360 lines
11 KiB
Go
360 lines
11 KiB
Go
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package certmagic
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import (
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"context"
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"crypto/x509"
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"errors"
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"fmt"
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"log"
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"net/http"
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"net/url"
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"strings"
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"time"
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"github.com/go-acme/lego/v3/acme"
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"github.com/go-acme/lego/v3/certificate"
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"github.com/go-acme/lego/v3/challenge"
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"github.com/go-acme/lego/v3/challenge/dns01"
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)
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// ACMEManager gets certificates using ACME. It implements the PreChecker,
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// Issuer, and Revoker interfaces.
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//
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// It is NOT VALID to use an ACMEManager without calling NewACMEManager().
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// It fills in default values from DefaultACME as well as setting up
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// internal state that is necessary for valid use. Always call
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// NewACMEManager() to get a valid ACMEManager value.
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type ACMEManager struct {
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// The endpoint of the directory for the ACME
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// CA we are to use
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CA string
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// TestCA is the endpoint of the directory for
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// an ACME CA to use to test domain validation,
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// but any certs obtained from this CA are
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// discarded
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TestCA string
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// The email address to use when creating or
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// selecting an existing ACME server account
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Email string
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// Set to true if agreed to the CA's
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// subscriber agreement
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Agreed bool
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// An optional external account to associate
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// with this ACME account
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ExternalAccount *ExternalAccountBinding
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// Disable all HTTP challenges
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DisableHTTPChallenge bool
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// Disable all TLS-ALPN challenges
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DisableTLSALPNChallenge bool
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// The host (ONLY the host, not port) to listen
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// on if necessary to start a listener to solve
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// an ACME challenge
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ListenHost string
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// The alternate port to use for the ACME HTTP
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// challenge; if non-empty, this port will be
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// used instead of HTTPChallengePort to spin up
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// a listener for the HTTP challenge
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AltHTTPPort int
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// The alternate port to use for the ACME
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// TLS-ALPN challenge; the system must forward
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// TLSALPNChallengePort to this port for
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// challenge to succeed
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AltTLSALPNPort int
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// The DNS provider to use when solving the
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// ACME DNS challenge
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DNSProvider challenge.Provider
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// The ChallengeOption struct to provide
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// custom precheck or name resolution options
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// for DNS challenge validation and execution
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DNSChallengeOption dns01.ChallengeOption
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// TrustedRoots specifies a pool of root CA
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// certificates to trust when communicating
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// over a network to a peer.
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TrustedRoots *x509.CertPool
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// The maximum amount of time to allow for
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// obtaining a certificate. If empty, the
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// default from the underlying lego lib is
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// used. If set, it must not be too low so
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// as to cancel orders too early, running
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// the risk of rate limiting.
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CertObtainTimeout time.Duration
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config *Config
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}
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// NewACMEManager constructs a valid ACMEManager based on a template
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// configuration; any empty values will be filled in by defaults in
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// DefaultACME. The associated config is also required.
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//
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// Typically, you'll create the Config first, then call NewACMEManager(),
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// then assign the return value to the Issuer/Revoker fields of the Config.
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func NewACMEManager(cfg *Config, template ACMEManager) *ACMEManager {
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if cfg == nil {
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panic("cannot make valid ACMEManager without an associated CertMagic config")
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}
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if template.CA == "" {
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template.CA = DefaultACME.CA
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}
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if template.TestCA == "" {
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template.TestCA = DefaultACME.TestCA
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}
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if template.Email == "" {
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template.Email = DefaultACME.Email
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}
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if !template.Agreed {
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template.Agreed = DefaultACME.Agreed
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}
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if !template.DisableHTTPChallenge {
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template.DisableHTTPChallenge = DefaultACME.DisableHTTPChallenge
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}
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if !template.DisableTLSALPNChallenge {
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template.DisableTLSALPNChallenge = DefaultACME.DisableTLSALPNChallenge
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}
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if template.ListenHost == "" {
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template.ListenHost = DefaultACME.ListenHost
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}
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if template.AltHTTPPort == 0 {
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template.AltHTTPPort = DefaultACME.AltHTTPPort
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}
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if template.AltTLSALPNPort == 0 {
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template.AltTLSALPNPort = DefaultACME.AltTLSALPNPort
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}
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if template.DNSProvider == nil {
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template.DNSProvider = DefaultACME.DNSProvider
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}
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if template.DNSChallengeOption == nil {
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template.DNSChallengeOption = DefaultACME.DNSChallengeOption
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}
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if template.TrustedRoots == nil {
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template.TrustedRoots = DefaultACME.TrustedRoots
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}
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if template.CertObtainTimeout == 0 {
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template.CertObtainTimeout = DefaultACME.CertObtainTimeout
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}
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template.config = cfg
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return &template
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}
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// IssuerKey returns the unique issuer key for the
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// confgured CA endpoint.
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func (am *ACMEManager) IssuerKey() string {
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return am.issuerKey(am.CA)
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}
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func (am *ACMEManager) issuerKey(ca string) string {
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key := ca
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if caURL, err := url.Parse(key); err == nil {
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key = caURL.Host
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if caURL.Path != "" {
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// keep the path, but make sure it's a single
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// component (i.e. no forward slashes, and for
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// good measure, no backward slashes either)
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const hyphen = "-"
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repl := strings.NewReplacer(
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"/", hyphen,
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"\\", hyphen,
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)
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path := strings.Trim(repl.Replace(caURL.Path), hyphen)
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if path != "" {
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key += hyphen + path
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}
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}
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}
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return key
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}
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// PreCheck performs a few simple checks before obtaining or
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// renewing a certificate with ACME, and returns whether this
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// batch is eligible for certificates if using Let's Encrypt.
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// It also ensures that an email address is available.
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func (am *ACMEManager) PreCheck(names []string, interactive bool) error {
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letsEncrypt := strings.Contains(am.CA, "api.letsencrypt.org")
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if letsEncrypt {
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for _, name := range names {
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if !SubjectQualifiesForPublicCert(name) {
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return fmt.Errorf("subject does not qualify for a Let's Encrypt certificate: %s", name)
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}
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}
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}
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return am.getEmail(interactive)
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}
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// Issue implements the Issuer interface. It obtains a certificate for the given csr using
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// the ACME configuration am.
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func (am *ACMEManager) Issue(ctx context.Context, csr *x509.CertificateRequest) (*IssuedCertificate, error) {
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if am.config == nil {
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panic("missing config pointer (must use NewACMEManager)")
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}
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var isRetry bool
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if attempts, ok := ctx.Value(AttemptsCtxKey).(*int); ok {
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isRetry = *attempts > 0
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}
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cert, usedTestCA, err := am.doIssue(ctx, csr, isRetry)
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if err != nil {
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return nil, err
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}
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// important to note that usedTestCA is not necessarily the same as isRetry
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// (usedTestCA can be true if the main CA and the test CA happen to be the same)
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if isRetry && usedTestCA && am.CA != am.TestCA {
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// succeeded with testing endpoint, so try again with production endpoint
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// (only if the production endpoint is different from the testing endpoint)
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// TODO: This logic is imperfect and could benefit from some refinement.
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// The two CA endpoints likely have different states, which could cause one
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// to succeed and the other to fail, even if it's not a validation error.
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// Two common cases would be:
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// 1) Rate limiter state. This is more likely to cause prod to fail while
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// staging succeeds, since prod usually has tighter rate limits. Thus, if
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// initial attempt failed in prod due to rate limit, first retry (on staging)
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// might succeed, and then trying prod again right way would probably still
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// fail; normally this would terminate retries but the right thing to do in
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// this case is to back off and retry again later. We could refine this logic
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// to stick with the production endpoint on retries unless the error changes.
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// 2) Cached authorizations state. If a domain validates successfully with
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// one endpoint, but then the other endpoint is used, it might fail, e.g. if
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// DNS was just changed or is still propagating. In this case, the second CA
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// should continue to be retried with backoff, without switching back to the
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// other endpoint. This is more likely to happen if a user is testing with
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// the staging CA as the main CA, then changes their configuration once they
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// think they are ready for the production endpoint.
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cert, _, err = am.doIssue(ctx, csr, false)
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if err != nil {
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// succeeded with test CA but failed just now with the production CA;
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// either we are observing differing internal states of each CA that will
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// work out with time, or there is a bug/misconfiguration somewhere
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// externally; it is hard to tell which! one easy cue is whether the
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// error is specifically a 429 (Too Many Requests); if so, we should
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// probably keep retrying
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var acmeErr acme.ProblemDetails
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if errors.As(err, &acmeErr) {
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if acmeErr.HTTPStatus == http.StatusTooManyRequests {
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// DON'T abort retries; the test CA succeeded (even
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// if it's cached, it recently succeeded!) so we just
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// need to keep trying (with backoff) until this CA's
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// rate limits expire...
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// TODO: as mentioned in comment above, we would benefit
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// by pinning the main CA at this point instead of
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// needlessly retrying with the test CA first each time
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return nil, err
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}
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}
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return nil, ErrNoRetry{err}
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}
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}
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return cert, err
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}
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func (am *ACMEManager) doIssue(ctx context.Context, csr *x509.CertificateRequest, useTestCA bool) (*IssuedCertificate, bool, error) {
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client, err := am.newACMEClientWithRetry(useTestCA)
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if err != nil {
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return nil, false, err
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}
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usingTestCA := client.usingTestCA()
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nameSet := namesFromCSR(csr)
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if !useTestCA {
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if err := client.throttle(ctx, nameSet); err != nil {
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return nil, usingTestCA, err
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}
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}
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certRes, err := client.tryAllEnabledChallenges(ctx, csr)
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if err != nil {
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return nil, usingTestCA, fmt.Errorf("%v %w", nameSet, err)
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}
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ic := &IssuedCertificate{
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Certificate: certRes.Certificate,
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Metadata: certRes,
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}
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return ic, usingTestCA, nil
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}
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func (c *acmeClient) tryAllEnabledChallenges(ctx context.Context, csr *x509.CertificateRequest) (*certificate.Resource, error) {
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// start with all enabled challenges
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challenges := c.initialChallenges()
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if len(challenges) == 0 {
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return nil, fmt.Errorf("no challenge types enabled")
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}
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// try while a challenge type is still available
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var cert *certificate.Resource
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var err error
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for len(challenges) > 0 {
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var chosenChallenge challenge.Type
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chosenChallenge, challenges = c.nextChallenge(challenges)
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cert, err = c.acmeClient.Certificate.ObtainForCSR(*csr, true)
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if err == nil {
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return cert, nil
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}
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log.Printf("[ERROR] %s (challenge=%s remaining=%v)", err, chosenChallenge, challenges)
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time.Sleep(2 * time.Second)
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}
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return cert, err
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}
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// Revoke implements the Revoker interface. It revokes the given certificate.
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func (am *ACMEManager) Revoke(ctx context.Context, cert CertificateResource) error {
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client, err := am.newACMEClient(false, false)
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if err != nil {
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return err
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}
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meta := cert.IssuerData.(map[string]interface{})
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cr := certificate.Resource{
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Domain: meta["domain"].(string),
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CertURL: meta["certUrl"].(string),
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CertStableURL: meta["certStableURL"].(string),
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}
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return client.revoke(ctx, cr)
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}
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// ExternalAccountBinding contains information for
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// binding an external account to an ACME account.
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type ExternalAccountBinding struct {
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KeyID string
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HMAC []byte
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}
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// DefaultACME specifies the default settings
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// to use for ACMEManagers.
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var DefaultACME = ACMEManager{
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CA: LetsEncryptProductionCA,
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TestCA: LetsEncryptStagingCA,
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}
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// Some well-known CA endpoints available to use.
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const (
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LetsEncryptStagingCA = "https://acme-staging-v02.api.letsencrypt.org/directory"
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LetsEncryptProductionCA = "https://acme-v02.api.letsencrypt.org/directory"
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)
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// prefixACME is the storage key prefix used for ACME-specific assets.
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const prefixACME = "acme"
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// Interface guards
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var (
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_ PreChecker = (*ACMEManager)(nil)
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_ Issuer = (*ACMEManager)(nil)
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_ Revoker = (*ACMEManager)(nil)
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)
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