Start IPv6 - Lord help me

TODO.txt

@@ -14,6 +14,9 @@ Check if Block FullVerify is actually verifying fully (not missing any condition
 
 A loophole in the reorg penalty system could potentially exist where someone broadcasts blocks one-at-a-time. Determine a solution to this.
 
+IPv6 support for the P2P node. Come on guys, it's 2026. RFC 2460 was in 1998. It's about time.
+    Like if someone is behind NAT, fine, workable. CGNAT? Lmao good luck.
+
 TO TEST:
 Implement Horizen's "Reorg Penalty" system to make it harder for the young chain to be attacked by a powerful miner.
 

include/tcpd/tcpconnection.h

@@ -19,8 +19,17 @@ typedef enum {
 typedef struct tcp_connection_t tcp_connection_t;
 
 struct tcp_connection_t {
+    // TODO: We should make it so only ONE of this needs to be available. 
+    // Because of my temporary "I just need something that works" horseshit that I'm about to write, you'll need IPv4 and IPv6 is optional.
+    // Note to self: Don't pull an IETF and some "NAT exists, we're fine" bullshit, because if we end up with our eqvivalent of Teredo or CGNAT, I'm gonna be fucking pissed.
+    // And no, the solution isn't "eh, just bind to 0.0.0.0 and ignore it", because if we do that, we'll inevitably end up with a host that only has IPv6 and then we'll be fucked.
+    // Honestly, I'm proud of whoever runs IPv6-only. Brave soul.
     int sockFd;
     struct sockaddr_in peerAddr;
+#ifdef USE_IPV6
+    int sockFd6; // For IPv6 support
+    struct sockaddr_in6 peerAddr6; // For IPv6 support
+#endif
     uint32_t connectionId;
     tcp_connection_role_t role;
 
@@ -54,6 +63,7 @@ int TcpConnection_SetDataBuffer(tcp_connection_t* conn, const unsigned char* dat
 void TcpConnection_ResetFramingState(tcp_connection_t* conn);
 int TcpConnection_FeedFramedData(tcp_connection_t* conn, const unsigned char* input, size_t inputLen);
 
+// This just takes a socket ID, so it's independent from the v4/v6 stuff. It works for both.
 int TcpConnection_SendRaw(int sockFd, const void* data, size_t len);
 int TcpConnection_SendFramed(tcp_connection_t* conn, const void* payload, size_t payloadLen);
 

include/tcpd/tcpserver.h

@@ -11,7 +11,12 @@
 typedef struct {
     int sockFd;
     struct sockaddr_in addr;
+#ifdef USE_IPV6
+    int sockFd6; // IPv6 support
+    struct sockaddr_in6 addr6; // IPv6 support
+#endif
     int opt;
+    int opt6; // IPv6 support
     int isRunning;
     void* owner;
 

src/tcpd/tcpconnection.c

@@ -214,10 +214,26 @@ int TcpConnection_SendFramed(tcp_connection_t* conn, const void* payload, size_t
 
     pthread_mutex_lock(&conn->sendLock);
 
+#ifdef USE_IPV6
+    int sock;
+    if (conn->sockFd6 >= 0) {
+        // IPv6 is available, attempt to send on it. If it fails, we'll fall back to IPv4 if available.
+        sock = conn->sockFd6;
+    } else {
+        // IPv4 fallback
+        sock = conn->sockFd;
+    }
+
+    int rc = TcpConnection_SendRaw(sock, &beLen, sizeof(beLen));
+    if (rc == 0 && payloadLen > 0) {
+        rc = TcpConnection_SendRaw(sock, payload, payloadLen);
+    }
+#else
     int rc = TcpConnection_SendRaw(conn->sockFd, &beLen, sizeof(beLen));
     if (rc == 0 && payloadLen > 0) {
         rc = TcpConnection_SendRaw(conn->sockFd, payload, payloadLen);
     }
+#endif
 
     pthread_mutex_unlock(&conn->sendLock);
 
@@ -235,6 +251,11 @@ void TcpConnection_RequestClose(tcp_connection_t* conn) {
         if (conn->sockFd >= 0) {
             shutdown(conn->sockFd, SHUT_RDWR);
         }
+#ifdef USE_IPV6
+        if (conn->sockFd6 >= 0) {
+            shutdown(conn->sockFd6, SHUT_RDWR);
+        }
+#endif
     }
     pthread_mutex_unlock(&conn->stateLock);
 }

src/tcpd/tcpserver.c

@@ -172,6 +172,9 @@ tcp_server_t* TcpServer_Create() {
     svr->isRunning = 0;
     svr->maxClients = 0;
     svr->clientsArrPtr = NULL;
+#ifdef USE_IPV6
+    svr->sockFd6 = -1;
+#endif
 
     if (pthread_mutex_init(&svr->clientsMutex, NULL) != 0) {
         free(svr);
@@ -217,6 +220,28 @@ void TcpServer_Init(tcp_server_t* ptr, unsigned short port, const char* addr) {
         close(ptr->sockFd);
         ptr->sockFd = -1;
     }
+
+#ifdef USE_IPV6
+    // IPv6 support
+    ptr->sockFd6 = socket(AF_INET6, SOCK_STREAM, 0);
+    if (ptr->sockFd6 >= 0) {
+        ptr->opt6 = 1;
+        setsockopt(ptr->sockFd6, SOL_SOCKET, SO_REUSEADDR, &ptr->opt6, sizeof(int));
+        memset(&ptr->addr6, 0, sizeof(ptr->addr6));
+        ptr->addr6.sin6_family = AF_INET6;
+        ptr->addr6.sin6_port = htons(port);
+        inet_pton(AF_INET6, addr, &ptr->addr6.sin6_addr);
+        if (bind(ptr->sockFd6, (struct sockaddr*)&ptr->addr6, sizeof(ptr->addr6)) < 0) {
+            close(ptr->sockFd6);
+            ptr->sockFd6 = -1;
+        }
+    } else {
+        ptr->sockFd6 = -1; // IPv6 is optional, so if it isn't available, we just set it to -1
+    }
+#else
+    // Safety for my future "I forgot the ifdef guard" self
+    ptr->sockFd6 = -1; // IPv6 not supported in this build
+#endif
 }
 
 void TcpServer_Start(tcp_server_t* ptr, int maxcons) {
@@ -228,6 +253,15 @@ void TcpServer_Start(tcp_server_t* ptr, int maxcons) {
         return;
     }
 
+#ifdef USE_IPV6
+    if (ptr->sockFd6 >= 0) {
+        if (listen(ptr->sockFd6, maxcons) < 0) {
+            close(ptr->sockFd6);
+            ptr->sockFd6 = -1;
+        }
+    }
+#endif
+
     pthread_mutex_lock(&ptr->clientsMutex);
 
     ptr->maxClients = (size_t)maxcons;
@@ -268,6 +302,14 @@ void TcpServer_Stop(tcp_server_t* ptr) {
         ptr->sockFd = -1;
     }
 
+#ifdef USE_IPV6
+    if (ptr->sockFd6 >= 0) {
+        shutdown(ptr->sockFd6, SHUT_RDWR);
+        close(ptr->sockFd6);
+        ptr->sockFd6 = -1;
+    }
+#endif
+
     if (ptr->svrThread != 0 && !pthread_equal(ptr->svrThread, pthread_self())) {
         pthread_join(ptr->svrThread, NULL);
     }
@@ -339,6 +381,12 @@ void TcpServer_KillClient(tcp_server_t* ptr, tcp_connection_t* cli) {
     so_linger.l_linger = 0;
     setsockopt(cli->sockFd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
 
+#ifdef USE_IPV6
+    if (cli->sockFd6 >= 0) {
+        setsockopt(cli->sockFd6, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
+    }
+#endif
+
     TcpServer_Disconnect(ptr, cli);
 }