lego/acme/client.go
2016-01-08 10:14:41 +01:00

619 lines
19 KiB
Go

package acme
import (
"crypto"
"crypto/rsa"
"crypto/x509"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"log"
"net"
"regexp"
"strconv"
"strings"
"time"
)
var (
// Logger is an optional custom logger.
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
}
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
keyBits int
issuerCert []byte
solvers map[string]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. It will
// generate private keys for certificates of size keyBits.
func NewClient(caDirURL string, user User, keyBits int) (*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)
}
var dir directory
if _, err := getJSON(caDirURL, &dir); err != nil {
return nil, fmt.Errorf("get directory at '%s': %v", caDirURL, 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, validate: validate}
solvers["tls-sni-01"] = &tlsSNIChallenge{jws: jws, validate: validate}
return &Client{directory: dir, user: user, jws: jws, keyBits: keyBits, solvers: solvers}, 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.
func (c *Client) SetHTTPAddress(iface string) error {
host, port, err := net.SplitHostPort(iface)
if err != nil {
return err
}
if chlng, ok := c.solvers["http-01"]; ok {
chlng.(*httpChallenge).iface = host
chlng.(*httpChallenge).port = port
}
return nil
}
// SetTLSAddress specifies a custom interface:port to be used for TLS based challenges.
// If this option is not used, the default port 443 and all interfaces will be used.
// To only specify a port and no interface use the ":port" notation.
func (c *Client) SetTLSAddress(iface string) error {
host, port, err := net.SplitHostPort(iface)
if err != nil {
return err
}
if chlng, ok := c.solvers["tls-sni-01"]; ok {
chlng.(*tlsSNIChallenge).iface = host
chlng.(*tlsSNIChallenge).port = port
}
return nil
}
// ExcludeChallenges explicitly removes challenges from the pool for solving.
func (c *Client) ExcludeChallenges(challenges []string) {
// Loop through all challenges and delete the requested one if found.
for _, challenge := range challenges {
if _, ok := c.solvers[challenge]; ok {
delete(c.solvers, challenge)
}
}
}
// 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{}
}
var serverReg Registration
hdr, err := postJSON(c.jws, c.directory.NewRegURL, regMsg, &serverReg)
if err != nil {
return nil, err
}
reg := &RegistrationResource{Body: serverReg}
links := parseLinks(hdr["Link"])
reg.URI = hdr.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"
_, err := postJSON(c.jws, c.user.GetRegistration().URI, c.user.GetRegistration().Body, nil)
return err
}
// 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) (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, ", "))
}
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][%s] acme: Validations succeeded; requesting certificates", strings.Join(domains, ", "))
cert, err := c.requestCertificate(challenges, bundle, privKey)
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)
_, err = postJSON(c.jws, c.directory.RevokeCertURL, revokeCertMessage{Resource: "revoke-cert", 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 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()))
// The first step of renewal is to check if we get a renewed cert
// directly from the cert URL.
resp, err := httpGet(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][%s] acme: Server responded with renewed certificate", cert.Domain)
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][%s] acme: 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
}
var privKey crypto.PrivateKey
if cert.PrivateKey != nil {
privKey, err = parsePEMPrivateKey(cert.PrivateKey)
if err != nil {
return CertificateResource{}, err
}
}
newCert, failures := c.ObtainCertificate([]string{cert.Domain}, bundle, privKey)
return newCert, failures[cert.Domain]
}
// 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("[%s] acme: Could not determine solvers", 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("[INFO][%s] acme: Could not find solver for: %s", domain, 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) {
authMsg := authorization{Resource: "new-authz", Identifier: identifier{Type: "dns", Value: domain}}
var authz authorization
hdr, err := postJSON(c.jws, c.user.GetRegistration().NewAuthzURL, authMsg, &authz)
if err != nil {
errc <- domainError{Domain: domain, Error: err}
return
}
links := parseLinks(hdr["Link"])
if links["next"] == "" {
logf("[ERROR][%s] acme: Server did not provide next link to proceed", domain)
return
}
resc <- authorizationResource{Body: authz, NewCertURL: links["next"], AuthURL: hdr.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
}
func (c *Client) requestCertificate(authz []authorizationResource, bundle bool, privKey crypto.PrivateKey) (CertificateResource, error) {
if len(authz) == 0 {
return CertificateResource{}, errors.New("Passed no authorizations to requestCertificate!")
}
commonName := authz[0]
var err error
if privKey == nil {
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(limitReader(resp.Body, 1024*1024))
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][%s] acme: 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("[INFO][%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][%s] acme: 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 = httpGet(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 := httpGet(url)
if err != nil {
return nil, err
}
defer resp.Body.Close()
issuerBytes, err := ioutil.ReadAll(limitReader(resp.Body, 1024*1024))
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
}
// validate makes the ACME server start validating a
// challenge response, only returning once it is done.
func validate(j *jws, domain, uri string, chlng challenge) error {
var challengeResponse challenge
hdr, err := postJSON(j, uri, chlng, &challengeResponse)
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 challengeResponse.Status {
case "valid":
logf("[INFO][%s] The server validated our request", domain)
return nil
case "pending":
break
case "invalid":
return handleChallengeError(challengeResponse)
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 = 1
}
time.Sleep(time.Duration(ra) * time.Second)
hdr, err = getJSON(uri, &challengeResponse)
if err != nil {
return err
}
}
}