From 7befa753900bc9b4bceef627e164f30ce00520a4 Mon Sep 17 00:00:00 2001
From: Jitpanu Maneeratpongsuk <jitpanu.maneeratpongsuk@rwth-aachen.de>
Date: Thu, 9 Jan 2025 15:10:25 +0000
Subject: [PATCH] fix: Add reconnect attempt after the connection is broken.

Move the establishment of tcp connection out of socket_start so that it will not block other node.

Signed-off-by: Jitpanu Maneeratpongsuk <jitpanu.maneeratpongsuk@rwth-aachen.de>
---
 include/villas/nodes/socket.hpp |  3 ++
 lib/nodes/socket.cpp            | 85 +++++++++++++++++++--------------
 2 files changed, 51 insertions(+), 37 deletions(-)

diff --git a/include/villas/nodes/socket.hpp b/include/villas/nodes/socket.hpp
index 671d508f4..1c78de648 100644
--- a/include/villas/nodes/socket.hpp
+++ b/include/villas/nodes/socket.hpp
@@ -24,6 +24,7 @@ struct Socket {
   int sd; // The socket descriptor
   int clt_sd; // TCP client socket descriptor
   int verify_source; // Verify the source address of incoming packets against socket::remote.
+  bool tcp_connect = false; // TCP connection status bit
 
   enum SocketLayer
       layer; // The OSI / IP layer which should be used for this socket
@@ -69,6 +70,8 @@ int socket_read(NodeCompat *n, struct Sample *const smps[], unsigned cnt);
 
 int socket_parse(NodeCompat *n, json_t *json);
 
+void socket_tcp_connection(NodeCompat *n, Socket *s);
+
 char *socket_print(NodeCompat *n);
 
 } // namespace node
diff --git a/lib/nodes/socket.cpp b/lib/nodes/socket.cpp
index 47983df17..6050c1208 100644
--- a/lib/nodes/socket.cpp
+++ b/lib/nodes/socket.cpp
@@ -28,7 +28,7 @@
 #include <villas/kernel/nl.hpp>
 #endif // WITH_NETEM
 
-#define MAX_CONNECTION_RETRIES 5
+#define MAX_CONNECTION_RETRIES 40
 #define RETRIES_DELAY 2
 
 using namespace villas;
@@ -249,43 +249,11 @@ int villas::node::socket_start(NodeCompat *n) {
     addrlen = sizeof(s->in.saddr);
   }
 
-  if (s->layer == SocketLayer::TCP_CLIENT) {
-    // Attempt to connect to TCP server.
-    int retries = 0;
-    while (retries < MAX_CONNECTION_RETRIES) {
-      n->logger->info("Attempting to connect to server: attempt={}...", retries + 1);
-      ret = connect(s->sd, (struct sockaddr *)&s->out.saddr, addrlen);
-      if (ret == 0) {
-        break;
-      } else {
-        retries++;
-        if (retries < MAX_CONNECTION_RETRIES) {
-          sleep(RETRIES_DELAY);
-        }
-      }
-    }
-
-  } else {
+  if (s->layer != SocketLayer::TCP_CLIENT)
     ret = bind(s->sd, (struct sockaddr *)&s->in.saddr, addrlen);
-  }
 
-  if (ret < 0) {
-    if (s->layer == SocketLayer::TCP_CLIENT) {
-      throw SystemError("Failed to connect to TCP server");
-    } else {
-      throw SystemError("Failed to bind socket");
-    }
-  }
-
-  // TCP Server listen for client connection.
-  if (s->layer == SocketLayer::TCP_SERVER) {
-    listen(s->sd, 5);
-    // Accept client connection and get client socket descriptor.
-    s->clt_sd = accept(s->sd, nullptr, nullptr);
-    if (s->clt_sd < 0) {
-      throw SystemError("Failed to accept connection");
-    }
-  }
+  if (ret < 0)
+    throw SystemError("Failed to bind socket");
 
   if (s->multicast.enabled) {
     ret = setsockopt(s->sd, IPPROTO_IP, IP_MULTICAST_LOOP, &s->multicast.loop,
@@ -400,9 +368,15 @@ int villas::node::socket_read(NodeCompat *n, struct Sample *const smps[],
 
   if (s->layer == SocketLayer::TCP_CLIENT) {
     // Receive data from server.
+    if (!s->tcp_connect)
+      villas::node::socket_tcp_connection(n, s);
+
     bytes = recv(s->sd, s->in.buf, s->in.buflen, 0);
   } else if (s->layer == SocketLayer::TCP_SERVER) {
     // Receive data from client.
+    if (!s->tcp_connect)
+      villas::node::socket_tcp_connection(n, s);
+
     bytes = recv(s->clt_sd, s->in.buf, s->in.buflen, 0);
   } else {
     bytes = recvfrom(s->sd, s->in.buf, s->in.buflen, 0, &src.sa, &srclen);
@@ -413,8 +387,12 @@ int villas::node::socket_read(NodeCompat *n, struct Sample *const smps[],
       return -1;
 
     throw SystemError("Failed recvfrom()");
-  } else if (bytes == 0)
+  } else if (bytes == 0) {
+    if (s->layer == SocketLayer::TCP_CLIENT || s->layer == SocketLayer::TCP_SERVER)
+      s->tcp_connect = false;
+
     return 0;
+  }
 
   ptr = s->in.buf;
 
@@ -456,6 +434,39 @@ int villas::node::socket_read(NodeCompat *n, struct Sample *const smps[],
   return ret;
 }
 
+void villas::node::socket_tcp_connection(NodeCompat *n, Socket *s) {
+  int ret;
+  if (s->layer == SocketLayer::TCP_CLIENT) {
+    close(s->sd);
+    s->sd = socket(s->in.saddr.sa.sa_family, SOCK_STREAM, 0);
+    // Attemp to connect to TCP server.
+    int retries = 0;
+    while (retries < MAX_CONNECTION_RETRIES) {
+      n->logger->info("Attempting to connect to server: attempt={}...", retries + 1);
+      ret = connect(s->sd, (struct sockaddr *)&s->out.saddr, sizeof(s->in.saddr));
+      if (ret == 0) {
+        s->tcp_connect = true;
+        break;
+      } else {
+        retries++;
+        if (retries < MAX_CONNECTION_RETRIES) {
+          sleep(RETRIES_DELAY);
+        }
+      }
+    }
+    if (ret < 0)
+      throw SystemError("Failed to conenct to TCP server");
+  } else if (s->layer == SocketLayer::TCP_SERVER) {
+    listen(s->sd, 5);
+    // Accept client connection and get client socket descriptor.
+    s->clt_sd = accept(s->sd, nullptr, nullptr);
+    if (s->clt_sd < 0) {
+      throw SystemError("Failed to accept connection");
+    }
+    s->tcp_connect = true;
+  }
+}
+
 int villas::node::socket_write(NodeCompat *n, struct Sample *const smps[],
                                unsigned cnt) {
   auto *s = n->getData<struct Socket>();