nghttpx: Support trailer-part in h2 <- h2 path

src/shrpx_downstream.cc

@@ -663,6 +663,18 @@ size_t Downstream::get_response_headers_sum() const {
   return response_headers_sum_;
 }
 
+const Headers &Downstream::get_response_trailers() const {
+  return response_trailers_;
+}
+
+void Downstream::add_response_trailer(const uint8_t *name, size_t namelen,
+                                      const uint8_t *value, size_t valuelen,
+                                      bool no_index, int16_t token) {
+  response_headers_sum_ += namelen + valuelen;
+  http2::add_header(response_trailers_, name, namelen, value, valuelen,
+                    no_index, -1);
+}
+
 unsigned int Downstream::get_response_http_status() const {
   return response_http_status_;
 }

src/shrpx_downstream.h

@@ -221,6 +221,11 @@ public:
 
   size_t get_response_headers_sum() const;
 
+  const Headers &get_response_trailers() const;
+  void add_response_trailer(const uint8_t *name, size_t namelen,
+                            const uint8_t *value, size_t valuelen,
+                            bool no_index, int16_t token);
+
   unsigned int get_response_http_status() const;
   void set_response_http_status(unsigned int status);
   void set_response_major(int major);
@@ -316,6 +321,7 @@ private:
   // trailer part.  For HTTP/1.1, trailer part is only included with
   // chunked encoding.  For HTTP/2, there is no such limit.
   Headers request_trailers_;
+  Headers response_trailers_;
 
   std::chrono::high_resolution_clock::time_point request_start_time_;
 

src/shrpx_http2_downstream_connection.cc

@@ -203,10 +203,11 @@ ssize_t http2_data_read_callback(nghttp2_session *session, int32_t stream_id,
 
     *data_flags |= NGHTTP2_DATA_FLAG_EOF;
 
-    if (!downstream->get_request_trailers().empty()) {
+    auto &trailers = downstream->get_request_trailers();
+    if (!trailers.empty()) {
       std::vector<nghttp2_nv> nva;
-      nva.reserve(downstream->get_request_trailers().size());
-      for (auto &kv : downstream->get_request_trailers()) {
+      nva.reserve(trailers.size());
+      for (auto &kv : trailers) {
         nva.push_back(http2::make_nv(kv.name, kv.value, kv.no_index));
       }
       rv = nghttp2_submit_trailer(session, stream_id, nva.data(), nva.size());

src/shrpx_http2_session.cc

@@ -668,20 +668,35 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
     return 0;
   }
 
-  if (frame->hd.type != NGHTTP2_HEADERS ||
-      (frame->headers.cat != NGHTTP2_HCAT_RESPONSE &&
-       !downstream->get_expect_final_response())) {
+  if (frame->hd.type != NGHTTP2_HEADERS) {
     return 0;
   }
 
+  auto trailer = frame->headers.cat != NGHTTP2_HCAT_RESPONSE &&
+                 !downstream->get_expect_final_response();
+
   if (downstream->get_response_headers_sum() > Downstream::MAX_HEADERS_SUM) {
     if (LOG_ENABLED(INFO)) {
       DLOG(INFO, downstream) << "Too large header block size="
                              << downstream->get_response_headers_sum();
     }
+
+    if (trailer) {
+      // we don't care trailer part exceeds header size limit; just
+      // discard it.
+      return 0;
+    }
+
     return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
   }
 
+  if (trailer) {
+    // just store header fields for trailer part
+    downstream->add_response_trailer(name, namelen, value, valuelen,
+                                     flags & NGHTTP2_NV_FLAG_NO_INDEX, -1);
+    return 0;
+  }
+
   auto token = http2::lookup_token(name, namelen);
 
   if (token == http2::HD_CONTENT_LENGTH) {
@@ -891,10 +906,6 @@ int on_frame_recv_callback(nghttp2_session *session, const nghttp2_frame *frame,
         if (rv != 0) {
           return 0;
         }
-      } else if ((frame->hd.flags & NGHTTP2_FLAG_END_STREAM) == 0) {
-        http2session->submit_rst_stream(frame->hd.stream_id,
-                                        NGHTTP2_PROTOCOL_ERROR);
-        return 0;
       }
     }
 

src/shrpx_http2_upstream.cc

@@ -1068,6 +1068,7 @@ ssize_t downstream_data_read_callback(nghttp2_session *session,
                                       size_t length, uint32_t *data_flags,
                                       nghttp2_data_source *source,
                                       void *user_data) {
+  int rv;
   auto downstream = static_cast<Downstream *>(source->ptr);
   auto upstream = static_cast<Http2Upstream *>(downstream->get_upstream());
   auto body = downstream->get_response_buf();
@@ -1093,7 +1094,22 @@ ssize_t downstream_data_read_callback(nghttp2_session *session,
     *data_flags |= NGHTTP2_DATA_FLAG_EOF;
 
     if (!downstream->get_upgraded()) {
-
+      auto &trailers = downstream->get_response_trailers();
+      if (!trailers.empty()) {
+        std::vector<nghttp2_nv> nva;
+        nva.reserve(trailers.size());
+        for (auto &kv : trailers) {
+          nva.push_back(http2::make_nv(kv.name, kv.value, kv.no_index));
+        }
+        rv = nghttp2_submit_trailer(session, stream_id, nva.data(), nva.size());
+        if (rv != 0) {
+          if (nghttp2_is_fatal(rv)) {
+            return NGHTTP2_ERR_CALLBACK_FAILURE;
+          }
+        } else {
+          *data_flags |= NGHTTP2_DATA_FLAG_NO_END_STREAM;
+        }
+      }
       if (nghttp2_session_get_stream_remote_close(session, stream_id) == 0) {
         upstream->rst_stream(downstream, NGHTTP2_NO_ERROR);
       }