// Package acme implements the ACME protocol for Let's Encrypt and other conforming providers. package acme import ( "crypto" "crypto/x509" "encoding/base64" "errors" "fmt" "io/ioutil" "log" "net" "regexp" "strconv" "strings" "time" ) var ( // Logger is an optional custom logger. Logger *log.Logger ) const ( // maxBodySize is the maximum size of body that we will read. maxBodySize = 1024 * 1024 // overallRequestLimit is the overall number of request per second limited on the // “new-reg”, “new-authz” and “new-cert” endpoints. From the documentation the // limitation is 20 requests per second, but using 20 as value doesn't work but 18 do overallRequestLimit = 18 ) // logf writes a log entry. It uses Logger if not // nil, otherwise it uses the default log.Logger. func logf(format string, args ...interface{}) { if Logger != nil { Logger.Printf(format, args...) } else { log.Printf(format, args...) } } // User interface is to be implemented by users of this library. // It is used by the client type to get user specific information. type User interface { GetEmail() string GetRegistration() *RegistrationResource GetPrivateKey() crypto.PrivateKey } // Interface for all challenge solvers to implement. type solver interface { Solve(challenge challenge, domain string) error } type validateFunc func(j *jws, domain, uri string, chlng challenge) error // Client is the user-friendy way to ACME type Client struct { directory directory user User jws *jws keyType KeyType solvers map[Challenge]solver } // NewClient creates a new ACME client on behalf of the user. The client will depend on // the ACME directory located at caDirURL for the rest of its actions. A private // key of type keyType (see KeyType contants) will be generated when requesting a new // certificate if one isn't provided. func NewClient(caDirURL string, user User, keyType KeyType) (*Client, error) { privKey := user.GetPrivateKey() if privKey == nil { return nil, errors.New("private key was nil") } var dir directory if _, err := getJSON(caDirURL, &dir); err != nil { return nil, fmt.Errorf("get directory at '%s': %v", caDirURL, err) } if dir.NewAccountURL == "" { return nil, errors.New("directory missing new registration URL") } if dir.NewOrderURL == "" { return nil, errors.New("directory missing new order URL") } /*if dir.RevokeCertURL == "" { return nil, errors.New("directory missing revoke certificate URL") }*/ jws := &jws{privKey: privKey, getNonceURL: dir.NewNonceURL} if reg := user.GetRegistration(); reg != nil { jws.kid = reg.URI } // REVIEW: best possibility? // Add all available solvers with the right index as per ACME // spec to this map. Otherwise they won`t be found. solvers := make(map[Challenge]solver) solvers[HTTP01] = &httpChallenge{jws: jws, validate: validate, provider: &HTTPProviderServer{}} return &Client{directory: dir, user: user, jws: jws, keyType: keyType, solvers: solvers}, nil } // SetChallengeProvider specifies a custom provider p that can solve the given challenge type. func (c *Client) SetChallengeProvider(challenge Challenge, p ChallengeProvider) error { switch challenge { case HTTP01: c.solvers[challenge] = &httpChallenge{jws: c.jws, validate: validate, provider: p} case DNS01: c.solvers[challenge] = &dnsChallenge{jws: c.jws, validate: validate, provider: p} default: return fmt.Errorf("Unknown challenge %v", challenge) } return nil } // SetHTTPAddress specifies a custom interface:port to be used for HTTP based challenges. // If this option is not used, the default port 80 and all interfaces will be used. // To only specify a port and no interface use the ":port" notation. // // NOTE: This REPLACES any custom HTTP provider previously set by calling // c.SetChallengeProvider with the default HTTP challenge provider. func (c *Client) SetHTTPAddress(iface string) error { host, port, err := net.SplitHostPort(iface) if err != nil { return err } if chlng, ok := c.solvers[HTTP01]; ok { chlng.(*httpChallenge).provider = NewHTTPProviderServer(host, port) } return nil } // ExcludeChallenges explicitly removes challenges from the pool for solving. func (c *Client) ExcludeChallenges(challenges []Challenge) { // Loop through all challenges and delete the requested one if found. for _, challenge := range challenges { delete(c.solvers, challenge) } } // GetToSURL returns the current ToS URL from the Directory func (c *Client) GetToSURL() string { return c.directory.Meta.TermsOfService } // Register the current account to the ACME server. func (c *Client) Register(tosAgreed bool) (*RegistrationResource, error) { if c == nil || c.user == nil { return nil, errors.New("acme: cannot register a nil client or user") } logf("[INFO] acme: Registering account for %s", c.user.GetEmail()) accMsg := accountMessage{} if c.user.GetEmail() != "" { accMsg.Contact = []string{"mailto:" + c.user.GetEmail()} } else { accMsg.Contact = []string{} } accMsg.TermsOfServiceAgreed = tosAgreed var serverReg accountMessage hdr, err := postJSON(c.jws, c.directory.NewAccountURL, accMsg, &serverReg) if err != nil { remoteErr, ok := err.(RemoteError) if ok && remoteErr.StatusCode == 409 { } else { return nil, err } } reg := &RegistrationResource{ URI: hdr.Get("Location"), Body: serverReg, } c.jws.kid = reg.URI return reg, nil } // ResolveAccountByKey will attempt to look up an account using the given account key // and return its registration resource. func (c *Client) ResolveAccountByKey() (*RegistrationResource, error) { logf("[INFO] acme: Trying to resolve account by key") acc := accountMessage{OnlyReturnExisting: true} hdr, err := postJSON(c.jws, c.directory.NewAccountURL, acc, &acc) if err != nil { return nil, err } accountLink := hdr.Get("Location") if accountLink == "" { return nil, errors.New("Server did not return the account link") } var retAccount accountMessage c.jws.kid = accountLink hdr, err = postJSON(c.jws, accountLink, accountMessage{}, &retAccount) if err != nil { return nil, err } return &RegistrationResource{URI: accountLink, Body: retAccount}, nil } // DeleteRegistration deletes the client's user registration from the ACME // server. func (c *Client) DeleteRegistration() error { if c == nil || c.user == nil { return errors.New("acme: cannot unregister a nil client or user") } logf("[INFO] acme: Deleting account for %s", c.user.GetEmail()) accMsg := accountMessage{ Status: "deactivated", } _, err := postJSON(c.jws, c.user.GetRegistration().URI, accMsg, nil) if err != nil { return err } return nil } // QueryRegistration runs a POST request on the client's registration and // returns the result. // // This is similar to the Register function, but acting on an existing // registration link and resource. func (c *Client) QueryRegistration() (*RegistrationResource, error) { if c == nil || c.user == nil { return nil, errors.New("acme: cannot query the registration of a nil client or user") } // Log the URL here instead of the email as the email may not be set logf("[INFO] acme: Querying account for %s", c.user.GetRegistration().URI) accMsg := accountMessage{} var serverReg accountMessage _, err := postJSON(c.jws, c.user.GetRegistration().URI, accMsg, &serverReg) if err != nil { return nil, err } reg := &RegistrationResource{Body: serverReg} // Location: header is not returned so this needs to be populated off of // existing URI reg.URI = c.user.GetRegistration().URI return reg, nil } // ObtainCertificateForCSR tries to obtain a certificate matching the CSR passed into it. // The domains are inferred from the CommonName and SubjectAltNames, if any. The private key // for this CSR is not required. // If bundle is true, the []byte contains both the issuer certificate and // your issued certificate as a bundle. // This function will never return a partial certificate. If one domain in the list fails, // the whole certificate will fail. func (c *Client) ObtainCertificateForCSR(csr x509.CertificateRequest, bundle bool) (CertificateResource, map[string]error) { // figure out what domains it concerns // start with the common name domains := []string{csr.Subject.CommonName} // loop over the SubjectAltName DNS names DNSNames: for _, sanName := range csr.DNSNames { for _, existingName := range domains { if existingName == sanName { // duplicate; skip this name continue DNSNames } } // name is unique domains = append(domains, sanName) } if bundle { logf("[INFO][%s] acme: Obtaining bundled SAN certificate given a CSR", strings.Join(domains, ", ")) } else { logf("[INFO][%s] acme: Obtaining SAN certificate given a CSR", strings.Join(domains, ", ")) } order, err := c.createOrderForIdentifiers(domains) if err != nil { identErrors := make(map[string]error) for _, auth := range order.Identifiers { identErrors[auth.Value] = err } } authz, failures := c.getAuthzForOrder(order) // If any challenge fails - return. Do not generate partial SAN certificates. if len(failures) > 0 { /*for _, auth := range authz { c.disableAuthz(auth) }*/ return CertificateResource{}, failures } errs := c.solveChallengeForAuthz(authz) // If any challenge fails - return. Do not generate partial SAN certificates. if len(errs) > 0 { return CertificateResource{}, errs } logf("[INFO][%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", ")) cert, err := c.requestCertificateForCsr(order, bundle, csr.Raw, nil) if err != nil { for _, chln := range authz { failures[chln.Identifier.Value] = err } } // Add the CSR to the certificate so that it can be used for renewals. cert.CSR = pemEncode(&csr) return cert, failures } // ObtainCertificate tries to obtain a single certificate using all domains passed into it. // The first domain in domains is used for the CommonName field of the certificate, all other // domains are added using the Subject Alternate Names extension. A new private key is generated // for every invocation of this function. If you do not want that you can supply your own private key // in the privKey parameter. If this parameter is non-nil it will be used instead of generating a new one. // If bundle is true, the []byte contains both the issuer certificate and // your issued certificate as a bundle. // This function will never return a partial certificate. If one domain in the list fails, // the whole certificate will fail. func (c *Client) ObtainCertificate(domains []string, bundle bool, privKey crypto.PrivateKey, mustStaple bool) (CertificateResource, map[string]error) { if bundle { logf("[INFO][%s] acme: Obtaining bundled SAN certificate", strings.Join(domains, ", ")) } else { logf("[INFO][%s] acme: Obtaining SAN certificate", strings.Join(domains, ", ")) } order, err := c.createOrderForIdentifiers(domains) if err != nil { identErrors := make(map[string]error) for _, auth := range order.Identifiers { identErrors[auth.Value] = err } } authz, failures := c.getAuthzForOrder(order) // If any challenge fails - return. Do not generate partial SAN certificates. if len(failures) > 0 { /*for _, auth := range authz { c.disableAuthz(auth) }*/ return CertificateResource{}, failures } errs := c.solveChallengeForAuthz(authz) // If any challenge fails - return. Do not generate partial SAN certificates. if len(errs) > 0 { return CertificateResource{}, errs } logf("[INFO][%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", ")) cert, err := c.requestCertificateForOrder(order, bundle, privKey, mustStaple) if err != nil { for _, auth := range authz { failures[auth.Identifier.Value] = err } } return cert, failures } // RevokeCertificate takes a PEM encoded certificate or bundle and tries to revoke it at the CA. func (c *Client) RevokeCertificate(certificate []byte) error { certificates, err := parsePEMBundle(certificate) if err != nil { return err } x509Cert := certificates[0] if x509Cert.IsCA { return fmt.Errorf("Certificate bundle starts with a CA certificate") } encodedCert := base64.URLEncoding.EncodeToString(x509Cert.Raw) _, err = postJSON(c.jws, c.directory.RevokeCertURL, revokeCertMessage{Certificate: encodedCert}, nil) return err } // RenewCertificate takes a CertificateResource and tries to renew the certificate. // If the renewal process succeeds, the new certificate will ge returned in a new CertResource. // Please be aware that this function will return a new certificate in ANY case that is not an error. // If the server does not provide us with a new cert on a GET request to the CertURL // this function will start a new-cert flow where a new certificate gets generated. // If bundle is true, the []byte contains both the issuer certificate and // your issued certificate as a bundle. // For private key reuse the PrivateKey property of the passed in CertificateResource should be non-nil. func (c *Client) RenewCertificate(cert CertificateResource, bundle, mustStaple bool) (CertificateResource, error) { // Input certificate is PEM encoded. Decode it here as we may need the decoded // cert later on in the renewal process. The input may be a bundle or a single certificate. certificates, err := parsePEMBundle(cert.Certificate) if err != nil { return CertificateResource{}, err } x509Cert := certificates[0] if x509Cert.IsCA { return CertificateResource{}, fmt.Errorf("[%s] Certificate bundle starts with a CA certificate", cert.Domain) } // This is just meant to be informal for the user. timeLeft := x509Cert.NotAfter.Sub(time.Now().UTC()) logf("[INFO][%s] acme: Trying renewal with %d hours remaining", cert.Domain, int(timeLeft.Hours())) // We always need to request a new certificate to renew. // Start by checking to see if the certificate was based off a CSR, and // use that if it's defined. if len(cert.CSR) > 0 { csr, err := pemDecodeTox509CSR(cert.CSR) if err != nil { return CertificateResource{}, err } newCert, failures := c.ObtainCertificateForCSR(*csr, bundle) return newCert, failures[cert.Domain] } var privKey crypto.PrivateKey if cert.PrivateKey != nil { privKey, err = parsePEMPrivateKey(cert.PrivateKey) if err != nil { return CertificateResource{}, err } } var domains []string var failures map[string]error // check for SAN certificate if len(x509Cert.DNSNames) > 1 { domains = append(domains, x509Cert.Subject.CommonName) for _, sanDomain := range x509Cert.DNSNames { if sanDomain == x509Cert.Subject.CommonName { continue } domains = append(domains, sanDomain) } } else { domains = append(domains, x509Cert.Subject.CommonName) } newCert, failures := c.ObtainCertificate(domains, bundle, privKey, mustStaple) return newCert, failures[cert.Domain] } func (c *Client) createOrderForIdentifiers(domains []string) (orderResource, error) { var identifiers []identifier for _, domain := range domains { identifiers = append(identifiers, identifier{Type: "dns", Value: domain}) } order := orderMessage{ Identifiers: identifiers, } var response orderMessage hdr, err := postJSON(c.jws, c.directory.NewOrderURL, order, &response) if err != nil { return orderResource{}, err } orderRes := orderResource{ URL: hdr.Get("Location"), orderMessage: response, } return orderRes, nil } // Looks through the challenge combinations to find a solvable match. // Then solves the challenges in series and returns. func (c *Client) solveChallengeForAuthz(authorizations []authorization) map[string]error { // loop through the resources, basically through the domains. failures := make(map[string]error) for _, authz := range authorizations { if authz.Status == "valid" { // Boulder might recycle recent validated authz (see issue #267) logf("[INFO][%s] acme: Authorization already valid; skipping challenge", authz.Identifier.Value) continue } // no solvers - no solving if i, solver := c.chooseSolver(authz, authz.Identifier.Value); solver != nil { err := solver.Solve(authz.Challenges[i], authz.Identifier.Value) if err != nil { //c.disableAuthz(authz.Identifier) failures[authz.Identifier.Value] = err } } else { //c.disableAuthz(authz) failures[authz.Identifier.Value] = fmt.Errorf("[%s] acme: Could not determine solvers", authz.Identifier.Value) } } return failures } // Checks all challenges from the server in order and returns the first matching solver. func (c *Client) chooseSolver(auth authorization, domain string) (int, solver) { for i, challenge := range auth.Challenges { if solver, ok := c.solvers[Challenge(challenge.Type)]; ok { return i, solver } logf("[INFO][%s] acme: Could not find solver for: %s", domain, challenge.Type) } return 0, nil } // Get the challenges needed to proof our identifier to the ACME server. func (c *Client) getAuthzForOrder(order orderResource) ([]authorization, map[string]error) { resc, errc := make(chan authorization), make(chan domainError) delay := time.Second / overallRequestLimit for _, authzURL := range order.Authorizations { time.Sleep(delay) go func(authzURL string) { var authz authorization _, err := getJSON(authzURL, &authz) if err != nil { errc <- domainError{Domain: authz.Identifier.Value, Error: err} return } resc <- authz }(authzURL) } var responses []authorization failures := make(map[string]error) for i := 0; i < len(order.Authorizations); i++ { select { case res := <-resc: responses = append(responses, res) case err := <-errc: failures[err.Domain] = err.Error } } logAuthz(order) close(resc) close(errc) return responses, failures } func logAuthz(order orderResource) { for i, auth := range order.Authorizations { logf("[INFO][%s] AuthURL: %s", order.Identifiers[i].Value, auth) } } // cleanAuthz loops through the passed in slice and disables any auths which are not "valid" func (c *Client) disableAuthz(authURL string) error { var disabledAuth authorization _, err := postJSON(c.jws, authURL, deactivateAuthMessage{Status: "deactivated"}, &disabledAuth) return err } func (c *Client) requestCertificateForOrder(order orderResource, bundle bool, privKey crypto.PrivateKey, mustStaple bool) (CertificateResource, error) { var err error if privKey == nil { privKey, err = generatePrivateKey(c.keyType) if err != nil { return CertificateResource{}, err } } // determine certificate name(s) based on the authorization resources commonName := order.Identifiers[0].Value var san []string for _, auth := range order.Identifiers { san = append(san, auth.Value) } // TODO: should the CSR be customizable? csr, err := generateCsr(privKey, commonName, san, mustStaple) if err != nil { return CertificateResource{}, err } return c.requestCertificateForCsr(order, bundle, csr, pemEncode(privKey)) } func (c *Client) requestCertificateForCsr(order orderResource, bundle bool, csr []byte, privateKeyPem []byte) (CertificateResource, error) { commonName := order.Identifiers[0].Value var authURLs []string for _, auth := range order.Identifiers[1:] { authURLs = append(authURLs, auth.Value) } csrString := base64.RawURLEncoding.EncodeToString(csr) var retOrder orderMessage _, error := postJSON(c.jws, order.Finalize, csrMessage{Csr: csrString}, &retOrder) if error != nil { return CertificateResource{}, error } if retOrder.Status == "invalid" { return CertificateResource{}, error } certRes := CertificateResource{ Domain: commonName, CertURL: retOrder.Certificate, PrivateKey: privateKeyPem, } if retOrder.Status == "valid" { // if the certificate is available right away, short cut! ok, err := c.checkCertResponse(retOrder, &certRes, bundle) if err != nil { return CertificateResource{}, err } if ok { return certRes, nil } } maxChecks := 1000 for i := 0; i < maxChecks; i++ { _, err := getJSON(order.URL, &retOrder) if err != nil { return CertificateResource{}, err } done, err := c.checkCertResponse(retOrder, &certRes, bundle) if err != nil { return CertificateResource{}, err } if done { break } if i == maxChecks-1 { return CertificateResource{}, fmt.Errorf("polled for certificate %d times; giving up", i) } } return certRes, nil } // checkCertResponse checks to see if the certificate is ready and a link is contained in the // response. if so, loads it into certRes and returns true. If the cert // is not yet ready, it returns false. The certRes input // should already have the Domain (common name) field populated. If bundle is // true, the certificate will be bundled with the issuer's cert. func (c *Client) checkCertResponse(order orderMessage, certRes *CertificateResource, bundle bool) (bool, error) { switch order.Status { case "valid": resp, err := httpGet(order.Certificate) if err != nil { return false, err } cert, err := ioutil.ReadAll(limitReader(resp.Body, maxBodySize)) if err != nil { return false, err } // The issuer certificate link is always supplied via an "up" link // in the response headers of a new certificate. links := parseLinks(resp.Header["Link"]) if link, ok := links["up"]; ok { issuerCert, err := c.getIssuerCertificate(link) if err != nil { // If we fail to acquire the issuer cert, return the issued certificate - do not fail. logf("[WARNING][%s] acme: Could not bundle issuer certificate: %v", certRes.Domain, err) } else { issuerCert = pemEncode(derCertificateBytes(issuerCert)) // If bundle is true, we want to return a certificate bundle. // To do this, we append the issuer cert to the issued cert. if bundle { cert = append(cert, issuerCert...) } certRes.IssuerCertificate = issuerCert } } certRes.Certificate = cert certRes.CertURL = order.Certificate certRes.CertStableURL = order.Certificate logf("[INFO][%s] Server responded with a certificate.", certRes.Domain) return true, nil case "processing": return false, nil case "invalid": return false, errors.New("Order has invalid state: invalid") } return false, nil } // getIssuerCertificate requests the issuer certificate func (c *Client) getIssuerCertificate(url string) ([]byte, error) { logf("[INFO] acme: Requesting issuer cert from %s", url) resp, err := httpGet(url) if err != nil { return nil, err } defer resp.Body.Close() issuerBytes, err := ioutil.ReadAll(limitReader(resp.Body, maxBodySize)) if err != nil { return nil, err } _, err = x509.ParseCertificate(issuerBytes) if err != nil { return nil, err } return issuerBytes, err } func parseLinks(links []string) map[string]string { aBrkt := regexp.MustCompile("[<>]") slver := regexp.MustCompile("(.+) *= *\"(.+)\"") linkMap := make(map[string]string) for _, link := range links { link = aBrkt.ReplaceAllString(link, "") parts := strings.Split(link, ";") matches := slver.FindStringSubmatch(parts[1]) if len(matches) > 0 { linkMap[matches[2]] = parts[0] } } return linkMap } // validate makes the ACME server start validating a // challenge response, only returning once it is done. func validate(j *jws, domain, uri string, c challenge) error { var chlng challenge hdr, err := postJSON(j, uri, c, &chlng) if err != nil { return err } // After the path is sent, the ACME server will access our server. // Repeatedly check the server for an updated status on our request. for { switch chlng.Status { case "valid": logf("[INFO][%s] The server validated our request", domain) return nil case "pending": break case "invalid": return handleChallengeError(chlng) default: return errors.New("The server returned an unexpected state") } ra, err := strconv.Atoi(hdr.Get("Retry-After")) if err != nil { // The ACME server MUST return a Retry-After. // If it doesn't, we'll just poll hard. ra = 5 } time.Sleep(time.Duration(ra) * time.Second) hdr, err = getJSON(uri, &chlng) if err != nil { return err } } }