Simple TLS server tester in Go

tlsserver.go

package main

import (
	"bufio"
	"crypto/tls"
	"flag"
	"fmt"
	"net"
)

var (
	cert     = flag.String("cert", "", "")
	key      = flag.String("key", "", "")
	insecure = flag.Bool("insecure", false, "")
	host     = flag.String("host", "localhost", "")
	port     = flag.String("port", "8080", "")
)

func main() {
	flag.Parse()

	cert, err := tls.LoadX509KeyPair(*cert, *key)
	if err != nil {
		panic(err)
	}

	tlsConfig := &tls.Config{
		Certificates:             []tls.Certificate{cert},
		ServerName:               *host,
		InsecureSkipVerify:       *insecure,
		PreferServerCipherSuites: true,
		CurvePreferences:         []tls.CurveID{tls.CurveP521, tls.CurveP384, tls.CurveP256},
		// CipherSuites: []uint16{
		// 	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
		// 	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
		// 	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
		// 	tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
		// 	tls.TLS_RSA_WITH_AES_256_CBC_SHA,
		// },
		// CipherSuites: []uint16{
		// 	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
		// 	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
		// 	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
		// 	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
		// 	tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
		// 	tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
		// 	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
		// 	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
		// 	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
		// 	tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
		// 	tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
		// 	tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
		// 	tls.TLS_RSA_WITH_AES_128_CBC_SHA,
		// 	tls.TLS_RSA_WITH_AES_256_CBC_SHA,
		// },
		CipherSuites: []uint16{
			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
			// Not available in crypto/tls/cipher_suites.go
			// tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,
			// 0xC028,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
			// Not available in crypto/tls/cipher_suites.go
			// tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,
			// 0xC024,
			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
			tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
			tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
		},
		MinVersion: tls.VersionTLS12,
	}

	l, err := tls.Listen("tcp", fmt.Sprintf("%s:%s", *host, *port), tlsConfig)
	if err != nil {
		panic(err)
	}
	defer l.Close()

	for {
		conn, err := l.Accept()
		if err != nil {
			fmt.Println(err)
			continue
		}
		go client(conn)
	}
}

func client(conn net.Conn) {
	defer conn.Close()
	r := bufio.NewReader(conn)
	for {
		msg, err := r.ReadString('\n')
		if err != nil {
			fmt.Println(err)
			return
		}

		println(msg)

		n, err := conn.Write([]byte(msg))
		if err != nil {
			fmt.Println(n, err)
			return
		}
	}
}