lego/certificate/certificates.go
2019-05-25 16:12:37 +02:00

522 lines
16 KiB
Go

package certificate
import (
"bytes"
"crypto"
"crypto/x509"
"encoding/base64"
"errors"
"fmt"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/go-acme/lego/acme"
"github.com/go-acme/lego/acme/api"
"github.com/go-acme/lego/certcrypto"
"github.com/go-acme/lego/challenge"
"github.com/go-acme/lego/log"
"github.com/go-acme/lego/platform/wait"
"golang.org/x/crypto/ocsp"
"golang.org/x/net/idna"
)
// maxBodySize is the maximum size of body that we will read.
const maxBodySize = 1024 * 1024
// Resource represents a CA issued certificate.
// PrivateKey, Certificate and IssuerCertificate are all
// already PEM encoded and can be directly written to disk.
// Certificate may be a certificate bundle,
// depending on the options supplied to create it.
type Resource struct {
Domain string `json:"domain"`
CertURL string `json:"certUrl"`
CertStableURL string `json:"certStableUrl"`
PrivateKey []byte `json:"-"`
Certificate []byte `json:"-"`
IssuerCertificate []byte `json:"-"`
CSR []byte `json:"-"`
}
// ObtainRequest The request to obtain certificate.
//
// The first domain in domains is used for the CommonName field of the certificate,
// all other domains are added using the Subject Alternate Names extension.
//
// A new private key is generated for every invocation of the function Obtain.
// If you do not want that you can supply your own private key in the privateKey parameter.
// If this parameter is non-nil it will be used instead of generating a new one.
//
// If bundle is true, the []byte contains both the issuer certificate and your issued certificate as a bundle.
type ObtainRequest struct {
Domains []string
Bundle bool
PrivateKey crypto.PrivateKey
MustStaple bool
}
type resolver interface {
Solve(authorizations []acme.Authorization) error
}
type CertifierOptions struct {
KeyType certcrypto.KeyType
Timeout time.Duration
}
// Certifier A service to obtain/renew/revoke certificates.
type Certifier struct {
core *api.Core
resolver resolver
options CertifierOptions
}
// NewCertifier creates a Certifier.
func NewCertifier(core *api.Core, resolver resolver, options CertifierOptions) *Certifier {
return &Certifier{
core: core,
resolver: resolver,
options: options,
}
}
// Obtain tries to obtain a single certificate using all domains passed into it.
//
// This function will never return a partial certificate.
// If one domain in the list fails, the whole certificate will fail.
func (c *Certifier) Obtain(request ObtainRequest) (*Resource, error) {
if len(request.Domains) == 0 {
return nil, errors.New("no domains to obtain a certificate for")
}
domains := sanitizeDomain(request.Domains)
if request.Bundle {
log.Infof("[%s] acme: Obtaining bundled SAN certificate", strings.Join(domains, ", "))
} else {
log.Infof("[%s] acme: Obtaining SAN certificate", strings.Join(domains, ", "))
}
order, err := c.core.Orders.New(domains)
if err != nil {
return nil, err
}
authz, err := c.getAuthorizations(order)
if err != nil {
// If any challenge fails, return. Do not generate partial SAN certificates.
c.deactivateAuthorizations(order)
return nil, err
}
err = c.resolver.Solve(authz)
if err != nil {
// If any challenge fails, return. Do not generate partial SAN certificates.
c.deactivateAuthorizations(order)
return nil, err
}
log.Infof("[%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", "))
failures := make(obtainError)
cert, err := c.getForOrder(domains, order, request.Bundle, request.PrivateKey, request.MustStaple)
if err != nil {
for _, auth := range authz {
failures[challenge.GetTargetedDomain(auth)] = err
}
}
// Do not return an empty failures map, because
// it would still be a non-nil error value
if len(failures) > 0 {
return cert, failures
}
return cert, nil
}
// ObtainForCSR tries to obtain a certificate matching the CSR passed into it.
//
// The domains are inferred from the CommonName and SubjectAltNames, if any.
// The private key for this CSR is not required.
//
// If bundle is true, the []byte contains both the issuer certificate and your issued certificate as a bundle.
//
// This function will never return a partial certificate.
// If one domain in the list fails, the whole certificate will fail.
func (c *Certifier) ObtainForCSR(csr x509.CertificateRequest, bundle bool) (*Resource, error) {
// figure out what domains it concerns
// start with the common name
domains := certcrypto.ExtractDomainsCSR(&csr)
if bundle {
log.Infof("[%s] acme: Obtaining bundled SAN certificate given a CSR", strings.Join(domains, ", "))
} else {
log.Infof("[%s] acme: Obtaining SAN certificate given a CSR", strings.Join(domains, ", "))
}
order, err := c.core.Orders.New(domains)
if err != nil {
return nil, err
}
authz, err := c.getAuthorizations(order)
if err != nil {
// If any challenge fails, return. Do not generate partial SAN certificates.
c.deactivateAuthorizations(order)
return nil, err
}
err = c.resolver.Solve(authz)
if err != nil {
// If any challenge fails, return. Do not generate partial SAN certificates.
c.deactivateAuthorizations(order)
return nil, err
}
log.Infof("[%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", "))
failures := make(obtainError)
cert, err := c.getForCSR(domains, order, bundle, csr.Raw, nil)
if err != nil {
for _, auth := range authz {
failures[challenge.GetTargetedDomain(auth)] = err
}
}
if cert != nil {
// Add the CSR to the certificate so that it can be used for renewals.
cert.CSR = certcrypto.PEMEncode(&csr)
}
// Do not return an empty failures map,
// because it would still be a non-nil error value
if len(failures) > 0 {
return cert, failures
}
return cert, nil
}
func (c *Certifier) getForOrder(domains []string, order acme.ExtendedOrder, bundle bool, privateKey crypto.PrivateKey, mustStaple bool) (*Resource, error) {
if privateKey == nil {
var err error
privateKey, err = certcrypto.GeneratePrivateKey(c.options.KeyType)
if err != nil {
return nil, err
}
}
// Determine certificate name(s) based on the authorization resources
commonName := domains[0]
// ACME draft Section 7.4 "Applying for Certificate Issuance"
// https://tools.ietf.org/html/draft-ietf-acme-acme-12#section-7.4
// says:
// Clients SHOULD NOT make any assumptions about the sort order of
// "identifiers" or "authorizations" elements in the returned order
// object.
san := []string{commonName}
for _, auth := range order.Identifiers {
if auth.Value != commonName {
san = append(san, auth.Value)
}
}
// TODO: should the CSR be customizable?
csr, err := certcrypto.GenerateCSR(privateKey, commonName, san, mustStaple)
if err != nil {
return nil, err
}
return c.getForCSR(domains, order, bundle, csr, certcrypto.PEMEncode(privateKey))
}
func (c *Certifier) getForCSR(domains []string, order acme.ExtendedOrder, bundle bool, csr []byte, privateKeyPem []byte) (*Resource, error) {
respOrder, err := c.core.Orders.UpdateForCSR(order.Finalize, csr)
if err != nil {
return nil, err
}
commonName := domains[0]
certRes := &Resource{
Domain: commonName,
CertURL: respOrder.Certificate,
PrivateKey: privateKeyPem,
}
if respOrder.Status == acme.StatusValid {
// if the certificate is available right away, short cut!
ok, errR := c.checkResponse(respOrder, certRes, bundle)
if errR != nil {
return nil, errR
}
if ok {
return certRes, nil
}
}
timeout := c.options.Timeout
if c.options.Timeout <= 0 {
timeout = 30 * time.Second
}
err = wait.For("certificate", timeout, timeout/60, func() (bool, error) {
ord, errW := c.core.Orders.Get(order.Location)
if errW != nil {
return false, errW
}
done, errW := c.checkResponse(ord, certRes, bundle)
if errW != nil {
return false, errW
}
return done, nil
})
return certRes, err
}
// checkResponse checks to see if the certificate is ready and a link is contained in the response.
//
// If so, loads it into certRes and returns true.
// If the cert is not yet ready, it returns false.
//
// The certRes input should already have the Domain (common name) field populated.
//
// If bundle is true, the certificate will be bundled with the issuer's cert.
func (c *Certifier) checkResponse(order acme.Order, certRes *Resource, bundle bool) (bool, error) {
valid, err := checkOrderStatus(order)
if err != nil || !valid {
return valid, err
}
cert, issuer, err := c.core.Certificates.Get(order.Certificate, bundle)
if err != nil {
return false, err
}
log.Infof("[%s] Server responded with a certificate.", certRes.Domain)
certRes.IssuerCertificate = issuer
certRes.Certificate = cert
certRes.CertURL = order.Certificate
certRes.CertStableURL = order.Certificate
return true, nil
}
// Revoke takes a PEM encoded certificate or bundle and tries to revoke it at the CA.
func (c *Certifier) Revoke(cert []byte) error {
certificates, err := certcrypto.ParsePEMBundle(cert)
if err != nil {
return err
}
x509Cert := certificates[0]
if x509Cert.IsCA {
return fmt.Errorf("certificate bundle starts with a CA certificate")
}
revokeMsg := acme.RevokeCertMessage{
Certificate: base64.RawURLEncoding.EncodeToString(x509Cert.Raw),
}
return c.core.Certificates.Revoke(revokeMsg)
}
// Renew takes a Resource and tries to renew the certificate.
//
// If the renewal process succeeds, the new certificate will ge returned in a new CertResource.
// Please be aware that this function will return a new certificate in ANY case that is not an error.
// If the server does not provide us with a new cert on a GET request to the CertURL
// this function will start a new-cert flow where a new certificate gets generated.
//
// If bundle is true, the []byte contains both the issuer certificate and your issued certificate as a bundle.
//
// For private key reuse the PrivateKey property of the passed in Resource should be non-nil.
func (c *Certifier) Renew(certRes Resource, bundle, mustStaple bool) (*Resource, error) {
// Input certificate is PEM encoded.
// Decode it here as we may need the decoded cert later on in the renewal process.
// The input may be a bundle or a single certificate.
certificates, err := certcrypto.ParsePEMBundle(certRes.Certificate)
if err != nil {
return nil, err
}
x509Cert := certificates[0]
if x509Cert.IsCA {
return nil, fmt.Errorf("[%s] Certificate bundle starts with a CA certificate", certRes.Domain)
}
// This is just meant to be informal for the user.
timeLeft := x509Cert.NotAfter.Sub(time.Now().UTC())
log.Infof("[%s] acme: Trying renewal with %d hours remaining", certRes.Domain, int(timeLeft.Hours()))
// We always need to request a new certificate to renew.
// Start by checking to see if the certificate was based off a CSR,
// and use that if it's defined.
if len(certRes.CSR) > 0 {
csr, errP := certcrypto.PemDecodeTox509CSR(certRes.CSR)
if errP != nil {
return nil, errP
}
return c.ObtainForCSR(*csr, bundle)
}
var privateKey crypto.PrivateKey
if certRes.PrivateKey != nil {
privateKey, err = certcrypto.ParsePEMPrivateKey(certRes.PrivateKey)
if err != nil {
return nil, err
}
}
query := ObtainRequest{
Domains: certcrypto.ExtractDomains(x509Cert),
Bundle: bundle,
PrivateKey: privateKey,
MustStaple: mustStaple,
}
return c.Obtain(query)
}
// GetOCSP takes a PEM encoded cert or cert bundle returning the raw OCSP response,
// the parsed response, and an error, if any.
//
// The returned []byte can be passed directly into the OCSPStaple property of a tls.Certificate.
// If the bundle only contains the issued certificate,
// this function will try to get the issuer certificate from the IssuingCertificateURL in the certificate.
//
// If the []byte and/or ocsp.Response return values are nil, the OCSP status may be assumed OCSPUnknown.
func (c *Certifier) GetOCSP(bundle []byte) ([]byte, *ocsp.Response, error) {
certificates, err := certcrypto.ParsePEMBundle(bundle)
if err != nil {
return nil, nil, err
}
// We expect the certificate slice to be ordered downwards the chain.
// SRV CRT -> CA. We need to pull the leaf and issuer certs out of it,
// which should always be the first two certificates.
// If there's no OCSP server listed in the leaf cert, there's nothing to do.
// And if we have only one certificate so far, we need to get the issuer cert.
issuedCert := certificates[0]
if len(issuedCert.OCSPServer) == 0 {
return nil, nil, errors.New("no OCSP server specified in cert")
}
if len(certificates) == 1 {
// TODO: build fallback. If this fails, check the remaining array entries.
if len(issuedCert.IssuingCertificateURL) == 0 {
return nil, nil, errors.New("no issuing certificate URL")
}
resp, errC := c.core.HTTPClient.Get(issuedCert.IssuingCertificateURL[0])
if errC != nil {
return nil, nil, errC
}
defer resp.Body.Close()
issuerBytes, errC := ioutil.ReadAll(http.MaxBytesReader(nil, resp.Body, maxBodySize))
if errC != nil {
return nil, nil, errC
}
issuerCert, errC := x509.ParseCertificate(issuerBytes)
if errC != nil {
return nil, nil, errC
}
// Insert it into the slice on position 0
// We want it ordered right SRV CRT -> CA
certificates = append(certificates, issuerCert)
}
issuerCert := certificates[1]
// Finally kick off the OCSP request.
ocspReq, err := ocsp.CreateRequest(issuedCert, issuerCert, nil)
if err != nil {
return nil, nil, err
}
resp, err := c.core.HTTPClient.Post(issuedCert.OCSPServer[0], "application/ocsp-request", bytes.NewReader(ocspReq))
if err != nil {
return nil, nil, err
}
defer resp.Body.Close()
ocspResBytes, err := ioutil.ReadAll(http.MaxBytesReader(nil, resp.Body, maxBodySize))
if err != nil {
return nil, nil, err
}
ocspRes, err := ocsp.ParseResponse(ocspResBytes, issuerCert)
if err != nil {
return nil, nil, err
}
return ocspResBytes, ocspRes, nil
}
// Get attempts to fetch the certificate at the supplied URL.
// The URL is the same as what would normally be supplied at the Resource's CertURL.
//
// The returned Resource will not have the PrivateKey and CSR fields populated as these will not be available.
//
// If bundle is true, the Certificate field in the returned Resource includes the issuer certificate.
func (c *Certifier) Get(url string, bundle bool) (*Resource, error) {
cert, issuer, err := c.core.Certificates.Get(url, bundle)
if err != nil {
return nil, err
}
// Parse the returned cert bundle so that we can grab the domain from the common name.
x509Certs, err := certcrypto.ParsePEMBundle(cert)
if err != nil {
return nil, err
}
return &Resource{
Domain: x509Certs[0].Subject.CommonName,
Certificate: cert,
IssuerCertificate: issuer,
CertURL: url,
CertStableURL: url,
}, nil
}
func checkOrderStatus(order acme.Order) (bool, error) {
switch order.Status {
case acme.StatusValid:
return true, nil
case acme.StatusInvalid:
return false, order.Error
default:
return false, nil
}
}
// https://tools.ietf.org/html/draft-ietf-acme-acme-16#section-7.1.4
// The domain name MUST be encoded
// in the form in which it would appear in a certificate. That is, it
// MUST be encoded according to the rules in Section 7 of [RFC5280].
//
// https://tools.ietf.org/html/rfc5280#section-7
func sanitizeDomain(domains []string) []string {
var sanitizedDomains []string
for _, domain := range domains {
sanitizedDomain, err := idna.ToASCII(domain)
if err != nil {
log.Infof("skip domain %q: unable to sanitize (punnycode): %v", domain, err)
} else {
sanitizedDomains = append(sanitizedDomains, sanitizedDomain)
}
}
return sanitizedDomains
}