package main

import (
	"crypto/tls"
	"crypto/x509"
	"io"
	"io/ioutil"
	"log"
	"net/http"
)

func helloHandler(w http.ResponseWriter, r *http.Request) {
	// Write "Hello, world!" to the response body
	io.WriteString(w, "Hello, world!\n")
}

func main() {
	// Set up a /hello resource handler
	http.HandleFunc("/hello", helloHandler)

	// Create a CA certificate pool and add cert.pem to it
	caCert, err := ioutil.ReadFile("ca.pem")
	if err != nil {
		log.Fatal(err)
	}
	caCertPool := x509.NewCertPool()
	ok := caCertPool.AppendCertsFromPEM(caCert)
	if !ok {
		panic("failed to parse root certificate")
	}

	// Create the TLS Config with the CA pool and enable Client certificate validation
	tlsConfig := &tls.Config{
		MinVersion:               tls.VersionTLS12,
		ClientCAs:                caCertPool,
		ClientAuth:               tls.RequireAndVerifyClientCert,
	}

	// Create a Server instance to listen on port 8443 with the TLS config
	server := &http.Server{
		Addr:      ":8443",
		TLSConfig: tlsConfig,
	}

	// Listen to HTTPS connections with the server certificate and wait
	log.Fatal(server.ListenAndServeTLS("server-cert.pem", "server-key.pem"))
}

package main

import (
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)

func main() {
	// Read the key pair to create certificate
	cert, err := tls.LoadX509KeyPair("client-cert.pem", "client-key.pem")
	if err != nil {
		log.Fatal(err)
	}

	// Create a CA certificate pool and add cert.pem to it
	caCert, err := ioutil.ReadFile("ca.pem")
	if err != nil {
		log.Fatal(err)
	}
	caCertPool := x509.NewCertPool()
	caCertPool.AppendCertsFromPEM(caCert)

	// Create a HTTPS client and supply the created CA pool and certificate
	client := &http.Client{
		Transport: &http.Transport{
			TLSClientConfig: &tls.Config{
				RootCAs:      caCertPool,
				Certificates: []tls.Certificate{cert},
			},
		},
	}

	// Request /hello via the created HTTPS client over port 8443 via GET
	r, err := client.Get("https://localhost:8443/hello")
	if err != nil {
		log.Fatal(err)
	}

	// Read the response body
	defer r.Body.Close()
	body, err := ioutil.ReadAll(r.Body)
	if err != nil {
		log.Fatal(err)
	}

	// Print the response body to stdout
	fmt.Printf("%s\n", body)
}