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zts-svccert.go
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zts-svccert.go
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package main
import (
"bytes"
"crypto"
"crypto/rand"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"flag"
"fmt"
"io/ioutil"
"log"
"strings"
"time"
"github.com/yahoo/athenz/clients/go/zts"
"github.com/yahoo/athenz/libs/go/zmssvctoken"
)
const authHeader = "Athenz-Principal-Auth"
type signer struct {
key crypto.Signer
}
func main() {
var ztsUrl, privateKeyFile, domain, service, keyVersion, certFile, dnsDomain string
flag.StringVar(&certFile, "cert-file", "", "output certificate file")
flag.StringVar(&privateKeyFile, "private-key", "", "private key file")
flag.StringVar(&domain, "domain", "", "domain of service")
flag.StringVar(&service, "service", "", "name of service")
flag.StringVar(&keyVersion, "key-version", "", "key version")
flag.StringVar(&ztsUrl, "zts", "", "url of the ZTS Service")
flag.StringVar(&dnsDomain, "dns-domain", "", "dns domain suffix to be included in the csr")
flag.Parse()
if privateKeyFile == "" || domain == "" || service == "" ||
keyVersion == "" || ztsUrl == "" || dnsDomain == "" {
log.Fatalln("usage: zts-svccert -domain <domain> -service <service> -private-key <key-file> -key-version <version> -zts <zts-server-url> -dns-domain <dns-domain> [-cert-file <output-cert-file>]")
}
// load private key
bytes, err := ioutil.ReadFile(privateKeyFile)
if err != nil {
log.Fatalln(err)
}
// get token builder instance
builder, err := zmssvctoken.NewTokenBuilder(domain, service, bytes, keyVersion)
if err != nil {
log.Fatalln(err)
}
// set optional attributes
builder.SetExpiration(10 * time.Minute)
// get a token instance that always gives you unexpired tokens values
// safe for concurrent use
tok := builder.Token()
// get a token for use
ntoken, err := tok.Value()
if err != nil {
log.Fatalln(err)
}
// use the ntoken to talk to Athenz
client := zts.NewClient(ztsUrl, nil)
client.AddCredentials(authHeader, ntoken)
// get our private key signer for csr
pkSigner, err := newSigner(bytes)
if err != nil {
log.Fatalln(err)
}
// generate a csr for this service
hyphenDomain := strings.Replace(domain, ".", "-", -1)
host := fmt.Sprintf("%s.%s.%s", service, hyphenDomain, dnsDomain)
commonName := fmt.Sprintf("%s.%s", domain, service)
csr, err := generateCSR(pkSigner, commonName, host)
if err != nil {
log.Fatalln(err)
}
req := &zts.InstanceRefreshRequest{Csr: csr}
// request a tls certificate for this service
identity, err := client.PostInstanceRefreshRequest(zts.CompoundName(domain), zts.SimpleName(service), req)
if err != nil {
log.Fatalln(err)
}
if certFile != "" {
err = ioutil.WriteFile(certFile, []byte(identity.Certificate), 0444)
if err != nil {
log.Fatalln(err)
}
} else {
fmt.Println(identity.Certificate)
}
}
func newSigner(privateKeyPEM []byte) (*signer, error) {
block, _ := pem.Decode(privateKeyPEM)
if block == nil {
return nil, fmt.Errorf("Unable to load private key")
}
switch block.Type {
case "EC PRIVATE KEY":
key, err := x509.ParseECPrivateKey(block.Bytes)
if err != nil {
return nil, err
}
return &signer{key: key}, nil
case "RSA PRIVATE KEY":
key, err := x509.ParsePKCS1PrivateKey(block.Bytes)
if err != nil {
return nil, err
}
return &signer{key: key}, nil
default:
return nil, fmt.Errorf("Unsupported private key type: %s", block.Type)
}
}
func generateCSR(keySigner *signer, commonName, host string) (string, error) {
//note: RFC 6125 states that if the SAN (Subject Alternative Name) exists,
//it is used, not the CA. So, we will always put the Athenz name in the CN
//(it is *not* a DNS domain name), and put the host name into the SAN.
subj := pkix.Name{CommonName: commonName}
subj.OrganizationalUnit = []string{"Athenz"}
template := x509.CertificateRequest{
Subject: subj,
SignatureAlgorithm: x509.SHA256WithRSA,
}
if host != "" {
template.DNSNames = []string{host}
}
csr, err := x509.CreateCertificateRequest(rand.Reader, &template, keySigner.key)
if err != nil {
return "", fmt.Errorf("Cannot create CSR: %v", err)
}
block := &pem.Block{
Type: "CERTIFICATE REQUEST",
Bytes: csr,
}
var buf bytes.Buffer
err = pem.Encode(&buf, block)
if err != nil {
return "", fmt.Errorf("Cannot encode CSR to PEM: %v", err)
}
return buf.String(), nil
}