package acme import ( "crypto/rsa" "crypto/x509" "encoding/base64" "encoding/json" "errors" "fmt" "io/ioutil" "log" "net/http" "regexp" "strconv" "strings" "time" ) // Logger is an optional custom logger. var Logger *log.Logger // 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() *rsa.PrivateKey } // Interface for all challenge solvers to implement. type solver interface { Solve(challenge challenge, domain string) error } // Client is the user-friendy way to ACME type Client struct { directory directory user User jws *jws keyBits int issuerCert []byte solvers map[string]solver } // NewClient creates a new ACME client on behalf of user. The client will depend on // the ACME directory located at caDirURL for the rest of its actions. It will // generate private keys for certificates of size keyBits. And, if the challenge // type requires it, the client will open a port at optPort to solve the challenge. // If optPort is blank, the port required by the spec will be used, but you must // forward the required port to optPort for the challenge to succeed. func NewClient(caDirURL string, user User, keyBits int, optPort string) (*Client, error) { privKey := user.GetPrivateKey() if privKey == nil { return nil, errors.New("private key was nil") } if err := privKey.Validate(); err != nil { return nil, fmt.Errorf("invalid private key: %v", err) } dirResp, err := http.Get(caDirURL) if err != nil { return nil, fmt.Errorf("get directory at '%s': %v", caDirURL, err) } defer dirResp.Body.Close() var dir directory err = json.NewDecoder(dirResp.Body).Decode(&dir) if err != nil { return nil, fmt.Errorf("decode directory: %v", err) } if dir.NewRegURL == "" { return nil, errors.New("directory missing new registration URL") } if dir.NewAuthzURL == "" { return nil, errors.New("directory missing new authz URL") } if dir.NewCertURL == "" { return nil, errors.New("directory missing new certificate URL") } if dir.RevokeCertURL == "" { return nil, errors.New("directory missing revoke certificate URL") } jws := &jws{privKey: privKey, directoryURL: caDirURL} // 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[string]solver) solvers["http-01"] = &httpChallenge{jws: jws, optPort: optPort} return &Client{directory: dir, user: user, jws: jws, keyBits: keyBits, solvers: solvers}, nil } // Register the current account to the ACME server. func (c *Client) Register() (*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()) regMsg := registrationMessage{ Resource: "new-reg", } if c.user.GetEmail() != "" { regMsg.Contact = []string{"mailto:" + c.user.GetEmail()} } else { regMsg.Contact = []string{} } jsonBytes, err := json.Marshal(regMsg) if err != nil { return nil, err } resp, err := c.jws.post(c.directory.NewRegURL, jsonBytes) if err != nil { return nil, err } defer resp.Body.Close() if resp.StatusCode >= http.StatusBadRequest { return nil, handleHTTPError(resp) } var serverReg Registration decoder := json.NewDecoder(resp.Body) err = decoder.Decode(&serverReg) if err != nil { return nil, err } reg := &RegistrationResource{Body: serverReg} links := parseLinks(resp.Header["Link"]) reg.URI = resp.Header.Get("Location") if links["terms-of-service"] != "" { reg.TosURL = links["terms-of-service"] } if links["next"] != "" { reg.NewAuthzURL = links["next"] } else { return nil, errors.New("acme: The server did not return 'next' link to proceed") } return reg, nil } // AgreeToTOS updates the Client registration and sends the agreement to // the server. func (c *Client) AgreeToTOS() error { c.user.GetRegistration().Body.Agreement = c.user.GetRegistration().TosURL c.user.GetRegistration().Body.Resource = "reg" jsonBytes, err := json.Marshal(&c.user.GetRegistration().Body) if err != nil { return err } resp, err := c.jws.post(c.user.GetRegistration().URI, jsonBytes) if err != nil { return err } defer resp.Body.Close() if resp.StatusCode != http.StatusAccepted { return handleHTTPError(resp) } return nil } // ObtainCertificates tries to obtain certificates from the CA server // using the challenges it has configured. The returned certificates are // PEM encoded byte slices. // If bundle is true, the []byte contains both the issuer certificate and // your issued certificate as a bundle. func (c *Client) ObtainCertificates(domains []string, bundle bool) ([]CertificateResource, map[string]error) { if bundle { logf("[INFO] acme: Obtaining bundled certificates for %v", strings.Join(domains, ", ")) } else { logf("[INFO] acme: Obtaining certificates for %v", strings.Join(domains, ", ")) } challenges, failures := c.getChallenges(domains) if len(challenges) == 0 { return nil, failures } err := c.solveChallenges(challenges) for k, v := range err { failures[k] = v } if len(failures) == len(domains) { return nil, failures } // remove failed challenges from slice var succeededChallenges []authorizationResource for _, chln := range challenges { if failures[chln.Domain] == nil { succeededChallenges = append(succeededChallenges, chln) } } logf("[INFO] acme: Validations succeeded; requesting certificates") certs, err := c.requestCertificates(succeededChallenges, bundle) for k, v := range err { failures[k] = v } return certs, failures } // ObtainSANCertificate 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. // If bundle is true, the []byte contains both the issuer certificate and // your issued certificate as a bundle. func (c *Client) ObtainSANCertificate(domains []string, bundle bool) (CertificateResource, map[string]error) { if bundle { logf("[INFO] acme: Obtaining bundled SAN certificate for %v", strings.Join(domains, ", ")) } else { logf("[INFO] acme: Obtaining SAN certificate for %v", strings.Join(domains, ", ")) } challenges, failures := c.getChallenges(domains) // If any challenge fails - return. Do not generate partial SAN certificates. if len(failures) > 0 { return CertificateResource{}, failures } errs := c.solveChallenges(challenges) // If any challenge fails - return. Do not generate partial SAN certificates. if len(errs) > 0 { return CertificateResource{}, errs } logf("[INFO] acme: Validations succeeded; requesting certificates") cert, err := c.requestCertificate(challenges, bundle) if err != nil { for _, chln := range challenges { failures[chln.Domain] = 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) jsonBytes, err := json.Marshal(revokeCertMessage{Resource: "revoke-cert", Certificate: encodedCert}) if err != nil { return err } resp, err := c.jws.post(c.directory.RevokeCertURL, jsonBytes) if err != nil { return err } defer resp.Body.Close() if resp.StatusCode != http.StatusOK { return handleHTTPError(resp) } return nil } // 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. func (c *Client) RenewCertificate(cert CertificateResource, revokeOld bool, bundle 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] acme: [%s] Trying renewal with %d hours remaining", cert.Domain, int(timeLeft.Hours())) // The first step of renewal is to check if we get a renewed cert // directly from the cert URL. resp, err := http.Get(cert.CertURL) if err != nil { return CertificateResource{}, err } defer resp.Body.Close() serverCertBytes, err := ioutil.ReadAll(resp.Body) if err != nil { return CertificateResource{}, err } serverCert, err := x509.ParseCertificate(serverCertBytes) if err != nil { return CertificateResource{}, err } // If the server responds with a different certificate we are effectively renewed. // TODO: Further test if we can actually use the new certificate (Our private key works) if !x509Cert.Equal(serverCert) { logf("[INFO] acme: [%s] Server responded with renewed certificate", cert.Domain) if revokeOld { c.RevokeCertificate(cert.Certificate) } issuedCert := pemEncode(derCertificateBytes(serverCertBytes)) // If bundle is true, we want to return a certificate bundle. // To do this, we need the issuer certificate. if bundle { // The issuer certificate link is always supplied via an "up" link // in the response headers of a new certificate. links := parseLinks(resp.Header["Link"]) issuerCert, err := c.getIssuerCertificate(links["up"]) if err != nil { // If we fail to aquire the issuer cert, return the issued certificate - do not fail. logf("[ERROR] acme: [%s] Could not bundle issuer certificate: %v", cert.Domain, err) } else { // Success - append the issuer cert to the issued cert. issuerCert = pemEncode(derCertificateBytes(issuerCert)) issuedCert = append(issuedCert, issuerCert...) cert.Certificate = issuedCert } } cert.Certificate = issuedCert return cert, nil } newCerts, failures := c.ObtainCertificates([]string{cert.Domain}, bundle) if len(failures) > 0 { return CertificateResource{}, failures[cert.Domain] } if revokeOld { c.RevokeCertificate(cert.Certificate) } return newCerts[0], nil } // Looks through the challenge combinations to find a solvable match. // Then solves the challenges in series and returns. func (c *Client) solveChallenges(challenges []authorizationResource) map[string]error { // loop through the resources, basically through the domains. failures := make(map[string]error) for _, authz := range challenges { // no solvers - no solving if solvers := c.chooseSolvers(authz.Body, authz.Domain); solvers != nil { for i, solver := range solvers { // TODO: do not immediately fail if one domain fails to validate. err := solver.Solve(authz.Body.Challenges[i], authz.Domain) if err != nil { failures[authz.Domain] = err } } } else { failures[authz.Domain] = fmt.Errorf("acme: Could not determine solvers for %s", authz.Domain) } } return failures } // Checks all combinations from the server and returns an array of // solvers which should get executed in series. func (c *Client) chooseSolvers(auth authorization, domain string) map[int]solver { for _, combination := range auth.Combinations { solvers := make(map[int]solver) for _, idx := range combination { if solver, ok := c.solvers[auth.Challenges[idx].Type]; ok { solvers[idx] = solver } else { logf("[ERROR] acme: Could not find solver for: %s", auth.Challenges[idx].Type) } } // If we can solve the whole combination, return the solvers if len(solvers) == len(combination) { return solvers } } return nil } // Get the challenges needed to proof our identifier to the ACME server. func (c *Client) getChallenges(domains []string) ([]authorizationResource, map[string]error) { resc, errc := make(chan authorizationResource), make(chan domainError) for _, domain := range domains { go func(domain string) { jsonBytes, err := json.Marshal(authorization{Resource: "new-authz", Identifier: identifier{Type: "dns", Value: domain}}) if err != nil { errc <- domainError{Domain: domain, Error: err} return } resp, err := c.jws.post(c.user.GetRegistration().NewAuthzURL, jsonBytes) if err != nil { errc <- domainError{Domain: domain, Error: err} return } if resp.StatusCode != http.StatusCreated { errc <- domainError{Domain: domain, Error: handleHTTPError(resp)} } links := parseLinks(resp.Header["Link"]) if links["next"] == "" { logf("[ERROR] acme: Server did not provide next link to proceed") return } var authz authorization decoder := json.NewDecoder(resp.Body) err = decoder.Decode(&authz) if err != nil { errc <- domainError{Domain: domain, Error: err} } resp.Body.Close() resc <- authorizationResource{Body: authz, NewCertURL: links["next"], AuthURL: resp.Header.Get("Location"), Domain: domain} }(domain) } responses := make(map[string]authorizationResource) failures := make(map[string]error) for i := 0; i < len(domains); i++ { select { case res := <-resc: responses[res.Domain] = res case err := <-errc: failures[err.Domain] = err.Error } } challenges := make([]authorizationResource, 0, len(responses)) for _, domain := range domains { if challenge, ok := responses[domain]; ok { challenges = append(challenges, challenge) } } close(resc) close(errc) return challenges, failures } // requestCertificates iterates all granted authorizations, creates RSA private keys and CSRs. // It then uses these to request a certificate from the CA and returns the list of successfully // granted certificates. func (c *Client) requestCertificates(challenges []authorizationResource, bundle bool) ([]CertificateResource, map[string]error) { resc, errc := make(chan CertificateResource), make(chan domainError) for _, authz := range challenges { go func(authz authorizationResource, resc chan CertificateResource, errc chan domainError) { certRes, err := c.requestCertificate([]authorizationResource{authz}, bundle) if err != nil { errc <- domainError{Domain: authz.Domain, Error: err} } else { resc <- certRes } }(authz, resc, errc) } var certs []CertificateResource failures := make(map[string]error) for i := 0; i < len(challenges); i++ { select { case res := <-resc: certs = append(certs, res) case err := <-errc: failures[err.Domain] = err.Error } } close(resc) close(errc) return certs, failures } func (c *Client) requestCertificate(authz []authorizationResource, bundle bool) (CertificateResource, error) { if len(authz) == 0 { return CertificateResource{}, errors.New("Passed no authorizations to requestCertificate!") } commonName := authz[0] privKey, err := generatePrivateKey(rsakey, c.keyBits) if err != nil { return CertificateResource{}, err } var san []string var authURLs []string for _, auth := range authz[1:] { san = append(san, auth.Domain) authURLs = append(authURLs, auth.AuthURL) } // TODO: should the CSR be customizable? csr, err := generateCsr(privKey.(*rsa.PrivateKey), commonName.Domain, san) if err != nil { return CertificateResource{}, err } csrString := base64.URLEncoding.EncodeToString(csr) jsonBytes, err := json.Marshal(csrMessage{Resource: "new-cert", Csr: csrString, Authorizations: authURLs}) if err != nil { return CertificateResource{}, err } resp, err := c.jws.post(commonName.NewCertURL, jsonBytes) if err != nil { return CertificateResource{}, err } privateKeyPem := pemEncode(privKey) cerRes := CertificateResource{ Domain: commonName.Domain, CertURL: resp.Header.Get("Location"), PrivateKey: privateKeyPem} for { switch resp.StatusCode { case 202: case 201: cert, err := ioutil.ReadAll(resp.Body) resp.Body.Close() if err != nil { return CertificateResource{}, err } // The server returns a body with a length of zero if the // certificate was not ready at the time this request completed. // Otherwise the body is the certificate. if len(cert) > 0 { cerRes.CertStableURL = resp.Header.Get("Content-Location") issuedCert := pemEncode(derCertificateBytes(cert)) // If bundle is true, we want to return a certificate bundle. // To do this, we need the issuer certificate. if bundle { // The issuer certificate link is always supplied via an "up" link // in the response headers of a new certificate. links := parseLinks(resp.Header["Link"]) issuerCert, err := c.getIssuerCertificate(links["up"]) if err != nil { // If we fail to aquire the issuer cert, return the issued certificate - do not fail. logf("[WARNING] acme: [%s] Could not bundle issuer certificate: %v", commonName.Domain, err) } else { // Success - append the issuer cert to the issued cert. issuerCert = pemEncode(derCertificateBytes(issuerCert)) issuedCert = append(issuedCert, issuerCert...) } } cerRes.Certificate = issuedCert logf("[%s] Server responded with a certificate.", commonName.Domain) return cerRes, nil } // The certificate was granted but is not yet issued. // Check retry-after and loop. ra := resp.Header.Get("Retry-After") retryAfter, err := strconv.Atoi(ra) if err != nil { return CertificateResource{}, err } logf("[INFO] acme: [%s] Server responded with status 202; retrying after %ds", commonName.Domain, retryAfter) time.Sleep(time.Duration(retryAfter) * time.Second) break default: return CertificateResource{}, handleHTTPError(resp) } resp, err = http.Get(cerRes.CertURL) if err != nil { return CertificateResource{}, err } } } // getIssuerCertificate requests the issuer certificate and caches it for // subsequent requests. func (c *Client) getIssuerCertificate(url string) ([]byte, error) { logf("[INFO] acme: Requesting issuer cert from %s", url) if c.issuerCert != nil { return c.issuerCert, nil } resp, err := http.Get(url) if err != nil { return nil, err } issuerBytes, err := ioutil.ReadAll(resp.Body) if err != nil { return nil, err } _, err = x509.ParseCertificate(issuerBytes) if err != nil { return nil, err } c.issuerCert = issuerBytes 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 }