/
checkcrl.go
134 lines (116 loc) · 3.22 KB
/
checkcrl.go
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package main
import (
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/base64"
"encoding/pem"
"flag"
"fmt"
"io/ioutil"
"time"
)
func check(e error) {
if e != nil {
panic(e)
}
}
func loadCertPool(filename string) (*x509.CertPool, []*x509.Certificate) {
dat, err := ioutil.ReadFile(filename)
check(err)
pool := x509.NewCertPool()
// annoyingly, we have to parse the PEM ourselves since we need each cert
// outside of the cert pool
var certs []*x509.Certificate
for len(dat) > 0 {
var block *pem.Block
block, dat = pem.Decode(dat)
if block == nil {
break
}
if block.Type != "CERTIFICATE" || len(block.Headers) != 0 {
continue
}
cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
continue
}
certs = append(certs, cert)
pool.AddCert(cert)
}
return pool, certs
}
func findSigningCert(certs []*x509.Certificate, crl *pkix.CertificateList) *x509.Certificate{
for _, cert := range certs {
if nil == cert.CheckCRLSignature(crl) {
return cert
}
}
return nil
}
func main() {
interPEMPtr := flag.String("inter", "", "a PEM file containing intermediates")
rootPEMPtr := flag.String("roots", "", "a PEM file containing roots")
crlPtr := flag.String("crl", "", "a CRL file")
flag.Parse()
var rootPool, intermediatePool *x509.CertPool
var roots, intermediates []*x509.Certificate
if nil != rootPEMPtr && len(*rootPEMPtr) > 0 {
rootPool, roots = loadCertPool(*rootPEMPtr)
}
if nil != interPEMPtr && len(*interPEMPtr) > 0 {
intermediatePool, intermediates = loadCertPool(*interPEMPtr)
}
var crlData []byte
if nil != crlPtr && len(*crlPtr) > 0 {
// Get the crl from the args
var err error
crlData, err = ioutil.ReadFile(*crlPtr)
check(err)
}
if len(crlData) > 0{
// Maybe it's PEM; try to parse as PEM, if that fails, just use the bytes
block, _ := pem.Decode(crlData)
if block != nil {
crlData = block.Bytes
}
crl, err := x509.ParseCRL(crlData)
if err != nil {
panic("could not parse CRL")
}
// check the CRL is still current
if crl.HasExpired(time.Now()) {
fmt.Printf("crl has expired\n")
}
var signer *x509.Certificate
if (nil != roots) {
signer = findSigningCert(roots, crl)
if nil == signer {
fmt.Printf("Not signed by a root; trying known intermediates\n");
if nil != intermediates {
signer = findSigningCert(intermediates, crl)
}
}
}
if nil != signer {
fmt.Printf("found signer! %v\n", signer.Subject)
opts := x509.VerifyOptions{
Roots: rootPool,
Intermediates: intermediatePool,
}
if _,err := signer.Verify(opts); err != nil {
fmt.Println("Warning! Can't verify signer!")
}
}
issuerData, err := asn1.Marshal(crl.TBSCertList.Issuer)
if nil == err {
issuerString := base64.StdEncoding.EncodeToString(issuerData)
fmt.Printf("%v\n", issuerString);
}
for revoked := range crl.TBSCertList.RevokedCertificates {
cert := crl.TBSCertList.RevokedCertificates[revoked]
fmt.Printf(" %v\n",
base64.StdEncoding.EncodeToString(cert.SerialNumber.Bytes()))
}
}
}