ares: handle channel being destroyed early

We are destroying the ares channel already when we shutdown
resolving. Querying the pollset afterwards is still happening,
especially in event based processing and needs to work in the
absence of a channel.

Fixes #18317
Reported-by: Natris on github
Closes #18318

diff --git a/lib/asyn-ares.c b/lib/asyn-ares.c
index bb3f4af0b9d73c738827d31b26667f7bbadadcb3..3eb769d93471db42291ba2459fe79e8f1ba6bf1c 100644 (file)
--- a/lib/asyn-ares.c
+++ b/lib/asyn-ares.c
@@ -280,8 +280,9 @@ void Curl_async_ares_destroy(struct Curl_easy *data)
 CURLcode Curl_async_pollset(struct Curl_easy *data, struct easy_pollset *ps)
 {
   struct async_ares_ctx *ares = &data->state.async.ares;
-  DEBUGASSERT(ares->channel);
-  return Curl_ares_pollset(data, ares->channel, ps);
+  if(ares->channel)
+    return Curl_ares_pollset(data, ares->channel, ps);
+  return CURLE_OK;
 }
 
 /*

diff --git a/lib/asyn-base.c b/lib/asyn-base.c
index c0df7aac5e0c5a3a050cc54d25ceb3db4ebce1ca..eb2240b816c9a775e6e83d3a05c0ea3448a815c2 100644 (file)
--- a/lib/asyn-base.c
+++ b/lib/asyn-base.c
@@ -91,6 +91,10 @@ CURLcode Curl_ares_pollset(struct Curl_easy *data,
   timediff_t milli;
   CURLcode result = CURLE_OK;
 
+  DEBUGASSERT(channel);
+  if(!channel)
+    return CURLE_FAILED_INIT;
+
   bitmap = ares_getsock(channel, (ares_socket_t *)sockets,
                         CURL_ARRAYSIZE(sockets));
   for(i = 0; i < CURL_ARRAYSIZE(sockets); ++i) {
@@ -107,6 +111,8 @@ CURLcode Curl_ares_pollset(struct Curl_easy *data,
   }
 
   timeout = ares_timeout(channel, &maxtime, &timebuf);
+  if(!timeout)
+    timeout = &maxtime;
   milli = curlx_tvtoms(timeout);
   Curl_expire(data, milli, EXPIRE_ASYNC_NAME);
   return result;