package main


import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"encoding/pem"
	"math/big"
	"net"
	"net/http"
	"os"
	"time"
	"fmt"
)

func generateSelfSignedCert(host string) (tls.Certificate, error) {
	cert := &x509.Certificate{
		SerialNumber:          big.NewInt(0),
		NotBefore:             time.Now(),
		NotAfter:              time.Now().AddDate(10, 0, 0),
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		KeyUsage:              x509.KeyUsageDigitalSignature,
		BasicConstraintsValid: true,
	}

	cert.DNSNames = []string{host}
	certPrivKey, err := rsa.GenerateKey(rand.Reader, 4096)
	if err != nil {
		return tls.Certificate{}, err
	}
	certBytes, err := x509.CreateCertificate(rand.Reader, cert, cert, &certPrivKey.PublicKey, certPrivKey)
	if err != nil {
		return tls.Certificate{}, err
	}
	certPEM := new(bytes.Buffer)
	pem.Encode(certPEM, &pem.Block{
		Type:  "CERTIFICATE",
		Bytes: certBytes,
	})
	certPrivKeyPEM := new(bytes.Buffer)
	pem.Encode(certPrivKeyPEM, &pem.Block{
		Type:  "RSA PRIVATE KEY",
		Bytes: x509.MarshalPKCS1PrivateKey(certPrivKey),
	})
	serverCert, err := tls.X509KeyPair(certPEM.Bytes(), certPrivKeyPEM.Bytes())
	if err != nil {
		return tls.Certificate{}, err
	}
	return serverCert, err
}

type myHandler struct{
	nreq int
}

func (h myHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Printf("accepted request number %d", h.nreq)
	fmt.Fprintf(w, "request number: %d", h.nreq)
}

func main() {
	hostname, err := os.Hostname()
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	cert, err := generateSelfSignedCert(hostname)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	tlsConfig := &tls.Config{
		Certificates: []tls.Certificate{cert},
		ClientAuth: tls.RequireAnyClientCert,
	}

	srv := &http.Server{
		Addr:         ":8080",
		Handler:      myHandler{nreq: 0},
		ReadTimeout:  5 * time.Minute,
		WriteTimeout: 5 * time.Minute,
		IdleTimeout:  5 * time.Minute,
		ConnState: func(conn net.Conn, event http.ConnState) {
			fmt.Printf("addr: %s, changed state to: %s", conn.RemoteAddr(), event.String())
		},
		TLSConfig: tlsConfig,
	}

	srv.ListenAndServeTLS("", "")
}