package certificate import ( "bytes" "crypto" "crypto/x509" "encoding/base64" "errors" "fmt" "io/ioutil" "net/http" "strings" "time" "github.com/go-acme/lego/v3/acme" "github.com/go-acme/lego/v3/acme/api" "github.com/go-acme/lego/v3/certcrypto" "github.com/go-acme/lego/v3/challenge" "github.com/go-acme/lego/v3/log" "github.com/go-acme/lego/v3/platform/wait" "golang.org/x/crypto/ocsp" "golang.org/x/net/idna" ) // maxBodySize is the maximum size of body that we will read. const maxBodySize = 1024 * 1024 // Resource represents a CA issued certificate. // PrivateKey, Certificate and IssuerCertificate are all // already PEM encoded and can be directly written to disk. // Certificate may be a certificate bundle, // depending on the options supplied to create it. type Resource struct { Domain string `json:"domain"` CertURL string `json:"certUrl"` CertStableURL string `json:"certStableUrl"` PrivateKey []byte `json:"-"` Certificate []byte `json:"-"` IssuerCertificate []byte `json:"-"` CSR []byte `json:"-"` } // ObtainRequest The request to obtain certificate. // // 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 the function Obtain. // If you do not want that you can supply your own private key in the privateKey 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. type ObtainRequest struct { Domains []string Bundle bool PrivateKey crypto.PrivateKey MustStaple bool } type resolver interface { Solve(authorizations []acme.Authorization) error } type CertifierOptions struct { KeyType certcrypto.KeyType Timeout time.Duration } // Certifier A service to obtain/renew/revoke certificates. type Certifier struct { core *api.Core resolver resolver options CertifierOptions } // NewCertifier creates a Certifier. func NewCertifier(core *api.Core, resolver resolver, options CertifierOptions) *Certifier { return &Certifier{ core: core, resolver: resolver, options: options, } } // Obtain tries to obtain a single certificate using all domains passed into it. // // This function will never return a partial certificate. // If one domain in the list fails, the whole certificate will fail. func (c *Certifier) Obtain(request ObtainRequest) (*Resource, error) { if len(request.Domains) == 0 { return nil, errors.New("no domains to obtain a certificate for") } domains := sanitizeDomain(request.Domains) if request.Bundle { log.Infof("[%s] acme: Obtaining bundled SAN certificate", strings.Join(domains, ", ")) } else { log.Infof("[%s] acme: Obtaining SAN certificate", strings.Join(domains, ", ")) } order, err := c.core.Orders.New(domains) if err != nil { return nil, err } authz, err := c.getAuthorizations(order) if err != nil { // If any challenge fails, return. Do not generate partial SAN certificates. c.deactivateAuthorizations(order) return nil, err } err = c.resolver.Solve(authz) if err != nil { // If any challenge fails, return. Do not generate partial SAN certificates. c.deactivateAuthorizations(order) return nil, err } log.Infof("[%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", ")) failures := make(obtainError) cert, err := c.getForOrder(domains, order, request.Bundle, request.PrivateKey, request.MustStaple) if err != nil { for _, auth := range authz { failures[challenge.GetTargetedDomain(auth)] = err } } // Do not return an empty failures map, because // it would still be a non-nil error value if len(failures) > 0 { return cert, failures } return cert, nil } // ObtainForCSR 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 *Certifier) ObtainForCSR(csr x509.CertificateRequest, bundle bool) (*Resource, error) { // figure out what domains it concerns // start with the common name domains := certcrypto.ExtractDomainsCSR(&csr) if bundle { log.Infof("[%s] acme: Obtaining bundled SAN certificate given a CSR", strings.Join(domains, ", ")) } else { log.Infof("[%s] acme: Obtaining SAN certificate given a CSR", strings.Join(domains, ", ")) } order, err := c.core.Orders.New(domains) if err != nil { return nil, err } authz, err := c.getAuthorizations(order) if err != nil { // If any challenge fails, return. Do not generate partial SAN certificates. c.deactivateAuthorizations(order) return nil, err } err = c.resolver.Solve(authz) if err != nil { // If any challenge fails, return. Do not generate partial SAN certificates. c.deactivateAuthorizations(order) return nil, err } log.Infof("[%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", ")) failures := make(obtainError) cert, err := c.getForCSR(domains, order, bundle, csr.Raw, nil) if err != nil { for _, auth := range authz { failures[challenge.GetTargetedDomain(auth)] = err } } if cert != nil { // Add the CSR to the certificate so that it can be used for renewals. cert.CSR = certcrypto.PEMEncode(&csr) } // Do not return an empty failures map, // because it would still be a non-nil error value if len(failures) > 0 { return cert, failures } return cert, nil } func (c *Certifier) getForOrder(domains []string, order acme.ExtendedOrder, bundle bool, privateKey crypto.PrivateKey, mustStaple bool) (*Resource, error) { if privateKey == nil { var err error privateKey, err = certcrypto.GeneratePrivateKey(c.options.KeyType) if err != nil { return nil, err } } // Determine certificate name(s) based on the authorization resources commonName := domains[0] // RFC8555 Section 7.4 "Applying for Certificate Issuance" // https://tools.ietf.org/html/rfc8555#section-7.4 // says: // Clients SHOULD NOT make any assumptions about the sort order of // "identifiers" or "authorizations" elements in the returned order // object. san := []string{commonName} for _, auth := range order.Identifiers { if auth.Value != commonName { san = append(san, auth.Value) } } // TODO: should the CSR be customizable? csr, err := certcrypto.GenerateCSR(privateKey, commonName, san, mustStaple) if err != nil { return nil, err } return c.getForCSR(domains, order, bundle, csr, certcrypto.PEMEncode(privateKey)) } func (c *Certifier) getForCSR(domains []string, order acme.ExtendedOrder, bundle bool, csr []byte, privateKeyPem []byte) (*Resource, error) { respOrder, err := c.core.Orders.UpdateForCSR(order.Finalize, csr) if err != nil { return nil, err } commonName := domains[0] certRes := &Resource{ Domain: commonName, CertURL: respOrder.Certificate, PrivateKey: privateKeyPem, } if respOrder.Status == acme.StatusValid { // if the certificate is available right away, short cut! ok, errR := c.checkResponse(respOrder, certRes, bundle) if errR != nil { return nil, errR } if ok { return certRes, nil } } timeout := c.options.Timeout if c.options.Timeout <= 0 { timeout = 30 * time.Second } err = wait.For("certificate", timeout, timeout/60, func() (bool, error) { ord, errW := c.core.Orders.Get(order.Location) if errW != nil { return false, errW } done, errW := c.checkResponse(ord, certRes, bundle) if errW != nil { return false, errW } return done, nil }) return certRes, err } // checkResponse 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 *Certifier) checkResponse(order acme.Order, certRes *Resource, bundle bool) (bool, error) { valid, err := checkOrderStatus(order) if err != nil || !valid { return valid, err } cert, issuer, err := c.core.Certificates.Get(order.Certificate, bundle) if err != nil { return false, err } log.Infof("[%s] Server responded with a certificate.", certRes.Domain) certRes.IssuerCertificate = issuer certRes.Certificate = cert certRes.CertURL = order.Certificate certRes.CertStableURL = order.Certificate return true, nil } // Revoke takes a PEM encoded certificate or bundle and tries to revoke it at the CA. func (c *Certifier) Revoke(cert []byte) error { certificates, err := certcrypto.ParsePEMBundle(cert) if err != nil { return err } x509Cert := certificates[0] if x509Cert.IsCA { return errors.New("certificate bundle starts with a CA certificate") } revokeMsg := acme.RevokeCertMessage{ Certificate: base64.RawURLEncoding.EncodeToString(x509Cert.Raw), } return c.core.Certificates.Revoke(revokeMsg) } // Renew takes a Resource 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 Resource should be non-nil. func (c *Certifier) Renew(certRes Resource, bundle, mustStaple bool) (*Resource, 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 := certcrypto.ParsePEMBundle(certRes.Certificate) if err != nil { return nil, err } x509Cert := certificates[0] if x509Cert.IsCA { return nil, fmt.Errorf("[%s] Certificate bundle starts with a CA certificate", certRes.Domain) } // This is just meant to be informal for the user. timeLeft := x509Cert.NotAfter.Sub(time.Now().UTC()) log.Infof("[%s] acme: Trying renewal with %d hours remaining", certRes.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(certRes.CSR) > 0 { csr, errP := certcrypto.PemDecodeTox509CSR(certRes.CSR) if errP != nil { return nil, errP } return c.ObtainForCSR(*csr, bundle) } var privateKey crypto.PrivateKey if certRes.PrivateKey != nil { privateKey, err = certcrypto.ParsePEMPrivateKey(certRes.PrivateKey) if err != nil { return nil, err } } query := ObtainRequest{ Domains: certcrypto.ExtractDomains(x509Cert), Bundle: bundle, PrivateKey: privateKey, MustStaple: mustStaple, } return c.Obtain(query) } // GetOCSP takes a PEM encoded cert or cert bundle returning the raw OCSP response, // the parsed response, and an error, if any. // // The returned []byte can be passed directly into the OCSPStaple property of a tls.Certificate. // If the bundle only contains the issued certificate, // this function will try to get the issuer certificate from the IssuingCertificateURL in the certificate. // // If the []byte and/or ocsp.Response return values are nil, the OCSP status may be assumed OCSPUnknown. func (c *Certifier) GetOCSP(bundle []byte) ([]byte, *ocsp.Response, error) { certificates, err := certcrypto.ParsePEMBundle(bundle) if err != nil { return nil, nil, err } // We expect the certificate slice to be ordered downwards the chain. // SRV CRT -> CA. We need to pull the leaf and issuer certs out of it, // which should always be the first two certificates. // If there's no OCSP server listed in the leaf cert, there's nothing to do. // And if we have only one certificate so far, we need to get the issuer cert. issuedCert := certificates[0] if len(issuedCert.OCSPServer) == 0 { return nil, nil, errors.New("no OCSP server specified in cert") } if len(certificates) == 1 { // TODO: build fallback. If this fails, check the remaining array entries. if len(issuedCert.IssuingCertificateURL) == 0 { return nil, nil, errors.New("no issuing certificate URL") } resp, errC := c.core.HTTPClient.Get(issuedCert.IssuingCertificateURL[0]) if errC != nil { return nil, nil, errC } defer resp.Body.Close() issuerBytes, errC := ioutil.ReadAll(http.MaxBytesReader(nil, resp.Body, maxBodySize)) if errC != nil { return nil, nil, errC } issuerCert, errC := x509.ParseCertificate(issuerBytes) if errC != nil { return nil, nil, errC } // Insert it into the slice on position 0 // We want it ordered right SRV CRT -> CA certificates = append(certificates, issuerCert) } issuerCert := certificates[1] // Finally kick off the OCSP request. ocspReq, err := ocsp.CreateRequest(issuedCert, issuerCert, nil) if err != nil { return nil, nil, err } resp, err := c.core.HTTPClient.Post(issuedCert.OCSPServer[0], "application/ocsp-request", bytes.NewReader(ocspReq)) if err != nil { return nil, nil, err } defer resp.Body.Close() ocspResBytes, err := ioutil.ReadAll(http.MaxBytesReader(nil, resp.Body, maxBodySize)) if err != nil { return nil, nil, err } ocspRes, err := ocsp.ParseResponse(ocspResBytes, issuerCert) if err != nil { return nil, nil, err } return ocspResBytes, ocspRes, nil } // Get attempts to fetch the certificate at the supplied URL. // The URL is the same as what would normally be supplied at the Resource's CertURL. // // The returned Resource will not have the PrivateKey and CSR fields populated as these will not be available. // // If bundle is true, the Certificate field in the returned Resource includes the issuer certificate. func (c *Certifier) Get(url string, bundle bool) (*Resource, error) { cert, issuer, err := c.core.Certificates.Get(url, bundle) if err != nil { return nil, err } // Parse the returned cert bundle so that we can grab the domain from the common name. x509Certs, err := certcrypto.ParsePEMBundle(cert) if err != nil { return nil, err } return &Resource{ Domain: x509Certs[0].Subject.CommonName, Certificate: cert, IssuerCertificate: issuer, CertURL: url, CertStableURL: url, }, nil } func checkOrderStatus(order acme.Order) (bool, error) { switch order.Status { case acme.StatusValid: return true, nil case acme.StatusInvalid: return false, order.Error default: return false, nil } } // https://tools.ietf.org/html/rfc8555#section-7.1.4 // The domain name MUST be encoded // in the form in which it would appear in a certificate. That is, it // MUST be encoded according to the rules in Section 7 of [RFC5280]. // // https://tools.ietf.org/html/rfc5280#section-7 func sanitizeDomain(domains []string) []string { var sanitizedDomains []string for _, domain := range domains { sanitizedDomain, err := idna.ToASCII(domain) if err != nil { log.Infof("skip domain %q: unable to sanitize (punnycode): %v", domain, err) } else { sanitizedDomains = append(sanitizedDomains, sanitizedDomain) } } return sanitizedDomains }