http2: fix handling of RST and GOAWAY to recognize partial transfers

- a reset transfer (HTTP/2 RST) did not always lead to the proper
  error message on receiving its response, leading to wrong reports
  of a successful transfer
- test_05_02 was able to trigger this condition with increased transfer
  count. The simulated response errors did not carry a 'Content-Length'
  so only proper RST handling could detect the abort
- When doing such transfers in parallel, a connection could enter the
  state where
  a) it had been closed (GOAWAY received)
  b) the RST had not been "seen" for the transfer yet
  or c) the GOAWAY announced an error and the last successful
  stream id was not checked against ongoing transfers

Closes #10693

lib/http2.c

@@ -98,7 +98,6 @@ static size_t populate_binsettings(uint8_t *binsettings,
 struct cf_h2_ctx {
   nghttp2_session *h2;
   uint32_t max_concurrent_streams;
-  bool enable_push;
   /* The easy handle used in the current filter call, cleared at return */
   struct cf_call_data call_data;
 
@@ -116,6 +115,10 @@ struct cf_h2_ctx {
   int32_t pause_stream_id; /* stream ID which paused
                               nghttp2_session_mem_recv */
   size_t drain_total; /* sum of all stream's UrlState.drain */
+  int32_t goaway_error;
+  int32_t last_stream_id;
+  BIT(goaway);
+  BIT(enable_push);
 };
 
 /* How to access `call_data` from a cf_h2 filter */
@@ -815,7 +818,7 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
       ctx->max_concurrent_streams = nghttp2_session_get_remote_settings(
           session, NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS);
       ctx->enable_push = nghttp2_session_get_remote_settings(
-          session, NGHTTP2_SETTINGS_ENABLE_PUSH);
+          session, NGHTTP2_SETTINGS_ENABLE_PUSH) != 0;
       DEBUGF(LOG_CF(data, cf, "MAX_CONCURRENT_STREAMS == %d",
                     ctx->max_concurrent_streams));
       DEBUGF(LOG_CF(data, cf, "ENABLE_PUSH == %s",
@@ -829,9 +832,12 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
       break;
     }
     case NGHTTP2_GOAWAY:
+      ctx->goaway = TRUE;
+      ctx->goaway_error = frame->goaway.error_code;
+      ctx->last_stream_id = frame->goaway.last_stream_id;
       if(data) {
         infof(data, "recveived GOAWAY, error=%d, last_stream=%u",
-                    frame->goaway.error_code, frame->goaway.last_stream_id);
+                    ctx->goaway_error, ctx->last_stream_id);
         multi_connchanged(data->multi);
       }
       break;
@@ -940,6 +946,7 @@ static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
     break;
   case NGHTTP2_RST_STREAM:
     DEBUGF(LOG_CF(data_s, cf, "[h2sid=%u] recv RST", stream_id));
+    stream->closed = TRUE;
     stream->reset = TRUE;
     break;
   case NGHTTP2_WINDOW_UPDATE:
@@ -1722,6 +1729,18 @@ static ssize_t cf_h2_recv(struct Curl_cfilter *cf, struct Curl_easy *data,
 
   CF_DATA_SAVE(save, cf, data);
 
+  /* IFF transfer was RST by server or
+   * we got a final GOAWAY and the last processed stream ID, as announced
+   * by the server, is lower than this stream's ID, we will never see
+   * anything more for this stream, so give up */
+  if(stream->reset ||
+     (ctx->goaway && ctx->goaway_error &&
+      ctx->last_stream_id < stream->stream_id)) {
+    *err = stream->bodystarted? CURLE_PARTIAL_FILE : CURLE_RECV_ERROR;
+    nread = -1;
+    goto out;
+  }
+
   if(should_close_session(ctx)) {
     DEBUGF(LOG_CF(data, cf, "http2_recv: nothing to do in this session"));
     if(cf->conn->bits.close) {
@@ -1871,7 +1890,7 @@ static ssize_t cf_h2_recv(struct Curl_cfilter *cf, struct Curl_easy *data,
         goto out;
       }
       else if(nread == 0) {
-        if(!stream->closed) {
+        if(!stream->closed || stream->reset) {
           /* This will happen when the server or proxy server is SIGKILLed
              during data transfer. We should emit an error since our data
              received may be incomplete. */

tests/http/test_05_errors.py

@@ -75,7 +75,7 @@ class TestErrors:
             pytest.skip("h3 not supported")
         if proto == 'h3' and env.curl_uses_lib('quiche'):
             pytest.skip("quiche not reliable, sometimes reports success")
-        count = 5
+        count = 20
         curl = CurlClient(env=env)
         urln = f'https://{env.authority_for(env.domain1, proto)}' \
                f'/curltest/tweak?id=[0-{count - 1}]'\
@@ -87,6 +87,6 @@ class TestErrors:
         assert len(r.stats) == count, f'did not get all stats: {r}'
         invalid_stats = []
         for idx, s in enumerate(r.stats):
-            if 'exitcode' not in s or s['exitcode'] not in [18, 56, 92]:
+            if 'exitcode' not in s or s['exitcode'] not in [18, 56, 92, 95]:
                 invalid_stats.append(f'request {idx} exit with {s["exitcode"]}\n{s}')
         assert len(invalid_stats) == 0, f'failed: {invalid_stats}'