Check if interface address returned by pj_getipinterface() is link-lo…

…cal address (#3442)

pjlib/src/pj/sock_common.c

@@ -1068,6 +1068,21 @@ PJ_DEF(pj_status_t) pj_getipinterface(int af,
         return PJ_ENOTFOUND;
     }
 
+#if defined(PJ_HAS_IPV6) && PJ_HAS_IPV6
+    /* Check if the local address is link-local but the destination
+     * is not link-local.
+     */
+    if (af == pj_AF_INET6() &&
+        IN6_IS_ADDR_LINKLOCAL(&itf_addr->ipv6.sin6_addr) &&
+        (!IN6_IS_ADDR_LINKLOCAL(&dst_addr.ipv6.sin6_addr)))
+    {
+        TRACE_((THIS_FILE, "Local interface address is link-local and "
+                           "the destination host is external"));
+
+        return PJ_ENOTFOUND;
+    }
+#endif
+
     if (p_dst_addr)
         *p_dst_addr = dst_addr;