/
cert.go
176 lines (145 loc) · 3.41 KB
/
cert.go
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package utils
import (
"crypto/ecdsa"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"math/big"
"net"
"os"
"time"
)
// Generate a self-signed X.509 certificate.
// Outputs will overwrite existing files.
func publicKey(priv interface{}) interface{} {
switch k := priv.(type) {
case *rsa.PrivateKey:
return &k.PublicKey
case *ecdsa.PrivateKey:
return &k.PublicKey
default:
return nil
}
}
func pemBlockForKey(priv interface{}) *pem.Block {
switch k := priv.(type) {
case *rsa.PrivateKey:
return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
case *ecdsa.PrivateKey:
b, err := x509.MarshalECPrivateKey(k)
if err != nil {
return nil
}
return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
default:
return nil
}
}
func generateCertificate(hosts []string, keyFile string, certFile string) error {
var priv interface{}
var err error
priv, err = rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return err
}
notBefore := time.Now()
notAfter := notBefore.Add(3650 * 24 * time.Hour)
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return err
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{"Aquasec"},
},
NotBefore: notBefore,
NotAfter: notAfter,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
for _, h := range hosts {
if ip := net.ParseIP(h); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, h)
}
}
template.IsCA = true
template.KeyUsage |= x509.KeyUsageCertSign
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
if err != nil {
return err
}
certOut, err := os.Create(certFile)
if err != nil {
return err
}
err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
if err != nil {
return err
}
certOut.Close()
keyOut, err := os.OpenFile(keyFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return err
}
err = pem.Encode(keyOut, pemBlockForKey(priv))
if err != nil {
return err
}
keyOut.Close()
return nil
}
func getHostnames() ([]string, error) {
var hosts []string
ifaces, err := net.Interfaces()
if err != nil {
return hosts, err
}
for _, iface := range ifaces {
if iface.Flags&net.FlagUp == 0 {
continue // interface down
}
if iface.Flags&net.FlagLoopback != 0 {
continue // loopback interface
}
addrs, err := iface.Addrs()
if err != nil {
return hosts, err
}
for _, addr := range addrs {
var ip net.IP
switch v := addr.(type) {
case *net.IPNet:
ip = v.IP
case *net.IPAddr:
ip = v.IP
}
if ip == nil || ip.IsLoopback() {
continue
}
ip = ip.To4()
if ip == nil {
continue // not an ipv4 address
}
hosts = append(hosts, ip.String())
hh, _ := net.LookupAddr(ip.String())
for _, h := range hh {
hosts = append(hosts, h)
}
}
}
return hosts, nil
}
func GenerateCertificate(keyFile string, certFile string) error {
hosts, err := getHostnames()
if err != nil {
return err
}
return generateCertificate(hosts, keyFile, certFile)
}