[wpinet] WebSocket: Send pong in response to ping (#5498)

This is required by the spec (RFC 6455 section 5.5.2).

wpinet/src/main/native/cpp/WebSocket.cpp

@@ -573,6 +573,19 @@ void WebSocket::HandleIncoming(uv::Buffer& buf, size_t size) {
             if (!fin) {
               return Fail(1002, "cannot fragment control frames");
             }
+            // If the connection is open, send a Pong in response
+            if (m_state == OPEN) {
+              SmallVector<uv::Buffer, 4> bufs;
+              {
+                raw_uv_ostream os{bufs, 4096};
+                os << m_payload;
+              }
+              SendPong(bufs, [](auto bufs, uv::Error) {
+                for (auto&& buf : bufs) {
+                  buf.Deallocate();
+                }
+              });
+            }
             ping(m_payload);
             break;
           case kOpPong:

wpinet/src/main/native/include/wpinet/WebSocket.h

@@ -460,7 +460,8 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
   sig::Signal<std::span<const uint8_t>, bool> binary;
 
   /**
-   * Ping event.  Emitted when a ping message is received.
+   * Ping event.  Emitted when a ping message is received.  A pong message is
+   * automatically sent in response, so this is simply a notification.
    */
   sig::Signal<std::span<const uint8_t>> ping;
 

wpinet/src/test/native/cpp/WebSocketIntegrationTest.cpp

@@ -147,4 +147,45 @@ TEST_F(WebSocketIntegrationTest, ClientSendText) {
   ASSERT_EQ(gotData, 1);
 }
 
+TEST_F(WebSocketIntegrationTest, ServerSendPing) {
+  int gotPing = 0;
+  int gotPong = 0;
+
+  serverPipe->Listen([&]() {
+    auto conn = serverPipe->Accept();
+    auto server = WebSocketServer::Create(*conn);
+    server->connected.connect([&](std::string_view, WebSocket& ws) {
+      ws.SendPing({uv::Buffer{"\x03\x04", 2}}, [&](auto, uv::Error) {});
+      ws.pong.connect([&](auto data) {
+        ++gotPong;
+        std::vector<uint8_t> recvData{data.begin(), data.end()};
+        std::vector<uint8_t> expectData{0x03, 0x04};
+        ASSERT_EQ(recvData, expectData);
+        ws.Close();
+      });
+    });
+  });
+
+  clientPipe->Connect(pipeName, [&] {
+    auto ws = WebSocket::CreateClient(*clientPipe, "/test", pipeName);
+    ws->closed.connect([&](uint16_t code, std::string_view reason) {
+      Finish();
+      if (code != 1005 && code != 1006) {
+        FAIL() << "Code: " << code << " Reason: " << reason;
+      }
+    });
+    ws->ping.connect([&](auto data) {
+      ++gotPing;
+      std::vector<uint8_t> recvData{data.begin(), data.end()};
+      std::vector<uint8_t> expectData{0x03, 0x04};
+      ASSERT_EQ(recvData, expectData);
+    });
+  });
+
+  loop->Run();
+
+  ASSERT_EQ(gotPing, 1);
+  ASSERT_EQ(gotPong, 1);
+}
+
 }  // namespace wpi