Update vendor (whatsapp)

1 files changed, 72 insertions, 369 deletions

diff --git a/vendor/golang.org/x/crypto/acme/acme.go b/vendor/golang.org/x/crypto/acme/acme.go
index 73b19ef3..f2d23f69 100644
--- a/vendor/golang.org/x/crypto/acme/acme.go
+++ b/vendor/golang.org/x/crypto/acme/acme.go
@@ -3,17 +3,20 @@
 // license that can be found in the LICENSE file.
 
 // Package acme provides an implementation of the
-// Automatic Certificate Management Environment (ACME) spec.
-// The initial implementation was based on ACME draft-02 and
-// is now being extended to comply with RFC 8555.
-// See https://tools.ietf.org/html/draft-ietf-acme-acme-02
-// and https://tools.ietf.org/html/rfc8555 for details.
+// Automatic Certificate Management Environment (ACME) spec,
+// most famously used by Let's Encrypt.
+//
+// The initial implementation of this package was based on an early version
+// of the spec. The current implementation supports only the modern
+// RFC 8555 but some of the old API surface remains for compatibility.
+// While code using the old API will still compile, it will return an error.
+// Note the deprecation comments to update your code.
+//
+// See https://tools.ietf.org/html/rfc8555 for the spec.
 //
 // 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 (
@@ -33,8 +36,6 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
-	"io"
-	"io/ioutil"
 	"math/big"
 	"net/http"
 	"strings"
@@ -72,6 +73,7 @@ const (
 )
 
 // Client is an ACME client.
+//
 // The only required field is Key. An example of creating a client with a new key
 // is as follows:
 //
@@ -125,7 +127,9 @@ type Client struct {
 
 	cacheMu sync.Mutex
 	dir     *Directory // cached result of Client's Discover method
-	kid     keyID      // cached Account.URI obtained from registerRFC or getAccountRFC
+	// KID is the key identifier provided by the CA. If not provided it will be
+	// retrieved from the CA by making a call to the registration endpoint.
+	KID KeyID
 
 	noncesMu sync.Mutex
 	nonces   map[string]struct{} // nonces collected from previous responses
@@ -140,23 +144,22 @@ type Client struct {
 //
 // When in pre-RFC mode or when c.getRegRFC responds with an error, accountKID
 // returns noKeyID.
-func (c *Client) accountKID(ctx context.Context) keyID {
+func (c *Client) accountKID(ctx context.Context) KeyID {
 	c.cacheMu.Lock()
 	defer c.cacheMu.Unlock()
-	if !c.dir.rfcCompliant() {
-		return noKeyID
-	}
-	if c.kid != noKeyID {
-		return c.kid
+	if c.KID != noKeyID {
+		return c.KID
 	}
 	a, err := c.getRegRFC(ctx)
 	if err != nil {
 		return noKeyID
 	}
-	c.kid = keyID(a.URI)
-	return c.kid
+	c.KID = KeyID(a.URI)
+	return c.KID
 }
 
+var errPreRFC = errors.New("acme: server does not support the RFC 8555 version of ACME")
+
 // Discover performs ACME server discovery using c.DirectoryURL.
 //
 // It caches successful result. So, subsequent calls will not result in
@@ -177,53 +180,36 @@ func (c *Client) Discover(ctx context.Context) (Directory, error) {
 	c.addNonce(res.Header)
 
 	var v struct {
-		Reg          string `json:"new-reg"`
-		RegRFC       string `json:"newAccount"`
-		Authz        string `json:"new-authz"`
-		AuthzRFC     string `json:"newAuthz"`
-		OrderRFC     string `json:"newOrder"`
-		Cert         string `json:"new-cert"`
-		Revoke       string `json:"revoke-cert"`
-		RevokeRFC    string `json:"revokeCert"`
-		NonceRFC     string `json:"newNonce"`
-		KeyChangeRFC string `json:"keyChange"`
-		Meta         struct {
-			Terms           string   `json:"terms-of-service"`
-			TermsRFC        string   `json:"termsOfService"`
-			WebsiteRFC      string   `json:"website"`
-			CAA             []string `json:"caa-identities"`
-			CAARFC          []string `json:"caaIdentities"`
-			ExternalAcctRFC bool     `json:"externalAccountRequired"`
+		Reg       string `json:"newAccount"`
+		Authz     string `json:"newAuthz"`
+		Order     string `json:"newOrder"`
+		Revoke    string `json:"revokeCert"`
+		Nonce     string `json:"newNonce"`
+		KeyChange string `json:"keyChange"`
+		Meta      struct {
+			Terms        string   `json:"termsOfService"`
+			Website      string   `json:"website"`
+			CAA          []string `json:"caaIdentities"`
+			ExternalAcct bool     `json:"externalAccountRequired"`
 		}
 	}
 	if err := json.NewDecoder(res.Body).Decode(&v); err != nil {
 		return Directory{}, err
 	}
-	if v.OrderRFC == "" {
-		// Non-RFC compliant ACME CA.
-		c.dir = &Directory{
-			RegURL:    v.Reg,
-			AuthzURL:  v.Authz,
-			CertURL:   v.Cert,
-			RevokeURL: v.Revoke,
-			Terms:     v.Meta.Terms,
-			Website:   v.Meta.WebsiteRFC,
-			CAA:       v.Meta.CAA,
-		}
-		return *c.dir, nil
+	if v.Order == "" {
+		return Directory{}, errPreRFC
 	}
-	// RFC compliant ACME CA.
 	c.dir = &Directory{
-		RegURL:                  v.RegRFC,
-		AuthzURL:                v.AuthzRFC,
-		OrderURL:                v.OrderRFC,
-		RevokeURL:               v.RevokeRFC,
-		NonceURL:                v.NonceRFC,
-		KeyChangeURL:            v.KeyChangeRFC,
-		Terms:                   v.Meta.TermsRFC,
-		Website:                 v.Meta.WebsiteRFC,
-		CAA:                     v.Meta.CAARFC,
-		ExternalAccountRequired: v.Meta.ExternalAcctRFC,
+		RegURL:                  v.Reg,
+		AuthzURL:                v.Authz,
+		OrderURL:                v.Order,
+		RevokeURL:               v.Revoke,
+		NonceURL:                v.Nonce,
+		KeyChangeURL:            v.KeyChange,
+		Terms:                   v.Meta.Terms,
+		Website:                 v.Meta.Website,
+		CAA:                     v.Meta.CAA,
+		ExternalAccountRequired: v.Meta.ExternalAcct,
 	}
 	return *c.dir, nil
 }
@@ -235,55 +221,11 @@ func (c *Client) directoryURL() string {
 	return LetsEncryptURL
 }
 
-// CreateCert requests a new certificate using the Certificate Signing Request csr encoded in DER format.
-// It is incompatible with RFC 8555. Callers should use CreateOrderCert when interfacing
-// with an RFC-compliant CA.
+// CreateCert was part of the old version of ACME. It is incompatible with RFC 8555.
 //
-// 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 a 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.
+// Deprecated: this was for the pre-RFC 8555 version of ACME. Callers should use CreateOrderCert.
 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.post(ctx, nil, c.dir.CertURL, req, wantStatus(http.StatusCreated))
-	if err != nil {
-		return nil, "", err
-	}
-	defer res.Body.Close()
-
-	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 := c.responseCert(ctx, res, bundle)
-	return cert, curl, err
+	return nil, "", errPreRFC
 }
 
 // FetchCert retrieves already issued certificate from the given url, in DER format.
@@ -297,20 +239,10 @@ func (c *Client) CreateCert(ctx context.Context, csr []byte, exp time.Duration,
 // 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) {
-	dir, err := c.Discover(ctx)
-	if err != nil {
-		return nil, err
-	}
-	if dir.rfcCompliant() {
-		return c.fetchCertRFC(ctx, url, bundle)
-	}
-
-	// Legacy non-authenticated GET request.
-	res, err := c.get(ctx, url, wantStatus(http.StatusOK))
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
-	return c.responseCert(ctx, res, bundle)
+	return c.fetchCertRFC(ctx, url, bundle)
 }
 
 // RevokeCert revokes a previously issued certificate cert, provided in DER format.
@@ -320,30 +252,10 @@ func (c *Client) FetchCert(ctx context.Context, url string, bundle bool) ([][]by
 // 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 {
-	dir, err := c.Discover(ctx)
-	if err != nil {
-		return err
-	}
-	if dir.rfcCompliant() {
-		return c.revokeCertRFC(ctx, key, cert, reason)
-	}
-
-	// Legacy CA.
-	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),
-	}
-	res, err := c.post(ctx, key, dir.RevokeURL, body, wantStatus(http.StatusOK))
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return err
 	}
-	defer res.Body.Close()
-	return nil
+	return c.revokeCertRFC(ctx, key, cert, reason)
 }
 
 // AcceptTOS always returns true to indicate the acceptance of a CA's Terms of Service
@@ -366,75 +278,33 @@ func (c *Client) Register(ctx context.Context, acct *Account, prompt func(tosURL
 	if c.Key == nil {
 		return nil, errors.New("acme: client.Key must be set to Register")
 	}
-
-	dir, err := c.Discover(ctx)
-	if err != nil {
-		return nil, err
-	}
-	if dir.rfcCompliant() {
-		return c.registerRFC(ctx, acct, prompt)
-	}
-
-	// Legacy ACME draft registration flow.
-	a, err := c.doReg(ctx, dir.RegURL, "new-reg", acct)
-	if err != nil {
+	if _, err := c.Discover(ctx); 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
+	return c.registerRFC(ctx, acct, prompt)
 }
 
 // GetReg retrieves an existing account associated with c.Key.
 //
-// The url argument is an Account URI used with pre-RFC 8555 CAs.
-// It is ignored when interfacing with an RFC-compliant CA.
+// The url argument is a legacy artifact of the pre-RFC 8555 API
+// and is ignored.
 func (c *Client) GetReg(ctx context.Context, url string) (*Account, error) {
-	dir, err := c.Discover(ctx)
-	if err != nil {
-		return nil, err
-	}
-	if dir.rfcCompliant() {
-		return c.getRegRFC(ctx)
-	}
-
-	// Legacy CA.
-	a, err := c.doReg(ctx, url, "reg", nil)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
-	a.URI = url
-	return a, nil
+	return c.getRegRFC(ctx)
 }
 
 // UpdateReg updates an existing registration.
 // It returns an updated account copy. The provided account is not modified.
 //
-// When interfacing with RFC-compliant CAs, a.URI is ignored and the account URL
-// associated with c.Key is used instead.
+// The account's URI is ignored and the account URL associated with
+// c.Key is used instead.
 func (c *Client) UpdateReg(ctx context.Context, acct *Account) (*Account, error) {
-	dir, err := c.Discover(ctx)
-	if err != nil {
-		return nil, err
-	}
-	if dir.rfcCompliant() {
-		return c.updateRegRFC(ctx, acct)
-	}
-
-	// Legacy CA.
-	uri := acct.URI
-	a, err := c.doReg(ctx, uri, "reg", acct)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
-	a.URI = uri
-	return a, nil
+	return c.updateRegRFC(ctx, acct)
 }
 
 // Authorize performs the initial step in the pre-authorization flow,
@@ -503,17 +373,11 @@ func (c *Client) authorize(ctx context.Context, typ, val string) (*Authorization
 // 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) {
-	dir, err := c.Discover(ctx)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
 
-	var res *http.Response
-	if dir.rfcCompliant() {
-		res, err = c.postAsGet(ctx, url, wantStatus(http.StatusOK))
-	} else {
-		res, err = c.get(ctx, url, wantStatus(http.StatusOK, http.StatusAccepted))
-	}
+	res, err := c.postAsGet(ctx, url, wantStatus(http.StatusOK))
 	if err != nil {
 		return nil, err
 	}
@@ -535,7 +399,6 @@ func (c *Client) GetAuthorization(ctx context.Context, url string) (*Authorizati
 //
 // It does not revoke existing certificates.
 func (c *Client) RevokeAuthorization(ctx context.Context, url string) error {
-	// Required for c.accountKID() when in RFC mode.
 	if _, err := c.Discover(ctx); err != nil {
 		return err
 	}
@@ -565,18 +428,11 @@ func (c *Client) RevokeAuthorization(ctx context.Context, url string) error {
 // In all other cases WaitAuthorization returns an error.
 // If the Status is StatusInvalid, the returned error is of type *AuthorizationError.
 func (c *Client) WaitAuthorization(ctx context.Context, url string) (*Authorization, error) {
-	// Required for c.accountKID() when in RFC mode.
-	dir, err := c.Discover(ctx)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
-	getfn := c.postAsGet
-	if !dir.rfcCompliant() {
-		getfn = c.get
-	}
-
 	for {
-		res, err := getfn(ctx, url, wantStatus(http.StatusOK, http.StatusAccepted))
+		res, err := c.postAsGet(ctx, url, wantStatus(http.StatusOK, http.StatusAccepted))
 		if err != nil {
 			return nil, err
 		}
@@ -619,17 +475,11 @@ func (c *Client) WaitAuthorization(ctx context.Context, url string) (*Authorizat
 //
 // A client typically polls a challenge status using this method.
 func (c *Client) GetChallenge(ctx context.Context, url string) (*Challenge, error) {
-	// Required for c.accountKID() when in RFC mode.
-	dir, err := c.Discover(ctx)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
 
-	getfn := c.postAsGet
-	if !dir.rfcCompliant() {
-		getfn = c.get
-	}
-	res, err := getfn(ctx, url, wantStatus(http.StatusOK, http.StatusAccepted))
+	res, err := c.postAsGet(ctx, url, wantStatus(http.StatusOK, http.StatusAccepted))
 	if err != nil {
 		return nil, err
 	}
@@ -647,29 +497,11 @@ func (c *Client) GetChallenge(ctx context.Context, url string) (*Challenge, erro
 //
 // The server will then perform the validation asynchronously.
 func (c *Client) Accept(ctx context.Context, chal *Challenge) (*Challenge, error) {
-	// Required for c.accountKID() when in RFC mode.
-	dir, err := c.Discover(ctx)
-	if err != nil {
+	if _, err := c.Discover(ctx); err != nil {
 		return nil, err
 	}
 
-	var req interface{} = json.RawMessage("{}") // RFC-compliant CA
-	if !dir.rfcCompliant() {
-		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.post(ctx, nil, chal.URI, req, wantStatus(
+	res, err := c.post(ctx, nil, chal.URI, json.RawMessage("{}"), wantStatus(
 		http.StatusOK,       // according to the spec
 		http.StatusAccepted, // Let's Encrypt: see https://goo.gl/WsJ7VT (acme-divergences.md)
 	))
@@ -720,7 +552,7 @@ func (c *Client) HTTP01ChallengePath(token string) string {
 
 // TLSSNI01ChallengeCert creates a certificate for TLS-SNI-01 challenge response.
 //
-// Deprecated: This challenge type is unused in both draft-02 and RFC versions of ACME spec.
+// Deprecated: This challenge type is unused in both draft-02 and RFC versions of the ACME spec.
 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 {
@@ -738,7 +570,7 @@ func (c *Client) TLSSNI01ChallengeCert(token string, opt ...CertOption) (cert tl
 
 // TLSSNI02ChallengeCert creates a certificate for TLS-SNI-02 challenge response.
 //
-// Deprecated: This challenge type is unused in both draft-02 and RFC versions of ACME spec.
+// Deprecated: This challenge type is unused in both draft-02 and RFC versions of the ACME spec.
 func (c *Client) TLSSNI02ChallengeCert(token string, opt ...CertOption) (cert tls.Certificate, name string, err error) {
 	b := sha256.Sum256([]byte(token))
 	h := hex.EncodeToString(b[:])
@@ -805,63 +637,6 @@ func (c *Client) TLSALPN01ChallengeCert(token, domain string, opt ...CertOption)
 	return tlsChallengeCert([]string{domain}, newOpt)
 }
 
-// doReg sends all types of registration requests the old way (pre-RFC world).
-// 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.post(ctx, nil, url, req, wantStatus(
-		http.StatusOK,       // updates and deletes
-		http.StatusCreated,  // new account creation
-		http.StatusAccepted, // Let's Encrypt divergent implementation
-	))
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-
-	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
-}
-
 // popNonce returns a nonce value previously stored with c.addNonce
 // or fetches a fresh one from c.dir.NonceURL.
 // If NonceURL is empty, it first tries c.directoryURL() and, failing that,
@@ -936,78 +711,6 @@ func nonceFromHeader(h http.Header) string {
 	return h.Get("Replay-Nonce")
 }
 
-func (c *Client) responseCert(ctx context.Context, 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 := c.chainCert(ctx, url, 0)
-		if err != nil {
-			return nil, err
-		}
-		cert = append(cert, cc...)
-	}
-	return cert, nil
-}
-
-// 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 (c *Client) chainCert(ctx context.Context, url string, depth int) ([][]byte, error) {
-	if depth >= maxChainLen {
-		return nil, errors.New("acme: certificate chain is too deep")
-	}
-
-	res, err := c.get(ctx, url, wantStatus(http.StatusOK))
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-	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 := c.chainCert(ctx, 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.
@@ -1098,5 +801,5 @@ func encodePEM(typ string, b []byte) []byte {
 	return pem.EncodeToMemory(pb)
 }
 
-// timeNow is useful for testing for fixed current time.
+// timeNow is time.Now, except in tests which can mess with it.
 var timeNow = time.Now