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local.go
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local.go
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// Copyright 2017 Google Inc.
//
// 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 store
import (
"bufio"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"io/ioutil"
"math/big"
"os"
"path/filepath"
"regexp"
"strings"
"time"
"crypto/x509"
"github.com/google/easypki/pkg/certificate"
)
// Predifined directory names.
const (
LocalCertsDir = "certs"
LocalKeysDir = "keys"
LocalCrlsDir = "crls"
)
var (
// Index format
// 0 full string
// 1 Valid/Revoked/Expired
// 2 Expiration date
// 3 Revocation date
// 4 Serial
// 5 Filename
// 6 Subject
indexRegexp = regexp.MustCompile("^(V|R|E)\t([0-9]{12}Z)\t([0-9]{12}Z)?\t([0-9a-fA-F]{2,})\t([^\t]+)\t(.+)")
)
// Local lets us store a Certificate Authority on the local filesystem.
//
// The structure used makes it compatible with openssl.
type Local struct {
Root string
}
// path returns private and public key path.
func (l *Local) path(caName, name string) (key string, cert string) {
key = filepath.Join(l.Root, caName, LocalKeysDir, name+".key")
cert = filepath.Join(l.Root, caName, LocalCertsDir, name+".crt")
return
}
// Exists checks if a certificate or private key already exist on the local
// filesystem for a given name.
func (l *Local) Exists(caName, name string) bool {
privPath, certPath := l.path(caName, name)
if _, err := os.Stat(privPath); err == nil {
return true
}
if _, err := os.Stat(certPath); err == nil {
return true
}
return false
}
// Fetch fetchs the private key and certificate for a given name signed by caName.
func (l *Local) Fetch(caName, name string) ([]byte, []byte, error) {
filepath.Join(l.Root, caName)
keyPath, certPath := l.path(caName, name)
k, err := readPEM(keyPath)
if err != nil {
return nil, nil, fmt.Errorf("failed reading CA private key from file %v: %v", keyPath, err)
}
c, err := readPEM(certPath)
if err != nil {
return nil, nil, fmt.Errorf("failed reading CA cert from file %v: %v", certPath, err)
}
return k, c, nil
}
func readPEM(path string) ([]byte, error) {
bytes, err := ioutil.ReadFile(path)
if err != nil {
return nil, fmt.Errorf("failed reading %v: %v", path, err)
}
p, _ := pem.Decode(bytes)
if p == nil {
return nil, fmt.Errorf("no PEM data found for certificate")
}
return p.Bytes, nil
}
// Add adds the given bundle to the local filesystem.
func (l *Local) Add(caName, name string, isCa bool, key, cert []byte) error {
if l.Exists(caName, name) {
return fmt.Errorf("a bundle already exists for the name %v within CA %v", name, caName)
}
if err := l.writeBundle(caName, name, isCa, key, cert); err != nil {
return fmt.Errorf("failed writing bundle %v within CA %v to the local filesystem: %v", name, caName, err)
}
if err := l.updateIndex(caName, name, cert); err != nil {
return fmt.Errorf("failed updating CA %v index: %v", caName, err)
}
return nil
}
// writeBundle encodes in PEM format the bundle private key and
// certificate and stores them on the local filesystem.
func (l *Local) writeBundle(caName, name string, isCa bool, key, cert []byte) error {
caDir := filepath.Join(l.Root, caName)
if _, err := os.Stat(caDir); err != nil {
if err := InitCADir(caDir); err != nil {
return fmt.Errorf("root directory for CA %v does not exist and cannot be created: %v", caDir, err)
}
}
keyPath, certPath := l.path(caName, name)
if err := encodeAndWrite(keyPath, "RSA PRIVATE KEY", key); err != nil {
return fmt.Errorf("failed encoding and writing private key file: %v", err)
}
if err := encodeAndWrite(certPath, "CERTIFICATE", cert); err != nil {
return fmt.Errorf("failed encoding and writing cert file: %v", err)
}
if isCa && name != caName {
intCaDir := filepath.Join(l.Root, name)
if err := InitCADir(intCaDir); err != nil {
return fmt.Errorf("root directory for CA %v does not exist and cannot be created: %v", intCaDir, err)
}
kp, cp := l.path(name, name)
if err := os.Link(keyPath, kp); err != nil {
return fmt.Errorf("failed creating hard link from %v to %v: %v", keyPath, kp, err)
}
if err := os.Link(certPath, cp); err != nil {
return fmt.Errorf("failed creating hard link from %v to %v: %v", certPath, cp, err)
}
}
return nil
}
func encodeAndWrite(path, pemType string, data []byte) error {
f, err := os.Create(path)
if err != nil {
return err
}
defer f.Close()
return pem.Encode(f, &pem.Block{
Type: pemType,
Bytes: data,
})
}
// updateIndex appends a line to the index.txt with few information about the
// given the certificate.
func (l *Local) updateIndex(caName, name string, rawCert []byte) error {
f, err := os.OpenFile(filepath.Join(l.Root, caName, "index.txt"), os.O_WRONLY|os.O_APPEND, 0644)
if err != nil {
return err
}
defer f.Close()
cert, err := x509.ParseCertificate(rawCert)
if err != nil {
return fmt.Errorf("failed parsing raw certificate %v: %v", name, err)
}
sn := fmt.Sprintf("%X", cert.SerialNumber)
// For compatibility with openssl we need an even length.
if len(sn)%2 == 1 {
sn = "0" + sn
}
// Date format: yymmddHHMMSSZ
// E|R|V<tab>Expiry<tab>[RevocationDate]<tab>Serial<tab>filename<tab>SubjectDN
var subject string
if strs := cert.Subject.Country; len(strs) == 1 {
subject += "/C=" + strs[0]
}
if strs := cert.Subject.Organization; len(strs) == 1 {
subject += "/O=" + strs[0]
}
if strs := cert.Subject.OrganizationalUnit; len(strs) == 1 {
subject += "/OU=" + strs[0]
}
if strs := cert.Subject.Locality; len(strs) == 1 {
subject += "/L=" + strs[0]
}
if strs := cert.Subject.Province; len(strs) == 1 {
subject += "/ST=" + strs[0]
}
subject += "/CN=" + cert.Subject.CommonName
n, err := fmt.Fprintf(f, "V\t%vZ\t\t%v\t%v.crt\t%v\n",
cert.NotAfter.UTC().Format("060102150405"),
sn,
name,
subject)
if err != nil {
return err
}
if n == 0 {
return fmt.Errorf("written 0 bytes in index file")
}
return nil
}
// Update updates the state of a given certificate in the index.txt.
func (l *Local) Update(caName string, sn *big.Int, st certificate.State) error {
f, err := os.OpenFile(filepath.Join(l.Root, caName, "index.txt"), os.O_RDWR, 0644)
if err != nil {
return err
}
defer f.Close()
var state string
switch st {
case certificate.Valid:
state = "V"
case certificate.Revoked:
state = "R"
case certificate.Expired:
state = "E"
default:
return fmt.Errorf("unhandled certificate state: %v", st)
}
var lines []string
scanner := bufio.NewScanner(f)
for scanner.Scan() {
matches := indexRegexp.FindStringSubmatch(scanner.Text())
if len(matches) != 7 {
return fmt.Errorf("line [%v] is incorrectly formated", scanner.Text())
}
matchedSerial := big.NewInt(0)
fmt.Sscanf(matches[4], "%X", matchedSerial)
if matchedSerial.Cmp(sn) == 0 {
if matches[1] == state {
return nil
}
lines = append(lines, fmt.Sprintf("%v\t%v\t%vZ\t%v\t%v\t%v",
state,
matches[2],
time.Now().UTC().Format("060102150405"),
matches[4],
matches[5],
matches[6]))
} else {
lines = append(lines, matches[0])
}
}
f.Truncate(0)
f.Seek(0, 0)
for _, line := range lines {
n, err := fmt.Fprintln(f, line)
if err != nil {
return fmt.Errorf("failed writing line [%v]: %v", line, err)
}
if n == 0 {
return fmt.Errorf("failed writing line [%v]: written 0 bytes", line)
}
}
return nil
}
// Revoked returns a list of revoked certificates.
func (l *Local) Revoked(caName string) ([]pkix.RevokedCertificate, error) {
index, err := os.Open(filepath.Join(l.Root, caName, "index.txt"))
if err != nil {
return nil, err
}
defer index.Close()
var revokedCerts []pkix.RevokedCertificate
scanner := bufio.NewScanner(index)
for scanner.Scan() {
matches := indexRegexp.FindStringSubmatch(scanner.Text())
if len(matches) != 7 {
return nil, fmt.Errorf("line [%v] is incorrectly formated", scanner.Text())
}
if matches[1] != "R" {
continue
}
sn := big.NewInt(0)
fmt.Sscanf(matches[4], "%X", sn)
t, err := time.Parse("060102150405", strings.TrimSuffix(matches[3], "Z"))
if err != nil {
return nil, fmt.Errorf("failed parsing revocation time %v: %v", matches[3], err)
}
revokedCerts = append(revokedCerts, pkix.RevokedCertificate{
SerialNumber: sn,
RevocationTime: t,
})
}
return revokedCerts, nil
}
// InitCADir creates the basic structure of a CA subdirectory.
//
// |- crlnumber
// |- index.txt
// |- index.txt.attr
// |- serial
// |- certs/
// |- ca.crt
// |- name.crt
// |- keys/
// |- ca.key
// |- name.key
func InitCADir(path string) error {
if _, err := os.Stat(path); err == nil {
return nil
}
if err := os.Mkdir(path, 0755); err != nil {
return fmt.Errorf("failed creating CA root directory %v: %v", path, err)
}
dirs := map[string]os.FileMode{
filepath.Join(path, LocalCrlsDir): 0700,
filepath.Join(path, LocalCertsDir): 0755,
filepath.Join(path, LocalKeysDir): 0700,
}
for d, m := range dirs {
if err := os.Mkdir(d, m); err != nil {
return fmt.Errorf("failed creating directory %v: %v", d, err)
}
}
files := []struct {
Name string
Content string
}{
{Name: "serial", Content: "01"},
{Name: "crlnumber", Content: "01"},
{Name: "index.txt", Content: ""},
{Name: "index.txt.attr", Content: "unique_subject = no"},
}
for _, f := range files {
if err := createFile(filepath.Join(path, f.Name), f.Content); err != nil {
return err
}
}
return nil
}
func createFile(path, content string) error {
fh, err := os.Create(path)
if err != nil {
return fmt.Errorf("failed creating file %v: %v", path, err)
}
defer fh.Close()
if content == "" {
return nil
}
n, err := fmt.Fprintln(fh, content)
if err != nil {
return fmt.Errorf("failed wrinting %v in %v: %v", content, path, err)
}
if n == 0 {
return fmt.Errorf("failed writing %v in %v: 0 bytes written", content, path)
}
return nil
}