lego/acme/client.go

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package acme
import (
"crypto/rsa"
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"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
}
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// Interface for all challenge solvers to implement.
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type solver interface {
Solve(challenge challenge, domain string) error
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}
// 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)
}
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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}
solvers["tls-sni-01"] = &tlsSNIChallenge{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())
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regMsg := registrationMessage{
Resource: "new-reg",
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}
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
}
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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
}
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resp, err := c.jws.post(c.user.GetRegistration().URI, jsonBytes)
if err != nil {
return err
}
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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
}
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// 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")
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certs, err := c.requestCertificates(succeededChallenges, bundle)
for k, v := range err {
failures[k] = v
}
return certs, failures
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}
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// 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.
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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 {
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return CertificateResource{}, failures
}
errs := c.solveChallenges(challenges)
// If any challenge fails - return. Do not generate partial SAN certificates.
if len(errs) > 0 {
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return CertificateResource{}, errs
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}
logf("[INFO] acme: Validations succeeded; requesting certificates")
cert, err := c.requestCertificate(challenges, bundle)
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if err != nil {
for _, chln := range challenges {
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failures[chln.Domain] = err
}
}
return cert, failures
}
// RevokeCertificate takes a PEM encoded certificate or bundle and tries to revoke it at the CA.
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func (c *Client) RevokeCertificate(certificate []byte) error {
certificates, err := parsePEMBundle(certificate)
if err != nil {
return err
}
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x509Cert := certificates[0]
if x509Cert.IsCA {
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return fmt.Errorf("Certificate bundle starts with a CA certificate")
}
encodedCert := base64.URLEncoding.EncodeToString(x509Cert.Raw)
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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
}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
return handleHTTPError(resp)
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}
return nil
}
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// RenewCertificate takes a CertificateResource and tries to renew the certificate.
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// If the renewal process succeeds, the new certificate will ge returned in a new CertResource.
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// 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) {
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// 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)
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if err != nil {
return CertificateResource{}, err
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}
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x509Cert := certificates[0]
if x509Cert.IsCA {
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return CertificateResource{}, fmt.Errorf("[%s] Certificate bundle starts with a CA certificate", cert.Domain)
}
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// 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()))
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// 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)
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if err != nil {
return CertificateResource{}, err
}
defer resp.Body.Close()
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serverCertBytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
return CertificateResource{}, err
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}
serverCert, err := x509.ParseCertificate(serverCertBytes)
if err != nil {
return CertificateResource{}, err
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}
// 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 {
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// Success - append the issuer cert to the issued cert.
issuerCert = pemEncode(derCertificateBytes(issuerCert))
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issuedCert = append(issuedCert, issuerCert...)
cert.Certificate = issuedCert
}
}
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cert.Certificate = issuedCert
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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)
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}
return newCerts[0], nil
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}
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// Looks through the challenge combinations to find a solvable match.
// Then solves the challenges in series and returns.
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func (c *Client) solveChallenges(challenges []authorizationResource) map[string]error {
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// 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)
}
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}
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("[INFO] 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
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}
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// Get the challenges needed to proof our identifier to the ACME server.
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func (c *Client) getChallenges(domains []string) ([]authorizationResource, map[string]error) {
resc, errc := make(chan authorizationResource), make(chan domainError)
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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
}
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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}
}
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resp.Body.Close()
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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
}
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// 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.
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func (c *Client) requestCertificates(challenges []authorizationResource, bundle bool) ([]CertificateResource, map[string]error) {
resc, errc := make(chan CertificateResource), make(chan domainError)
for _, authz := range challenges {
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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)
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return certs, failures
}
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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 {
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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?
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csr, err := generateCsr(privKey.(*rsa.PrivateKey), commonName.Domain, san)
if err != nil {
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return CertificateResource{}, err
}
csrString := base64.URLEncoding.EncodeToString(csr)
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jsonBytes, err := json.Marshal(csrMessage{Resource: "new-cert", Csr: csrString, Authorizations: authURLs})
if err != nil {
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return CertificateResource{}, err
}
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resp, err := c.jws.post(commonName.NewCertURL, jsonBytes)
if err != nil {
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return CertificateResource{}, err
}
privateKeyPem := pemEncode(privKey)
cerRes := CertificateResource{
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Domain: commonName.Domain,
CertURL: resp.Header.Get("Location"),
PrivateKey: privateKeyPem}
for {
switch resp.StatusCode {
case 202:
case 201:
cert, err := ioutil.ReadAll(resp.Body)
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resp.Body.Close()
if err != nil {
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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.
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logf("[WARNING] acme: [%s] Could not bundle issuer certificate: %v", commonName.Domain, err)
} else {
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// Success - append the issuer cert to the issued cert.
issuerCert = pemEncode(derCertificateBytes(issuerCert))
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issuedCert = append(issuedCert, issuerCert...)
}
}
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cerRes.Certificate = issuedCert
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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 {
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return CertificateResource{}, err
}
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logf("[INFO] acme: [%s] Server responded with status 202; retrying after %ds", commonName.Domain, retryAfter)
time.Sleep(time.Duration(retryAfter) * time.Second)
break
default:
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return CertificateResource{}, handleHTTPError(resp)
}
resp, err = http.Get(cerRes.CertURL)
if err != nil {
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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
}