X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fnet_socket.c;h=3b6399bfc0cb9727a6e236700d2c24760ac18e33;hb=e57daac63b6f703af8e7c8209ef61a4d3b2180c3;hp=939aa9c4577b8e15d794e82aca1f3b43938e0c1b;hpb=0c026f3c6dec784c3267ad7e2c4709d5393dc292;p=tinc

diff --git a/src/net_socket.c b/src/net_socket.c
index 939aa9c4..3b6399bf 100644
--- a/src/net_socket.c
+++ b/src/net_socket.c
@@ -401,19 +401,38 @@ static void handle_meta_io(void *data, int flags) {
 	connection_t *c = data;
 
 	if(c->status.connecting) {
-		c->status.connecting = false;
-
-		int result;
-		socklen_t len = sizeof result;
-		getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
-
-		if(!result)
-			finish_connecting(c);
-		else {
-			logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
-			terminate_connection(c, false);
+		/*
+		   The event loop does not protect against spurious events. Verify that we are actually connected
+		   by issuing an empty send() call.
+
+		   Note that the behavior of send() on potentially unconnected sockets differ between platforms:
+		   +------------+-----------+-------------+-----------+
+		   |   Event    |   POSIX   |    Linux    |  Windows  |
+		   +------------+-----------+-------------+-----------+
+		   | Spurious   | ENOTCONN  | EWOULDBLOCK | ENOTCONN  |
+		   | Failed     | ENOTCONN  | (cause)     | ENOTCONN  |
+		   | Successful | (success) | (success)   | (success) |
+		   +------------+-----------+-------------+-----------+
+		*/
+		if (send(c->socket, NULL, 0, 0) != 0) {
+			if (sockwouldblock(sockerrno))
+				return;
+			int socket_error;
+			if (!socknotconn(sockerrno))
+				socket_error = sockerrno;
+			else {
+				int len = sizeof socket_error;
+				getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&socket_error, &len);
+			}
+			if (socket_error) {
+				logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(socket_error));
+				terminate_connection(c, false);
+			}
 			return;
 		}
+
+		c->status.connecting = false;
+		finish_connecting(c);
 	}
 
 	if(flags & IO_WRITE)