Ignore rogue DNS servers reported by windows

joyent · Oct 20, 2011 · d6cf655 · d6cf655
1 parent 51e9dbc
commit d6cf655
Showing 1 changed file with 9 additions and 4 deletions.
diff --git a/src/ares/ares_init.c b/src/ares/ares_init.c
@@ -696,17 +696,22 @@ static int get_iphlpapi_dns_info (char *ret_buf, size_t ret_size)
           struct sockaddr_in6 *pIPv6Addr = ( struct sockaddr_in6 * ) pGenericAddr;
           ares_inet_ntop( AF_INET6, &pIPv6Addr->sin6_addr, ret, ipv6_size - 1 ); /* -1 for comma */
 
+          stringlen = strlen( ret );
+
+          /* Windows apparently always reports some IPv6 DNS servers that
+             prefixed with fec0:0:0:ffff. These ususally do not point to
+             working DNS servers, we we ignore them. */
+          if (strncmp(ret, "fec0:0:0:ffff:", 14) == 0) {
+            continue;
+          }
+
           /* Append a comma to the end, THEN NULL. Should be OK because we
              already tested the size at the top of the if statement. */
-          stringlen = strlen( ret );
           ret[ stringlen ] = ',';
           ret[ stringlen + 1 ] = '\0';
           ret += stringlen + 1;
           left -= ret - ret_buf;
           ++count;
-
-          /* NB on Windows this also returns stuff in the fec0::/10 range,
-             seems to be hard-coded somehow. Do we need to ignore them? */
         }
       }
     }