[libsoup/carlosgc/http2-protocol-errors: 2/2] http2: always try to write before every read

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 20643a063ba7e55c62d7324cd7448e6bb3f18ad8
Author: Carlos Garcia Campos <cgarcia igalia com>
Date:   Wed Aug 31 14:35:40 2022 +0200

    http2: always try to write before every read
    
    It can happen that an error handled by nghttp2 generates a reset stream
    frame that needs to be sent, so we need to try to write even if we haven't
    made any explict call that requires writing. Also give more priority to
    write source than read source.
    
    Fixes #298

 libsoup/http2/soup-client-message-io-http2.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/libsoup/http2/soup-client-message-io-http2.c b/libsoup/http2/soup-client-message-io-http2.c
index 6f7dd747..86d3f3ae 100644
--- a/libsoup/http2/soup-client-message-io-http2.c
+++ b/libsoup/http2/soup-client-message-io-http2.c
@@ -373,6 +373,8 @@ io_try_write (SoupClientMessageIOHTTP2 *io,
                 g_clear_error (&error);
                 io->write_source = g_pollable_output_stream_create_source (G_POLLABLE_OUTPUT_STREAM 
(io->ostream), NULL);
                 g_source_set_name (io->write_source, "Soup HTTP/2 write source");
+                /* Give write more priority than read */
+                g_source_set_priority (io->write_source, G_PRIORITY_DEFAULT - 1);
                 g_source_set_callback (io->write_source, (GSourceFunc)io_write_ready, io, NULL);
                 g_source_attach (io->write_source, g_main_context_get_thread_default ());
         }
@@ -391,6 +393,9 @@ io_read (SoupClientMessageIOHTTP2  *io,
         gssize read;
         int ret;
 
+        /* Always try to write before read, in case there's a pending reset stream after an error. */
+        io_try_write (io, blocking);
+
         if ((read = g_pollable_stream_read (io->istream, buffer, sizeof (buffer),
                                             blocking, cancellable, error)) < 0)
             return FALSE;
@@ -1723,6 +1728,7 @@ soup_client_message_io_http2_set_owner (SoupClientMessageIOHTTP2 *io,
 
         io->read_source = g_pollable_input_stream_create_source (G_POLLABLE_INPUT_STREAM (io->istream), 
NULL);
         g_source_set_name (io->read_source, "Soup HTTP/2 read source");
+        g_source_set_priority (io->read_source, G_PRIORITY_DEFAULT);
         g_source_set_callback (io->read_source, (GSourceFunc)io_read_ready, io, NULL);
         g_source_attach (io->read_source, g_main_context_get_thread_default ());
 }