High priority and critical issues

src/client/main.cpp

@@ -5,6 +5,7 @@
 #include <asio.hpp>
 #include <csignal>
 #include <iostream>
+#include <filesystem>
 #include <columnlynx/common/utils.hpp>
 #include <columnlynx/common/panic_handler.hpp>
 #include <columnlynx/client/net/tcp/tcp_client.hpp>
@@ -90,7 +91,20 @@ int main(int argc, char** argv) {
         std::string configPath = optionsObj["config-dir"].as<std::string>();
         const char* envConfigPath = std::getenv("COLUMNLYNX_CONFIG_DIR");
         if (envConfigPath != nullptr) {
-            configPath = std::string(envConfigPath);
+            // Validate and canonicalize environment-provided path
+            try {
+                namespace fs = std::filesystem;
+                std::error_code ec;
+                fs::path candidate(envConfigPath);
+                fs::path abs = fs::absolute(candidate, ec);
+                if (!ec) {
+                    configPath = abs.string();
+                } else {
+                    warn(std::string("Invalid COLUMNLYNX_CONFIG_DIR value: ") + envConfigPath + " - using default");
+                }
+            } catch (const std::exception& e) {
+                warn(std::string("Failed to canonicalize COLUMNLYNX_CONFIG_DIR: ") + e.what());
+            }
         }
 
         if (configPath.back() != '/' && configPath.back() != '\\') {

src/client/net/tcp/tcp_client.cpp

@@ -159,7 +159,13 @@ namespace ColumnLynx::Net::TCP {
     void TCPClient::mHandleMessage(ServerMessageType type, const std::string& data) {
         switch (type) {
             case ServerMessageType::HANDSHAKE_IDENTIFY: {
-                    std::memcpy(mServerPublicKey, data.data(), std::min(data.size(), sizeof(mServerPublicKey)));
+                    if (data.size() != sizeof(mServerPublicKey)) {
+                        Utils::warn("HANDSHAKE_IDENTIFY has invalid size: " + std::to_string(data.size()));
+                        disconnect();
+                        return;
+                    }
+
+                    std::memcpy(mServerPublicKey, data.data(), sizeof(mServerPublicKey));
                     std::string hexServerPub = Utils::bytesToHexString(mServerPublicKey, 32);
                     Utils::log("Received server identity. Public Key: " + hexServerPub);
 
@@ -188,7 +194,13 @@ namespace ColumnLynx::Net::TCP {
                 {
                     // Verify the signature
                     Signature sig{};
-                    std::memcpy(sig.data(), data.data(), std::min(data.size(), sig.size()));
+                    if (data.size() != sig.size()) {
+                        Utils::warn("HANDSHAKE_CHALLENGE_RESPONSE has invalid size: " + std::to_string(data.size()));
+                        disconnect();
+                        return;
+                    }
+
+                    std::memcpy(sig.data(), data.data(), sig.size());
                     if (Utils::LibSodiumWrapper::verifyMessage(mSubmittedChallenge.data(), mSubmittedChallenge.size(), sig, mServerPublicKey)) {
                         Utils::log("Challenge response verified successfully.");
                         

src/client/net/udp/udp_client.cpp

@@ -73,7 +73,7 @@ namespace ColumnLynx::Net::UDP {
             reinterpret_cast<uint8_t*>(&hdr) + sizeof(UDPPacketHeader)
         );
         uint32_t sessionID = static_cast<uint32_t>(ClientSession::getInstance().getSessionID());
-        uint32_t sessionIDNet = sessionID;
+        uint32_t sessionIDNet = htonl(sessionID);
         packet.insert(packet.end(),
             reinterpret_cast<uint8_t*>(&sessionIDNet),
             reinterpret_cast<uint8_t*>(&sessionIDNet) + sizeof(uint32_t)
@@ -136,9 +136,24 @@ namespace ColumnLynx::Net::UDP {
         }
 
         // Decrypt payload
+        // Extract ciphertext safely
+        size_t headerLen = sizeof(UDPPacketHeader) + sizeof(uint32_t);
+        if (bytes < headerLen) {
+            Utils::warn("UDP Client received packet too small after header check.");
+            return;
+        }
+
+        size_t ciphertextLen = bytes - headerLen;
+        // Enforce reasonable maximum (UDP payload practical limit)
+        const size_t MAX_UDP_PAYLOAD = 65507; // 65535 - UDP/IP headers
+        if (ciphertextLen > MAX_UDP_PAYLOAD) {
+            Utils::warn("UDP Client received packet with excessive payload size: " + std::to_string(ciphertextLen));
+            return;
+        }
+
         std::vector<uint8_t> ciphertext(
-            mRecvBuffer.begin() + sizeof(UDPPacketHeader) + sizeof(uint32_t),
-            mRecvBuffer.begin() + bytes
+            mRecvBuffer.begin() + headerLen,
+            mRecvBuffer.begin() + headerLen + ciphertextLen
         );
 
         if (ClientSession::getInstance().getAESKey().empty()) {