[Minor] Disable ipv6 check via bind to a random port

Issue: #3221

diff --git a/src/libutil/addr.c b/src/libutil/addr.c
index 03e7e9918f4208749a13d9294d7b000ee5be37a1..27e63cd797fac0223c482eedf9434e55dfb7722e 100644 (file)
--- a/src/libutil/addr.c
+++ b/src/libutil/addr.c
@@ -146,34 +146,39 @@ static void
 rspamd_ip_check_ipv6 (void)
 {
        if (ipv6_status == RSPAMD_IPV6_UNDEFINED) {
-               gint s, r;
-               struct sockaddr_in6 sin6;
-               const struct in6_addr ip6_local = IN6ADDR_LOOPBACK_INIT;
+               gint s;
 
                s = socket (AF_INET6, SOCK_STREAM, 0);
+
                if (s == -1) {
                        ipv6_status = RSPAMD_IPV6_UNSUPPORTED;
                }
                else {
                        /*
-                        * Some systems allow ipv6 sockets creating but not binding,
-                        * so here we try to bind to some local address and check, whether it
-                        * is possible
+                        * Try to check /proc if we are on Linux (the common case)
                         */
-                       memset (&sin6, 0, sizeof (sin6));
-                       sin6.sin6_family = AF_INET6;
-                       sin6.sin6_port = rspamd_random_uint64_fast () % 40000 + 20000;
-                       sin6.sin6_addr = ip6_local;
-
-                       r = bind (s, (struct sockaddr *)&sin6, sizeof (sin6));
-                       if (r == -1 && errno != EADDRINUSE) {
-                               ipv6_status = RSPAMD_IPV6_UNSUPPORTED;
+                       struct stat st;
+
+                       close (s);
+
+                       if (stat ("/proc/net/dev", &st) != -1) {
+                               if (stat ("/proc/net/if_inet6", &st) != -1) {
+                                       if (st.st_size != 0) {
+                                               ipv6_status = RSPAMD_IPV6_SUPPORTED;
+                                       }
+                                       else {
+                                               /* Empty file, no ipv6 configuration at all */
+                                               ipv6_status = RSPAMD_IPV6_UNSUPPORTED;
+                                       }
+                               }
+                               else {
+                                       ipv6_status = RSPAMD_IPV6_UNSUPPORTED;
+                               }
                        }
                        else {
+                               /* Not a Linux, so we assume it supports ipv6 somehow... */
                                ipv6_status = RSPAMD_IPV6_SUPPORTED;
                        }
-
-                       close (s);
                }
        }
 }