Avoid ports that are in use by not all address families.

[meshlink] / src / meshlink.c

diff --git a/src/meshlink.c b/src/meshlink.c
index 4e32761fa1b30fcbf5713fa46db005383a517453..c6b14b8f043c1b0bdb4c38b6db8aa687651659b7 100644 (file)
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -540,6 +540,8 @@ static bool try_bind(int port) {
        bool success = false;
 
        for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
+               /* Try to bind to TCP. */
+
                int tcp_fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
 
                if(tcp_fd == -1) {
@@ -550,24 +552,33 @@ static bool try_bind(int port) {
                closesocket(tcp_fd);
 
                if(result) {
-                       continue;
+                       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) {
-                       continue;
+                       success = false;
+                       break;
                }
 
                result = bind(udp_fd, aip->ai_addr, aip->ai_addrlen);
                closesocket(udp_fd);
 
                if(result) {
-                       continue;
-               } else {
-                       success = true;
+                       success = false;
                        break;
                }
+
+               success = true;
        }
 
        freeaddrinfo(ai);