nghttpx: Fix crash when upgrading HTTP/2 failed

src/shrpx_client_handler.cc

@@ -662,6 +662,7 @@ int ClientHandler::perform_http2_upgrade(HttpsUpstream *http) {
                       "Upgrade: " NGHTTP2_CLEARTEXT_PROTO_VERSION_ID "\r\n"
                       "\r\n";
   wb_.write(res, sizeof(res) - 1);
+  signal_write();
   return 0;
 }
 

src/shrpx_http2_upstream.cc

@@ -116,8 +116,10 @@ int Http2Upstream::upgrade_upstream(HttpsUpstream *http) {
       session_, reinterpret_cast<const uint8_t *>(settings_payload.c_str()),
       settings_payload.size(), nullptr);
   if (rv != 0) {
-    ULOG(WARN, this) << "nghttp2_session_upgrade() returned error: "
-                     << nghttp2_strerror(rv);
+    if (LOG_ENABLED(INFO)) {
+      ULOG(INFO, this) << "nghttp2_session_upgrade() returned error: "
+                       << nghttp2_strerror(rv);
+    }
     return -1;
   }
   pre_upstream_.reset(http);

src/shrpx_https_upstream.cc

@@ -234,13 +234,11 @@ int htp_msg_completecb(http_parser *htp) {
   }
 
   if (handler->get_http2_upgrade_allowed() &&
-      downstream->get_http2_upgrade_request()) {
-
-    if (handler->perform_http2_upgrade(upstream) != 0) {
-      return -1;
+      downstream->get_http2_upgrade_request() &&
+      handler->perform_http2_upgrade(upstream) != 0) {
+    if (LOG_ENABLED(INFO)) {
+      ULOG(INFO, upstream) << "HTTP Upgrade to HTTP/2 failed";
     }
-
-    handler->signal_write();
   }
 
   // Stop further processing to complete this request