From 754ae103989a6ad0869d23a6a427d652b5b4a2fe Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 28 Feb 2019 20:34:36 +0100
Subject: [PATCH] threaded-resolver: shutdown the resolver thread without error
 message

When a transfer is done, the resolver thread will be brought down. That
could accidentally generate an error message in the error buffer even
though this is not an error situationand the transfer would still return
OK.  An application that still reads the error buffer could find a
"Could not resolve host: [host name]" message there and get confused.

Reported-by: Michael Schmid
Fixes #3629
Closes #3630
---
 lib/asyn-thread.c | 76 ++++++++++++++++++++++++++---------------------
 1 file changed, 42 insertions(+), 34 deletions(-)

diff --git a/lib/asyn-thread.c b/lib/asyn-thread.c
index a9679d062e..55e0811c5c 100644
--- a/lib/asyn-thread.c
+++ b/lib/asyn-thread.c
@@ -461,38 +461,9 @@ static CURLcode resolver_error(struct connectdata *conn)
   return result;
 }
 
-/*
- * Until we gain a way to signal the resolver threads to stop early, we must
- * simply wait for them and ignore their results.
- */
-void Curl_resolver_kill(struct connectdata *conn)
-{
-  struct thread_data *td = (struct thread_data*) conn->async.os_specific;
-
-  /* If we're still resolving, we must wait for the threads to fully clean up,
-     unfortunately.  Otherwise, we can simply cancel to clean up any resolver
-     data. */
-  if(td && td->thread_hnd != curl_thread_t_null)
-    (void)Curl_resolver_wait_resolv(conn, NULL);
-  else
-    Curl_resolver_cancel(conn);
-}
-
-/*
- * Curl_resolver_wait_resolv()
- *
- * Waits for a resolve to finish. This function should be avoided since using
- * this risk getting the multi interface to "hang".
- *
- * If 'entry' is non-NULL, make it point to the resolved dns entry
- *
- * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
- * CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
- *
- * This is the version for resolves-in-a-thread.
- */
-CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
-                                   struct Curl_dns_entry **entry)
+static CURLcode thread_wait_resolv(struct connectdata *conn,
+                                   struct Curl_dns_entry **entry,
+                                   bool report)
 {
   struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
   CURLcode result = CURLE_OK;
@@ -513,18 +484,55 @@ CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
   if(entry)
     *entry = conn->async.dns;
 
-  if(!conn->async.dns)
+  if(!conn->async.dns && report)
     /* a name was not resolved, report error */
     result = resolver_error(conn);
 
   destroy_async_data(&conn->async);
 
-  if(!conn->async.dns)
+  if(!conn->async.dns && report)
     connclose(conn, "asynch resolve failed");
 
   return result;
 }
 
+
+/*
+ * Until we gain a way to signal the resolver threads to stop early, we must
+ * simply wait for them and ignore their results.
+ */
+void Curl_resolver_kill(struct connectdata *conn)
+{
+  struct thread_data *td = (struct thread_data*) conn->async.os_specific;
+
+  /* If we're still resolving, we must wait for the threads to fully clean up,
+     unfortunately.  Otherwise, we can simply cancel to clean up any resolver
+     data. */
+  if(td && td->thread_hnd != curl_thread_t_null)
+    (void)thread_wait_resolv(conn, NULL, FALSE);
+  else
+    Curl_resolver_cancel(conn);
+}
+
+/*
+ * Curl_resolver_wait_resolv()
+ *
+ * Waits for a resolve to finish. This function should be avoided since using
+ * this risk getting the multi interface to "hang".
+ *
+ * If 'entry' is non-NULL, make it point to the resolved dns entry
+ *
+ * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
+ * CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
+ *
+ * This is the version for resolves-in-a-thread.
+ */
+CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
+                                   struct Curl_dns_entry **entry)
+{
+  return thread_wait_resolv(conn, entry, TRUE);
+}
+
 /*
  * Curl_resolver_is_resolved() is called repeatedly to check if a previous
  * name resolve request has completed. It should also make sure to time-out if