Leave only the HTTP/auth bits in localapi. Change-Id: I8e23fb417367f1e0e31483e2982c343ca74086ab Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>main
Brad Fitzpatrick
3 years ago
committed by
Brad Fitzpatrick
parent
9be8d15979
commit
6d8320a6e9
@ -0,0 +1,454 @@ |
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// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build !js
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package ipnlocal |
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import ( |
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"bytes" |
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"context" |
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"crypto" |
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"crypto/ecdsa" |
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"crypto/elliptic" |
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"crypto/rand" |
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"crypto/rsa" |
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"crypto/tls" |
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"crypto/x509" |
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"crypto/x509/pkix" |
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"encoding/json" |
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"encoding/pem" |
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"errors" |
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"fmt" |
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"io" |
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"log" |
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"net" |
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"os" |
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"path/filepath" |
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"runtime" |
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"strings" |
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"sync" |
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"time" |
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"golang.org/x/crypto/acme" |
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"tailscale.com/envknob" |
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"tailscale.com/ipn/ipnstate" |
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"tailscale.com/types/logger" |
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"tailscale.com/version" |
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"tailscale.com/version/distro" |
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) |
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// Process-wide cache. (A new *Handler is created per connection,
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// effectively per request)
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var ( |
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// acmeMu guards all ACME operations, so concurrent requests
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// for certs don't slam ACME. The first will go through and
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// populate the on-disk cache and the rest should use that.
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acmeMu sync.Mutex |
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renewMu sync.Mutex // lock order: don't hold acmeMu and renewMu at the same time
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lastRenewCheck = map[string]time.Time{} |
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) |
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// certDir returns (creating if needed) the directory in which cached
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// cert keypairs are stored.
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func (b *LocalBackend) certDir() (string, error) { |
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d := b.TailscaleVarRoot() |
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// As a workaround for Synology DSM6 not having a "var" directory, use the
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// app's "etc" directory (on a small partition) to hold certs at least.
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// See https://github.com/tailscale/tailscale/issues/4060#issuecomment-1186592251
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if d == "" && runtime.GOOS == "linux" && distro.Get() == distro.Synology && distro.DSMVersion() == 6 { |
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d = "/var/packages/Tailscale/etc" // base; we append "certs" below
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} |
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if d == "" { |
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return "", errors.New("no TailscaleVarRoot") |
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} |
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full := filepath.Join(d, "certs") |
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if err := os.MkdirAll(full, 0700); err != nil { |
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return "", err |
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} |
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return full, nil |
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} |
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var acmeDebug = envknob.RegisterBool("TS_DEBUG_ACME") |
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// getCertPEM gets the KeyPair for domain, either from cache, via the ACME
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// process, or from cache and kicking off an async ACME renewal.
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func (b *LocalBackend) GetCertPEM(ctx context.Context, domain string) (*TLSCertKeyPair, error) { |
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if !validLookingCertDomain(domain) { |
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return nil, errors.New("invalid domain") |
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} |
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logf := logger.WithPrefix(b.logf, fmt.Sprintf("cert(%q): ", domain)) |
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dir, err := b.certDir() |
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if err != nil { |
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logf("failed to get certDir: %v", err) |
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return nil, err |
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} |
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now := time.Now() |
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traceACME := func(v any) { |
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if !acmeDebug() { |
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return |
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} |
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j, _ := json.MarshalIndent(v, "", "\t") |
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log.Printf("acme %T: %s", v, j) |
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} |
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if pair, ok := getCertPEMCached(dir, domain, now); ok { |
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future := now.AddDate(0, 0, 14) |
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if shouldStartDomainRenewal(dir, domain, future) { |
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logf("starting async renewal") |
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// Start renewal in the background.
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go b.getCertPEM(context.Background(), logf, traceACME, dir, domain, future) |
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} |
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return pair, nil |
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} |
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pair, err := b.getCertPEM(ctx, logf, traceACME, dir, domain, now) |
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if err != nil { |
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logf("getCertPEM: %v", err) |
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return nil, err |
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} |
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return pair, nil |
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} |
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func shouldStartDomainRenewal(dir, domain string, future time.Time) bool { |
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renewMu.Lock() |
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defer renewMu.Unlock() |
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now := time.Now() |
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if last, ok := lastRenewCheck[domain]; ok && now.Sub(last) < time.Minute { |
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// We checked very recently. Don't bother reparsing &
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// validating the x509 cert.
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return false |
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} |
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lastRenewCheck[domain] = now |
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_, ok := getCertPEMCached(dir, domain, future) |
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return !ok |
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} |
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// TLSCertKeyPair is a TLS public and private key, and whether they were obtained
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// from cache or freshly obtained.
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type TLSCertKeyPair struct { |
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CertPEM []byte // public key, in PEM form
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KeyPEM []byte // private key, in PEM form
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Cached bool // whether result came from cache
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} |
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func keyFile(dir, domain string) string { return filepath.Join(dir, domain+".key") } |
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func certFile(dir, domain string) string { return filepath.Join(dir, domain+".crt") } |
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// getCertPEMCached returns a non-nil keyPair and true if a cached
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// keypair for domain exists on disk in dir that is valid at the
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// provided now time.
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func getCertPEMCached(dir, domain string, now time.Time) (p *TLSCertKeyPair, ok bool) { |
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if !validLookingCertDomain(domain) { |
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// Before we read files from disk using it, validate it's halfway
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// reasonable looking.
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return nil, false |
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} |
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if keyPEM, err := os.ReadFile(keyFile(dir, domain)); err == nil { |
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certPEM, _ := os.ReadFile(certFile(dir, domain)) |
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if validCertPEM(domain, keyPEM, certPEM, now) { |
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return &TLSCertKeyPair{CertPEM: certPEM, KeyPEM: keyPEM, Cached: true}, true |
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} |
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} |
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return nil, false |
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} |
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func (b *LocalBackend) getCertPEM(ctx context.Context, logf logger.Logf, traceACME func(any), dir, domain string, now time.Time) (*TLSCertKeyPair, error) { |
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acmeMu.Lock() |
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defer acmeMu.Unlock() |
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if p, ok := getCertPEMCached(dir, domain, now); ok { |
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return p, nil |
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} |
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key, err := acmeKey(dir) |
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if err != nil { |
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return nil, fmt.Errorf("acmeKey: %w", err) |
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} |
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ac := &acme.Client{ |
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Key: key, |
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UserAgent: "tailscaled/" + version.Long, |
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} |
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a, err := ac.GetReg(ctx, "" /* pre-RFC param */) |
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switch { |
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case err == nil: |
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// Great, already registered.
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logf("already had ACME account.") |
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case err == acme.ErrNoAccount: |
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a, err = ac.Register(ctx, new(acme.Account), acme.AcceptTOS) |
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if err == acme.ErrAccountAlreadyExists { |
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// Potential race. Double check.
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a, err = ac.GetReg(ctx, "" /* pre-RFC param */) |
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} |
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if err != nil { |
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return nil, fmt.Errorf("acme.Register: %w", err) |
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} |
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logf("registered ACME account.") |
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traceACME(a) |
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default: |
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return nil, fmt.Errorf("acme.GetReg: %w", err) |
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} |
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if a.Status != acme.StatusValid { |
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return nil, fmt.Errorf("unexpected ACME account status %q", a.Status) |
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} |
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// Before hitting LetsEncrypt, see if this is a domain that Tailscale will do DNS challenges for.
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st := b.StatusWithoutPeers() |
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if err := checkCertDomain(st, domain); err != nil { |
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return nil, err |
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} |
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order, err := ac.AuthorizeOrder(ctx, []acme.AuthzID{{Type: "dns", Value: domain}}) |
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if err != nil { |
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return nil, err |
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} |
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traceACME(order) |
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for _, aurl := range order.AuthzURLs { |
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az, err := ac.GetAuthorization(ctx, aurl) |
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if err != nil { |
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return nil, err |
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} |
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traceACME(az) |
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for _, ch := range az.Challenges { |
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if ch.Type == "dns-01" { |
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rec, err := ac.DNS01ChallengeRecord(ch.Token) |
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if err != nil { |
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return nil, err |
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} |
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key := "_acme-challenge." + domain |
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var resolver net.Resolver |
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var ok bool |
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txts, _ := resolver.LookupTXT(ctx, key) |
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for _, txt := range txts { |
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if txt == rec { |
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ok = true |
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logf("TXT record already existed") |
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break |
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} |
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} |
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if !ok { |
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logf("starting SetDNS call...") |
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err = b.SetDNS(ctx, key, rec) |
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if err != nil { |
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return nil, fmt.Errorf("SetDNS %q => %q: %w", key, rec, err) |
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} |
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logf("did SetDNS") |
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} |
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chal, err := ac.Accept(ctx, ch) |
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if err != nil { |
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return nil, fmt.Errorf("Accept: %v", err) |
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} |
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traceACME(chal) |
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break |
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} |
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} |
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} |
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orderURI := order.URI |
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order, err = ac.WaitOrder(ctx, orderURI) |
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if err != nil { |
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if ctx.Err() != nil { |
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return nil, ctx.Err() |
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} |
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if oe, ok := err.(*acme.OrderError); ok { |
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logf("acme: WaitOrder: OrderError status %q", oe.Status) |
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} else { |
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logf("acme: WaitOrder error: %v", err) |
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} |
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return nil, err |
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} |
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traceACME(order) |
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certPrivKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader) |
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if err != nil { |
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return nil, err |
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} |
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var privPEM bytes.Buffer |
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if err := encodeECDSAKey(&privPEM, certPrivKey); err != nil { |
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return nil, err |
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} |
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if err := os.WriteFile(keyFile(dir, domain), privPEM.Bytes(), 0600); err != nil { |
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return nil, err |
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} |
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csr, err := certRequest(certPrivKey, domain, nil) |
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if err != nil { |
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return nil, err |
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} |
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logf("requesting cert...") |
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der, _, err := ac.CreateOrderCert(ctx, order.FinalizeURL, csr, true) |
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if err != nil { |
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return nil, fmt.Errorf("CreateOrder: %v", err) |
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} |
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logf("got cert") |
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var certPEM bytes.Buffer |
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for _, b := range der { |
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pb := &pem.Block{Type: "CERTIFICATE", Bytes: b} |
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if err := pem.Encode(&certPEM, pb); err != nil { |
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return nil, err |
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} |
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} |
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if err := os.WriteFile(certFile(dir, domain), certPEM.Bytes(), 0644); err != nil { |
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return nil, err |
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} |
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return &TLSCertKeyPair{CertPEM: certPEM.Bytes(), KeyPEM: privPEM.Bytes()}, nil |
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} |
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// certRequest generates a CSR for the given common name cn and optional SANs.
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func certRequest(key crypto.Signer, cn string, ext []pkix.Extension, san ...string) ([]byte, error) { |
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req := &x509.CertificateRequest{ |
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Subject: pkix.Name{CommonName: cn}, |
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DNSNames: san, |
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ExtraExtensions: ext, |
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} |
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return x509.CreateCertificateRequest(rand.Reader, req, key) |
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} |
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func encodeECDSAKey(w io.Writer, key *ecdsa.PrivateKey) error { |
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b, err := x509.MarshalECPrivateKey(key) |
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if err != nil { |
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return err |
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} |
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pb := &pem.Block{Type: "EC PRIVATE KEY", Bytes: b} |
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return pem.Encode(w, pb) |
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} |
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// parsePrivateKey is a copy of x/crypto/acme's parsePrivateKey.
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//
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// Attempt to parse the given private key DER block. OpenSSL 0.9.8 generates
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// PKCS#1 private keys by default, while OpenSSL 1.0.0 generates PKCS#8 keys.
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// OpenSSL ecparam generates SEC1 EC private keys for ECDSA. We try all three.
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//
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// Inspired by parsePrivateKey in crypto/tls/tls.go.
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func parsePrivateKey(der []byte) (crypto.Signer, error) { |
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if key, err := x509.ParsePKCS1PrivateKey(der); err == nil { |
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return key, nil |
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} |
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if key, err := x509.ParsePKCS8PrivateKey(der); err == nil { |
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switch key := key.(type) { |
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case *rsa.PrivateKey: |
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return key, nil |
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case *ecdsa.PrivateKey: |
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return key, nil |
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default: |
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return nil, errors.New("acme/autocert: unknown private key type in PKCS#8 wrapping") |
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} |
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} |
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if key, err := x509.ParseECPrivateKey(der); err == nil { |
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return key, nil |
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} |
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return nil, errors.New("acme/autocert: failed to parse private key") |
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} |
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func acmeKey(dir string) (crypto.Signer, error) { |
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pemName := filepath.Join(dir, "acme-account.key.pem") |
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if v, err := os.ReadFile(pemName); err == nil { |
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priv, _ := pem.Decode(v) |
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if priv == nil || !strings.Contains(priv.Type, "PRIVATE") { |
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return nil, errors.New("acme/autocert: invalid account key found in cache") |
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} |
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return parsePrivateKey(priv.Bytes) |
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} |
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privKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader) |
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if err != nil { |
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return nil, err |
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} |
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var pemBuf bytes.Buffer |
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if err := encodeECDSAKey(&pemBuf, privKey); err != nil { |
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return nil, err |
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} |
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if err := os.WriteFile(pemName, pemBuf.Bytes(), 0600); err != nil { |
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return nil, err |
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} |
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return privKey, nil |
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} |
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func validCertPEM(domain string, keyPEM, certPEM []byte, now time.Time) bool { |
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if len(keyPEM) == 0 || len(certPEM) == 0 { |
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return false |
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} |
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tlsCert, err := tls.X509KeyPair(certPEM, keyPEM) |
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if err != nil { |
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return false |
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} |
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var leaf *x509.Certificate |
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intermediates := x509.NewCertPool() |
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for i, certDER := range tlsCert.Certificate { |
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cert, err := x509.ParseCertificate(certDER) |
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if err != nil { |
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return false |
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} |
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if i == 0 { |
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leaf = cert |
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} else { |
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intermediates.AddCert(cert) |
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} |
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} |
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if leaf == nil { |
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return false |
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} |
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_, err = leaf.Verify(x509.VerifyOptions{ |
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DNSName: domain, |
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CurrentTime: now, |
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Intermediates: intermediates, |
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}) |
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return err == nil |
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} |
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// validLookingCertDomain reports whether name looks like a valid domain name that
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// we might be able to get a cert for.
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//
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// It's a light check primarily for double checking before it's used
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// as part of a filesystem path. The actual validation happens in checkCertDomain.
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func validLookingCertDomain(name string) bool { |
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if name == "" || |
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strings.Contains(name, "..") || |
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strings.ContainsAny(name, ":/\\\x00") || |
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!strings.Contains(name, ".") { |
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return false |
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} |
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return true |
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} |
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func checkCertDomain(st *ipnstate.Status, domain string) error { |
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if domain == "" { |
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return errors.New("missing domain name") |
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} |
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for _, d := range st.CertDomains { |
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if d == domain { |
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return nil |
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} |
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} |
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// Transitional way while server doesn't yet populate CertDomains: also permit the client
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// attempting Self.DNSName.
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okay := st.CertDomains[:len(st.CertDomains):len(st.CertDomains)] |
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if st.Self != nil { |
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if v := strings.Trim(st.Self.DNSName, "."); v != "" { |
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if v == domain { |
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return nil |
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} |
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okay = append(okay, v) |
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} |
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} |
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switch len(okay) { |
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case 0: |
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return errors.New("your Tailscale account does not support getting TLS certs") |
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case 1: |
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return fmt.Errorf("invalid domain %q; only %q is permitted", domain, okay[0]) |
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default: |
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return fmt.Errorf("invalid domain %q; must be one of %q", domain, okay) |
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} |
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} |
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