diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/acme/acme.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/acme/acme.go | 999 |
1 files changed, 999 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/acme/acme.go b/vendor/golang.org/x/crypto/acme/acme.go new file mode 100644 index 00000000..8619508e --- /dev/null +++ b/vendor/golang.org/x/crypto/acme/acme.go @@ -0,0 +1,999 @@ +// Copyright 2015 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 acme provides an implementation of the +// Automatic Certificate Management Environment (ACME) spec. +// See https://tools.ietf.org/html/draft-ietf-acme-acme-02 for details. +// +// Most common scenarios will want to use autocert subdirectory instead, +// which 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 acme + +import ( + "bytes" + "crypto" + "crypto/ecdsa" + "crypto/elliptic" + "crypto/rand" + "crypto/sha256" + "crypto/tls" + "crypto/x509" + "encoding/base64" + "encoding/hex" + "encoding/json" + "encoding/pem" + "errors" + "fmt" + "io" + "io/ioutil" + "math/big" + "net/http" + "strconv" + "strings" + "sync" + "time" + + "golang.org/x/net/context" + "golang.org/x/net/context/ctxhttp" +) + +// LetsEncryptURL is the Directory endpoint of Let's Encrypt CA. +const LetsEncryptURL = "https://acme-v01.api.letsencrypt.org/directory" + +const ( + maxChainLen = 5 // max depth and breadth of a certificate chain + maxCertSize = 1 << 20 // max size of a certificate, in bytes + + // Max number of collected nonces kept in memory. + // Expect usual peak of 1 or 2. + maxNonces = 100 +) + +// CertOption is an optional argument type for Client methods which manipulate +// certificate data. +type CertOption interface { + privateCertOpt() +} + +// WithKey creates an option holding a private/public key pair. +// The private part signs a certificate, and the public part represents the signee. +func WithKey(key crypto.Signer) CertOption { + return &certOptKey{key} +} + +type certOptKey struct { + key crypto.Signer +} + +func (*certOptKey) privateCertOpt() {} + +// WithTemplate creates an option for specifying a certificate template. +// See x509.CreateCertificate for template usage details. +// +// In TLSSNIxChallengeCert methods, the template is also used as parent, +// resulting in a self-signed certificate. +// The DNSNames field of t is always overwritten for tls-sni challenge certs. +func WithTemplate(t *x509.Certificate) CertOption { + return (*certOptTemplate)(t) +} + +type certOptTemplate x509.Certificate + +func (*certOptTemplate) privateCertOpt() {} + +// Client is an ACME client. +// The only required field is Key. An example of creating a client with a new key +// is as follows: +// +// key, err := rsa.GenerateKey(rand.Reader, 2048) +// if err != nil { +// log.Fatal(err) +// } +// client := &Client{Key: key} +// +type Client struct { + // Key is the account key used to register with a CA and sign requests. + // Key.Public() must return a *rsa.PublicKey or *ecdsa.PublicKey. + Key crypto.Signer + + // HTTPClient optionally specifies an HTTP client to use + // instead of http.DefaultClient. + HTTPClient *http.Client + + // DirectoryURL points to the CA directory endpoint. + // If empty, LetsEncryptURL is used. + // Mutating this value after a successful call of Client's Discover method + // will have no effect. + DirectoryURL string + + dirMu sync.Mutex // guards writes to dir + dir *Directory // cached result of Client's Discover method + + noncesMu sync.Mutex + nonces map[string]struct{} // nonces collected from previous responses +} + +// Discover performs ACME server discovery using c.DirectoryURL. +// +// It caches successful result. So, subsequent calls will not result in +// a network round-trip. This also means mutating c.DirectoryURL after successful call +// of this method will have no effect. +func (c *Client) Discover(ctx context.Context) (Directory, error) { + c.dirMu.Lock() + defer c.dirMu.Unlock() + if c.dir != nil { + return *c.dir, nil + } + + dirURL := c.DirectoryURL + if dirURL == "" { + dirURL = LetsEncryptURL + } + res, err := ctxhttp.Get(ctx, c.HTTPClient, dirURL) + if err != nil { + return Directory{}, err + } + defer res.Body.Close() + c.addNonce(res.Header) + if res.StatusCode != http.StatusOK { + return Directory{}, responseError(res) + } + + var v struct { + Reg string `json:"new-reg"` + Authz string `json:"new-authz"` + Cert string `json:"new-cert"` + Revoke string `json:"revoke-cert"` + Meta struct { + Terms string `json:"terms-of-service"` + Website string `json:"website"` + CAA []string `json:"caa-identities"` + } + } + if json.NewDecoder(res.Body).Decode(&v); err != nil { + return Directory{}, err + } + c.dir = &Directory{ + RegURL: v.Reg, + AuthzURL: v.Authz, + CertURL: v.Cert, + RevokeURL: v.Revoke, + Terms: v.Meta.Terms, + Website: v.Meta.Website, + CAA: v.Meta.CAA, + } + return *c.dir, nil +} + +// CreateCert requests a new certificate using the Certificate Signing Request csr encoded in DER format. +// The exp argument indicates the desired certificate validity duration. CA may issue a certificate +// with a different duration. +// If the bundle argument is true, the returned value will also contain the CA (issuer) certificate chain. +// +// In the case where CA server does not provide the issued certificate in the response, +// CreateCert will poll certURL using c.FetchCert, which will result in additional round-trips. +// In such scenario the caller can cancel the polling with ctx. +// +// CreateCert returns an error if the CA's response or chain was unreasonably large. +// Callers are encouraged to parse the returned value to ensure the certificate is valid and has the expected features. +func (c *Client) CreateCert(ctx context.Context, csr []byte, exp time.Duration, bundle bool) (der [][]byte, certURL string, err error) { + if _, err := c.Discover(ctx); err != nil { + return nil, "", err + } + + req := struct { + Resource string `json:"resource"` + CSR string `json:"csr"` + NotBefore string `json:"notBefore,omitempty"` + NotAfter string `json:"notAfter,omitempty"` + }{ + Resource: "new-cert", + CSR: base64.RawURLEncoding.EncodeToString(csr), + } + now := timeNow() + req.NotBefore = now.Format(time.RFC3339) + if exp > 0 { + req.NotAfter = now.Add(exp).Format(time.RFC3339) + } + + res, err := c.postJWS(ctx, c.Key, c.dir.CertURL, req) + if err != nil { + return nil, "", err + } + defer res.Body.Close() + if res.StatusCode != http.StatusCreated { + return nil, "", responseError(res) + } + + curl := res.Header.Get("location") // cert permanent URL + if res.ContentLength == 0 { + // no cert in the body; poll until we get it + cert, err := c.FetchCert(ctx, curl, bundle) + return cert, curl, err + } + // slurp issued cert and CA chain, if requested + cert, err := responseCert(ctx, c.HTTPClient, res, bundle) + return cert, curl, err +} + +// FetchCert retrieves already issued certificate from the given url, in DER format. +// It retries the request until the certificate is successfully retrieved, +// context is cancelled by the caller or an error response is received. +// +// The returned value will also contain the CA (issuer) certificate if the bundle argument is true. +// +// FetchCert returns an error if the CA's response or chain was unreasonably large. +// Callers are encouraged to parse the returned value to ensure the certificate is valid +// and has expected features. +func (c *Client) FetchCert(ctx context.Context, url string, bundle bool) ([][]byte, error) { + for { + res, err := ctxhttp.Get(ctx, c.HTTPClient, url) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode == http.StatusOK { + return responseCert(ctx, c.HTTPClient, res, bundle) + } + if res.StatusCode > 299 { + return nil, responseError(res) + } + d := retryAfter(res.Header.Get("retry-after"), 3*time.Second) + select { + case <-time.After(d): + // retry + case <-ctx.Done(): + return nil, ctx.Err() + } + } +} + +// RevokeCert revokes a previously issued certificate cert, provided in DER format. +// +// The key argument, used to sign the request, must be authorized +// to revoke the certificate. It's up to the CA to decide which keys are authorized. +// For instance, the key pair of the certificate may be authorized. +// If the key is nil, c.Key is used instead. +func (c *Client) RevokeCert(ctx context.Context, key crypto.Signer, cert []byte, reason CRLReasonCode) error { + if _, err := c.Discover(ctx); err != nil { + return err + } + + body := &struct { + Resource string `json:"resource"` + Cert string `json:"certificate"` + Reason int `json:"reason"` + }{ + Resource: "revoke-cert", + Cert: base64.RawURLEncoding.EncodeToString(cert), + Reason: int(reason), + } + if key == nil { + key = c.Key + } + res, err := c.postJWS(ctx, key, c.dir.RevokeURL, body) + if err != nil { + return err + } + defer res.Body.Close() + if res.StatusCode != http.StatusOK { + return responseError(res) + } + return nil +} + +// AcceptTOS always returns true to indicate the acceptance of a CA's Terms of Service +// during account registration. See Register method of Client for more details. +func AcceptTOS(tosURL string) bool { return true } + +// Register creates a new account registration by following the "new-reg" flow. +// It returns registered account. The a argument is not modified. +// +// The registration may require the caller to agree to the CA's Terms of Service (TOS). +// If so, and the account has not indicated the acceptance of the terms (see Account for details), +// Register 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 caller can use AcceptTOS. +func (c *Client) Register(ctx context.Context, a *Account, prompt func(tosURL string) bool) (*Account, error) { + if _, err := c.Discover(ctx); err != nil { + return nil, err + } + + var err error + if a, err = c.doReg(ctx, c.dir.RegURL, "new-reg", a); err != nil { + return nil, err + } + var accept bool + if a.CurrentTerms != "" && a.CurrentTerms != a.AgreedTerms { + accept = prompt(a.CurrentTerms) + } + if accept { + a.AgreedTerms = a.CurrentTerms + a, err = c.UpdateReg(ctx, a) + } + return a, err +} + +// GetReg retrieves an existing registration. +// The url argument is an Account URI. +func (c *Client) GetReg(ctx context.Context, url string) (*Account, error) { + a, err := c.doReg(ctx, url, "reg", nil) + if err != nil { + return nil, err + } + a.URI = url + return a, nil +} + +// UpdateReg updates an existing registration. +// It returns an updated account copy. The provided account is not modified. +func (c *Client) UpdateReg(ctx context.Context, a *Account) (*Account, error) { + uri := a.URI + a, err := c.doReg(ctx, uri, "reg", a) + if err != nil { + return nil, err + } + a.URI = uri + return a, nil +} + +// Authorize performs the initial step in an authorization flow. +// The caller will then need to choose from and perform a set of returned +// challenges using c.Accept in order to successfully complete authorization. +// +// If an authorization has been previously granted, the CA may return +// a valid authorization (Authorization.Status is StatusValid). If so, the caller +// need not fulfill any challenge and can proceed to requesting a certificate. +func (c *Client) Authorize(ctx context.Context, domain string) (*Authorization, error) { + if _, err := c.Discover(ctx); err != nil { + return nil, err + } + + type authzID struct { + Type string `json:"type"` + Value string `json:"value"` + } + req := struct { + Resource string `json:"resource"` + Identifier authzID `json:"identifier"` + }{ + Resource: "new-authz", + Identifier: authzID{Type: "dns", Value: domain}, + } + res, err := c.postJWS(ctx, c.Key, c.dir.AuthzURL, req) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode != http.StatusCreated { + return nil, responseError(res) + } + + var v wireAuthz + if err := json.NewDecoder(res.Body).Decode(&v); err != nil { + return nil, fmt.Errorf("acme: invalid response: %v", err) + } + if v.Status != StatusPending && v.Status != StatusValid { + return nil, fmt.Errorf("acme: unexpected status: %s", v.Status) + } + return v.authorization(res.Header.Get("Location")), nil +} + +// GetAuthorization retrieves an authorization identified by the given URL. +// +// If a caller needs to poll an authorization until its status is final, +// see the WaitAuthorization method. +func (c *Client) GetAuthorization(ctx context.Context, url string) (*Authorization, error) { + res, err := ctxhttp.Get(ctx, c.HTTPClient, url) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusAccepted { + return nil, responseError(res) + } + var v wireAuthz + if err := json.NewDecoder(res.Body).Decode(&v); err != nil { + return nil, fmt.Errorf("acme: invalid response: %v", err) + } + return v.authorization(url), nil +} + +// RevokeAuthorization relinquishes an existing authorization identified +// by the given URL. +// The url argument is an Authorization.URI value. +// +// If successful, the caller will be required to obtain a new authorization +// using the Authorize method before being able to request a new certificate +// for the domain associated with the authorization. +// +// It does not revoke existing certificates. +func (c *Client) RevokeAuthorization(ctx context.Context, url string) error { + req := struct { + Resource string `json:"resource"` + Status string `json:"status"` + Delete bool `json:"delete"` + }{ + Resource: "authz", + Status: "deactivated", + Delete: true, + } + res, err := c.postJWS(ctx, c.Key, url, req) + if err != nil { + return err + } + defer res.Body.Close() + if res.StatusCode != http.StatusOK { + return responseError(res) + } + return nil +} + +// WaitAuthorization polls an authorization at the given URL +// until it is in one of the final states, StatusValid or StatusInvalid, +// or the context is done. +// +// It returns a non-nil Authorization only if its Status is StatusValid. +// In all other cases WaitAuthorization returns an error. +// If the Status is StatusInvalid, the returned error is ErrAuthorizationFailed. +func (c *Client) WaitAuthorization(ctx context.Context, url string) (*Authorization, error) { + var count int + sleep := func(v string, inc int) error { + count += inc + d := backoff(count, 10*time.Second) + d = retryAfter(v, d) + wakeup := time.NewTimer(d) + defer wakeup.Stop() + select { + case <-ctx.Done(): + return ctx.Err() + case <-wakeup.C: + return nil + } + } + + for { + res, err := ctxhttp.Get(ctx, c.HTTPClient, url) + if err != nil { + return nil, err + } + retry := res.Header.Get("retry-after") + if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusAccepted { + res.Body.Close() + if err := sleep(retry, 1); err != nil { + return nil, err + } + continue + } + var raw wireAuthz + err = json.NewDecoder(res.Body).Decode(&raw) + res.Body.Close() + if err != nil { + if err := sleep(retry, 0); err != nil { + return nil, err + } + continue + } + if raw.Status == StatusValid { + return raw.authorization(url), nil + } + if raw.Status == StatusInvalid { + return nil, ErrAuthorizationFailed + } + if err := sleep(retry, 0); err != nil { + return nil, err + } + } +} + +// GetChallenge retrieves the current status of an challenge. +// +// A client typically polls a challenge status using this method. +func (c *Client) GetChallenge(ctx context.Context, url string) (*Challenge, error) { + res, err := ctxhttp.Get(ctx, c.HTTPClient, url) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusAccepted { + return nil, responseError(res) + } + v := wireChallenge{URI: url} + if err := json.NewDecoder(res.Body).Decode(&v); err != nil { + return nil, fmt.Errorf("acme: invalid response: %v", err) + } + return v.challenge(), nil +} + +// Accept informs the server that the client accepts one of its challenges +// previously obtained with c.Authorize. +// +// The server will then perform the validation asynchronously. +func (c *Client) Accept(ctx context.Context, chal *Challenge) (*Challenge, error) { + auth, err := keyAuth(c.Key.Public(), chal.Token) + if err != nil { + return nil, err + } + + req := struct { + Resource string `json:"resource"` + Type string `json:"type"` + Auth string `json:"keyAuthorization"` + }{ + Resource: "challenge", + Type: chal.Type, + Auth: auth, + } + res, err := c.postJWS(ctx, c.Key, chal.URI, req) + if err != nil { + return nil, err + } + defer res.Body.Close() + // Note: the protocol specifies 200 as the expected response code, but + // letsencrypt seems to be returning 202. + if res.StatusCode != http.StatusOK && res.StatusCode != http.StatusAccepted { + return nil, responseError(res) + } + + var v wireChallenge + if err := json.NewDecoder(res.Body).Decode(&v); err != nil { + return nil, fmt.Errorf("acme: invalid response: %v", err) + } + return v.challenge(), nil +} + +// DNS01ChallengeRecord returns a DNS record value for a dns-01 challenge response. +// A TXT record containing the returned value must be provisioned under +// "_acme-challenge" name of the domain being validated. +// +// The token argument is a Challenge.Token value. +func (c *Client) DNS01ChallengeRecord(token string) (string, error) { + ka, err := keyAuth(c.Key.Public(), token) + if err != nil { + return "", err + } + b := sha256.Sum256([]byte(ka)) + return base64.RawURLEncoding.EncodeToString(b[:]), nil +} + +// HTTP01ChallengeResponse returns the response for an http-01 challenge. +// Servers should respond with the value to HTTP requests at the URL path +// provided by HTTP01ChallengePath to validate the challenge and prove control +// over a domain name. +// +// The token argument is a Challenge.Token value. +func (c *Client) HTTP01ChallengeResponse(token string) (string, error) { + return keyAuth(c.Key.Public(), token) +} + +// HTTP01ChallengePath returns the URL path at which the response for an http-01 challenge +// should be provided by the servers. +// The response value can be obtained with HTTP01ChallengeResponse. +// +// The token argument is a Challenge.Token value. +func (c *Client) HTTP01ChallengePath(token string) string { + return "/.well-known/acme-challenge/" + token +} + +// TLSSNI01ChallengeCert creates a certificate for TLS-SNI-01 challenge response. +// Servers can present the certificate to validate the challenge and prove control +// over a domain name. +// +// The implementation is incomplete in that the returned value is a single certificate, +// computed only for Z0 of the key authorization. ACME CAs are expected to update +// their implementations to use the newer version, TLS-SNI-02. +// For more details on TLS-SNI-01 see https://tools.ietf.org/html/draft-ietf-acme-acme-01#section-7.3. +// +// The token argument is a Challenge.Token value. +// If a WithKey option is provided, its private part signs the returned cert, +// and the public part is used to specify the signee. +// If no WithKey option is provided, a new ECDSA key is generated using P-256 curve. +// +// The returned certificate is valid for the next 24 hours and must be presented only when +// the server name of the client hello matches exactly the returned name value. +func (c *Client) TLSSNI01ChallengeCert(token string, opt ...CertOption) (cert tls.Certificate, name string, err error) { + ka, err := keyAuth(c.Key.Public(), token) + if err != nil { + return tls.Certificate{}, "", err + } + b := sha256.Sum256([]byte(ka)) + h := hex.EncodeToString(b[:]) + name = fmt.Sprintf("%s.%s.acme.invalid", h[:32], h[32:]) + cert, err = tlsChallengeCert([]string{name}, opt) + if err != nil { + return tls.Certificate{}, "", err + } + return cert, name, nil +} + +// TLSSNI02ChallengeCert creates a certificate for TLS-SNI-02 challenge response. +// Servers can present the certificate to validate the challenge and prove control +// over a domain name. For more details on TLS-SNI-02 see +// https://tools.ietf.org/html/draft-ietf-acme-acme-03#section-7.3. +// +// The token argument is a Challenge.Token value. +// If a WithKey option is provided, its private part signs the returned cert, +// and the public part is used to specify the signee. +// If no WithKey option is provided, a new ECDSA key is generated using P-256 curve. +// +// The returned certificate is valid for the next 24 hours and must be presented only when +// the server name in the client hello matches exactly the returned name value. +func (c *Client) TLSSNI02ChallengeCert(token string, opt ...CertOption) (cert tls.Certificate, name string, err error) { + b := sha256.Sum256([]byte(token)) + h := hex.EncodeToString(b[:]) + sanA := fmt.Sprintf("%s.%s.token.acme.invalid", h[:32], h[32:]) + + ka, err := keyAuth(c.Key.Public(), token) + if err != nil { + return tls.Certificate{}, "", err + } + b = sha256.Sum256([]byte(ka)) + h = hex.EncodeToString(b[:]) + sanB := fmt.Sprintf("%s.%s.ka.acme.invalid", h[:32], h[32:]) + + cert, err = tlsChallengeCert([]string{sanA, sanB}, opt) + if err != nil { + return tls.Certificate{}, "", err + } + return cert, sanA, nil +} + +// doReg sends all types of registration requests. +// The type of request is identified by typ argument, which is a "resource" +// in the ACME spec terms. +// +// A non-nil acct argument indicates whether the intention is to mutate data +// of the Account. Only Contact and Agreement of its fields are used +// in such cases. +func (c *Client) doReg(ctx context.Context, url string, typ string, acct *Account) (*Account, error) { + req := struct { + Resource string `json:"resource"` + Contact []string `json:"contact,omitempty"` + Agreement string `json:"agreement,omitempty"` + }{ + Resource: typ, + } + if acct != nil { + req.Contact = acct.Contact + req.Agreement = acct.AgreedTerms + } + res, err := c.postJWS(ctx, c.Key, url, req) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode < 200 || res.StatusCode > 299 { + return nil, responseError(res) + } + + var v struct { + Contact []string + Agreement string + Authorizations string + Certificates string + } + if err := json.NewDecoder(res.Body).Decode(&v); err != nil { + return nil, fmt.Errorf("acme: invalid response: %v", err) + } + var tos string + if v := linkHeader(res.Header, "terms-of-service"); len(v) > 0 { + tos = v[0] + } + var authz string + if v := linkHeader(res.Header, "next"); len(v) > 0 { + authz = v[0] + } + return &Account{ + URI: res.Header.Get("Location"), + Contact: v.Contact, + AgreedTerms: v.Agreement, + CurrentTerms: tos, + Authz: authz, + Authorizations: v.Authorizations, + Certificates: v.Certificates, + }, nil +} + +// postJWS signs the body with the given key and POSTs it to the provided url. +// The body argument must be JSON-serializable. +func (c *Client) postJWS(ctx context.Context, key crypto.Signer, url string, body interface{}) (*http.Response, error) { + nonce, err := c.popNonce(ctx, url) + if err != nil { + return nil, err + } + b, err := jwsEncodeJSON(body, key, nonce) + if err != nil { + return nil, err + } + res, err := ctxhttp.Post(ctx, c.HTTPClient, url, "application/jose+json", bytes.NewReader(b)) + if err != nil { + return nil, err + } + c.addNonce(res.Header) + return res, nil +} + +// popNonce returns a nonce value previously stored with c.addNonce +// or fetches a fresh one from the given URL. +func (c *Client) popNonce(ctx context.Context, url string) (string, error) { + c.noncesMu.Lock() + defer c.noncesMu.Unlock() + if len(c.nonces) == 0 { + return fetchNonce(ctx, c.HTTPClient, url) + } + var nonce string + for nonce = range c.nonces { + delete(c.nonces, nonce) + break + } + return nonce, nil +} + +// addNonce stores a nonce value found in h (if any) for future use. +func (c *Client) addNonce(h http.Header) { + v := nonceFromHeader(h) + if v == "" { + return + } + c.noncesMu.Lock() + defer c.noncesMu.Unlock() + if len(c.nonces) >= maxNonces { + return + } + if c.nonces == nil { + c.nonces = make(map[string]struct{}) + } + c.nonces[v] = struct{}{} +} + +func fetchNonce(ctx context.Context, client *http.Client, url string) (string, error) { + resp, err := ctxhttp.Head(ctx, client, url) + if err != nil { + return "", err + } + defer resp.Body.Close() + nonce := nonceFromHeader(resp.Header) + if nonce == "" { + if resp.StatusCode > 299 { + return "", responseError(resp) + } + return "", errors.New("acme: nonce not found") + } + return nonce, nil +} + +func nonceFromHeader(h http.Header) string { + return h.Get("Replay-Nonce") +} + +func responseCert(ctx context.Context, client *http.Client, res *http.Response, bundle bool) ([][]byte, error) { + b, err := ioutil.ReadAll(io.LimitReader(res.Body, maxCertSize+1)) + if err != nil { + return nil, fmt.Errorf("acme: response stream: %v", err) + } + if len(b) > maxCertSize { + return nil, errors.New("acme: certificate is too big") + } + cert := [][]byte{b} + if !bundle { + return cert, nil + } + + // Append CA chain cert(s). + // At least one is required according to the spec: + // https://tools.ietf.org/html/draft-ietf-acme-acme-03#section-6.3.1 + up := linkHeader(res.Header, "up") + if len(up) == 0 { + return nil, errors.New("acme: rel=up link not found") + } + if len(up) > maxChainLen { + return nil, errors.New("acme: rel=up link is too large") + } + for _, url := range up { + cc, err := chainCert(ctx, client, url, 0) + if err != nil { + return nil, err + } + cert = append(cert, cc...) + } + return cert, nil +} + +// responseError creates an error of Error type from resp. +func responseError(resp *http.Response) error { + // don't care if ReadAll returns an error: + // json.Unmarshal will fail in that case anyway + b, _ := ioutil.ReadAll(resp.Body) + e := struct { + Status int + Type string + Detail string + }{ + Status: resp.StatusCode, + } + if err := json.Unmarshal(b, &e); err != nil { + // this is not a regular error response: + // populate detail with anything we received, + // e.Status will already contain HTTP response code value + e.Detail = string(b) + if e.Detail == "" { + e.Detail = resp.Status + } + } + return &Error{ + StatusCode: e.Status, + ProblemType: e.Type, + Detail: e.Detail, + Header: resp.Header, + } +} + +// chainCert fetches CA certificate chain recursively by following "up" links. +// Each recursive call increments the depth by 1, resulting in an error +// if the recursion level reaches maxChainLen. +// +// First chainCert call starts with depth of 0. +func chainCert(ctx context.Context, client *http.Client, url string, depth int) ([][]byte, error) { + if depth >= maxChainLen { + return nil, errors.New("acme: certificate chain is too deep") + } + + res, err := ctxhttp.Get(ctx, client, url) + if err != nil { + return nil, err + } + defer res.Body.Close() + if res.StatusCode != http.StatusOK { + return nil, responseError(res) + } + b, err := ioutil.ReadAll(io.LimitReader(res.Body, maxCertSize+1)) + if err != nil { + return nil, err + } + if len(b) > maxCertSize { + return nil, errors.New("acme: certificate is too big") + } + chain := [][]byte{b} + + uplink := linkHeader(res.Header, "up") + if len(uplink) > maxChainLen { + return nil, errors.New("acme: certificate chain is too large") + } + for _, up := range uplink { + cc, err := chainCert(ctx, client, up, depth+1) + if err != nil { + return nil, err + } + chain = append(chain, cc...) + } + + return chain, nil +} + +// linkHeader returns URI-Reference values of all Link headers +// with relation-type rel. +// See https://tools.ietf.org/html/rfc5988#section-5 for details. +func linkHeader(h http.Header, rel string) []string { + var links []string + for _, v := range h["Link"] { + parts := strings.Split(v, ";") + for _, p := range parts { + p = strings.TrimSpace(p) + if !strings.HasPrefix(p, "rel=") { + continue + } + if v := strings.Trim(p[4:], `"`); v == rel { + links = append(links, strings.Trim(parts[0], "<>")) + } + } + } + return links +} + +// retryAfter parses a Retry-After HTTP header value, +// trying to convert v into an int (seconds) or use http.ParseTime otherwise. +// It returns d if v cannot be parsed. +func retryAfter(v string, d time.Duration) time.Duration { + if i, err := strconv.Atoi(v); err == nil { + return time.Duration(i) * time.Second + } + t, err := http.ParseTime(v) + if err != nil { + return d + } + return t.Sub(timeNow()) +} + +// backoff computes a duration after which an n+1 retry iteration should occur +// using truncated exponential backoff algorithm. +// +// The n argument is always bounded between 0 and 30. +// The max argument defines upper bound for the returned value. +func backoff(n int, max time.Duration) time.Duration { + if n < 0 { + n = 0 + } + if n > 30 { + n = 30 + } + var d time.Duration + if x, err := rand.Int(rand.Reader, big.NewInt(1000)); err == nil { + d = time.Duration(x.Int64()) * time.Millisecond + } + d += time.Duration(1<<uint(n)) * time.Second + if d > max { + return max + } + return d +} + +// keyAuth generates a key authorization string for a given token. +func keyAuth(pub crypto.PublicKey, token string) (string, error) { + th, err := JWKThumbprint(pub) + if err != nil { + return "", err + } + return fmt.Sprintf("%s.%s", token, th), nil +} + +// tlsChallengeCert creates a temporary certificate for TLS-SNI challenges +// with the given SANs and auto-generated public/private key pair. +// To create a cert with a custom key pair, specify WithKey option. +func tlsChallengeCert(san []string, opt []CertOption) (tls.Certificate, error) { + var ( + key crypto.Signer + tmpl *x509.Certificate + ) + for _, o := range opt { + switch o := o.(type) { + case *certOptKey: + if key != nil { + return tls.Certificate{}, errors.New("acme: duplicate key option") + } + key = o.key + case *certOptTemplate: + var t = *(*x509.Certificate)(o) // shallow copy is ok + tmpl = &t + default: + // package's fault, if we let this happen: + panic(fmt.Sprintf("unsupported option type %T", o)) + } + } + if key == nil { + var err error + if key, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader); err != nil { + return tls.Certificate{}, err + } + } + if tmpl == nil { + tmpl = &x509.Certificate{ + SerialNumber: big.NewInt(1), + NotBefore: time.Now(), + NotAfter: time.Now().Add(24 * time.Hour), + BasicConstraintsValid: true, + KeyUsage: x509.KeyUsageKeyEncipherment, + } + } + tmpl.DNSNames = san + + der, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, key.Public(), key) + if err != nil { + return tls.Certificate{}, err + } + return tls.Certificate{ + Certificate: [][]byte{der}, + PrivateKey: key, + }, nil +} + +// encodePEM returns b encoded as PEM with block of type typ. +func encodePEM(typ string, b []byte) []byte { + pb := &pem.Block{Type: typ, Bytes: b} + return pem.EncodeToMemory(pb) +} + +// timeNow is useful for testing for fixed current time. +var timeNow = time.Now |