1
0
mirror of https://github.com/go-gitea/gitea.git synced 2024-12-24 15:45:45 +08:00
gitea/vendor/github.com/caddyserver/certmagic/config.go
techknowlogick d2ea21d0d8
Use caddy's certmagic library for extensible/robust ACME handling ()
* use certmagic for more extensible/robust ACME cert handling

* accept TOS based on config option

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
2021-01-25 01:37:35 +02:00

809 lines
25 KiB
Go
Vendored

// Copyright 2015 Matthew Holt
//
// 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 certmagic
import (
"bytes"
"context"
"crypto"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"fmt"
weakrand "math/rand"
"net"
"net/url"
"strings"
"time"
"github.com/mholt/acmez"
"go.uber.org/zap"
)
// Config configures a certificate manager instance.
// An empty Config is not valid: use New() to obtain
// a valid Config.
type Config struct {
// How much of a certificate's lifetime becomes the
// renewal window, which is the span of time at the
// end of the certificate's validity period in which
// it should be renewed; for most certificates, the
// global default is good, but for extremely short-
// lived certs, you may want to raise this to ~0.5.
RenewalWindowRatio float64
// An optional event callback clients can set
// to subscribe to certain things happening
// internally by this config; invocations are
// synchronous, so make them return quickly!
OnEvent func(event string, data interface{})
// DefaultServerName specifies a server name
// to use when choosing a certificate if the
// ClientHello's ServerName field is empty
DefaultServerName string
// The state needed to operate on-demand TLS;
// if non-nil, on-demand TLS is enabled and
// certificate operations are deferred to
// TLS handshakes (or as-needed)
// TODO: Can we call this feature "Reactive/Lazy/Passive TLS" instead?
OnDemand *OnDemandConfig
// Add the must staple TLS extension to the CSR
MustStaple bool
// The type that issues certificates; the
// default Issuer is ACMEManager
Issuer Issuer
// The type that revokes certificates; must
// be configured in conjunction with the Issuer
// field such that both the Issuer and Revoker
// are related (because issuance information is
// required for revocation)
Revoker Revoker
// The source of new private keys for certificates;
// the default KeySource is StandardKeyGenerator
KeySource KeyGenerator
// CertSelection chooses one of the certificates
// with which the ClientHello will be completed;
// if not set, DefaultCertificateSelector will
// be used
CertSelection CertificateSelector
// The storage to access when storing or
// loading TLS assets
Storage Storage
// Set a logger to enable logging
Logger *zap.Logger
// required pointer to the in-memory cert cache
certCache *Cache
}
// NewDefault makes a valid config based on the package
// Default config. Most users will call this function
// instead of New() since most use cases require only a
// single config for any and all certificates.
//
// If your requirements are more advanced (for example,
// multiple configs depending on the certificate), then use
// New() instead. (You will need to make your own Cache
// first.) If you only need a single Config to manage your
// certs (even if that config changes, as long as it is the
// only one), customize the Default package variable before
// calling NewDefault().
//
// All calls to NewDefault() will return configs that use the
// same, default certificate cache. All configs returned
// by NewDefault() are based on the values of the fields of
// Default at the time it is called.
func NewDefault() *Config {
defaultCacheMu.Lock()
if defaultCache == nil {
defaultCache = NewCache(CacheOptions{
// the cache will likely need to renew certificates,
// so it will need to know how to do that, which
// depends on the certificate being managed and which
// can change during the lifetime of the cache; this
// callback makes it possible to get the latest and
// correct config with which to manage the cert,
// but if the user does not provide one, we can only
// assume that we are to use the default config
GetConfigForCert: func(Certificate) (*Config, error) {
return NewDefault(), nil
},
})
}
certCache := defaultCache
defaultCacheMu.Unlock()
return newWithCache(certCache, Default)
}
// New makes a new, valid config based on cfg and
// uses the provided certificate cache. certCache
// MUST NOT be nil or this function will panic.
//
// Use this method when you have an advanced use case
// that requires a custom certificate cache and config
// that may differ from the Default. For example, if
// not all certificates are managed/renewed the same
// way, you need to make your own Cache value with a
// GetConfigForCert callback that returns the correct
// configuration for each certificate. However, for
// the vast majority of cases, there will be only a
// single Config, thus the default cache (which always
// uses the default Config) and default config will
// suffice, and you should use New() instead.
func New(certCache *Cache, cfg Config) *Config {
if certCache == nil {
panic("a certificate cache is required")
}
if certCache.options.GetConfigForCert == nil {
panic("cache must have GetConfigForCert set in its options")
}
return newWithCache(certCache, cfg)
}
// newWithCache ensures that cfg is a valid config by populating
// zero-value fields from the Default Config. If certCache is
// nil, this function panics.
func newWithCache(certCache *Cache, cfg Config) *Config {
if certCache == nil {
panic("cannot make a valid config without a pointer to a certificate cache")
}
if cfg.OnDemand == nil {
cfg.OnDemand = Default.OnDemand
}
if cfg.RenewalWindowRatio == 0 {
cfg.RenewalWindowRatio = Default.RenewalWindowRatio
}
if cfg.OnEvent == nil {
cfg.OnEvent = Default.OnEvent
}
if cfg.KeySource == nil {
cfg.KeySource = Default.KeySource
}
if cfg.DefaultServerName == "" {
cfg.DefaultServerName = Default.DefaultServerName
}
if cfg.OnDemand == nil {
cfg.OnDemand = Default.OnDemand
}
if !cfg.MustStaple {
cfg.MustStaple = Default.MustStaple
}
if cfg.Storage == nil {
cfg.Storage = Default.Storage
}
if cfg.Issuer == nil {
cfg.Issuer = Default.Issuer
if cfg.Issuer == nil {
// okay really, we need an issuer,
// that's kind of the point; most
// people would probably want ACME
cfg.Issuer = NewACMEManager(&cfg, DefaultACME)
}
// issuer and revoker go together; if user
// specifies their own issuer, we don't want
// to override their revoker, hence we only
// do this if Issuer was also nil
if cfg.Revoker == nil {
cfg.Revoker = Default.Revoker
if cfg.Revoker == nil {
cfg.Revoker = NewACMEManager(&cfg, DefaultACME)
}
}
}
// absolutely don't allow a nil storage,
// because that would make almost anything
// a config can do pointless
if cfg.Storage == nil {
cfg.Storage = defaultFileStorage
}
// ensure the unexported fields are valid
cfg.certCache = certCache
return &cfg
}
// ManageSync causes the certificates for domainNames to be managed
// according to cfg. If cfg.OnDemand is not nil, then this simply
// whitelists the domain names and defers the certificate operations
// to when they are needed. Otherwise, the certificates for each
// name are loaded from storage or obtained from the CA. If loaded
// from storage, they are renewed if they are expiring or expired.
// It then caches the certificate in memory and is prepared to serve
// them up during TLS handshakes.
//
// Note that name whitelisting for on-demand management only takes
// effect if cfg.OnDemand.DecisionFunc is not set (is nil); it will
// not overwrite an existing DecisionFunc, nor will it overwrite
// its decision; i.e. the implicit whitelist is only used if no
// DecisionFunc is set.
//
// This method is synchronous, meaning that certificates for all
// domainNames must be successfully obtained (or renewed) before
// it returns. It returns immediately on the first error for any
// of the given domainNames. This behavior is recommended for
// interactive use (i.e. when an administrator is present) so
// that errors can be reported and fixed immediately.
func (cfg *Config) ManageSync(domainNames []string) error {
return cfg.manageAll(nil, domainNames, false)
}
// ManageAsync is the same as ManageSync, except that ACME
// operations are performed asynchronously (in the background).
// This method returns before certificates are ready. It is
// crucial that the administrator monitors the logs and is
// notified of any errors so that corrective action can be
// taken as soon as possible. Any errors returned from this
// method occurred before ACME transactions started.
//
// As long as logs are monitored, this method is typically
// recommended for non-interactive environments.
//
// If there are failures loading, obtaining, or renewing a
// certificate, it will be retried with exponential backoff
// for up to about 30 days, with a maximum interval of about
// 24 hours. Cancelling ctx will cancel retries and shut down
// any goroutines spawned by ManageAsync.
func (cfg *Config) ManageAsync(ctx context.Context, domainNames []string) error {
return cfg.manageAll(ctx, domainNames, true)
}
func (cfg *Config) manageAll(ctx context.Context, domainNames []string, async bool) error {
if ctx == nil {
ctx = context.Background()
}
for _, domainName := range domainNames {
// if on-demand is configured, defer obtain and renew operations
if cfg.OnDemand != nil {
if !cfg.OnDemand.whitelistContains(domainName) {
cfg.OnDemand.hostWhitelist = append(cfg.OnDemand.hostWhitelist, domainName)
}
continue
}
// otherwise, begin management immediately
err := cfg.manageOne(ctx, domainName, async)
if err != nil {
return err
}
}
return nil
}
func (cfg *Config) manageOne(ctx context.Context, domainName string, async bool) error {
// first try loading existing certificate from storage
cert, err := cfg.CacheManagedCertificate(domainName)
if err != nil {
if _, ok := err.(ErrNotExist); !ok {
return fmt.Errorf("%s: caching certificate: %v", domainName, err)
}
// if we don't have one in storage, obtain one
obtain := func() error {
err := cfg.ObtainCert(ctx, domainName, !async)
if err != nil {
return fmt.Errorf("%s: obtaining certificate: %w", domainName, err)
}
cert, err = cfg.CacheManagedCertificate(domainName)
if err != nil {
return fmt.Errorf("%s: caching certificate after obtaining it: %v", domainName, err)
}
return nil
}
if async {
// Leave the job name empty so as to allow duplicate 'obtain'
// jobs; this is because Caddy calls ManageAsync() before the
// previous config is stopped (and before its context is
// canceled), which means that if an obtain job is still
// running for the same domain, Submit() would not queue the
// new one because it is still running, even though it is
// (probably) about to be canceled (it might not if the new
// config fails to finish loading, however). In any case, we
// presume it is safe to enqueue a duplicate obtain job because
// either the old one (or sometimes the new one) is about to be
// canceled. This seems like reasonable logic for any consumer
// of this lib. See https://github.com/caddyserver/caddy/issues/3202
jm.Submit(cfg.Logger, "", obtain)
return nil
}
return obtain()
}
// for an existing certificate, make sure it is renewed
renew := func() error {
err := cfg.RenewCert(ctx, domainName, !async)
if err != nil {
return fmt.Errorf("%s: renewing certificate: %w", domainName, err)
}
// successful renewal, so update in-memory cache
err = cfg.reloadManagedCertificate(cert)
if err != nil {
return fmt.Errorf("%s: reloading renewed certificate into memory: %v", domainName, err)
}
return nil
}
if cert.NeedsRenewal(cfg) {
if async {
jm.Submit(cfg.Logger, "renew_"+domainName, renew)
return nil
}
return renew()
}
return nil
}
// ObtainCert obtains a certificate for name using cfg, as long
// as a certificate does not already exist in storage for that
// name. The name must qualify and cfg must be flagged as Managed.
// This function is a no-op if storage already has a certificate
// for name.
//
// It only obtains and stores certificates (and their keys),
// it does not load them into memory. If interactive is true,
// the user may be shown a prompt.
// TODO: consider moving interactive param into the Config struct,
// and maybe retry settings into the Config struct as well? (same for RenewCert)
func (cfg *Config) ObtainCert(ctx context.Context, name string, interactive bool) error {
if cfg.storageHasCertResources(name) {
return nil
}
issuer, err := cfg.getPrecheckedIssuer(ctx, []string{name}, interactive)
if err != nil {
return err
}
if issuer == nil {
return nil
}
return cfg.obtainWithIssuer(ctx, issuer, name, interactive)
}
func loggerNamed(l *zap.Logger, name string) *zap.Logger {
if l == nil {
return nil
}
return l.Named(name)
}
func (cfg *Config) obtainWithIssuer(ctx context.Context, issuer Issuer, name string, interactive bool) error {
log := loggerNamed(cfg.Logger, "obtain")
if log != nil {
log.Info("acquiring lock", zap.String("identifier", name))
}
// ensure idempotency of the obtain operation for this name
lockKey := cfg.lockKey("cert_acme", name)
err := acquireLock(ctx, cfg.Storage, lockKey)
if err != nil {
return err
}
defer func() {
if log != nil {
log.Info("releasing lock", zap.String("identifier", name))
}
if err := releaseLock(cfg.Storage, lockKey); err != nil {
if log != nil {
log.Error("unable to unlock",
zap.String("identifier", name),
zap.String("lock_key", lockKey),
zap.Error(err))
}
}
}()
if log != nil {
log.Info("lock acquired", zap.String("identifier", name))
}
f := func(ctx context.Context) error {
// check if obtain is still needed -- might have been obtained during lock
if cfg.storageHasCertResources(name) {
if log != nil {
log.Info("certificate already exists in storage", zap.String("identifier", name))
}
return nil
}
privateKey, err := cfg.KeySource.GenerateKey()
if err != nil {
return err
}
privKeyPEM, err := encodePrivateKey(privateKey)
if err != nil {
return err
}
csr, err := cfg.generateCSR(privateKey, []string{name})
if err != nil {
return err
}
issuedCert, err := issuer.Issue(ctx, csr)
if err != nil {
return fmt.Errorf("[%s] Obtain: %w", name, err)
}
// success - immediately save the certificate resource
certRes := CertificateResource{
SANs: namesFromCSR(csr),
CertificatePEM: issuedCert.Certificate,
PrivateKeyPEM: privKeyPEM,
IssuerData: issuedCert.Metadata,
}
err = cfg.saveCertResource(certRes)
if err != nil {
return fmt.Errorf("[%s] Obtain: saving assets: %v", name, err)
}
cfg.emit("cert_obtained", name)
if log != nil {
log.Info("certificate obtained successfully", zap.String("identifier", name))
}
return nil
}
if interactive {
err = f(ctx)
} else {
err = doWithRetry(ctx, log, f)
}
return err
}
// RenewCert renews the certificate for name using cfg. It stows the
// renewed certificate and its assets in storage if successful. It
// DOES NOT update the in-memory cache with the new certificate.
func (cfg *Config) RenewCert(ctx context.Context, name string, interactive bool) error {
issuer, err := cfg.getPrecheckedIssuer(ctx, []string{name}, interactive)
if err != nil {
return err
}
if issuer == nil {
return nil
}
return cfg.renewWithIssuer(ctx, issuer, name, interactive)
}
func (cfg *Config) renewWithIssuer(ctx context.Context, issuer Issuer, name string, interactive bool) error {
log := loggerNamed(cfg.Logger, "renew")
if log != nil {
log.Info("acquiring lock", zap.String("identifier", name))
}
// ensure idempotency of the renew operation for this name
lockKey := cfg.lockKey("cert_acme", name)
err := acquireLock(ctx, cfg.Storage, lockKey)
if err != nil {
return err
}
defer func() {
if log != nil {
log.Info("releasing lock", zap.String("identifier", name))
}
if err := releaseLock(cfg.Storage, lockKey); err != nil {
if log != nil {
log.Error("unable to unlock",
zap.String("identifier", name),
zap.String("lock_key", lockKey),
zap.Error(err))
}
}
}()
if log != nil {
log.Info("lock acquired", zap.String("identifier", name))
}
f := func(ctx context.Context) error {
// prepare for renewal (load PEM cert, key, and meta)
certRes, err := cfg.loadCertResource(name)
if err != nil {
return err
}
// check if renew is still needed - might have been renewed while waiting for lock
timeLeft, needsRenew := cfg.managedCertNeedsRenewal(certRes)
if !needsRenew {
if log != nil {
log.Info("certificate appears to have been renewed already",
zap.String("identifier", name),
zap.Duration("remaining", timeLeft))
}
return nil
}
if log != nil {
log.Info("renewing certificate",
zap.String("identifier", name),
zap.Duration("remaining", timeLeft))
}
privateKey, err := decodePrivateKey(certRes.PrivateKeyPEM)
if err != nil {
return err
}
csr, err := cfg.generateCSR(privateKey, []string{name})
if err != nil {
return err
}
issuedCert, err := issuer.Issue(ctx, csr)
if err != nil {
return fmt.Errorf("[%s] Renew: %w", name, err)
}
// success - immediately save the renewed certificate resource
newCertRes := CertificateResource{
SANs: namesFromCSR(csr),
CertificatePEM: issuedCert.Certificate,
PrivateKeyPEM: certRes.PrivateKeyPEM,
IssuerData: issuedCert.Metadata,
}
err = cfg.saveCertResource(newCertRes)
if err != nil {
return fmt.Errorf("[%s] Renew: saving assets: %v", name, err)
}
cfg.emit("cert_renewed", name)
if log != nil {
log.Info("certificate renewed successfully", zap.String("identifier", name))
}
return nil
}
if interactive {
err = f(ctx)
} else {
err = doWithRetry(ctx, log, f)
}
return err
}
func (cfg *Config) generateCSR(privateKey crypto.PrivateKey, sans []string) (*x509.CertificateRequest, error) {
csrTemplate := new(x509.CertificateRequest)
for _, name := range sans {
if ip := net.ParseIP(name); ip != nil {
csrTemplate.IPAddresses = append(csrTemplate.IPAddresses, ip)
} else if strings.Contains(name, "@") {
csrTemplate.EmailAddresses = append(csrTemplate.EmailAddresses, name)
} else if u, err := url.Parse(name); err == nil && strings.Contains(name, "/") {
csrTemplate.URIs = append(csrTemplate.URIs, u)
} else {
csrTemplate.DNSNames = append(csrTemplate.DNSNames, name)
}
}
if cfg.MustStaple {
csrTemplate.ExtraExtensions = append(csrTemplate.ExtraExtensions, mustStapleExtension)
}
csrDER, err := x509.CreateCertificateRequest(rand.Reader, csrTemplate, privateKey)
if err != nil {
return nil, err
}
return x509.ParseCertificateRequest(csrDER)
}
// RevokeCert revokes the certificate for domain via ACME protocol. It requires
// that cfg.Issuer is properly configured with the same issuer that issued the
// certificate being revoked. See RFC 5280 §5.3.1 for reason codes.
func (cfg *Config) RevokeCert(ctx context.Context, domain string, reason int, interactive bool) error {
rev := cfg.Revoker
if rev == nil {
rev = Default.Revoker
}
certRes, err := cfg.loadCertResource(domain)
if err != nil {
return err
}
issuerKey := cfg.Issuer.IssuerKey()
if !cfg.Storage.Exists(StorageKeys.SitePrivateKey(issuerKey, domain)) {
return fmt.Errorf("private key not found for %s", certRes.SANs)
}
err = rev.Revoke(ctx, certRes, reason)
if err != nil {
return err
}
cfg.emit("cert_revoked", domain)
err = cfg.Storage.Delete(StorageKeys.SiteCert(issuerKey, domain))
if err != nil {
return fmt.Errorf("certificate revoked, but unable to delete certificate file: %v", err)
}
err = cfg.Storage.Delete(StorageKeys.SitePrivateKey(issuerKey, domain))
if err != nil {
return fmt.Errorf("certificate revoked, but unable to delete private key: %v", err)
}
err = cfg.Storage.Delete(StorageKeys.SiteMeta(issuerKey, domain))
if err != nil {
return fmt.Errorf("certificate revoked, but unable to delete certificate metadata: %v", err)
}
return nil
}
// TLSConfig is an opinionated method that returns a
// recommended, modern TLS configuration that can be
// used to configure TLS listeners, which also supports
// the TLS-ALPN challenge and serves up certificates
// managed by cfg.
//
// Unlike the package TLS() function, this method does
// not, by itself, enable certificate management for
// any domain names.
//
// Feel free to further customize the returned tls.Config,
// but do not mess with the GetCertificate or NextProtos
// fields unless you know what you're doing, as they're
// necessary to solve the TLS-ALPN challenge.
func (cfg *Config) TLSConfig() *tls.Config {
return &tls.Config{
// these two fields necessary for TLS-ALPN challenge
GetCertificate: cfg.GetCertificate,
NextProtos: []string{acmez.ACMETLS1Protocol},
// the rest recommended for modern TLS servers
MinVersion: tls.VersionTLS12,
CurvePreferences: []tls.CurveID{
tls.X25519,
tls.CurveP256,
},
CipherSuites: preferredDefaultCipherSuites(),
PreferServerCipherSuites: true,
}
}
// getPrecheckedIssuer returns an Issuer with pre-checks
// completed, if it is also a PreChecker. It also checks
// that storage is functioning. If a nil Issuer is returned
// with a nil error, that means to skip this operation
// (not an error, just a no-op).
func (cfg *Config) getPrecheckedIssuer(ctx context.Context, names []string, interactive bool) (Issuer, error) {
// ensure storage is writeable and readable
// TODO: this is not necessary every time; should only
// perform check once every so often for each storage,
// which may require some global state...
err := cfg.checkStorage()
if err != nil {
return nil, fmt.Errorf("failed storage check: %v - storage is probably misconfigured", err)
}
if prechecker, ok := cfg.Issuer.(PreChecker); ok {
err := prechecker.PreCheck(ctx, names, interactive)
if err != nil {
return nil, err
}
}
return cfg.Issuer, nil
}
// checkStorage tests the storage by writing random bytes
// to a random key, and then loading those bytes and
// comparing the loaded value. If this fails, the provided
// cfg.Storage mechanism should not be used.
func (cfg *Config) checkStorage() error {
key := fmt.Sprintf("rw_test_%d", weakrand.Int())
contents := make([]byte, 1024*10) // size sufficient for one or two ACME resources
_, err := weakrand.Read(contents)
if err != nil {
return err
}
err = cfg.Storage.Store(key, contents)
if err != nil {
return err
}
defer func() {
deleteErr := cfg.Storage.Delete(key)
if deleteErr != nil {
if cfg.Logger != nil {
cfg.Logger.Error("deleting test key from storage",
zap.String("key", key), zap.Error(err))
}
}
// if there was no other error, make sure
// to return any error returned from Delete
if err == nil {
err = deleteErr
}
}()
loaded, err := cfg.Storage.Load(key)
if err != nil {
return err
}
if !bytes.Equal(contents, loaded) {
return fmt.Errorf("load yielded different value than was stored; expected %d bytes, got %d bytes of differing elements", len(contents), len(loaded))
}
return nil
}
// storageHasCertResources returns true if the storage
// associated with cfg's certificate cache has all the
// resources related to the certificate for domain: the
// certificate, the private key, and the metadata.
func (cfg *Config) storageHasCertResources(domain string) bool {
issuerKey := cfg.Issuer.IssuerKey()
certKey := StorageKeys.SiteCert(issuerKey, domain)
keyKey := StorageKeys.SitePrivateKey(issuerKey, domain)
metaKey := StorageKeys.SiteMeta(issuerKey, domain)
return cfg.Storage.Exists(certKey) &&
cfg.Storage.Exists(keyKey) &&
cfg.Storage.Exists(metaKey)
}
// lockKey returns a key for a lock that is specific to the operation
// named op being performed related to domainName and this config's CA.
func (cfg *Config) lockKey(op, domainName string) string {
return fmt.Sprintf("%s_%s_%s", op, domainName, cfg.Issuer.IssuerKey())
}
// managedCertNeedsRenewal returns true if certRes is
// expiring soon or already expired, or if the process
// of checking the expiration returned an error.
func (cfg *Config) managedCertNeedsRenewal(certRes CertificateResource) (time.Duration, bool) {
cert, err := makeCertificate(certRes.CertificatePEM, certRes.PrivateKeyPEM)
if err != nil {
return 0, true
}
return time.Until(cert.Leaf.NotAfter), cert.NeedsRenewal(cfg)
}
func (cfg *Config) emit(eventName string, data interface{}) {
if cfg.OnEvent == nil {
return
}
cfg.OnEvent(eventName, data)
}
// CertificateSelector is a type which can select a certificate to use given multiple choices.
type CertificateSelector interface {
SelectCertificate(*tls.ClientHelloInfo, []Certificate) (Certificate, error)
}
// Constants for PKIX MustStaple extension.
var (
tlsFeatureExtensionOID = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 1, 24}
ocspMustStapleFeature = []byte{0x30, 0x03, 0x02, 0x01, 0x05}
mustStapleExtension = pkix.Extension{
Id: tlsFeatureExtensionOID,
Value: ocspMustStapleFeature,
}
)