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|
package localca
import (
"bytes"
"crypto"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/hex"
"encoding/pem"
"fmt"
"io/ioutil"
"math"
"math/big"
"net"
"os"
"strings"
"time"
)
type issuer struct {
key crypto.Signer
cert *x509.Certificate
}
func getIssuer(keyFile, certFile string, autoCreate bool) (*issuer, error) {
keyContents, keyErr := ioutil.ReadFile(keyFile)
certContents, certErr := ioutil.ReadFile(certFile)
if os.IsNotExist(keyErr) && os.IsNotExist(certErr) {
err := makeIssuer(keyFile, certFile)
if err != nil {
return nil, err
}
return getIssuer(keyFile, certFile, false)
} else if keyErr != nil {
return nil, fmt.Errorf("%s (but %s exists)", keyErr, certFile)
} else if certErr != nil {
return nil, fmt.Errorf("%s (but %s exists)", certErr, keyFile)
}
key, err := readPrivateKey(keyContents)
if err != nil {
return nil, fmt.Errorf("reading private key from %s: %s", keyFile, err)
}
cert, err := readCert(certContents)
if err != nil {
return nil, fmt.Errorf("reading CA certificate from %s: %s", certFile, err)
}
equal, err := publicKeysEqual(key.Public(), cert.PublicKey)
if err != nil {
return nil, fmt.Errorf("comparing public keys: %s", err)
} else if !equal {
return nil, fmt.Errorf("public key in CA certificate %s doesn't match private key in %s",
certFile, keyFile)
}
return &issuer{key, cert}, nil
}
func readPrivateKey(keyContents []byte) (crypto.Signer, error) {
block, _ := pem.Decode(keyContents)
if block == nil {
return nil, fmt.Errorf("no PEM found")
} else if block.Type != "RSA PRIVATE KEY" && block.Type != "ECDSA PRIVATE KEY" {
return nil, fmt.Errorf("incorrect PEM type %s", block.Type)
}
return x509.ParsePKCS1PrivateKey(block.Bytes)
}
func readCert(certContents []byte) (*x509.Certificate, error) {
block, _ := pem.Decode(certContents)
if block == nil {
return nil, fmt.Errorf("no PEM found")
} else if block.Type != "CERTIFICATE" {
return nil, fmt.Errorf("incorrect PEM type %s", block.Type)
}
return x509.ParseCertificate(block.Bytes)
}
func makeIssuer(keyFile, certFile string) error {
keyData, key, err := makeKey()
if err != nil {
return err
}
ioutil.WriteFile(keyFile, keyData, 0600)
certData, _, err := makeRootCert(key, certFile)
if err != nil {
return err
}
ioutil.WriteFile(certFile, certData, 0600)
return nil
}
func makeKey() ([]byte, *rsa.PrivateKey, error) {
key, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, nil, err
}
der := x509.MarshalPKCS1PrivateKey(key)
if err != nil {
return nil, nil, err
}
buf := bytes.NewBuffer([]byte{})
err = pem.Encode(buf, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: der,
})
if err != nil {
return nil, nil, err
}
return buf.Bytes(), key, nil
}
func makeRootCert(key crypto.Signer, filename string) ([]byte, *x509.Certificate, error) {
serial, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
return nil, nil, err
}
template := &x509.Certificate{
Subject: pkix.Name{
CommonName: "localca root ca " + hex.EncodeToString(serial.Bytes()[:3]),
},
SerialNumber: serial,
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(100, 0, 0),
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
BasicConstraintsValid: true,
IsCA: true,
MaxPathLenZero: true,
}
der, err := x509.CreateCertificate(rand.Reader, template, template, key.Public(), key)
if err != nil {
return nil, nil, err
}
buf := bytes.NewBuffer([]byte{})
err = pem.Encode(buf, &pem.Block{
Type: "CERTIFICATE",
Bytes: der,
})
if err != nil {
return nil, nil, err
}
result, err := x509.ParseCertificate(der)
return buf.Bytes(), result, err
}
func parseIPs(ipAddresses []string) ([]net.IP, error) {
var parsed []net.IP
for _, s := range ipAddresses {
p := net.ParseIP(s)
if p == nil {
return nil, fmt.Errorf("invalid IP address %s", s)
}
parsed = append(parsed, p)
}
return parsed, nil
}
func publicKeysEqual(a, b interface{}) (bool, error) {
aBytes, err := x509.MarshalPKIXPublicKey(a)
if err != nil {
return false, err
}
bBytes, err := x509.MarshalPKIXPublicKey(b)
if err != nil {
return false, err
}
return bytes.Compare(aBytes, bBytes) == 0, nil
}
func (iss *issuer) sign(domains []string, ipAddresses []string) ([]byte, *x509.Certificate, error) {
var cn string
if len(domains) > 0 {
cn = domains[0]
} else if len(ipAddresses) > 0 {
cn = ipAddresses[0]
} else {
return nil, nil, fmt.Errorf("must specify at least one domain name or IP address")
}
keyData, key, err := makeKey()
if err != nil {
return nil, nil, err
}
buf := bytes.NewBuffer([]byte{})
buf.Write(keyData)
parsedIPs, err := parseIPs(ipAddresses)
if err != nil {
return nil, nil, err
}
serial, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
return nil, nil, err
}
template := &x509.Certificate{
DNSNames: domains,
IPAddresses: parsedIPs,
Subject: pkix.Name{
CommonName: cn,
},
SerialNumber: serial,
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(90, 0, 0),
KeyUsage: x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
BasicConstraintsValid: true,
IsCA: false,
}
der, err := x509.CreateCertificate(rand.Reader, template, iss.cert, key.Public(), iss.key)
if err !=
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