package main import ( "net" "os" "fmt" "bufio" "regexp" ) type ProxyServer struct { port uint16 } func NewProxyServer(port uint16) *ProxyServer { return &ProxyServer{port} } func (s *ProxyServer) Run() { addr := fmt.Sprintf("0.0.0.0:%d", s.port) server, err := net.Listen("tcp", addr) if err != nil { fmt.Println("Error listening:", err.Error()) os.Exit(1) } defer server.Close() fmt.Println("ProxyServer waiting for client...") for { connection, err := server.Accept() if err != nil { fmt.Println("Error accepting: ", err.Error()) os.Exit(1) } fmt.Println("client connected") s.start(connection) } } func (s *ProxyServer) start(down net.Conn) { addr := "chat.protohackers.com:16963" up, err := net.Dial("tcp", addr) if err != nil { fmt.Println(err) return } go s.stream(up, down) go s.stream(down, up) } func (s *ProxyServer) stream(input net.Conn, output net.Conn) { r := bufio.NewReader(input) var err error for err == nil { msg, err := r.ReadString('\n') if err != nil { break } msg = s.transform(msg) _, err = output.Write([]byte(msg)) } input.Close() output.Close() } func (s *ProxyServer) transform(input string) string { fmt.Printf(">> %s", input) tony := "${1}7YWHMfk9JZe0LM0g1ZauHuiSxhI${3}" r := regexp.MustCompile(`(^|\s)(7[a-zA-Z0-9]{25,34})($|\s)`) output := r.ReplaceAllString(input, tony) fmt.Printf("<< %s", output) return output }