基于Golang和WebSocket打造自已的反向代理

当我们在开发的时候，有时想要把自已开发的接口暴露给其他开发者或者第三方的服务，方便我们调试和排查问题，那就需要某种机制把我们本地的服务接口暴露到互联网上，本文将要介绍如何通过Golang和WebSocket来实现这一功能 ## 为什么我们需要开发自已的代理服务 目前已经有许多可用的代理服务了，比如ngrok和localtunnel,但ngrok有个缺点就是提供的域名只能用几个小时，然后需要新生成新的域名，如果想要固定域名就要花钱，但我们自已实现的代理可以用一个固定的域名，如果给前端同学来调试的话，不用改来改去，很方便。 ## ggrok简介  ggrok是通过Golang和WebSocket实现的代理应用，你可以通过Github[仓库](https://github.com/onyas/ggrok)上的Heroku按钮非常方便的部署，然后就可以拥有一个固定的域名了。 ## 如何实现 ### Step1 在服务器和客户端建立WebSocket连接 服务端基于gorilla，监听WebSocket连接 ```golang func (s *Server) Register(w http.ResponseWriter, r *http.Request) { c, err := upgrader.Upgrade(w, r, nil) if err != nil { log.Print("upgrade:", err) return } gconn := &Connection{ Socket: c, mu: sync.Mutex{}, } connections[r.Host] = gconn log.Println("current connections: ", connections) } http.HandleFunc("/$$ggrok", s.Register) ``` 客户端连接服务端 ```golang func (ggclient *GGrokClient) Proxy() { interrupt := make(chan os.Signal, 1) signal.Notify(interrupt, os.Interrupt) u := url.URL{Scheme: "ws", Host: ggclient.RemoteServer, Path: "/$$ggrok"} log.Printf("connecting to %s", u.String()) c, _, err := websocket.DefaultDialer.Dial(u.String(), nil) if err != nil { log.Fatal("dial:", err) } defer c.Close() done := make(chan struct{}) for { select { case <-done: return } } } ``` ### Step2 服务端收到http请求以后转成WebSocket消息转发给客户端 ```golang http.HandleFunc("/", s.Proxy) func (s *Server) Proxy(w http.ResponseWriter, r *http.Request) { remoteConn := connections[r.Host] if remoteConn == nil || remoteConn.Socket == nil { io.WriteString(w, "client not register") return } wsRequest := httpRequestToWebSocketRequest(r) wsRes := triggerWS(remoteConn, wsRequest) } func triggerWS(remoteConn *Connection, reqRemote WebSocketRequest) WebSocketResponse { remoteConn.mu.Lock() defer remoteConn.mu.Unlock() remoteConn.Socket.WriteJSON(reqRemote) var wsRes WebSocketResponse err := remoteConn.Socket.ReadJSON(&wsRes) if err != nil { log.Println("read remote client response error", err) } log.Println("remote client response: ", wsRes) return wsRes } func httpRequestToWebSocketRequest(r *http.Request) (ws WebSocketRequest) { reqStr, err := captureRequestData(r) if err != nil { log.Println("captureRequestData error:", err) } log.Println("req serialized: ", reqStr) reqRemote := WebSocketRequest{Req: reqStr, URL: r.URL.String()} return reqRemote } ``` ### Step3 客户端收到WebSocket消息以后转发到LocalServer,并把LocalServer的响应返回给服务端 ```golang go func() { defer close(done) for { websocketReq := readWebSocketReq(c) localRequest := socketToLocalRequest(websocketReq, ggclient.ProxyLocalPort) resp, err := (&http.Client{}).Do(localRequest) if err != nil { log.Println("local http request error:", err) continue } wsRes := localResponseToWebSocketResponse(resp) // log.Printf("client send response: %s \n", wsRes.Body) c.WriteJSON(wsRes) } }() func socketToLocalRequest(websocketReq WebSocketRequest, port int) *http.Request { r := bufio.NewReader(bytes.NewReader([]byte(websocketReq.Req))) localRequest, err := http.ReadRequest(r) if err != nil { log.Println("deserialize request error", err) return localRequest } localRequest.RequestURI = "" u, err := url.Parse(websocketReq.URL) if err != nil { log.Println("parse url error", err) } localRequest.URL = u localRequest.URL.Scheme = "http" localRequest.URL.Host = "localhost:" + strconv.Itoa(port) return localRequest } func localResponseToWebSocketResponse(resp *http.Response) WebSocketResponse { body, err := io.ReadAll(resp.Body) if err != nil { log.Println("read local response error ", err) } resp.Body.Close() wsRes := WebSocketResponse{Status: resp.Status, StatusCode: resp.StatusCode, Proto: resp.Proto, Header: resp.Header, Body: body, ContentType: resp.Header.Get("Content-Type")} return wsRes } ``` ### Step4 服务端收到响应以后返回给前端 ```golang func wsResToHttpResponse(w http.ResponseWriter, wsRes WebSocketResponse) { copyHeader(w, wsRes) io.Copy(w, bytes.NewReader(wsRes.Body)) } ``` 至此，通过ggrok我们实现了本地服务的代理，并发布到互联网上。以上是一些主要的代码，详细的可以看[github](https://github.com/onyas/ggrok)上面的代码，有问题请提issue或者pr，共同打造更健壮的开源系统。