todo update, forward block broadcasts, optional echo connect

include/constants.h

@@ -12,6 +12,7 @@
 // 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).
 

include/nets/net_node.h

@@ -14,6 +14,7 @@
 #include <stddef.h>
 
 #include <dynarr.h>
+#include <dynset.h>
 
 #include <pthread.h>
 
@@ -25,6 +26,12 @@ 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);
@@ -51,6 +58,10 @@ int Node_ConnectStartupPeers(net_node_t* node, const char** ips, const unsigned
 
 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);