nghttpx: Add SETTINGS ACK timeout to HTTP/2 backend connections

src/shrpx_spdy_session.cc

@@ -59,7 +59,8 @@ SpdySession::SpdySession(event_base *evbase, SSL_CTX *ssl_ctx)
     notified_(false),
     wrbev_(nullptr),
     rdbev_(nullptr),
-    flow_control_(false)
+    flow_control_(false),
+    settings_timerev_(nullptr)
 {}
 
 SpdySession::~SpdySession()
@@ -75,6 +76,11 @@ int SpdySession::disconnect()
   nghttp2_session_del(session_);
   session_ = nullptr;
 
+  if(settings_timerev_) {
+    event_free(settings_timerev_);
+    settings_timerev_ = nullptr;
+  }
+
   if(ssl_) {
     SSL_shutdown(ssl_);
   }
@@ -746,6 +752,50 @@ int on_stream_close_callback
 }
 } // namespace
 
+namespace {
+void settings_timeout_cb(evutil_socket_t fd, short what, void *arg)
+{
+  auto spdy = reinterpret_cast<SpdySession*>(arg);
+  SSLOG(INFO, spdy) << "SETTINGS timeout";
+  if(spdy->fail_session(NGHTTP2_SETTINGS_TIMEOUT) != 0) {
+    spdy->disconnect();
+    return;
+  }
+  if(spdy->send() != 0) {
+    spdy->disconnect();
+  }
+}
+} // namespace
+
+int SpdySession::start_settings_timer()
+{
+  int rv;
+  // We submit SETTINGS only once
+  if(settings_timerev_) {
+    return 0;
+  }
+  settings_timerev_ = evtimer_new(evbase_, settings_timeout_cb, this);
+  if(settings_timerev_ == nullptr) {
+    return -1;
+  }
+  // SETTINGS ACK timeout is 10 seconds for now
+  timeval settings_timeout = { 10, 0 };
+  rv = evtimer_add(settings_timerev_, &settings_timeout);
+  if(rv == -1) {
+    return -1;
+  }
+  return 0;
+}
+
+void SpdySession::stop_settings_timer()
+{
+  if(settings_timerev_ == nullptr) {
+    return;
+  }
+  event_free(settings_timerev_);
+  settings_timerev_ = nullptr;
+}
+
 namespace {
 int on_frame_recv_callback
 (nghttp2_session *session, const nghttp2_frame *frame, void *user_data)
@@ -898,6 +948,12 @@ int on_frame_recv_callback
     }
     break;
   }
+  case NGHTTP2_SETTINGS:
+    if((frame->hd.flags & NGHTTP2_FLAG_ACK) == 0) {
+      break;
+    }
+    spdy->stop_settings_timer();
+    break;
   case NGHTTP2_PUSH_PROMISE:
     if(LOG_ENABLED(INFO)) {
       SSLOG(INFO, spdy) << "Received downstream PUSH_PROMISE stream_id="
@@ -969,6 +1025,21 @@ int before_frame_send_callback(nghttp2_session *session,
 }
 } // namespace
 
+namespace {
+int on_frame_send_callback(nghttp2_session* session,
+                           const nghttp2_frame *frame, void *user_data)
+{
+  auto spdy = reinterpret_cast<SpdySession*>(user_data);
+  if(frame->hd.type == NGHTTP2_SETTINGS &&
+     (frame->hd.flags & NGHTTP2_FLAG_ACK) == 0) {
+    if(spdy->start_settings_timer() != 0) {
+      return NGHTTP2_ERR_CALLBACK_FAILURE;
+    }
+  }
+  return 0;
+}
+} // namespace
+
 namespace {
 int on_frame_not_send_callback(nghttp2_session *session,
                                const nghttp2_frame *frame,
@@ -1059,6 +1130,7 @@ int SpdySession::on_connect()
   callbacks.on_frame_recv_callback = on_frame_recv_callback;
   callbacks.on_data_chunk_recv_callback = on_data_chunk_recv_callback;
   callbacks.before_frame_send_callback = before_frame_send_callback;
+  callbacks.on_frame_send_callback = on_frame_send_callback;
   callbacks.on_frame_not_send_callback = on_frame_not_send_callback;
   callbacks.on_frame_recv_parse_error_callback =
     on_frame_recv_parse_error_callback;
@@ -1190,4 +1262,14 @@ void SpdySession::set_state(int state)
   state_ = state;
 }
 
+int SpdySession::fail_session(nghttp2_error_code error_code)
+{
+  int rv;
+  rv = nghttp2_session_fail_session(session_, error_code);
+  if(rv != 0) {
+    return -1;
+  }
+  return 0;
+}
+
 } // namespace shrpx

src/shrpx_spdy_session.h

@@ -74,6 +74,8 @@ public:
   // |dconn|.
   int submit_window_update(SpdyDownstreamConnection *dconn, int32_t amount);
 
+  int fail_session(nghttp2_error_code error_code);
+
   int32_t get_initial_window_size() const;
 
   nghttp2_session* get_session() const;
@@ -99,6 +101,9 @@ public:
   int get_state() const;
   void set_state(int state);
 
+  int start_settings_timer();
+  void stop_settings_timer();
+
   enum {
     // Disconnected
     DISCONNECTED,
@@ -134,6 +139,7 @@ private:
   bool flow_control_;
   // Used to parse the response from HTTP proxy
   std::unique_ptr<http_parser> proxy_htp_;
+  event *settings_timerev_;
 };
 
 } // namespace shrpx