X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fmeshlink.c;h=c6b14b8f043c1b0bdb4c38b6db8aa687651659b7;hb=e306efba0aa513ae498b84b7f383b05365022092;hp=6fd89daded547d5ad2ad6045d55540fc2cfd4a17;hpb=b5aaabe0fcb104ef7801a68f4f9e6b77732dbb28;p=meshlink

diff --git a/src/meshlink.c b/src/meshlink.c
index 6fd89dad..c6b14b8f 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -540,26 +540,45 @@ static bool try_bind(int port) {
 	bool success = false;
 
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
-		if(!(aip->ai_family == AF_INET || aip->ai_family == AF_INET6)) {
+		/* Try to bind to TCP. */
+
+		int tcp_fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
+
+		if(tcp_fd == -1) {
 			continue;
 		}
 
-		int fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
+		int result = bind(tcp_fd, aip->ai_addr, aip->ai_addrlen);
+		closesocket(tcp_fd);
 
-		if(fd == -1) {
+		if(result) {
+			if(errno == EADDRINUSE) {
+				/* If this port is in use for any address family, avoid it. */
+				success = false;
+				break;
+			} else {
+				continue;
+			}
+		}
+
+		/* If TCP worked, then we require that UDP works as well. */
+
+		int udp_fd = socket(aip->ai_family, SOCK_DGRAM, IPPROTO_UDP);
+
+		if(udp_fd == -1) {
 			success = false;
 			break;
 		}
 
-		int result = bind(fd, aip->ai_addr, aip->ai_addrlen);
-		closesocket(fd);
+		result = bind(udp_fd, aip->ai_addr, aip->ai_addrlen);
+		closesocket(udp_fd);
 
 		if(result) {
 			success = false;
 			break;
-		} else {
-			success = true;
 		}
+
+		success = true;
 	}
 
 	freeaddrinfo(ai);