nghttpx: Support trailer part in h2 -> h2 path

src/shrpx_downstream.cc

@@ -382,6 +382,20 @@ size_t Downstream::get_request_headers_sum() const {
   return request_headers_sum_;
 }
 
+void Downstream::add_request_trailer(const uint8_t *name, size_t namelen,
+                                     const uint8_t *value, size_t valuelen,
+                                     bool no_index, int16_t token) {
+  // we never index trailer part.  Header size limit should be applied
+  // to all request header fields combined.
+  request_headers_sum_ += namelen + valuelen;
+  http2::add_header(request_trailers_, name, namelen, value, valuelen, no_index,
+                    -1);
+}
+
+const Headers &Downstream::get_request_trailers() const {
+  return request_trailers_;
+}
+
 void Downstream::set_request_method(std::string method) {
   request_method_ = std::move(method);
 }

src/shrpx_downstream.h

@@ -127,6 +127,11 @@ public:
 
   size_t get_request_headers_sum() const;
 
+  const Headers &get_request_trailers() const;
+  void add_request_trailer(const uint8_t *name, size_t namelen,
+                           const uint8_t *value, size_t valuelen, bool no_index,
+                           int16_t token);
+
   void set_request_method(std::string method);
   const std::string &get_request_method() const;
   void set_request_path(std::string path);
@@ -308,6 +313,10 @@ private:
   Headers request_headers_;
   Headers response_headers_;
 
+  // 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_;
+
   std::chrono::high_resolution_clock::time_point request_start_time_;
 
   std::string request_method_;

src/shrpx_http2_downstream_connection.cc

@@ -159,6 +159,7 @@ ssize_t http2_data_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) {
+  int rv;
   auto sd = static_cast<StreamData *>(
       nghttp2_session_get_stream_user_data(session, stream_id));
   if (!sd || !sd->dconn) {
@@ -201,6 +202,22 @@ ssize_t http2_data_read_callback(nghttp2_session *session, int32_t stream_id,
         !downstream->get_upgraded()))) {
 
     *data_flags |= NGHTTP2_DATA_FLAG_EOF;
+
+    if (!downstream->get_request_trailers().empty()) {
+      std::vector<nghttp2_nv> nva;
+      nva.reserve(downstream->get_request_trailers().size());
+      for (auto &kv : downstream->get_request_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 (!input_empty) {
@@ -275,7 +292,7 @@ int Http2DownstreamConnection::push_request_headers() {
     cookies = downstream_->crumble_request_cookie();
   }
 
-  // 8 means:
+  // 9 means:
   // 1. :method
   // 2. :scheme
   // 3. :path
@@ -284,8 +301,9 @@ int Http2DownstreamConnection::push_request_headers() {
   // 6. via (optional)
   // 7. x-forwarded-for (optional)
   // 8. x-forwarded-proto (optional)
+  // 9. te (optional)
   auto nva = std::vector<nghttp2_nv>();
-  nva.reserve(nheader + 8 + cookies.size());
+  nva.reserve(nheader + 9 + cookies.size());
 
   std::string via_value;
   std::string xff_value;
@@ -432,6 +450,11 @@ int Http2DownstreamConnection::push_request_headers() {
     nva.push_back(http2::make_nv_ls("via", via_value));
   }
 
+  auto te = downstream_->get_request_header(http2::HD_TE);
+  if (te) {
+    nva.push_back(http2::make_nv_ls("te", te->value));
+  }
+
   if (LOG_ENABLED(INFO)) {
     std::stringstream ss;
     for (auto &nv : nva) {

src/shrpx_http2_upstream.cc

@@ -187,8 +187,7 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
     verbose_on_header_callback(session, frame, name, namelen, value, valuelen,
                                flags, user_data);
   }
-  if (frame->hd.type != NGHTTP2_HEADERS ||
-      frame->headers.cat != NGHTTP2_HCAT_REQUEST) {
+  if (frame->hd.type != NGHTTP2_HEADERS) {
     return 0;
   }
   auto upstream = static_cast<Http2Upstream *>(user_data);
@@ -207,12 +206,25 @@ int on_header_callback(nghttp2_session *session, const nghttp2_frame *frame,
                            << downstream->get_request_headers_sum();
     }
 
+    // just ignore header fields if this is trailer part.
+    if (frame->headers.cat == NGHTTP2_HCAT_HEADERS) {
+      return 0;
+    }
+
     if (upstream->error_reply(downstream, 431) != 0) {
       return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
 
     return 0;
   }
+
+  if (frame->headers.cat == NGHTTP2_HCAT_HEADERS) {
+    // just store header fields for trailer part
+    downstream->add_request_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) {