[libsoup/carlosgc/http2-early-hints: 4/4] http2: fix handling of 100 continue responses

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 6d22d79dba8ec17df17773e4389b4c94a6f9e2c0
Author: Carlos Garcia Campos <cgarcia igalia com>
Date:   Tue Mar 22 16:30:00 2022 +0100

    http2: fix handling of 100 continue responses
    
    When the request contains the continue expectation we only send the
    headers and wait for the 100 response to then send the body data.

 libsoup/http2/soup-client-message-io-http2.c | 86 ++++++++++++++++++++++------
 1 file changed, 68 insertions(+), 18 deletions(-)
---
diff --git a/libsoup/http2/soup-client-message-io-http2.c b/libsoup/http2/soup-client-message-io-http2.c
index c1f12f28..67feb582 100644
--- a/libsoup/http2/soup-client-message-io-http2.c
+++ b/libsoup/http2/soup-client-message-io-http2.c
@@ -119,9 +119,11 @@ typedef struct {
         gboolean paused;
         guint32 stream_id;
         gboolean can_be_restarted;
+        gboolean expect_continue;
 } SoupHTTP2MessageData;
 
 static void soup_client_message_io_http2_finished (SoupClientMessageIO *iface, SoupMessage *msg);
+static ssize_t on_data_source_read_callback (nghttp2_session *session, int32_t stream_id, uint8_t *buf, 
size_t length, uint32_t *data_flags, nghttp2_data_source *source, void *user_data);
 
 static void
 NGCHECK (int return_code)
@@ -168,6 +170,22 @@ frame_type_to_string (nghttp2_frame_type type)
         }
 }
 
+static const char *
+headers_category_to_string (nghttp2_headers_category catergory)
+{
+        switch (catergory) {
+        case NGHTTP2_HCAT_REQUEST:
+                return "REQUEST";
+        case NGHTTP2_HCAT_RESPONSE:
+                return "RESPONSE";
+        case NGHTTP2_HCAT_PUSH_RESPONSE:
+                return "PUSH_RESPONSE";
+        case NGHTTP2_HCAT_HEADERS:
+                return "HEADERS";
+        }
+        g_assert_not_reached ();
+}
+
 static const char *
 state_to_string (SoupHTTP2IOState state)
 {
@@ -599,7 +617,7 @@ on_begin_frame_callback (nghttp2_session        *session,
 
         switch (hd->type) {
         case NGHTTP2_HEADERS:
-                if (data->state < STATE_READ_HEADERS) {
+                if (data->state == STATE_WRITE_DONE) {
                         soup_message_set_metrics_timestamp (data->item->msg, 
SOUP_MESSAGE_METRICS_RESPONSE_START);
                         advance_state_from (data, STATE_WRITE_DONE, STATE_READ_HEADERS);
                 }
@@ -691,27 +709,53 @@ on_frame_recv_callback (nghttp2_session     *session,
         }
 
         switch (frame->hd.type) {
-        case NGHTTP2_HEADERS:
+        case NGHTTP2_HEADERS: {
+                guint status = soup_message_get_status (data->msg);
+
                 if (data->metrics)
                         data->metrics->response_header_bytes_received += frame->hd.length + 
FRAME_HEADER_SIZE;
 
-                if (frame->headers.cat == NGHTTP2_HCAT_RESPONSE && frame->hd.flags & 
NGHTTP2_FLAG_END_HEADERS) {
-                        h2_debug (io, data, "[HEADERS] status %u", soup_message_get_status (data->msg));
-                        if (SOUP_STATUS_IS_INFORMATIONAL (soup_message_get_status (data->msg))) {
+                h2_debug (io, data, "[HEADERS] category=%s status=%u",
+                          headers_category_to_string (frame->headers.cat), status);
+                switch (frame->headers.cat) {
+                case NGHTTP2_HCAT_HEADERS:
+                        if (!(frame->hd.flags & NGHTTP2_FLAG_END_HEADERS)) {
+                                io->in_callback--;
+                                return 0;
+                        }
+                        break;
+                case NGHTTP2_HCAT_RESPONSE:
+                        if (SOUP_STATUS_IS_INFORMATIONAL (status)) {
+                                if (data->expect_continue && status == SOUP_STATUS_CONTINUE) {
+                                        nghttp2_data_provider data_provider;
+
+                                        data_provider.source.ptr = soup_message_get_request_body_stream 
(data->msg);
+                                        data_provider.read_callback = on_data_source_read_callback;
+                                        nghttp2_submit_data (io->session, NGHTTP2_FLAG_END_STREAM, 
frame->hd.stream_id, &data_provider);
+                                        io_try_write (io, !data->item->async);
+                                }
+
                                 soup_message_got_informational (data->msg);
                                 soup_message_cleanup_response (data->msg);
                                 io->in_callback--;
                                 return 0;
                         }
+                        break;
+                case NGHTTP2_HCAT_PUSH_RESPONSE:
+                        g_warn_if_reached ();
+                        break;
+                default:
+                        g_assert_not_reached ();
+                }
 
-                        if (soup_message_get_status (data->msg) == SOUP_STATUS_NO_CONTENT ||
-                            frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-                                h2_debug (io, data, "Stream done");
-                                advance_state_from (data, STATE_READ_HEADERS, STATE_READ_DATA);
-                        }
-                        soup_message_got_headers (data->msg);
+                if (soup_message_get_status (data->msg) == SOUP_STATUS_NO_CONTENT || frame->hd.flags & 
NGHTTP2_FLAG_END_STREAM) {
+                        h2_debug (io, data, "Stream done");
+                        advance_state_from (data, STATE_READ_HEADERS, STATE_READ_DATA);
                 }
+                soup_message_got_headers (data->msg);
+
                 break;
+        }
         case NGHTTP2_DATA:
                 if (data->metrics)
                         data->metrics->response_body_bytes_received += frame->data.hd.length + 
FRAME_HEADER_SIZE;
@@ -825,7 +869,8 @@ on_frame_send_callback (nghttp2_session     *session,
         switch (frame->hd.type) {
         case NGHTTP2_HEADERS:
                 g_assert (data);
-                h2_debug (io, data, "[SEND] [HEADERS] finished=%d",
+                h2_debug (io, data, "[SEND] [HEADERS] category=%s finished=%d",
+                          headers_category_to_string (frame->headers.cat),
                           (frame->hd.flags & NGHTTP2_FLAG_END_HEADERS) ? 1 : 0);
 
                 if (data->metrics)
@@ -1266,13 +1311,18 @@ send_message_request (SoupMessage          *msg,
         nghttp2_priority_spec priority_spec;
         nghttp2_priority_spec_init (&priority_spec, 0, message_priority_to_weight (msg), 0);
 
-        nghttp2_data_provider data_provider;
-        if (body_stream) {
-                data_provider.source.ptr = body_stream;
-                data_provider.read_callback = on_data_source_read_callback;
+        int32_t stream_id;
+        if (body_stream && soup_message_headers_get_expectations (soup_message_get_request_headers (msg)) & 
SOUP_EXPECTATION_CONTINUE) {
+                data->expect_continue = TRUE;
+                stream_id = nghttp2_submit_headers (io->session, 0, -1, &priority_spec, (const nghttp2_nv 
*)headers->data, headers->len, data);
+        } else {
+                nghttp2_data_provider data_provider;
+                if (body_stream) {
+                        data_provider.source.ptr = body_stream;
+                        data_provider.read_callback = on_data_source_read_callback;
+                }
+                stream_id = nghttp2_submit_request (io->session, &priority_spec, (const nghttp2_nv 
*)headers->data, headers->len, body_stream ? &data_provider : NULL, data);
         }
-
-        int32_t stream_id = nghttp2_submit_request (io->session, &priority_spec, (const nghttp2_nv 
*)headers->data, headers->len, body_stream ? &data_provider : NULL, data);
         if (stream_id == NGHTTP2_ERR_STREAM_ID_NOT_AVAILABLE) {
                 set_error_for_data (data,
                                     g_error_new_literal (G_IO_ERROR, G_IO_ERROR_FAILED,