Destroy(conn);
+    free(conn);
+
+    client->connection = NULL;
+}
+
+#endif

src/tcpd/tcpconnection.c

@@ -0,0 +1,264 @@
+#ifndef _WIN32
+
+#include <tcpd/tcpconnection.h>
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+int TcpConnection_Init(tcp_connection_t* conn, int sockFd, const struct sockaddr_in* peerAddr, tcp_connection_role_t role) {
+    if (!conn || sockFd < 0 || !peerAddr) {
+        return -1;
+    }
+
+    memset(conn, 0, sizeof(*conn));
+    conn->sockFd = sockFd;
+    conn->peerAddr = *peerAddr;
+    conn->role = role;
+
+    if (pthread_mutex_init(&conn->sendLock, NULL) != 0) {
+        return -1;
+    }
+
+    if (pthread_mutex_init(&conn->stateLock, NULL) != 0) {
+        pthread_mutex_destroy(&conn->sendLock);
+        return -1;
+    }
+
+    conn->closing = false;
+    conn->disconnectedNotified = false;
+    conn->dataBuf = NULL;
+    conn->dataBufLen = 0;
+    conn->dataBufCap = 0;
+
+    TcpConnection_ResetFramingState(conn);
+
+    return 0;
+}
+
+void TcpConnection_Destroy(tcp_connection_t* conn) {
+    if (!conn) {
+        return;
+    }
+
+    if (conn->sockFd >= 0) {
+        close(conn->sockFd);
+        conn->sockFd = -1;
+    }
+
+    free(conn->dataBuf);
+    conn->dataBuf = NULL;
+    conn->dataBufLen = 0;
+    conn->dataBufCap = 0;
+
+    free(conn->frameBuf);
+    conn->frameBuf = NULL;
+    conn->frameBytesRead = 0;
+
+    pthread_mutex_destroy(&conn->stateLock);
+    pthread_mutex_destroy(&conn->sendLock);
+}
+
+int TcpConnection_SetDataBuffer(tcp_connection_t* conn, const unsigned char* data, size_t len) {
+    if (!conn || (!data && len > 0)) {
+        return -1;
+    }
+
+    if (len > conn->dataBufCap) {
+        unsigned char* resized = (unsigned char*)realloc(conn->dataBuf, len);
+        if (!resized) {
+            return -1;
+        }
+
+        conn->dataBuf = resized;
+        conn->dataBufCap = len;
+    }
+
+    if (len > 0) {
+        memcpy(conn->dataBuf, data, len);
+    }
+    conn->dataBufLen = len;
+
+    return 0;
+}
+
+void TcpConnection_ResetFramingState(tcp_connection_t* conn) {
+    if (!conn) {
+        return;
+    }
+
+    memset(conn->headerBuf, 0, sizeof(conn->headerBuf));
+    conn->headerBytesRead = 0;
+    conn->expectedPayloadLen = 0;
+    conn->frameBytesRead = 0;
+
+    free(conn->frameBuf);
+    conn->frameBuf = NULL;
+}
+
+int TcpConnection_FeedFramedData(tcp_connection_t* conn, const unsigned char* input, size_t inputLen) {
+    if (!conn || (!input && inputLen > 0)) {
+        return -1;
+    }
+
+    size_t offset = 0;
+
+    while (offset < inputLen) {
+        if (conn->headerBytesRead < TCP_FRAME_HEADER_SIZE) {
+            size_t needed = TCP_FRAME_HEADER_SIZE - conn->headerBytesRead;
+            size_t take = (inputLen - offset < needed) ? (inputLen - offset) : needed;
+
+            memcpy(conn->headerBuf + conn->headerBytesRead, input + offset, take);
+            conn->headerBytesRead += take;
+            offset += take;
+
+            if (conn->headerBytesRead < TCP_FRAME_HEADER_SIZE) {
+                continue;
+            }
+
+            uint32_t beLen = 0;
+            memcpy(&beLen, conn->headerBuf, sizeof(beLen));
+            conn->expectedPayloadLen = ntohl(beLen);
+
+            if (conn->expectedPayloadLen > TCP_MAX_FRAME_PAYLOAD) {
+                TcpConnection_ResetFramingState(conn);
+                return -1;
+            }
+
+            if (conn->expectedPayloadLen == 0) {
+                if (TcpConnection_SetDataBuffer(conn, NULL, 0) != 0) {
+                    TcpConnection_ResetFramingState(conn);
+                    return -1;
+                }
+
+                if (conn->on_data) {
+                    conn->on_data(conn);
+                }
+
+                conn->headerBytesRead = 0;
+                conn->expectedPayloadLen = 0;
+                continue;
+            }
+
+            conn->frameBuf = (unsigned char*)malloc(conn->expectedPayloadLen);
+            if (!conn->frameBuf) {
+                TcpConnection_ResetFramingState(conn);
+                return -1;
+            }
+            conn->frameBytesRead = 0;
+        }
+
+        size_t frameRemaining = conn->expectedPayloadLen - conn->frameBytesRead;
+        size_t take = (inputLen - offset < frameRemaining) ? (inputLen - offset) : frameRemaining;
+
+        memcpy(conn->frameBuf + conn->frameBytesRead, input + offset, take);
+        conn->frameBytesRead += take;
+        offset += take;
+
+        if (conn->frameBytesRead == conn->expectedPayloadLen) {
+            if (TcpConnection_SetDataBuffer(conn, conn->frameBuf, conn->expectedPayloadLen) != 0) {
+                TcpConnection_ResetFramingState(conn);
+                return -1;
+            }
+
+            if (conn->on_data) {
+                conn->on_data(conn);
+            }
+
+            conn->headerBytesRead = 0;
+            conn->expectedPayloadLen = 0;
+            conn->frameBytesRead = 0;
+            free(conn->frameBuf);
+            conn->frameBuf = NULL;
+        }
+    }
+
+    return 0;
+}
+
+int TcpConnection_SendRaw(int sockFd, const void* data, size_t len) {
+    if (sockFd < 0 || (!data && len > 0)) {
+        return -1;
+    }
+
+    size_t totalSent = 0;
+    const unsigned char* ptr = (const unsigned char*)data;
+
+    while (totalSent < len) {
+        ssize_t sent = send(sockFd, ptr + totalSent, len - totalSent, 0);
+        if (sent < 0) {
+            if (errno == EINTR) {
+                continue;
+            }
+            return -1;
+        }
+        if (sent == 0) {
+            return -1;
+        }
+
+        totalSent += (size_t)sent;
+    }
+
+    return 0;
+}
+
+int TcpConnection_SendFramed(tcp_connection_t* conn, const void* payload, size_t payloadLen) {
+    if (!conn || (!payload && payloadLen > 0) || payloadLen > TCP_MAX_FRAME_PAYLOAD) {
+        return -1;
+    }
+
+    uint32_t beLen = htonl((uint32_t)payloadLen);
+
+    pthread_mutex_lock(&conn->sendLock);
+
+    int rc = TcpConnection_SendRaw(conn->sockFd, &beLen, sizeof(beLen));
+    if (rc == 0 && payloadLen > 0) {
+        rc = TcpConnection_SendRaw(conn->sockFd, payload, payloadLen);
+    }
+
+    pthread_mutex_unlock(&conn->sendLock);
+
+    return rc;
+}
+
+void TcpConnection_RequestClose(tcp_connection_t* conn) {
+    if (!conn) {
+        return;
+    }
+
+    pthread_mutex_lock(&conn->stateLock);
+    if (!conn->closing) {
+        conn->closing = true;
+        if (conn->sockFd >= 0) {
+            shutdown(conn->sockFd, SHUT_RDWR);
+        }
+    }
+    pthread_mutex_unlock(&conn->stateLock);
+}
+
+void TcpConnection_MarkDisconnectNotified(tcp_connection_t* conn) {
+    if (!conn) {
+        return;
+    }
+
+    pthread_mutex_lock(&conn->stateLock);
+    conn->disconnectedNotified = true;
+    pthread_mutex_unlock(&conn->stateLock);
+}
+
+bool TcpConnection_IsDisconnectNotified(tcp_connection_t* conn) {
+    if (!conn) {
+        return true;
+    }
+
+    pthread_mutex_lock(&conn->stateLock);
+    bool notified = conn->disconnectedNotified;
+    pthread_mutex_unlock(&conn->stateLock);
+
+    return notified;
+}
+
+#endif

src/tcpd/tcpserver.c

@@ -1,317 +1,359 @@
+#ifndef _WIN32
+
 #include <tcpd/tcpserver.h>
 
-TcpServer* TcpServer_Create() {
-    TcpServer* svr = (TcpServer*)malloc(sizeof(TcpServer));
+#include <errno.h>
+#include <numgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
 
-    if (!svr) {
-        perror("tcpserver - creation failure");
-        exit(1);
+static void TcpServer_RemoveClientByPtrUnlocked(tcp_server_t* svr, tcp_connection_t* cli) {
+    if (!svr || !svr->clientsArrPtr || !cli) {
+        return;
     }
 
+    size_t idx = Generic_FindClientInArrayByPtr(svr->clientsArrPtr, cli, svr->maxClients);
+    if (idx != SIZE_MAX) {
+        svr->clientsArrPtr[idx] = NULL;
+    }
+}
+
+static void* TcpServer_clientthreadprocess(void* ptr) {
+    tcpclient_thread_args* args = (tcpclient_thread_args*)ptr;
+    if (!args || !args->clientPtr || !args->serverPtr) {
+        free(args);
+        return NULL;
+    }
+
+    tcp_connection_t* cli = args->clientPtr;
+    tcp_server_t* svr = args->serverPtr;
+    free(args);
+
+    unsigned char ioBuf[TCP_IO_BUFFER_SIZE];
+
+    while (1) {
+        ssize_t n = recv(cli->sockFd, ioBuf, sizeof(ioBuf), 0);
+        if (n == 0) {
+            break;
+        }
+
+        if (n < 0) {
+            if (errno == EINTR) {
+                continue;
+            }
+            break;
+        }
+
+        if (TcpConnection_FeedFramedData(cli, ioBuf, (size_t)n) != 0) {
+            break;
+        }
+    }
+
+    TcpConnection_RequestClose(cli);
+
+    if (!TcpConnection_IsDisconnectNotified(cli) && cli->on_disconnect) {
+        TcpConnection_MarkDisconnectNotified(cli);
+        cli->on_disconnect(cli);
+    }
+
+    pthread_mutex_lock(&svr->clientsMutex);
+    TcpServer_RemoveClientByPtrUnlocked(svr, cli);
+    pthread_mutex_unlock(&svr->clientsMutex);
+
+    TcpConnection_Destroy(cli);
+    free(cli);
+
+    return NULL;
+}
+
+static void* TcpServer_threadprocess(void* ptr) {
+    tcp_server_t* svr = (tcp_server_t*)ptr;
+    if (!svr) {
+        return NULL;
+    }
+
+    while (svr->isRunning) {
+        struct sockaddr_in clientAddr;
+        socklen_t clientSize = sizeof(clientAddr);
+        int clientFd = accept(svr->sockFd, (struct sockaddr*)&clientAddr, &clientSize);
+
+        if (clientFd < 0) {
+            if (!svr->isRunning) {
+                break;
+            }
+            if (errno == EINTR) {
+                continue;
+            }
+            continue;
+        }
+
+        tcp_connection_t* heapCli = (tcp_connection_t*)malloc(sizeof(*heapCli));
+        if (!heapCli) {
+            close(clientFd);
+            continue;
+        }
+
+        if (TcpConnection_Init(heapCli, clientFd, &clientAddr, TCP_CONNECTION_ROLE_INBOUND) != 0) {
+            close(clientFd);
+            free(heapCli);
+            continue;
+        }
+
+        heapCli->connectionId = random_four_byte();
+        heapCli->on_data = svr->on_data;
+        heapCli->on_disconnect = svr->on_disconnect;
+        heapCli->owner = svr->owner;
+
+        pthread_mutex_lock(&svr->clientsMutex);
+
+        size_t insertIdx = SIZE_MAX;
+        for (size_t i = 0; i < svr->maxClients; ++i) {
+            if (svr->clientsArrPtr[i] == NULL) {
+                insertIdx = i;
+                break;
+            }
+        }
+
+        if (insertIdx == SIZE_MAX) {
+            pthread_mutex_unlock(&svr->clientsMutex);
+            struct linger so_linger;
+            so_linger.l_onoff = 1;
+            so_linger.l_linger = 0;
+            setsockopt(heapCli->sockFd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
+            TcpConnection_Destroy(heapCli);
+            free(heapCli);
+            continue;
+        }
+
+        svr->clientsArrPtr[insertIdx] = heapCli;
+        pthread_mutex_unlock(&svr->clientsMutex);
+
+        if (svr->on_connect) {
+            svr->on_connect(heapCli);
+        }
+
+        tcpclient_thread_args* arg = (tcpclient_thread_args*)malloc(sizeof(*arg));
+        if (!arg) {
+            TcpServer_Disconnect(svr, heapCli);
+            continue;
+        }
+
+        arg->clientPtr = heapCli;
+        arg->serverPtr = svr;
+
+        pthread_attr_t attr;
+        pthread_attr_init(&attr);
+        pthread_attr_setstacksize(&attr, TCP_THREAD_STACK_SIZE);
+
+        if (pthread_create(&heapCli->ioThread, &attr, TcpServer_clientthreadprocess, arg) != 0) {
+            free(arg);
+            TcpServer_Disconnect(svr, heapCli);
+            pthread_attr_destroy(&attr);
+            continue;
+        }
+        pthread_attr_destroy(&attr);
+    }
+
+    return NULL;
+}
+
+tcp_server_t* TcpServer_Create() {
+    tcp_server_t* svr = (tcp_server_t*)malloc(sizeof(*svr));
+    if (!svr) {
+        return NULL;
+    }
+
+    memset(svr, 0, sizeof(*svr));
     svr->sockFd = -1;
     svr->svrThread = 0;
-    svr->on_connect = NULL;
-    svr->on_data = NULL;
-    svr->on_disconnect = NULL;
-
-    svr->clients = 0;
+    svr->isRunning = 0;
+    svr->maxClients = 0;
     svr->clientsArrPtr = NULL;
 
+    if (pthread_mutex_init(&svr->clientsMutex, NULL) != 0) {
+        free(svr);
+        return NULL;
+    }
+
     return svr;
 }
 
-void TcpServer_Destroy(TcpServer* ptr) {
-    if (ptr) {
-        if (ptr->clientsArrPtr) {
-            for (size_t i = 0; i < ptr->clients; i++) {
-                if (ptr->clientsArrPtr[i]) {
-                    free(ptr->clientsArrPtr[i]);
-                }
-            }
+void TcpServer_Destroy(tcp_server_t* ptr) {
+    if (!ptr) {
+        return;
+    }
 
-            free(ptr->clientsArrPtr);
-        }
+    TcpServer_Stop(ptr);
 
+    free(ptr->clientsArrPtr);
+    ptr->clientsArrPtr = NULL;
+
+    pthread_mutex_destroy(&ptr->clientsMutex);
+    free(ptr);
+}
+
+void TcpServer_Init(tcp_server_t* ptr, unsigned short port, const char* addr) {
+    if (!ptr || !addr) {
+        return;
+    }
+
+    ptr->sockFd = socket(AF_INET, SOCK_STREAM, 0);
+    if (ptr->sockFd < 0) {
+        return;
+    }
+
+    ptr->opt = 1;
+    setsockopt(ptr->sockFd, SOL_SOCKET, SO_REUSEADDR, &ptr->opt, sizeof(int));
+
+    memset(&ptr->addr, 0, sizeof(ptr->addr));
+    ptr->addr.sin_family = AF_INET;
+    ptr->addr.sin_port = htons(port);
+    inet_pton(AF_INET, addr, &ptr->addr.sin_addr);
+
+    if (bind(ptr->sockFd, (struct sockaddr*)&ptr->addr, sizeof(ptr->addr)) < 0) {
         close(ptr->sockFd);
-        free(ptr);
+        ptr->sockFd = -1;
     }
 }
 
-void TcpServer_Init(TcpServer* ptr, unsigned short port, const char* addr) {
-    if (ptr) {
-        // Create socket
-        ptr->sockFd = socket(AF_INET, SOCK_STREAM, 0);
-        if (ptr->sockFd < 0) {
-            perror("tcpserver - socket");
-            exit(EXIT_FAILURE);
-        }
+void TcpServer_Start(tcp_server_t* ptr, int maxcons) {
+    if (!ptr || ptr->sockFd < 0 || maxcons <= 0 || ptr->isRunning) {
+        return;
+    }
 
-        // Allow quick port resue
-        ptr->opt = 1;
-        setsockopt(ptr->sockFd, SOL_SOCKET, SO_REUSEADDR, &ptr->opt, sizeof(int));
+    if (listen(ptr->sockFd, maxcons) < 0) {
+        return;
+    }
 
-        // Fill address structure
-        memset(&ptr->addr, 0, sizeof(ptr->addr));
-        ptr->addr.sin_family = AF_INET;
-        ptr->addr.sin_port = htons(port);
-        inet_pton(AF_INET, addr, &ptr->addr.sin_addr);
+    pthread_mutex_lock(&ptr->clientsMutex);
 
-        // Bind
-        if (bind(ptr->sockFd, (struct sockaddr*)&ptr->addr, sizeof(ptr->addr)) < 0) {
-            perror("tcpserver - bind");
-            close(ptr->sockFd);
-            exit(EXIT_FAILURE);
-        }
+    ptr->maxClients = (size_t)maxcons;
+    ptr->clientsArrPtr = (tcp_connection_t**)malloc(sizeof(tcp_connection_t*) * ptr->maxClients);
+    if (!ptr->clientsArrPtr) {
+        ptr->maxClients = 0;
+        pthread_mutex_unlock(&ptr->clientsMutex);
+        return;
+    }
+
+    for (size_t i = 0; i < ptr->maxClients; ++i) {
+        ptr->clientsArrPtr[i] = NULL;
+    }
+
+    ptr->isRunning = 1;
+    pthread_mutex_unlock(&ptr->clientsMutex);
+
+    if (pthread_create(&ptr->svrThread, NULL, TcpServer_threadprocess, ptr) != 0) {
+        pthread_mutex_lock(&ptr->clientsMutex);
+        ptr->isRunning = 0;
+        free(ptr->clientsArrPtr);
+        ptr->clientsArrPtr = NULL;
+        ptr->maxClients = 0;
+        pthread_mutex_unlock(&ptr->clientsMutex);
     }
 }
 
-// Do not call outside of func.
-void* TcpServer_clientthreadprocess(void* ptr) {
-    if (!ptr) {
-        perror("Client ptr is null!\n");
-        return NULL;
+void TcpServer_Stop(tcp_server_t* ptr) {
+    if (!ptr || !ptr->isRunning) {
+        return;
     }
 
-    tcpclient_thread_args* args = (tcpclient_thread_args*)ptr;
+    ptr->isRunning = 0;
 
-    TcpClient* cli = args->clientPtr;
-    TcpServer* svr = args->serverPtr;
-
-    if (args) {
-        free(args);
+    if (ptr->sockFd >= 0) {
+        shutdown(ptr->sockFd, SHUT_RDWR);
+        close(ptr->sockFd);
+        ptr->sockFd = -1;
     }
 
-    while (1) {
-        memset(cli->dataBuf, 0, MTU); // Reset buffer
-        ssize_t n = recv(cli->clientFd, cli->dataBuf, MTU, 0);
-        cli->dataBufLen = n;
-
-        if (n == 0) {
-            break; // Client disconnected
-        } else if (n > 0) {
-            if (cli->on_data) {
-                cli->on_data(cli);
-            }
-        }
-
-        pthread_testcancel(); // Check for thread death
-    }
-
-    cli->on_disconnect(cli);
-
-    // Close on exit
-    close(cli->clientFd);
-
-    // Destroy
-    TcpClient** arr = svr->clientsArrPtr;
-    size_t idx = Generic_FindClientInArrayByPtr(arr, cli, svr->clients);
-    if (idx != SIZE_MAX) {
-        if (arr[idx]) {
-            free(arr[idx]);
-            arr[idx] = NULL;
-        }
-    } else {
-        perror("tcpserver (client thread) - something already freed the client!");
-    }
-    
-    //free(ptr);
-
-    return NULL;
-}
-
-// Do not call outside of func.
-void* TcpServer_threadprocess(void* ptr) {
-    if (!ptr) {
-        perror("Client ptr is null!\n");
-        return NULL;
-    }
-    
-    TcpServer* svr = (TcpServer*)ptr;
-    while (1) {
-        TcpClient tempclient;
-        socklen_t clientsize = sizeof(tempclient.clientAddr);
-        int client = accept(svr->sockFd, (struct sockaddr*)&tempclient.clientAddr, &clientsize);
-        if (client >= 0) {
-            tempclient.clientFd = client;
-            tempclient.on_data = svr->on_data;
-            tempclient.on_disconnect = svr->on_disconnect;
-
-            // I'm lazy, so I'm just copying the data for now (I should probably make this a better way)
-            TcpClient* heapCli = (TcpClient*)malloc(sizeof(TcpClient));
-            if (!heapCli) {
-                perror("tcpserver - client failed to allocate");
-                exit(EXIT_FAILURE); // Wtf just happened???
-            }
-
-            heapCli->clientAddr = tempclient.clientAddr;
-            heapCli->clientFd = tempclient.clientFd;
-            heapCli->on_data = tempclient.on_data;
-            heapCli->on_disconnect = tempclient.on_disconnect;
-            heapCli->clientId = random_four_byte();
-            heapCli->dataBufLen = 0;
-
-            size_t i;
-            for (i = 0; i < svr->clients; i++) {
-                if (svr->clientsArrPtr[i] == NULL) {
-                    // Make use of that space
-                    svr->clientsArrPtr[i] = heapCli; // We have now transfered the ownership :)
-                    break;
-                }
-            }
-
-            if (i == svr->clients) {
-                // Not found
-                // RST; Thread doesn't exist yet
-                struct linger so_linger;
-                so_linger.l_onoff = 1;
-                so_linger.l_linger = 0;
-                setsockopt(heapCli->clientFd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
-                close(heapCli->clientFd);
-                
-                free(heapCli);
-                heapCli = NULL;
-                //svr->clientsArrPtr[i] = NULL;
-
-                continue;
-            }
-            
-            tcpclient_thread_args* arg = (tcpclient_thread_args*)malloc(sizeof(tcpclient_thread_args));
-            arg->clientPtr = heapCli;
-            arg->serverPtr = svr;
-
-            if (svr->on_connect) {
-                svr->on_connect(heapCli);
-            }
-            
-            pthread_create(&heapCli->clientThread, NULL, TcpServer_clientthreadprocess, arg);
-            pthread_detach(heapCli->clientThread); // May not work :(
-        }
-
-        pthread_testcancel(); // Check for thread death
-    }
-
-    return NULL;
-}
-
-void TcpServer_Start(TcpServer* ptr, int maxcons) {
-    if (ptr) {
-        if (listen(ptr->sockFd, maxcons) < 0) {
-            perror("tcpserver - listen");
-            close(ptr->sockFd);
-            exit(EXIT_FAILURE);
-        }
-
-        ptr->clients = maxcons;
-        ptr->clientsArrPtr = (TcpClient**)malloc(sizeof(TcpClient*) * maxcons);
-
-        if (!ptr->clientsArrPtr) {
-            perror("tcpserver - allocation of client space fatally errored");
-            exit(EXIT_FAILURE);
-        }
-
-        // Fucking null out everything
-        for (int i = 0; i < maxcons; i++) {
-            ptr->clientsArrPtr[i] = NULL;
-        }
-    }
-
-    // Spawn server thread
-    pthread_create(&ptr->svrThread, NULL, TcpServer_threadprocess, ptr);
-}
-
-void TcpServer_Stop(TcpServer* ptr) {
-    if (ptr && ptr->svrThread != 0) {
-        // Stop server
-        pthread_cancel(ptr->svrThread);
+    if (ptr->svrThread != 0 && !pthread_equal(ptr->svrThread, pthread_self())) {
         pthread_join(ptr->svrThread, NULL);
+    }
+    ptr->svrThread = 0;
 
-        // Disconnect clients
-        for (size_t i = 0; i < ptr->clients; i++) {
-            TcpClient* cliPtr = ptr->clientsArrPtr[i];
-            if (cliPtr) {
-                close(cliPtr->clientFd);
-                pthread_cancel(cliPtr->clientThread);
-            }
+    pthread_mutex_lock(&ptr->clientsMutex);
+    size_t maxClients = ptr->maxClients;
+    tcp_connection_t** local = ptr->clientsArrPtr;
+    pthread_mutex_unlock(&ptr->clientsMutex);
+
+    for (size_t i = 0; i < maxClients; ++i) {
+        tcp_connection_t* cli = local[i];
+        if (!cli) {
+            continue;
         }
 
-        ptr->svrThread = 0;
+        TcpConnection_RequestClose(cli);
+    }
+
+    for (size_t i = 0; i < maxClients; ++i) {
+        tcp_connection_t* cli = local[i];
+        if (!cli) {
+            continue;
+        }
+
+        if (!pthread_equal(cli->ioThread, pthread_self())) {
+            pthread_join(cli->ioThread, NULL);
+        }
+    }
+
+    pthread_mutex_lock(&ptr->clientsMutex);
+    free(ptr->clientsArrPtr);
+    ptr->clientsArrPtr = NULL;
+    ptr->maxClients = 0;
+    pthread_mutex_unlock(&ptr->clientsMutex);
+}
+
+int TcpServer_Send(tcp_server_t* ptr, tcp_connection_t* cli, const void* data, size_t len) {
+    if (!ptr || !cli || !data || len == 0) {
+        return -1;
+    }
+
+    return TcpConnection_SendFramed(cli, data, len);
+}
+
+void Generic_SendSocket(int sock, const void* data, size_t len) {
+    (void)TcpConnection_SendRaw(sock, data, len);
+}
+
+void TcpServer_Disconnect(tcp_server_t* ptr, tcp_connection_t* cli) {
+    if (!ptr || !cli) {
+        return;
+    }
+
+    TcpConnection_RequestClose(cli);
+
+    if (!pthread_equal(cli->ioThread, pthread_self())) {
+        pthread_join(cli->ioThread, NULL);
     }
 }
 
-void TcpServer_Send(TcpServer* ptr, TcpClient* cli, void* data, size_t len) {
-    if (ptr && cli && data && len > 0) {
-        size_t sent = 0;
-        while (sent < len) {
-            // Ensure that all data is sent. TCP can split sends.
-            ssize_t n = send(cli->clientFd, (unsigned char*)data + sent, len - sent, 0);
-            if (n < 0) {
-                perror("tcpserver - send error");
-                break;
-            }
-            sent += n;
-        }
+void TcpServer_KillClient(tcp_server_t* ptr, tcp_connection_t* cli) {
+    if (!ptr || !cli) {
+        return;
     }
+
+    struct linger so_linger;
+    so_linger.l_onoff = 1;
+    so_linger.l_linger = 0;
+    setsockopt(cli->sockFd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
+
+    TcpServer_Disconnect(ptr, cli);
 }
 
-void Generic_SendSocket(int sock, void* data, size_t len) {
-    if (sock > 0 && data && len > 0) {
-        size_t sent = 0;
-        while (sent < len) {
-            ssize_t n = send(sock, (unsigned char*)data + sent, len - sent, 0);
-            if (n < 0) {
-                perror("generic - send socket error");
-                break;
-            }
-            sent += n;
-        }
+size_t Generic_FindClientInArrayByPtr(tcp_connection_t** arr, tcp_connection_t* ptr, size_t len) {
+    if (!arr || !ptr) {
+        return SIZE_MAX;
     }
-}
 
-void TcpServer_Disconnect(TcpServer* ptr, TcpClient* cli) {
-    if (ptr && cli) {
-        close(cli->clientFd);
-        pthread_cancel(cli->clientThread);
-
-        size_t idx = Generic_FindClientInArrayByPtr(ptr->clientsArrPtr, cli, ptr->clients);
-        if (idx != SIZE_MAX) {
-            if (ptr->clientsArrPtr[idx]) {
-                free(ptr->clientsArrPtr[idx]);
-            }
-            ptr->clientsArrPtr[idx] = NULL;
-        } else {
-            perror("tcpserver - didn't find client to disconnect in array!");
-        }
-    }
-}
-
-void TcpServer_KillClient(TcpServer* ptr, TcpClient* cli) {
-    if (ptr && cli) {
-        // RST the connection
-        struct linger so_linger;
-        so_linger.l_onoff = 1;
-        so_linger.l_linger = 0;
-        setsockopt(cli->clientFd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
-        close(cli->clientFd);
-        pthread_cancel(cli->clientThread);
-        
-        size_t idx = Generic_FindClientInArrayByPtr(ptr->clientsArrPtr, cli, ptr->clients);
-        if (idx != SIZE_MAX) {
-            if (ptr->clientsArrPtr[idx]) {
-                free(ptr->clientsArrPtr[idx]);
-            }
-            ptr->clientsArrPtr[idx] = NULL;
-        } else {
-            perror("tcpserver - didn't find client to kill in array!");
-        }
-    }
-}
-
-size_t Generic_FindClientInArrayByPtr(TcpClient** arr, TcpClient* ptr, size_t len) {
-    for (size_t i = 0; i < len; i++) {
+    for (size_t i = 0; i < len; ++i) {
         if (arr[i] == ptr) {
             return i;
         }
     }
 
-    return SIZE_MAX; // Returns max unsigned, likely improbable to be correct
+    return SIZE_MAX;
 }
+
+#endif

src/txmempool.c

@@ -0,0 +1,71 @@
+#include <txmempool.h>
+
+khash_t(tx_mempool_map_m)* txMempool = NULL;
+
+void TxMempool_Init() {
+    txMempool = kh_init(tx_mempool_map_m);
+}
+
+int TxMempool_Insert(signed_transaction_t tx) {
+    if (!txMempool) { return -1; }
+
+    uint8_t txHash[32];
+    Transaction_CalculateHash(&tx, txHash);
+
+    key32_t key;
+    memcpy(key.bytes, txHash, 32);
+
+    int ret;
+    khiter_t k = kh_put(tx_mempool_map_m, txMempool, key, &ret);
+    if (k == kh_end(txMempool)) {
+        return -1;
+    }
+
+    kh_value(txMempool, k) = tx;
+
+    return ret;
+}
+
+bool TxMempool_Lookup(uint8_t* txHash, signed_transaction_t* out) {
+    if (!txMempool || !txHash || !out) { return false; }
+    
+    key32_t key;
+    memcpy(key.bytes, txHash, 32);
+
+    khiter_t k = kh_get(tx_mempool_map_m, txMempool, key);
+    if (k != kh_end(txMempool)) {
+        signed_transaction_t tx = kh_value(txMempool, k);
+        memcpy(out, &tx, sizeof(signed_transaction_t));
+        return true;
+    }
+
+    return false;
+}
+
+void TxMempool_Print() {
+    if (!txMempool) { return; }
+
+    khiter_t k;
+    for (k = kh_begin(txMempool); k != kh_end(txMempool); ++k) {
+        if (kh_exist(txMempool, k)) {
+            signed_transaction_t tx = kh_val(txMempool, k);
+            char senderHex[65];
+            char recipient1Hex[65];
+            char recipient2Hex[65];
+            AddressToHexString(tx.transaction.senderAddress, senderHex);
+            AddressToHexString(tx.transaction.recipientAddress1, recipient1Hex);
+            AddressToHexString(tx.transaction.recipientAddress2, recipient2Hex);
+            printf("TX in mempool: sender=%s recipient1=%s recipient2=%s amount1=%llu amount2=%llu fee=%llu\n",
+                senderHex, recipient1Hex, recipient2Hex,
+                (unsigned long long)tx.transaction.amount1,
+                (unsigned long long)tx.transaction.amount2,
+                (unsigned long long)tx.transaction.fee);
+        }
+    }
+}
+
+void TxMempool_Destroy() {
+    if (txMempool) {
+        kh_destroy(tx_mempool_map_m, txMempool);
+    }
+}