API question

[Aymsd]

In file: oatpp-websocket/Handshaker.hpp

Question

First of all I want to thank you for this amazing framework. I have a small question regarding a use case of oat++ websocket. in my case I'm trying to set up a websocket (with stomp) I have almost made it work but I'm still missing a header while doing the handshake. The header I'm missing in this case is "Sec-WebSocket-Protocol" this one is expected from the client's side. My issue is that I cannot add a header using the putHeader function. as soon as I do that the Handshake does not happen anymore. Here is a sample of my controller. I'm guessing that I should not do it in an Action act(). But what would be the solution then please ?

`

ENDPOINT_ASYNC("GET", "PPLATFORM", WS){

    ENDPOINT_ASYNC_INIT(WS)

        Action act() override{
auto response = oatpp::websocket::Handshaker::serversideHandshake(request->getHeaders(), controller->websocketConnectionHandler);
response->putHeader("Sec-WebSocket-Protocol", "v11.stomp");   /* This is my issue */

return _return(response);
}

}

`

Thank you so much in advance

[lganzzzo]

Hello @Aymsd ,

It looks like you are doing everything right.

You can find the handshake with subprotocol example in this issue - https://github.com/oatpp/oatpp-websocket/issues/31

Here is a sample of my controller. I'm guessing that I should not do it in an Action act(). But what would be the solution then please ?

It is safe to call Handshaker::serversideHandshake in act() method. Nothing wrong here.

My issue is that I cannot add a header using the putHeader function. as soon as I do that the Handshake does not happen anymore.

What do you mean by "does not happen anymore." do you receive any errors?

[Aymsd]

Thank you for the reply.

Yes that issue does help. I cannot however put 5 arguments to the ENDPOINT_ASYNC macro. (I tried to copy it but I get: error: macro "ENDPOINT_ASYNC" passed 5 arguments, but takes just 3) (this might be just because i'm doing something stupid as I usually do..)

But when I said the handshake does not happen anymore what I tried to say is that the connection fails without even getting a handshake from my app.

To be more specific mainly my issue is that : I use two clients to test the app: 1- Client that does not verify sub-protocol : this one does work just fine if I do not add the "response->putHeader("Sec-WebSocket-Protocol", "v11.stomp");" As soon as I add that it fails "WebSocket connection to 'ws://127.0.0.1:7499/PPLATFORM' failed" with no more detail from my debug tool

2- Client that does check for the subprotocol and this one raises the issue: "WebSocket connection to 'ws://[127.0.0.1:7499/PPLATFORM](http://127.0.0.1:7499/PPLATFORM)' failed: Error during WebSocket handshake: Sent non-empty 'Sec-WebSocket-Protocol' header but no response was received " if do not add the "response->putHeader("Sec-WebSocket-Protocol", "v11.stomp");".

When I do add it I get an issue WebSocket connection to ws://127.0.0.1:7499/PPLATFORM failed: Connection closed before receiving a handshake response

Thank you so much again.

[lganzzzo]

Hello @Aymsd ,

It looks like you are doing everything right. Make sure that the name of the subprotocol matches - the one requested by the client and the one you include in response from the server.

Basically, your client should include Sec-WebSocket-Protocol: v11.stomp header, and your server should return a successful handshake response with the exact same header.

Yes that issue does help. I cannot however put 5 arguments to the ENDPOINT_ASYNC macro. (I tried to copy it but I get: error: macro "ENDPOINT_ASYNC" passed 5 arguments, but takes just 3) (this might be just because i'm doing something stupid as I usually do..)

ENDPOINT_ASYNC doesn't support header mapping like simple API does. Instead you have to use direct calls to request->getHeader()

Client that does check for the subprotocol and this one raises the issue: "WebSocket connection to 'ws://127.0.0.1:7499/PPLATFORM' failed: Error during WebSocket handshake: Sent non-empty 'Sec-WebSocket-Protocol' header but no response was received " if do not add the "response->putHeader("Sec-WebSocket-Protocol", "v11.stomp");".

When I do add it I get an issue WebSocket connection to ws://127.0.0.1:7499/PPLATFORM failed: Connection closed before receiving a handshake response

This looks correct. Please double-check the following:

• The name of the subprotocol sent by the client matches the name of the subprotocol you are answering to the client from the server.
• Try to identify why the connection is closed? It may be that the client receives a different subprotocl name and closes the connection.

[Aymsd]

Thank you for the reply.

That makes sens. I will try maybe using some other websocket debug tools. I will update this in the next few days.

Thank you so much.