cert.go

package mars

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"math/big"
	"net"
	"strings"
	"time"
)

func createCertificate(organization, domainNames string) (tls.Certificate, error) {
	INFO.Printf("Creating self-signed TLS certificate for %s\n", organization)
	priv, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		ERROR.Fatalf("Failed to generate private key: %s", err)
	}

	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
	if err != nil {
		ERROR.Fatalf("failed to generate serial number: %s", err)
	}

	template := x509.Certificate{
		SerialNumber: serialNumber,
		Subject: pkix.Name{
			Organization: []string{organization},
		},
		NotBefore: time.Now(),
		NotAfter:  time.Now().Add(10 * 365 * 24 * time.Hour),

		IsCA:                  true,
		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
	}

	hosts := strings.Split(strings.TrimSpace(strings.Replace(domainNames, ",", " ", -1)), " ")
	for _, h := range hosts {
		if ip := net.ParseIP(h); ip != nil {
			template.IPAddresses = append(template.IPAddresses, ip)
		} else {
			template.DNSNames = append(template.DNSNames, h)
		}
	}

	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
	if err != nil {
		ERROR.Fatalf("Failed to create certificate: %s", err)
	}
	cert := &bytes.Buffer{}
	pem.Encode(cert, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})

	key := &bytes.Buffer{}
	pem.Encode(key, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})

	return tls.X509KeyPair(cert.Bytes(), key.Bytes())
}