lib-http: client: When a request is destroyed prematurely during payl…

…oad input, consider the payload stream destroyed and act accordingly.

The application may hold a reference to the payload stream still, and it may be difficult to prevent that.
This causes lib-http to keep waiting for the payload to be destroyed.
When nothing else is going on, the current ioloop may then become empty, which caused the familiar assert failure.

src/lib-http/http-client-connection.c

@@ -646,7 +646,7 @@ static void http_client_payload_destroyed(struct http_client_request *req)
 void http_client_connection_request_destroyed(
 	struct http_client_connection *conn, struct http_client_request *req)
 {
-	struct istream *payload = conn->incoming_payload;
+	struct istream *payload;
 
 	i_assert(req->conn == conn);
 	if (conn->pending_request != req)
@@ -655,10 +655,28 @@ void http_client_connection_request_destroyed(
 	http_client_connection_debug(conn,
 		"Pending request destroyed prematurely");
 
-	if (payload == NULL)
+	payload = conn->incoming_payload;
+	if (payload == NULL) {
+		/* payload already gone */
 		return;
+	}
+
+	/* destroy the payload, so that the timeout istream is closed */
 	i_stream_ref(payload);
 	i_stream_destroy(&payload);
+
+	payload = conn->incoming_payload;
+	if (payload == NULL) {
+		/* not going to happen, but check for it anyway */
+		return;
+	}
+
+	/* the application still holds a reference to the payload stream, but it
+	   is closed and we don't care about it anymore, so act as though it is
+	   destroyed. */
+	i_stream_remove_destroy_callback(payload,
+					 http_client_payload_destroyed);
+	http_client_payload_destroyed(req);
 }
 
 static bool