[tcpproxy/udpproxy] Add dummy TCP and UDP clients to facilitate revie…

…wing and testing (thanks to @

samutamm)

example/backend-service/echo/echo.go

@@ -1,14 +1,17 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"io"
+	"log"
+	"net"
 	"net/http"
 	"os"
 	"time"
 )
 
-// TeeWriter is an io.Writer wapper.
+// TeeWriter is an io.Writer wrapper.
 type TeeWriter struct {
 	writers []io.Writer
 }
@@ -26,7 +29,7 @@ func (tw *TeeWriter) Write(p []byte) (n int, err error) {
 	return len(p), nil
 }
 
-func main() {
+func httpServer() {
 	echoHandler := func(w http.ResponseWriter, req *http.Request) {
 		time.Sleep(10 * time.Millisecond)
 		body, err := io.ReadAll(req.Body)
@@ -60,3 +63,79 @@ func main() {
 	http.ListenAndServe(":9095", nil)
 	fmt.Println("listen and serve failed")
 }
+
+func tcpServer() {
+	echoHandler := func(conn net.Conn) {
+		time.Sleep(10 * time.Millisecond)
+		reader := bufio.NewReader(conn)
+		for {
+			message, err := reader.ReadString('\n')
+			if err != nil {
+				conn.Close()
+				return
+			}
+			fmt.Println("Message incoming: ", string(message))
+			responseMsg := []byte(
+				"\nYour Message \n" +
+					"============== \n" +
+					"Message incoming: " + string(message) + "\n",
+			)
+			conn.Write(responseMsg)
+		}
+	}
+
+	listener, err := net.Listen("tcp", "127.0.0.1:9095")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer listener.Close()
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Fatal(err)
+		}
+		go echoHandler(conn)
+	}
+}
+
+func udpServer() {
+	echoHandler := func(pc net.PacketConn, addr net.Addr, buf []byte) {
+		time.Sleep(10 * time.Millisecond)
+
+		fmt.Println("Your Message")
+		fmt.Println("==============")
+		fmt.Printf("Message incoming: %s \n", string(buf))
+
+		pc.WriteTo(buf, addr)
+	}
+	pc, err := net.ListenPacket("udp", ":9095")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer pc.Close()
+
+	for {
+		buf := make([]byte, 1024)
+		n, addr, err := pc.ReadFrom(buf)
+		if err != nil {
+			continue
+		}
+		go echoHandler(pc, addr, buf[:n])
+	}
+}
+
+func main() {
+	protocol := "http"
+	if len(os.Args) > 1 {
+		protocol = os.Args[1]
+	}
+	switch protocol {
+	case "tcp":
+		tcpServer()
+	case "udp":
+		udpServer()
+	default:
+		httpServer()
+	}
+}

example/client/tcp_udp.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"os"
+)
+
+func tcpClient() {
+	strEcho := "Hello from client! \n"
+	servAddr := "127.0.0.1:10080"
+	if len(os.Args) > 2 {
+		servAddr = os.Args[2]
+	}
+	tcpAddr, err := net.ResolveTCPAddr("tcp", servAddr)
+	if err != nil {
+		fmt.Println("ResolveTCPAddr failed:", err.Error())
+		os.Exit(1)
+	}
+
+	conn, err := net.DialTCP("tcp", nil, tcpAddr)
+	if err != nil {
+		fmt.Println("Dial failed:", err.Error())
+		os.Exit(1)
+	}
+
+	_, err = conn.Write([]byte(strEcho))
+	if err != nil {
+		fmt.Println("Write to server failed:", err.Error())
+		os.Exit(1)
+	}
+
+	fmt.Println("write to server = ", strEcho)
+
+	reply := make([]byte, 1024)
+
+	_, err = conn.Read(reply)
+	if err != nil {
+		fmt.Println("Write to server failed:", err.Error())
+		os.Exit(1)
+	}
+
+	fmt.Println("reply from server=", string(reply))
+
+	_ = conn.Close()
+}
+
+func udpClient() {
+	p := make([]byte, 2048)
+	servAddr := "127.0.0.1:10070"
+	if len(os.Args) > 2 {
+		servAddr = os.Args[2]
+	}
+	conn, err := net.Dial("udp", servAddr)
+	if err != nil {
+		fmt.Printf("Some error %v", err)
+		return
+	}
+	_, _ = fmt.Fprintf(conn, "Ping from client")
+	_, err = bufio.NewReader(conn).Read(p)
+	if err == nil {
+		fmt.Printf("%s\n", p)
+	} else {
+		fmt.Printf("Some error %v\n", err)
+	}
+	_ = conn.Close()
+}
+
+func main() {
+	protocol := ""
+	if len(os.Args) > 1 {
+		protocol = os.Args[1]
+	}
+	switch protocol {
+	case "tcp":
+		tcpClient()
+	case "udp":
+		udpClient()
+	default:
+		fmt.Println("Please provide udp or tcp flag.")
+	}
+}