Update contrib/libs/c-ares to 1.34.3

commit_hash:a4dc6127c1976aed745669af6ede1483b05f9686

4 files changed, 92 insertions, 10 deletions

diff --git a/contrib/libs/c-ares/src/lib/ares_getaddrinfo.c b/contrib/libs/c-ares/src/lib/ares_getaddrinfo.c
index 09d34d3378..32791dc37d 100644
--- a/contrib/libs/c-ares/src/lib/ares_getaddrinfo.c
+++ b/contrib/libs/c-ares/src/lib/ares_getaddrinfo.c
@@ -481,6 +481,18 @@ static void terminate_retries(const struct host_query *hquery,
   query->no_retries = ARES_TRUE;
 }
 
+static ares_bool_t ai_has_ipv4(struct ares_addrinfo *ai)
+{
+  struct ares_addrinfo_node *node;
+
+  for (node = ai->nodes; node != NULL; node = node->ai_next) {
+    if (node->ai_family == AF_INET) {
+      return ARES_TRUE;
+    }
+  }
+  return ARES_FALSE;
+}
+
 static void host_callback(void *arg, ares_status_t status, size_t timeouts,
                           const ares_dns_record_t *dnsrec)
 {
@@ -496,7 +508,27 @@ static void host_callback(void *arg, ares_status_t status, size_t timeouts,
       addinfostatus =
         ares_parse_into_addrinfo(dnsrec, ARES_TRUE, hquery->port, hquery->ai);
     }
-    if (addinfostatus == ARES_SUCCESS) {
+
+    /* We sent out ipv4 and ipv6 requests simultaneously.  If we got a
+     * successful ipv4 response, we want to go ahead and tell the ipv6 request
+     * that if it fails or times out to not try again since we have the data
+     * we need.
+     *
+     * Our initial implementation of this would terminate retries if we got any
+     * successful response (ipv4 _or_ ipv6).  But we did get some user-reported
+     * issues with this that had bad system configs and odd behavior:
+     *  https://github.com/alpinelinux/docker-alpine/issues/366
+     *
+     * Essentially the ipv6 query succeeded but the ipv4 query failed or timed
+     * out, and so we only returned the ipv6 address, but the host couldn't
+     * use ipv6.  If we continued to allow ipv4 retries it would have found a
+     * server that worked and returned both address classes (this is clearly
+     * unexpected behavior).
+     *
+     * At some point down the road if ipv6 actually becomes required and
+     * reliable we can drop this ipv4 check.
+     */
+    if (addinfostatus == ARES_SUCCESS && ai_has_ipv4(hquery->ai)) {
       terminate_retries(hquery, ares_dns_record_get_id(dnsrec));
     }
   }
diff --git a/contrib/libs/c-ares/src/lib/ares_process.c b/contrib/libs/c-ares/src/lib/ares_process.c
index 62a6ae1dda..3d186ea9d5 100644
--- a/contrib/libs/c-ares/src/lib/ares_process.c
+++ b/contrib/libs/c-ares/src/lib/ares_process.c
@@ -650,6 +650,51 @@ done:
   return status;
 }
 
+static ares_bool_t issue_might_be_edns(const ares_dns_record_t *req,
+                                       const ares_dns_record_t *rsp)
+{
+  const ares_dns_rr_t *rr;
+
+  /* If we use EDNS and server answers with FORMERR without an OPT RR, the
+   * protocol extension is not understood by the responder. We must retry the
+   * query without EDNS enabled. */
+  if (ares_dns_record_get_rcode(rsp) != ARES_RCODE_FORMERR) {
+    return ARES_FALSE;
+  }
+
+  rr = ares_dns_get_opt_rr_const(req);
+  if (rr == NULL) {
+    /* We didn't send EDNS */
+    return ARES_FALSE;
+  }
+
+  if (ares_dns_get_opt_rr_const(rsp) == NULL) {
+    /* Spec says EDNS won't be echo'd back on non-supporting servers, so
+     * retry without EDNS */
+    return ARES_TRUE;
+  }
+
+  /* As per issue #911 some non-compliant servers that do indeed support EDNS
+   * but don't support unrecognized option codes exist.  At this point we
+   * expect them to have also returned an EDNS opt record, but we may remove
+   * that check in the future. Lets detect this situation if we're sending
+   * option codes */
+  if (ares_dns_rr_get_opt_cnt(rr, ARES_RR_OPT_OPTIONS) == 0) {
+    /* We didn't send any option codes */
+    return ARES_FALSE;
+  }
+
+  if (ares_dns_get_opt_rr_const(rsp) != NULL) {
+    /* At this time we're requiring the server to respond with EDNS opt
+     * records since that's what has been observed in the field.  We might
+     * find in the future we have to remove this, who knows. Lets go
+     * ahead and force a retry without EDNS*/
+    return ARES_TRUE;
+  }
+
+  return ARES_FALSE;
+}
+
 /* Handle an answer from a server. This must NEVER cleanup the
  * server connection! Return something other than ARES_SUCCESS to cause
  * the connection to be terminated after this call. */
@@ -713,12 +758,10 @@ static ares_status_t process_answer(ares_channel_t      *channel,
   ares_llist_node_destroy(query->node_queries_to_conn);
   query->node_queries_to_conn = NULL;
 
-  /* If we use EDNS and server answers with FORMERR without an OPT RR, the
-   * protocol extension is not understood by the responder. We must retry the
-   * query without EDNS enabled. */
-  if (ares_dns_record_get_rcode(rdnsrec) == ARES_RCODE_FORMERR &&
-      ares_dns_get_opt_rr_const(query->query) != NULL &&
-      ares_dns_get_opt_rr_const(rdnsrec) == NULL) {
+  /* There are old servers that don't understand EDNS at all, then some servers
+   * that have non-compliant implementations.  Lets try to detect this sort
+   * of thing. */
+  if (issue_might_be_edns(query->query, rdnsrec)) {
     status = rewrite_without_edns(query);
     if (status != ARES_SUCCESS) {
       end_query(channel, server, query, status, NULL);
diff --git a/contrib/libs/c-ares/src/lib/ares_send.c b/contrib/libs/c-ares/src/lib/ares_send.c
index ca178a1741..6efa9580b2 100644
--- a/contrib/libs/c-ares/src/lib/ares_send.c
+++ b/contrib/libs/c-ares/src/lib/ares_send.c
@@ -153,6 +153,11 @@ ares_status_t ares_send_nolock(ares_channel_t *channel, ares_server_t *server,
   /* Duplicate Query */
   status = ares_dns_record_duplicate_ex(&query->query, dnsrec);
   if (status != ARES_SUCCESS) {
+    /* Sometimes we might get a EBADRESP response from duplicate due to
+     * the way it works (write and parse), rewrite it to EBADQUERY. */
+    if (status == ARES_EBADRESP) {
+      status = ARES_EBADQUERY;
+    }
     ares_free(query);
     callback(arg, status, 0, NULL);
     return status;
diff --git a/contrib/libs/c-ares/src/lib/event/ares_event_thread.c b/contrib/libs/c-ares/src/lib/event/ares_event_thread.c
index 24b55d6945..d59b7880a4 100644
--- a/contrib/libs/c-ares/src/lib/event/ares_event_thread.c
+++ b/contrib/libs/c-ares/src/lib/event/ares_event_thread.c
@@ -354,14 +354,16 @@ static void *ares_event_thread(void *arg)
       ares_process_pending_write(e->channel);
     }
 
+    /* Relock before we loop again */
+    ares_thread_mutex_lock(e->mutex);
+
     /* Each iteration should do timeout processing and any other cleanup
      * that may not have been performed */
     if (e->isup) {
+      ares_thread_mutex_unlock(e->mutex);
       ares_process_fds(e->channel, NULL, 0, ARES_PROCESS_FLAG_NONE);
+      ares_thread_mutex_lock(e->mutex);
     }
-
-    /* Relock before we loop again */
-    ares_thread_mutex_lock(e->mutex);
   }
 
   /* Lets cleanup while we're in the thread itself */