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cert.go
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cert.go
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// Copyright (C) 2017. See AUTHORS.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package openssl
// #include "shim.h"
import "C"
import (
"errors"
"fmt"
"io/ioutil"
"math/big"
"runtime"
"time"
"unsafe"
)
type EVP_MD int
const (
EVP_NULL EVP_MD = iota
EVP_MD5 EVP_MD = iota
EVP_MD4 EVP_MD = iota
EVP_SHA EVP_MD = iota
EVP_SHA1 EVP_MD = iota
EVP_DSS EVP_MD = iota
EVP_DSS1 EVP_MD = iota
EVP_MDC2 EVP_MD = iota
EVP_RIPEMD160 EVP_MD = iota
EVP_SHA224 EVP_MD = iota
EVP_SHA256 EVP_MD = iota
EVP_SHA384 EVP_MD = iota
EVP_SHA512 EVP_MD = iota
)
// X509_Version represents a version on an x509 certificate.
type X509_Version int
// Specify constants for x509 versions because the standard states that they
// are represented internally as one lower than the common version name.
const (
X509_V1 X509_Version = 0
X509_V3 X509_Version = 2
)
type Certificate struct {
x *C.X509
Issuer *Certificate
ref interface{}
pubKey PublicKey
}
type CertificateInfo struct {
Serial *big.Int
Issued time.Duration
Expires time.Duration
Country string
Organization string
CommonName string
}
type Name struct {
name *C.X509_NAME
}
// Allocate and return a new Name object.
func NewName() (*Name, error) {
n := C.X509_NAME_new()
if n == nil {
return nil, errors.New("could not create x509 name")
}
name := &Name{name: n}
runtime.SetFinalizer(name, func(n *Name) {
C.X509_NAME_free(n.name)
})
return name, nil
}
// AddTextEntry appends a text entry to an X509 NAME.
func (n *Name) AddTextEntry(field, value string) error {
cfield := C.CString(field)
defer C.free(unsafe.Pointer(cfield))
cvalue := (*C.uchar)(unsafe.Pointer(C.CString(value)))
defer C.free(unsafe.Pointer(cvalue))
ret := C.X509_NAME_add_entry_by_txt(
n.name, cfield, C.MBSTRING_ASC, cvalue, -1, -1, 0)
if ret != 1 {
return errors.New("failed to add x509 name text entry")
}
return nil
}
// AddTextEntries allows adding multiple entries to a name in one call.
func (n *Name) AddTextEntries(entries map[string]string) error {
for f, v := range entries {
if err := n.AddTextEntry(f, v); err != nil {
return err
}
}
return nil
}
// GetEntry returns a name entry based on NID. If no entry, then ("", false) is
// returned.
func (n *Name) GetEntry(nid NID) (entry string, ok bool) {
entrylen := C.X509_NAME_get_text_by_NID(n.name, C.int(nid), nil, 0)
if entrylen == -1 {
return "", false
}
buf := (*C.char)(C.malloc(C.size_t(entrylen + 1)))
defer C.free(unsafe.Pointer(buf))
C.X509_NAME_get_text_by_NID(n.name, C.int(nid), buf, entrylen+1)
return C.GoStringN(buf, entrylen), true
}
// NewCertificate generates a basic certificate based
// on the provided CertificateInfo struct
func NewCertificate(info *CertificateInfo, key PublicKey) (*Certificate, error) {
c := &Certificate{x: C.X509_new()}
runtime.SetFinalizer(c, func(c *Certificate) {
C.X509_free(c.x)
})
name, err := c.GetSubjectName()
if err != nil {
return nil, err
}
err = name.AddTextEntries(map[string]string{
"C": info.Country,
"O": info.Organization,
"CN": info.CommonName,
})
if err != nil {
return nil, err
}
// self-issue for now
if err := c.SetIssuerName(name); err != nil {
return nil, err
}
if err := c.SetSerial(info.Serial); err != nil {
return nil, err
}
if err := c.SetIssueDate(info.Issued); err != nil {
return nil, err
}
if err := c.SetExpireDate(info.Expires); err != nil {
return nil, err
}
if err := c.SetPubKey(key); err != nil {
return nil, err
}
return c, nil
}
func (c *Certificate) GetSubjectName() (*Name, error) {
n := C.X509_get_subject_name(c.x)
if n == nil {
return nil, errors.New("failed to get subject name")
}
return &Name{name: n}, nil
}
func (c *Certificate) GetIssuerName() (*Name, error) {
n := C.X509_get_issuer_name(c.x)
if n == nil {
return nil, errors.New("failed to get issuer name")
}
return &Name{name: n}, nil
}
func (c *Certificate) SetSubjectName(name *Name) error {
if C.X509_set_subject_name(c.x, name.name) != 1 {
return errors.New("failed to set subject name")
}
return nil
}
// SetIssuer updates the stored Issuer cert
// and the internal x509 Issuer Name of a certificate.
// The stored Issuer reference is used when adding extensions.
func (c *Certificate) SetIssuer(issuer *Certificate) error {
name, err := issuer.GetSubjectName()
if err != nil {
return err
}
if err = c.SetIssuerName(name); err != nil {
return err
}
c.Issuer = issuer
return nil
}
// SetIssuerName populates the issuer name of a certificate.
// Use SetIssuer instead, if possible.
func (c *Certificate) SetIssuerName(name *Name) error {
if C.X509_set_issuer_name(c.x, name.name) != 1 {
return errors.New("failed to set subject name")
}
return nil
}
// SetSerial sets the serial of a certificate.
func (c *Certificate) SetSerial(serial *big.Int) error {
sno := C.ASN1_INTEGER_new()
defer C.ASN1_INTEGER_free(sno)
bn := C.BN_new()
defer C.BN_free(bn)
serialBytes := serial.Bytes()
if bn = C.BN_bin2bn((*C.uchar)(unsafe.Pointer(&serialBytes[0])), C.int(len(serialBytes)), bn); bn == nil {
return errors.New("failed to set serial")
}
if sno = C.BN_to_ASN1_INTEGER(bn, sno); sno == nil {
return errors.New("failed to set serial")
}
if C.X509_set_serialNumber(c.x, sno) != 1 {
return errors.New("failed to set serial")
}
return nil
}
// GetIssueDate retrieves the certificate issue date.
func (c *Certificate) GetIssueDate() (time.Time, error) {
var ts time.Time
result := C.X_X509_get0_notBefore(c.x)
if result == nil {
return ts, errors.New("failed to get issue date")
}
str := C.GoString((*C.char)(unsafe.Pointer(result.data)))
ts, err := time.Parse("060102150405Z", str)
if err != nil {
return ts, fmt.Errorf("unable to parse timestamp: %v", err)
}
return ts, nil
}
// SetIssueDate sets the certificate issue date relative to the current time.
func (c *Certificate) SetIssueDate(when time.Duration) error {
offset := C.long(when / time.Second)
result := C.X509_gmtime_adj(C.X_X509_get0_notBefore(c.x), offset)
if result == nil {
return errors.New("failed to set issue date")
}
return nil
}
// GetExpireDate retrieves the certificate expiry date.
func (c *Certificate) GetExpireDate() (time.Time, error) {
var ts time.Time
result := C.X_X509_get0_notAfter(c.x)
if result == nil {
return ts, errors.New("failed to get expiry date")
}
str := C.GoString((*C.char)(unsafe.Pointer(result.data)))
ts, err := time.Parse("060102150405Z", str)
if err != nil {
return ts, fmt.Errorf("unable to parse timestamp: %v", err)
}
return ts, nil
}
// SetExpireDate sets the certificate issue date relative to the current time.
func (c *Certificate) SetExpireDate(when time.Duration) error {
offset := C.long(when / time.Second)
result := C.X509_gmtime_adj(C.X_X509_get0_notAfter(c.x), offset)
if result == nil {
return errors.New("failed to set expire date")
}
return nil
}
// SetPubKey assigns a new public key to a certificate.
func (c *Certificate) SetPubKey(pubKey PublicKey) error {
c.pubKey = pubKey
if C.X509_set_pubkey(c.x, pubKey.evpPKey()) != 1 {
return errors.New("failed to set public key")
}
return nil
}
// Sign a certificate using a private key and a digest name.
// Accepted digest names are 'sha256', 'sha384', and 'sha512'.
func (c *Certificate) Sign(privKey PrivateKey, digest EVP_MD) error {
switch digest {
case EVP_SHA256:
case EVP_SHA384:
case EVP_SHA512:
default:
return errors.New("Unsupported digest" +
"You're probably looking for 'EVP_SHA256' or 'EVP_SHA512'.")
}
return c.insecureSign(privKey, digest)
}
func (c *Certificate) insecureSign(privKey PrivateKey, digest EVP_MD) error {
var md *C.EVP_MD = getDigestFunction(digest)
if C.X509_sign(c.x, privKey.evpPKey(), md) <= 0 {
return errors.New("failed to sign certificate")
}
return nil
}
func getDigestFunction(digest EVP_MD) (md *C.EVP_MD) {
switch digest {
// please don't use these digest functions
case EVP_NULL:
md = C.X_EVP_md_null()
case EVP_MD5:
md = C.X_EVP_md5()
case EVP_SHA:
md = C.X_EVP_sha()
case EVP_SHA1:
md = C.X_EVP_sha1()
case EVP_DSS:
md = C.X_EVP_dss()
case EVP_DSS1:
md = C.X_EVP_dss1()
case EVP_RIPEMD160:
md = C.X_EVP_ripemd160()
case EVP_SHA224:
md = C.X_EVP_sha224()
// you actually want one of these
case EVP_SHA256:
md = C.X_EVP_sha256()
case EVP_SHA384:
md = C.X_EVP_sha384()
case EVP_SHA512:
md = C.X_EVP_sha512()
}
return md
}
// Add an extension to a certificate.
// Extension constants are NID_* as found in openssl.
func (c *Certificate) AddExtension(nid NID, value string) error {
issuer := c
if c.Issuer != nil {
issuer = c.Issuer
}
var ctx C.X509V3_CTX
C.X509V3_set_ctx(&ctx, c.x, issuer.x, nil, nil, 0)
ex := C.X509V3_EXT_conf_nid(nil, &ctx, C.int(nid), C.CString(value))
if ex == nil {
return errors.New("failed to create x509v3 extension")
}
defer C.X509_EXTENSION_free(ex)
if C.X509_add_ext(c.x, ex, -1) <= 0 {
return errors.New("failed to add x509v3 extension")
}
return nil
}
// Wraps AddExtension using a map of NID to text extension.
// Will return without finishing if it encounters an error.
func (c *Certificate) AddExtensions(extensions map[NID]string) error {
for nid, value := range extensions {
if err := c.AddExtension(nid, value); err != nil {
return err
}
}
return nil
}
// LoadCertificateFromPEM loads an X509 certificate from a PEM-encoded block.
func LoadCertificateFromPEM(pem_block []byte) (*Certificate, error) {
if len(pem_block) == 0 {
return nil, errors.New("empty pem block")
}
runtime.LockOSThread()
defer runtime.UnlockOSThread()
bio := C.BIO_new_mem_buf(unsafe.Pointer(&pem_block[0]),
C.int(len(pem_block)))
cert := C.PEM_read_bio_X509(bio, nil, nil, nil)
C.BIO_free(bio)
if cert == nil {
return nil, errorFromErrorQueue()
}
x := &Certificate{x: cert}
runtime.SetFinalizer(x, func(x *Certificate) {
C.X509_free(x.x)
})
return x, nil
}
// LoadCertificateFromDER loads an X509 certificate from a DER-encoded block.
func LoadCertificateFromDER(der_block []byte) (*Certificate, error) {
if len(der_block) == 0 {
return nil, errors.New("empty der block")
}
runtime.LockOSThread()
defer runtime.UnlockOSThread()
bio := C.BIO_new_mem_buf(unsafe.Pointer(&der_block[0]),
C.int(len(der_block)))
cert := C.d2i_X509_bio(bio, nil)
C.BIO_free(bio)
if cert == nil {
return nil, errorFromErrorQueue()
}
x := &Certificate{x: cert}
runtime.SetFinalizer(x, func(x *Certificate) {
C.X509_free(x.x)
})
return x, nil
}
// MarshalPEM converts the X509 certificate to PEM-encoded format
func (c *Certificate) MarshalPEM() (pem_block []byte, err error) {
bio := C.BIO_new(C.BIO_s_mem())
if bio == nil {
return nil, errors.New("failed to allocate memory BIO")
}
defer C.BIO_free(bio)
if int(C.PEM_write_bio_X509(bio, c.x)) != 1 {
return nil, errors.New("failed dumping certificate")
}
return ioutil.ReadAll(asAnyBio(bio))
}
// PublicKey returns the public key embedded in the X509 certificate.
func (c *Certificate) PublicKey() (PublicKey, error) {
pkey := C.X509_get_pubkey(c.x)
if pkey == nil {
return nil, errors.New("no public key found")
}
key := &pKey{key: pkey}
runtime.SetFinalizer(key, func(key *pKey) {
C.EVP_PKEY_free(key.key)
})
return key, nil
}
// GetSerialNumberHex returns the certificate's serial number in hex format
func (c *Certificate) GetSerialNumberHex() (serial string) {
asn1_i := C.X509_get_serialNumber(c.x)
bignum := C.ASN1_INTEGER_to_BN(asn1_i, nil)
hex := C.BN_bn2hex(bignum)
serial = C.GoString(hex)
C.BN_free(bignum)
C.X_OPENSSL_free(unsafe.Pointer(hex))
return
}
// GetVersion returns the X509 version of the certificate.
func (c *Certificate) GetVersion() X509_Version {
return X509_Version(C.X_X509_get_version(c.x))
}
// SetVersion sets the X509 version of the certificate.
func (c *Certificate) SetVersion(version X509_Version) error {
cvers := C.long(version)
if C.X_X509_set_version(c.x, cvers) != 1 {
return errors.New("failed to set certificate version")
}
return nil
}
type PKCS7 struct {
p7 *C.PKCS7
Certs []*Certificate
}
// LoadCertificatesFromPKCS7 loads certificates from a DER-encoded pkcs7.
func LoadCertificatesFromPKCS7(der_block []byte) (*PKCS7, error) {
if len(der_block) == 0 {
return nil, errors.New("empty der block")
}
bio := C.BIO_new_mem_buf(unsafe.Pointer(&der_block[0]),
C.int(len(der_block)))
if bio == nil {
return nil, errors.New("failed creating bio")
}
defer C.BIO_free(bio)
var p7 *C.PKCS7
p7 = C.d2i_PKCS7_bio(bio, nil)
if p7 == nil {
return nil, errors.New("failed reading pkcs7 data")
}
ret := &PKCS7{
p7: p7,
}
runtime.SetFinalizer(ret, func(pkcs7 *PKCS7) {
C.PKCS7_free(pkcs7.p7)
})
var certs *C.struct_stack_st_X509
i := C.OBJ_obj2nid(p7._type)
// credit goes to Chris Bandy who referenced Alan Shen's article for this cgo representation of a union:
// https://sunzenshen.github.io/tutorials/2015/05/09/cgotchas-intro.html
switch i {
case C.NID_pkcs7_signed:
signed := *(**C.PKCS7_SIGNED)(unsafe.Pointer(&p7.d[0]))
certs = signed.cert
case C.NID_pkcs7_signedAndEnveloped:
signedAndEnveloped := *(**C.PKCS7_SIGN_ENVELOPE)(unsafe.Pointer(&p7.d[0]))
certs = signedAndEnveloped.cert
}
err := ret.loadCertificateStack(certs)
if err != nil {
return nil, err
}
return ret, nil
}
// loadCertificateStack loads up a stack of x509 certificates into the PKCS7 struct.
func (p *PKCS7) loadCertificateStack(sk *C.struct_stack_st_X509) error {
sk_num := int(C.X_sk_X509_num(sk))
if sk_num < 0 {
return fmt.Errorf("invalid value returned by sk_X509_num: %d", sk_num)
}
p.Certs = make([]*Certificate, 0, sk_num)
for i := 0; i < sk_num; i++ {
x := C.X_sk_X509_value(sk, C.int(i))
// add a ref
if 1 != C.X_X509_add_ref(x) {
return errors.New("unable to add ref for X509")
}
cert := &Certificate{x: x}
runtime.SetFinalizer(cert, func(cert *Certificate) {
C.X509_free(cert.x)
})
p.Certs = append(p.Certs, cert)
}
return nil
}
// VerifyTrustAndGetIssuerCertificate takes a CertificateStore and verifies trust for the certificate.
// The issuing certificate from the CertificateStore is returned if found.
func (c *Certificate) VerifyTrustAndGetIssuerCertificate(store *CertificateStore) (*Certificate, VerifyResult, error) {
storeCtx := C.X509_STORE_CTX_new()
if storeCtx == nil {
return nil, 0, errors.New("failed to create new X509_STORE_CTX")
}
defer C.X509_STORE_CTX_free(storeCtx)
rc := C.X509_STORE_CTX_init(storeCtx, store.store, c.x, nil)
if rc == 0 {
return nil, 0, errors.New("unable to init X509_STORE_CTX")
}
i := C.X509_verify_cert(storeCtx)
var issuer *Certificate
verifyResult := Ok
if i != 1 {
verifyResult = VerifyResult(C.X509_STORE_CTX_get_error(storeCtx))
}
currentIssuer := C.X509_STORE_CTX_get0_current_issuer(storeCtx)
if currentIssuer != nil {
// need to clone the issuer cert so that it is not cleaned up when C.X509_STORE_CTX_free is called
ic := &Certificate{x: currentIssuer}
data, err := ic.MarshalPEM()
if err != nil {
return nil, 0, errors.New("error copying issuer cert")
}
issuer, err = LoadCertificateFromPEM(data)
if err != nil {
return nil, 0, errors.New("error loading issuer cert")
}
}
return issuer, verifyResult, nil
}