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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package autocert provides automatic access to certificates from Let's Encrypt
// and any other ACME-based CA.
//
// This package is a work in progress and makes no API stability promises.
package autocert
import (
"bytes"
"context"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"io"
mathrand "math/rand"
"net"
"net/http"
"path"
"strings"
"sync"
"time"
"golang.org/x/crypto/acme"
)
// createCertRetryAfter is how much time to wait before removing a failed state
// entry due to an unsuccessful createCert call.
// This is a variable instead of a const for testing.
// TODO: Consider making it configurable or an exp backoff?
var createCertRetryAfter = time.Minute
// pseudoRand is safe for concurrent use.
var pseudoRand *lockedMathRand
func init() {
src := mathrand.NewSource(time.Now().UnixNano())
pseudoRand = &lockedMathRand{rnd: mathrand.New(src)}
}
// AcceptTOS is a Manager.Prompt function that always returns true to
// indicate acceptance of the CA's Terms of Service during account
// registration.
func AcceptTOS(tosURL string) bool { return true }
// HostPolicy specifies which host names the Manager is allowed to respond to.
// It returns a non-nil error if the host should be rejected.
// The returned error is accessible via tls.Conn.Handshake and its callers.
// See Manager's HostPolicy field and GetCertificate method docs for more details.
type HostPolicy func(ctx context.Context, host string) error
// HostWhitelist returns a policy where only the specified host names are allowed.
// Only exact matches are currently supported. Subdomains, regexp or wildcard
// will not match.
func HostWhitelist(hosts ...string) HostPolicy {
whitelist := make(map[string]bool, len(hosts))
for _, h := range hosts {
whitelist[h] = true
}
return func(_ context.Context, host string) error {
if !whitelist[host] {
return errors.New("acme/autocert: host not configured")
}
return nil
}
}
// defaultHostPolicy is used when Manager.HostPolicy is not set.
func defaultHostPolicy(context.Context, string) error {
return nil
}
// Manager is a stateful certificate manager built on top of acme.Client.
// It obtains and refreshes certificates automatically using "tls-alpn-01",
// "tls-sni-01", "tls-sni-02" and "http-01" challenge types,
// as well as providing them to a TLS server via tls.Config.
//
// You must specify a cache implementation, such as DirCache,
// to reuse obtained certificates across program restarts.
// Otherwise your server is very likely to exceed the certificate
// issuer's request rate limits.
type Manager struct {
// Prompt specifies a callback function to conditionally accept a CA's Terms of Service (TOS).
// The registration may require the caller to agree to the CA's TOS.
// If so, Manager calls Prompt with a TOS URL provided by the CA. Prompt should report
// whether the caller agrees to the terms.
//
// To always accept the terms, the callers can use AcceptTOS.
Prompt func(tosURL string) bool
// Cache optionally stores and retrieves previously-obtained certificates
// and other state. If nil, certs will only be cached for the lifetime of
// the Manager. Multiple Managers can share the same Cache.
//
// Using a persistent Cache, such as DirCache, is strongly recommended.
Cache Cache
// HostPolicy controls which domains the Manager will attempt
// to retrieve new certificates for. It does not affect cached certs.
//
// If non-nil, HostPolicy is called before requesting a new cert.
// If nil, all hosts are currently allowed. This is not recommended,
// as it opens a potential attack where clients connect to a server
// by IP address and pretend to be asking for an incorrect host name.
// Manager will attempt to obtain a certificate for that host, incorrectly,
// eventually reaching the CA's rate limit for certificate requests
// and making it impossible to obtain actual certificates.
//
// See GetCertificate for more details.
HostPolicy HostPolicy
// RenewBefore optionally specifies how early certificates should
// be renewed before they expire.
//
// If zero, they're renewed 30 days before expiration.
RenewBefore time.Duration
// Client is used to perform low-level operations, such as account registration
// and requesting new certificates.
//
// If Client is nil, a zero-value acme.Client is used with acme.LetsEncryptURL
// as directory endpoint. If the Client.Key is nil, a new ECDSA P-256 key is
// generated and, if Cache is not nil, stored in cache.
//
// Mutating the field after the first call of GetCertificate method will have no effect.
Client *acme.Client
// Email optionally specifies a contact email address.
// This is used by CAs, such as Let's Encrypt, to notify about problems
// with issued certificates.
//
// If the Client's account key is already registered, Email is not used.
Email string
// ForceRSA used to make the Manager generate RSA certificates. It is now ignored.
//
// Deprecated: the Manager will request the correct type of certificate based
// on what each client supports.
ForceRSA bool
// ExtraExtensions are used when generating a new CSR (Certificate Request),
// thus allowing customization of the resulting certificate.
// For instance, TLS Feature Extension (RFC 7633) can be used
// to prevent an OCSP downgrade attack.
//
// The field value is passed to crypto/x509.CreateCertificateRequest
// in the template's ExtraExtensions field as is.
ExtraExtensions []pkix.Extension
clientMu sync.Mutex
client *acme.Client // initialized by acmeClient method
stateMu sync.Mutex
state map[certKey]*certState
// renewal tracks the set of domains currently running renewal timers.
renewalMu sync.Mutex
renewal map[certKey]*domainRenewal
// tokensMu guards the rest of the fields: tryHTTP01, certTokens and httpTokens.
tokensMu sync.RWMutex
// tryHTTP01 indicates whether the Manager should try "http-01" challenge type
// during the authorization flow.
tryHTTP01 bool
// httpTokens contains response body values for http-01 challenges
// and is keyed by the URL path at which a challenge response is expected
// to be provisioned.
// The entries are stored for the duration of the authorization flow.
httpTokens map[string][]byte
// certTokens contains temporary certificates for tls-sni and tls-alpn challenges
// and is keyed by token domain name, which matches server name of ClientHello.
// Keys always have ".acme.invalid" suffix for tls-sni. Otherwise, they are domain names
// for tls-alpn.
// The entries are stored for the duration of the authorization flow.
certTokens map[string]*tls.Certificate
// nowFunc, if not nil, returns the current time. This may be set for
// testing purposes.
nowFunc func() time.Time
}
// certKey is the key by which certificates are tracked in state, renewal and cache.
type certKey struct {
domain string // without trailing dot
isRSA bool // RSA cert for legacy clients (as opposed to default ECDSA)
isToken bool // tls-based challenge token cert; key type is undefined regardless of isRSA
}
func (c certKey) String() string {
if c.isToken {
return c.domain + "+token"
}
if c.isRSA {
return c.domain + "+rsa"
}
return c.domain
}
// TLSConfig creates a new TLS config suitable for net/http.Server servers,
// supporting HTTP/2 and the tls-alpn-01 ACME challenge type.
func (m *Manager) TLSConfig() *tls.Config {
return &tls.Config{
GetCertificate: m.GetCertificate,
NextProtos: []string{
"h2", "http/1.1", // enable HTTP/2
acme.ALPNProto, // enable tls-alpn ACME challenges
},
}
}
// GetCertificate implements the tls.Config.GetCertificate hook.
// It provides a TLS certificate for hello.ServerName host, including answering
// tls-alpn-01 and *.acme.invalid (tls-sni-01 and tls-sni-02) challenges.
// All other fields of hello are ignored.
//
// If m.HostPolicy is non-nil, GetCertificate calls the policy before requesting
// a new cert. A non-nil error returned from m.HostPolicy halts TLS negotiation.
// The error is propagated back to the caller of GetCertificate and is user-visible.
// This does not affect cached certs. See HostPolicy field description for more details.
//
// If GetCertificate is used directly, instead of via Manager.TLSConfig, package users will
// also have to add acme.ALPNProto to NextProtos for tls-alpn-01, or use HTTPHandler
// for http-01. (The tls-sni-* challenges have been deprecated by popular ACME providers
// due to security issues in the ecosystem.)
func (m *Manager) GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
if m.Prompt == nil {
return nil, errors.New("acme/autocert: Manager.Prompt not set")
}
name := hello.ServerName
if name == "" {
return nil, errors.New("acme/autocert: missing server name")
}
if !strings.Contains(strings.Trim(name, "."), ".") {
return nil, errors.New("acme/autocert: server name component count invalid")
}
if strings.ContainsAny(name, `+/\`) {
return nil, errors.New("acme/autocert: server name contains invalid character")
}
// In the worst-case scenario, the timeout needs to account for caching, host policy,
// domain ownership verification and certificate issuance.
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
defer cancel()
// Check whether this is a token cert requested for TLS-SNI or TLS-ALPN challenge.
if wantsTokenCert(hello) {
m.tokensMu.RLock()
defer m.tokensMu.RUnlock()
// It's ok to use the same token cert key for both tls-sni and tls-alpn
// because there's always at most 1 token cert per on-going domain authorization.
// See m.verify for details.
if cert := m.certTokens[name]; cert != nil {
return cert, nil
}
if cert, err := m.cacheGet(ctx, certKey{domain: name, isToken: true}); err == nil {
return cert, nil
}
// TODO: cache error results?
return nil, fmt.Errorf("acme/autocert: no token cert for %q", name)
}
// regular domain
ck := certKey{
domain: strings.TrimSuffix(name, "."), // golang.org/issue/18114
isRSA: !supportsECDSA(hello),
}
cert, err := m.cert(ctx, ck)
if err == nil {
return cert, nil
}
if err != ErrCacheMiss {
return nil, err
}
// first-time
if err := m.hostPolicy()(ctx, name); err != nil {
return nil, err
}
cert, err = m.createCert(ctx, ck)
if err != nil {
return nil, err
}
m.cachePut(ctx, ck, cert)
return cert, nil
}
// wantsTokenCert reports whether a TLS request with SNI is made by a CA server
// for a challenge verification.
func wantsTokenCert(hello *tls.ClientHelloInfo) bool {
// tls-alpn-01
if len(hello.SupportedProtos) == 1 && hello.SupportedProtos[0] == acme.ALPNProto {
return true
}
// tls-sni-xx
return strings.HasSuffix(hello.ServerName, ".acme.invalid")
}
func supportsECDSA(hello *tls.ClientHelloInfo) bool {
// The "signature_algorithms" extension, if present, limits the key exchange
// algorithms allowed by the cipher suites. See RFC 5246, section 7.4.1.4.1.
if hello.SignatureSchemes != nil {
ecdsaOK := false
schemeLoop:
for _, scheme := range hello.SignatureSchemes {
const tlsECDSAWithSHA1 tls.SignatureScheme = 0x0203 // constant added in Go 1.10
switch scheme {
case tlsECDSAWithSHA1, tls.ECDSAWithP256AndSHA256,
tls.ECDSAWithP384AndSHA384, tls.ECDSAWithP521AndSHA512:
ecdsaOK = true
break schemeLoop
}
}
if !ecdsaOK {
return false
}
}
if hello.SupportedCurves != nil {
ecdsaOK := false
for _, curve := range hello.SupportedCurves {
if curve == tls.CurveP256 {
ecdsaOK = true
break
}
}
if !ecdsaOK {
return false
}
}
for _, suite := range hello.CipherSuites {
switch suite {
case tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305:
return true
}
}
return false
}
// HTTPHandler configures the Manager to provision ACME "http-01" challenge responses.
// It returns an http.Handler that responds to the challenges and must be
// running on port 80. If it receives a request that is not an ACME challenge,
// it delegates the request to the optional fallback handler.
//
// If fallback is nil, the returned handler redirects all GET and HEAD requests
// to the default TLS port 443 with 302 Found status code, preserving the original
// request path and query. It responds with 400 Bad Request to all other HTTP methods.
// The fallback is not protected by the optional HostPolicy.
//
// Because the fallback handler is run with unencrypted port 80 requests,
// the fallback should not serve TLS-only requests.
//
// If HTTPHandler is never called, the Manager will only use the "tls-alpn-01"
// challenge for domain verification.
func (m *Manager) HTTPHandler(fallback http.Handler) http.Handler {
m.tokensMu.Lock()
defer m.tokensMu.Unlock()
m.tryHTTP01 = true
if fallback == nil {
fallback = http.HandlerFunc(handleHTTPRedirect)
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if !strings.HasPrefix(r.URL.Path, "/.well-known/acme-challenge/") {
fallback.ServeHTTP(w, r)
return
}
// A reasonable context timeout for cache and host policy only,
// because we don't wait for a new certificate issuance here.
ctx, cancel := context.WithTimeout(r.Context(), time.Minute)
defer cancel()
if err := m.hostPolicy()(ctx, r.Host); err != nil {
http.Error(w, err.Error(), http.StatusForbidden)
return
}
data, err := m.httpToken(ctx, r.URL.Path)
if err != nil {
http.Error(w, err.Error(), http.StatusNotFound)
return
}
w.Write(data)
})
}
func handleHTTPRedirect(w http.ResponseWriter, r *http.Request) {
if r.Method != "GET" && r.Method != "HEAD" {
http.Error(w, "Use HTTPS", http.StatusBadRequest)
return
}
target := "https://" + stripPort(r.Host) + r.URL.RequestURI()
http.Redirect(w, r, target, http.StatusFound)
}
func stripPort(hostport string) string {
host, _, err := net.SplitHostPort(hostport)
if err != nil {
return hostport
}
return net.JoinHostPort(host, "443")
}
// cert returns an existing certificate either from m.state or cache.
// If a certificate is found in cache but not in m.state, the latter will be filled
// with the cached value.
func (m *Manager) cert(ctx context.Context, ck certKey) (*tls.Certificate, error) {
m.stateMu.Lock()
if s, ok := m.state[ck]; ok {
m.stateMu.Unlock()
s.RLock()
defer s.RUnlock()
return s.tlscert()
}
defer m.stateMu.Unlock()
cert, err := m.cacheGet(ctx, ck)
if err != nil {
return nil, err
}
signer, ok := cert.PrivateKey.(crypto.Signer)
if !ok {
return nil, errors.New("acme/autocert: private key cannot sign")
}
if m.state == nil {
m.state = make(map[certKey]*certState)
}
s := &certState{
key: signer,
cert: cert.Certificate,
leaf: cert.Leaf,
}
m.state[ck] = s
go m.renew(ck, s.key, s.leaf.NotAfter)
return cert, nil
}
// cacheGet always returns a valid certificate, or an error otherwise.
// If a cached certificate exists but is not valid, ErrCacheMiss is returned.
func (m *Manager) cacheGet(ctx context.Context, ck certKey) (*tls.Certificate, error) {
if m.Cache == nil {
return nil, ErrCacheMiss
}
data, err := m.Cache.Get(ctx, ck.String())
if err != nil {
return nil, err
}
// private
priv, pub := pem.Decode(data)
if priv == nil || !strings.Contains(priv.Type, "PRIVATE") {
return nil, ErrCacheMiss
}
privKey, err := parsePrivateKey(priv.Bytes)
if err != nil {
return nil, err
}
// public
var pubDER [][]byte
for len(pub) > 0 {
var b *pem.Block
b, pub = pem.Decode(pub)
if b == nil {
break
}
pubDER = append(pubDER, b.Bytes)
}
if len(pub) > 0 {
// Leftover content not consumed by pem.Decode. Corrupt. Ignore.
return nil, ErrCacheMiss
}
// verify and create TLS cert
leaf, err := validCert(ck, pubDER, privKey, m.now())
if err != nil {
return nil, ErrCacheMiss
}
tlscert := &tls.Certificate{
Certificate: pubDER,
PrivateKey: privKey,
Leaf: leaf,
}
return tlscert, nil
}
func (m *Manager) cachePut(ctx context.Context, ck certKey, tlscert *tls.Certificate) error {
if m.Cache == nil {
return nil
}
// contains PEM-encoded data
var buf bytes.Buffer
// private
switch key := tlscert.PrivateKey.(type) {
case *ecdsa.PrivateKey:
if err := encodeECDSAKey(&buf, key); err != nil {
return err
}
case *rsa.PrivateKey:
b := x509.MarshalPKCS1PrivateKey(key)
pb := &pem.Block{Type: "RSA PRIVATE KEY", Bytes: b}
if err := pem.Encode(&buf, pb); err != nil {
return err
}
default:
return errors.New("acme/autocert: unknown private key type")
}
// public
for _, b := range tlscert.Certificate {
pb := &pem.Block{Type: "CERTIFICATE", Bytes: b}
if err := pem.Encode(&buf, pb); err != nil {
return err
}
}
return m.Cache.Put(ctx, ck.String(), buf.Bytes())
}
func encodeECDSAKey(w io.Writer, key *ecdsa.PrivateKey) error {
b, err := x509.MarshalECPrivateKey(key)
if err != nil {
return err
}
pb := &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
return pem.Encode(w, pb)
}
// createCert starts the domain ownership verification and returns a certificate
// for that domain upon success.
//
// If the domain is already being verified, it waits for the existing verification to complete.
// Either way, createCert blocks for the duration of the whole process.
func (m *Manager) createCert(ctx context.Context, ck certKey) (*tls.Certificate, error) {
// TODO: maybe rewrite this whole piece using sync.Once
state, err := m.certState(ck)
if err != nil {
return nil, err
}
// state may exist if another goroutine is already working on it
// in which case just wait for it to finish
if !state.locked {
state.RLock()
defer state.RUnlock()
return state.tlscert()
}
// We are the first; state is locked.
// Unblock the readers when domain ownership is verified
// and we got the cert or the process failed.
defer state.Unlock()
state.locked = false
der, leaf, err := m.authorizedCert(ctx, state.key, ck)
if err != nil {
// Remove the failed state after some time,
// making the manager call createCert again on the following TLS hello.
time.AfterFunc(createCertRetryAfter, func() {
defer testDidRemoveState(ck)
m.stateMu.Lock()
defer m.stateMu.Unlock()
// Verify the state hasn't changed and it's still invalid
// before deleting.
s, ok := m.state[ck]
if !ok {
return
}
if _, err := validCert(ck, s.cert, s.key, m.now()); err == nil {
return
}
delete(m.state, ck)
})
return nil, err
}
state.cert = der
state.leaf = leaf
go m.renew(ck, state.key, state.leaf.NotAfter)
return state.tlscert()
}
// certState returns a new or existing certState.
// If a new certState is returned, state.exist is false and the state is locked.
// The returned error is non-nil only in the case where a new state could not be created.
func (m *Manager) certState(ck certKey) (*certState, error) {
m.stateMu.Lock()
defer m.stateMu.Unlock()
if m.state == nil {
m.state = make(map[certKey]*certState)
}
// existing state
if state, ok := m.state[ck]; ok {
return state, nil
}
// new locked state
var (
err error
key crypto.Signer
)
if ck.isRSA {
key, err = rsa.GenerateKey(rand.Reader, 2048)
} else {
key, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
}
if err != nil {
return nil, err
}
state := &certState{
key: key,
locked: true,
}
state.Lock() // will be unlocked by m.certState caller
m.state[ck] = state
return state, nil
}
// authorizedCert starts the domain ownership verification process and requests a new cert upon success.
// The key argument is the certificate private key.
func (m *Manager) authorizedCert(ctx context.Context, key crypto.Signer, ck certKey) (der [][]byte, leaf *x509.Certificate, err error) {
client, err := m.acmeClient(ctx)
if err != nil {
return nil, nil, err
}
if err := m.verify(ctx, client, ck.domain); err != nil {
return nil, nil, err
}
csr, err := certRequest(key, ck.domain, m.ExtraExtensions)
if err != nil {
return nil, nil, err
}
der, _, err = client.CreateCert(ctx, csr, 0, true)
if err != nil {
return nil, nil, err
}
leaf, err = validCert(ck, der, key, m.now())
if err != nil {
return nil, nil, err
}
return der, leaf, nil
}
// revokePendingAuthz revokes all authorizations idenfied by the elements of uri slice.
// It ignores revocation errors.
func (m *Manager) revokePendingAuthz(ctx context.Context, uri []string) {
client, err := m.acmeClient(ctx)
if err != nil {
return
}
for _, u := range uri {
client.RevokeAuthorization(ctx, u)
}
}
// verify runs the identifier (domain) authorization flow
// using each applicable ACME challenge type.
func (m *Manager) verify(ctx context.Context, client *acme.Client, domain string) error {
// The list of challenge types we'll try to fulfill
// in this specific order.
challengeTypes := []string{"tls-alpn-01", "tls-sni-02", "tls-sni-01"}
m.tokensMu.RLock()
if m.tryHTTP01 {
challengeTypes = append(challengeTypes, "http-01")
}
m.tokensMu.RUnlock()
// Keep track of pending authzs and revoke the ones that did not validate.
pendingAuthzs := make(map[string]bool)
defer func() {
var uri []string
for k, pending := range pendingAuthzs {
if pending {
uri = append(uri, k)
}
}
if len(uri) > 0 {
// Use "detached" background context.
// The revocations need not happen in the current verification flow.
go m.revokePendingAuthz(context.Background(), uri)
}
}()
// errs accumulates challenge failure errors, printed if all fail
errs := make(map[*acme.Challenge]error)
var nextTyp int // challengeType index of the next challenge type to try
for {
// Start domain authorization and get the challenge.
authz, err := client.Authorize(ctx, domain)
if err != nil {
return err
}
// No point in accepting challenges if the authorization status
// is in a final state.
switch authz.Status {
case acme.StatusValid:
return nil // already authorized
case acme.StatusInvalid:
return fmt.Errorf("acme/autocert: invalid authorization %q", authz.URI)
}
pendingAuthzs[authz.URI] = true
// Pick the next preferred challenge.
var chal *acme.Challenge
for chal == nil && nextTyp < len(challengeTypes) {
chal = pickChallenge(challengeTypes[nextTyp], authz.Challenges)
nextTyp++
}
if chal == nil {
errorMsg := fmt.Sprintf("acme/autocert: unable to authorize %q", domain)
for chal, err := range errs {
errorMsg += fmt.Sprintf("; challenge %q failed with error: %v", chal.Type, err)
}
return errors.New(errorMsg)
}
cleanup, err := m.fulfill(ctx, client, chal, domain)
if err != nil {
errs[chal] = err
continue
}
defer cleanup()
if _, err := client.Accept(ctx, chal); err != nil {
errs[chal] = err
continue
}
// A challenge is fulfilled and accepted: wait for the CA to validate.
if _, err := client.WaitAuthorization(ctx, authz.URI); err != nil {
errs[chal] = err
continue
}
delete(pendingAuthzs, authz.URI)
return nil
}
}
// fulfill provisions a response to the challenge chal.
// The cleanup is non-nil only if provisioning succeeded.
func (m *Manager) fulfill(ctx context.Context, client *acme.Client, chal *acme.Challenge, domain string) (cleanup func(), err error) {
switch chal.Type {
case "tls-alpn-01":
cert, err := client.TLSALPN01ChallengeCert(chal.Token, domain)
if err != nil {
return nil, err
}
m.putCertToken(ctx, domain, &cert)
return func() { go m.deleteCertToken(domain) }, nil
case "tls-sni-01":
cert, name, err := client.TLSSNI01ChallengeCert(chal.Token)
if err != nil {
return nil, err
}
m.putCertToken(ctx, name, &cert)
return func() { go m.deleteCertToken(name) }, nil
case "tls-sni-02":
cert, name, err := client.TLSSNI02ChallengeCert(chal.Token)
if err != nil {
return nil, err
}
m.putCertToken(ctx, name, &cert)
return func() { go m.deleteCertToken(name) }, nil
case "http-01":
resp, err := client.HTTP01ChallengeResponse(chal.Token)
if err != nil {
return nil, err
}
p := client.HTTP01ChallengePath(chal.Token)
m.putHTTPToken(ctx, p, resp)
return func() { go m.deleteHTTPToken(p) }, nil
}
return nil, fmt.Errorf("acme/autocert: unknown challenge type %q", chal.Type)
}
func pickChallenge(typ string, chal []*acme.Challenge) *acme.Challenge {
for _, c := range chal {
if c.Type == typ {
return c
}
}
return nil
}
// putCertToken stores the token certificate with the specified name
// in both m.certTokens map and m.Cache.
func (m *Manager) putCertToken(ctx context.Context, name string, cert *tls.Certificate) {
m.tokensMu.Lock()
defer m.tokensMu.Unlock()
if m.certTokens == nil {
m.certTokens = make(map[string]*tls.Certificate)
}
m.certTokens[name] = cert
m.cachePut(ctx, certKey{domain: name, isToken: true}, cert)
}
// deleteCertToken removes the token certificate with the specified name
// from both m.certTokens map and m.Cache.
func (m *Manager) deleteCertToken(name string) {
m.tokensMu.Lock()
defer m.tokensMu.Unlock()
delete(m.certTokens, name)
if m.Cache != nil {
ck := certKey{domain: name, isToken: true}
m.Cache.Delete(context.Background(), ck.String())
}
}
// httpToken retrieves an existing http-01 token value from an in-memory map
// or the optional cache.
func (m *Manager) httpToken(ctx context.Context, tokenPath string) ([]byte, error) {
m.tokensMu.RLock()
defer m.tokensMu.RUnlock()
if v, ok := m.httpTokens[tokenPath]; ok {
return v, nil
}
if m.Cache == nil {
return nil, fmt.Errorf("acme/autocert: no token at %q", tokenPath)
}
return m.Cache.Get(ctx, httpTokenCacheKey(tokenPath))
}
// putHTTPToken stores an http-01 token value using tokenPath as key
// in both in-memory map and the optional Cache.
//
// It ignores any error returned from Cache.Put.
func (m *Manager) putHTTPToken(ctx context.Context, tokenPath, val string) {
m.tokensMu.Lock()
defer m.tokensMu.Unlock()
if m.httpTokens == nil {
m.httpTokens = make(map[string][]byte)
}
b := []byte(val)
m.httpTokens[tokenPath] = b
if m.Cache != nil {
m.Cache.Put(ctx, httpTokenCacheKey(tokenPath), b)
}
}
// deleteHTTPToken removes an http-01 token value from both in-memory map
// and the optional Cache, ignoring any error returned from the latter.
//
// If m.Cache is non-nil, it blocks until Cache.Delete returns without a timeout.
func (m *Manager) deleteHTTPToken(tokenPath string) {
m.tokensMu.Lock()
defer m.tokensMu.Unlock()
delete(m.httpTokens, tokenPath)
if m.Cache != nil {
m.Cache.Delete(context.Background(), httpTokenCacheKey(tokenPath))
}
}
// httpTokenCacheKey returns a key at which an http-01 token value may be stored
// in the Manager's optional Cache.
func httpTokenCacheKey(tokenPath string) string {
return path.Base(tokenPath) + "+http-01"
}
// renew starts a cert renewal timer loop, one per domain.
//
// The loop is scheduled in two cases:
// - a cert was fetched from cache for the first time (wasn't in m.state)
// - a new cert was created by m.createCert
//
// The key argument is a certificate private key.
// The exp argument is the cert expiration time (NotAfter).
func (m *Manager) renew(ck certKey, key crypto.Signer, exp time.Time) {
m.renewalMu.Lock()
defer m.renewalMu.Unlock()
if m.renewal[ck] != nil {
// another goroutine is already on it
return
}
if m.renewal == nil {
m.renewal = make(map[certKey]*domainRenewal)
}
dr := &domainRenewal{m: m, ck: ck, key: key}
m.renewal[ck] = dr
dr.start(exp)
}
// stopRenew stops all currently running cert renewal timers.
// The timers are not restarted during the lifetime of the Manager.
func (m *Manager) stopRenew() {
m.renewalMu.Lock()
defer m.renewalMu.Unlock()
for name, dr := range m.renewal {
delete(m.renewal, name)
dr.stop()
}
}
func (m *Manager) accountKey(ctx context.Context) (crypto.Signer, error) {
const keyName = "acme_account+key"
// Previous versions of autocert stored the value under a different key.
const legacyKeyName = "acme_account.key"
genKey := func() (*ecdsa.PrivateKey, error) {
return ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
}
if m.Cache == nil {
return genKey()
}
data, err := m.Cache.Get(ctx, keyName)
if err == ErrCacheMiss {
data, err = m.Cache.Get(ctx, legacyKeyName)
}
if err == ErrCacheMiss {
key, err := genKey()
if err != nil {
return nil, err
}
var buf bytes.Buffer
if err := encodeECDSAKey(&buf, key); err != nil {
return nil, err
}
if err := m.Cache.Put(ctx, keyName, buf.Bytes()); err != nil {
return nil, err
}
return key, nil
}
if err != nil {
return nil, err
}
priv, _ := pem.Decode(data)
if priv == nil || !strings.Contains(priv.Type, "PRIVATE") {
return nil, errors.New("acme/autocert: invalid account key found in cache")
}
return parsePrivateKey(priv.Bytes)
}
func (m *Manager) acmeClient(ctx context.Context) (*acme.Client, error) {
m.clientMu.Lock()
defer m.clientMu.Unlock()
if m.client != nil {
return m.client, nil
}
client := m.Client
if client == nil {
client = &acme.Client{DirectoryURL: acme.LetsEncryptURL}
}
if client.Key == nil {
var err error
client.Key, err = m.accountKey(ctx)
if err != nil {
return nil, err
}
}
var contact []string
if m.Email != "" {
contact = []string{"mailto:" + m.Email}
}
a := &acme.Account{Contact: contact}
_, err := client.Register(ctx, a, m.Prompt)
if ae, ok := err.(*acme.Error); err == nil || ok && ae.StatusCode == http.StatusConflict {
// conflict indicates the key is already registered
m.client = client
err = nil
}
return m.client, err
}
func (m *Manager) hostPolicy() HostPolicy {
if m.HostPolicy != nil {
return m.HostPolicy
}
return defaultHostPolicy
}
func (m *Manager) renewBefore() time.Duration {
if m.RenewBefore > renewJitter {
return m.RenewBefore
}
return 720 * time.Hour // 30 days
}
func (m *Manager) now() time.Time {
if m.nowFunc != nil {
return m.nowFunc()
}
return time.Now()
}
// certState is ready when its mutex is unlocked for reading.
type certState struct {
sync.RWMutex
locked bool // locked for read/write
key crypto.Signer // private key for cert
cert [][]byte // DER encoding
leaf *x509.Certificate // parsed cert[0]; always non-nil if cert != nil
}
// tlscert creates a tls.Certificate from s.key and s.cert.
// Callers should wrap it in s.RLock() and s.RUnlock().
func (s *certState) tlscert() (*tls.Certificate, error) {
if s.key == nil {
return nil, errors.New("acme/autocert: missing signer")
}
if len(s.cert) == 0 {
return nil, errors.New("acme/autocert: missing certificate")
}
return &tls.Certificate{
PrivateKey: s.key,
Certificate: s.cert,
Leaf: s.leaf,
}, nil
}
// certRequest generates a CSR for the given common name cn and optional SANs.
func certRequest(key crypto.Signer, cn string, ext []pkix.Extension, san ...string) ([]byte, error) {
req := &x509.CertificateRequest{
Subject: pkix.Name{CommonName: cn},
DNSNames: san,
ExtraExtensions: ext,
}
return x509.CreateCertificateRequest(rand.Reader, req, key)
}
// Attempt to parse the given private key DER block. OpenSSL 0.9.8 generates
// PKCS#1 private keys by default, while OpenSSL 1.0.0 generates PKCS#8 keys.
// OpenSSL ecparam generates SEC1 EC private keys for ECDSA. We try all three.
//
// Inspired by parsePrivateKey in crypto/tls/tls.go.
func parsePrivateKey(der []byte) (crypto.Signer, error) {
if key, err := x509.ParsePKCS1PrivateKey(der); err == nil {
return key, nil
}
if key, err := x509.ParsePKCS8PrivateKey(der); err == nil {
switch key := key.(type) {
case *rsa.PrivateKey:
return key, nil
case *ecdsa.PrivateKey:
return key, nil
default:
return nil, errors.New("acme/autocert: unknown private key type in PKCS#8 wrapping")
}
}
if key, err := x509.ParseECPrivateKey(der); err == nil {
return key, nil
}
return nil, errors.New("acme/autocert: failed to parse private key")
}
// validCert parses a cert chain provided as der argument and verifies the leaf and der[0]
// correspond to the private key, the domain and key type match, and expiration dates
// are valid. It doesn't do any revocation checking.
//
// The returned value is the verified leaf cert.
func validCert(ck certKey, der [][]byte, key crypto.Signer, now time.Time) (leaf *x509.Certificate, err error) {
// parse public part(s)
var n int
for _, b := range der {
n += len(b)
}
pub := make([]byte, n)
n = 0
for _, b := range der {
n += copy(pub[n:], b)
}
x509Cert, err := x509.ParseCertificates(pub)
if err != nil || len(x509Cert) == 0 {
return nil, errors.New("acme/autocert: no public key found")
}
// verify the leaf is not expired and matches the domain name
leaf = x509Cert[0]
if now.Before(leaf.NotBefore) {
return nil, errors.New("acme/autocert: certificate is not valid yet")
}
if now.After(leaf.NotAfter) {
return nil, errors.New("acme/autocert: expired certificate")
}
if err := leaf.VerifyHostname(ck.domain); err != nil {
return nil, err
}
// ensure the leaf corresponds to the private key and matches the certKey type
switch pub := leaf.PublicKey.(type) {
case *rsa.PublicKey:
prv, ok := key.(*rsa.PrivateKey)
if !ok {
return nil, errors.New("acme/autocert: private key type does not match public key type")
}
if pub.N.Cmp(prv.N) != 0 {
return nil, errors.New("acme/autocert: private key does not match public key")
}
if !ck.isRSA && !ck.isToken {
return nil, errors.New("acme/autocert: key type does not match expected value")
}
case *ecdsa.PublicKey:
prv, ok := key.(*ecdsa.PrivateKey)
if !ok {
return nil, errors.New("acme/autocert: private key type does not match public key type")
}
if pub.X.Cmp(prv.X) != 0 || pub.Y.Cmp(prv.Y) != 0 {
return nil, errors.New("acme/autocert: private key does not match public key")
}
if ck.isRSA && !ck.isToken {
return nil, errors.New("acme/autocert: key type does not match expected value")
}
default:
return nil, errors.New("acme/autocert: unknown public key algorithm")
}
return leaf, nil
}
type lockedMathRand struct {
sync.Mutex
rnd *mathrand.Rand
}
func (r *lockedMathRand) int63n(max int64) int64 {
r.Lock()
n := r.rnd.Int63n(max)
r.Unlock()
return n
}
// For easier testing.
var (
// Called when a state is removed.
testDidRemoveState = func(certKey) {}
)