package main import ( "context" "encoding/binary" "encoding/json" "fmt" "html/template" "io" "log" "net" "net/http" "os" "time" "golang.org/x/net/websocket" ) var ( addressBind string addressConnect string ) func clientToRelay( ctx context.Context, ws *websocket.Conn, conn net.Conn) bool { var j string if err := websocket.Message.Receive(ws, &j); err != nil { log.Println("Command receive failed: " + err.Error()) return false } log.Printf("?> %s\n", j) var m RelayCommandMessage if err := json.Unmarshal([]byte(j), &m); err != nil { log.Println("Command unmarshalling failed: " + err.Error()) return false } b, ok := m.AppendTo(make([]byte, 4)) if !ok { log.Println("Command serialization failed") return false } binary.BigEndian.PutUint32(b[:4], uint32(len(b)-4)) if _, err := conn.Write(b); err != nil { log.Println("Command send failed: " + err.Error()) return false } log.Printf("-> %v\n", b) return true } func relayToClient( ctx context.Context, ws *websocket.Conn, conn net.Conn) bool { var length uint32 if err := binary.Read(conn, binary.BigEndian, &length); err != nil { log.Println("Event receive failed: " + err.Error()) return false } b := make([]byte, length) if _, err := io.ReadFull(conn, b); err != nil { log.Println("Event receive failed: " + err.Error()) return false } log.Printf("<? %v\n", b) var m RelayEventMessage if after, ok := m.ConsumeFrom(b); !ok { log.Println("Event deserialization failed") return false } else if len(after) != 0 { log.Println("Event deserialization failed: trailing data") return false } j, err := json.Marshal(&m) if err != nil { log.Println("Event marshalling failed: " + err.Error()) return false } if err := websocket.Message.Send(ws, string(j)); err != nil { log.Println("Event send failed: " + err.Error()) return false } log.Printf("<- %s\n", j) return true } func errorToClient(ws *websocket.Conn, err error) bool { j, err := json.Marshal(&RelayEventMessage{ EventSeq: 0, Data: RelayEventData{ Interface: RelayEventDataError{ Event: RelayEventError, CommandSeq: 0, Error: err.Error(), }, }, }) if err != nil { log.Println("Event marshalling failed: " + err.Error()) return false } if err := websocket.Message.Send(ws, string(j)); err != nil { log.Println("Event send failed: " + err.Error()) return false } return true } func handleWebSocket(ws *websocket.Conn) { conn, err := net.Dial("tcp", addressConnect) if err != nil { errorToClient(ws, err) return } // We don't need to intervene, so it's just two separate pipes so far. ctx, cancel := context.WithCancel(ws.Request().Context()) go func() { for clientToRelay(ctx, ws, conn) { } cancel() }() go func() { for relayToClient(ctx, ws, conn) { } cancel() }() <-ctx.Done() } var staticHandler = http.FileServer(http.Dir(".")) var page = template.Must(template.New("/").Parse(`<!DOCTYPE html> <html> <head> <title>xP</title> <meta charset="utf-8" /> <link rel="stylesheet" href="xP.css" /> </head> <body> <script src="mithril.js"> </script> <script> let proxy = '{{ . }}' </script> <script src="xP.js"> </script> </body> </html>`)) func handleDefault(w http.ResponseWriter, r *http.Request) { if r.URL.Path != "/" { staticHandler.ServeHTTP(w, r) return } wsURI := fmt.Sprintf("ws://%s/ws", r.Host) if err := page.Execute(w, wsURI); err != nil { log.Println("Template execution failed: " + err.Error()) } } func main() { if len(os.Args) != 3 { log.Fatalf("usage: %s BIND CONNECT\n", os.Args[0]) } addressBind, addressConnect = os.Args[1], os.Args[2] http.Handle("/ws", websocket.Handler(handleWebSocket)) http.Handle("/", http.HandlerFunc(handleDefault)) s := &http.Server{ Addr: addressBind, ReadTimeout: 60 * time.Second, WriteTimeout: 60 * time.Second, MaxHeaderBytes: 32 << 10, } log.Fatal(s.ListenAndServe()) }