wstunnel VS wsp

This is the version I was able to use and to my best knowledge it doesn’t support UDP: https://github.com/mhzed/wstunnel

There are not that many examples of implementation reverse proxy over WebSocket. In JavaScript, mhzed/wstunnel is well known, in Haskell, erebe/wstunnel is.

func (s *Server) request(w http.ResponseWriter, r *http.Request) { // (omit): [1]: Receive requests to be proxied // [2]: Take a WebSocket connection available from pools for relaying received requests. request := NewConnectionRequest(s.Config.GetTimeout()) // "Dispatcher" is running in a separate thread from the server by `go s.dispatchConnections()`. // It waits to receive requests to dispatch connection from available pools to clients requests. // https://github.com/hgsgtk/wsp/blob/ea4902a8e11f820268e52a6245092728efeffd7f/server/server.go#L93 // // Notify request from handler to dispatcher through Server.dispatcher channel. s.dispatcher <- request // Dispatcher tries to find an available connection pool, // and it returns the connection through Server.connection channel. // https://github.com/hgsgtk/wsp/blob/ea4902a8e11f820268e52a6245092728efeffd7f/server/server.go#L189 // // Here waiting for a result from dispatcher. connection := <-request.connection if connection == nil { // It means that dispatcher has set `nil` which is a system error case that is // not expected in the normal flow. wsp.ProxyErrorf(w, "Unable to get a proxy connection") return } // [3]: Send the request to the peer through the WebSocket connection. if err := connection.proxyRequest(w, r); err != nil { // An error occurred throw the connection away log.Println(err) connection.Close() // Try to return an error to the client // This might fail if response headers have already been sent wsp.ProxyError(w, err) } }

This handler process registered an idle connection that can be used for relay. NewConnection() function mark a new connection as a usable connection for relay in the pool and start a thread (technically, start a new goroutine running) that keeps reading messages over the connected WebSocket connection from the wsp client.

Let's read the Go code. First is the main function (cmd/client/main.go), which is the entry point.

However, maintenance has stopped since the days of Go 1.6, so I'll proceed with this post based on code hgsgtk/wsp that I forked and modified for the Go situation in 2021 (Thank you root-gg).