mirror of
https://github.com/go-gitea/gitea.git
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624 lines
19 KiB
Go
624 lines
19 KiB
Go
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// Copyright 2015 Matthew Holt
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package certmagic
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import (
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"context"
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"crypto/tls"
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"encoding/json"
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"fmt"
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"log"
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"net"
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"net/http"
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"path"
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"runtime"
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"strings"
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"sync"
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"sync/atomic"
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"time"
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"github.com/libdns/libdns"
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"github.com/mholt/acmez"
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"github.com/mholt/acmez/acme"
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)
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// httpSolver solves the HTTP challenge. It must be
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// associated with a config and an address to use
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// for solving the challenge. If multiple httpSolvers
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// are initialized concurrently, the first one to
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// begin will start the server, and the last one to
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// finish will stop the server. This solver must be
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// wrapped by a distributedSolver to work properly,
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// because the only way the HTTP challenge handler
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// can access the keyAuth material is by loading it
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// from storage, which is done by distributedSolver.
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type httpSolver struct {
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closed int32 // accessed atomically
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acmeManager *ACMEManager
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address string
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}
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// Present starts an HTTP server if none is already listening on s.address.
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func (s *httpSolver) Present(ctx context.Context, _ acme.Challenge) error {
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solversMu.Lock()
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defer solversMu.Unlock()
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si := getSolverInfo(s.address)
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si.count++
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if si.listener != nil {
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return nil // already be served by us
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}
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// notice the unusual error handling here; we
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// only continue to start a challenge server if
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// we got a listener; in all other cases return
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ln, err := robustTryListen(s.address)
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if ln == nil {
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return err
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}
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// successfully bound socket, so save listener and start key auth HTTP server
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si.listener = ln
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go s.serve(si)
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return nil
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}
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// serve is an HTTP server that serves only HTTP challenge responses.
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func (s *httpSolver) serve(si *solverInfo) {
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defer func() {
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if err := recover(); err != nil {
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buf := make([]byte, stackTraceBufferSize)
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buf = buf[:runtime.Stack(buf, false)]
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log.Printf("panic: http solver server: %v\n%s", err, buf)
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}
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}()
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defer close(si.done)
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httpServer := &http.Server{Handler: s.acmeManager.HTTPChallengeHandler(http.NewServeMux())}
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httpServer.SetKeepAlivesEnabled(false)
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err := httpServer.Serve(si.listener)
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if err != nil && atomic.LoadInt32(&s.closed) != 1 {
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log.Printf("[ERROR] key auth HTTP server: %v", err)
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}
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}
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// CleanUp cleans up the HTTP server if it is the last one to finish.
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func (s *httpSolver) CleanUp(ctx context.Context, _ acme.Challenge) error {
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solversMu.Lock()
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defer solversMu.Unlock()
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si := getSolverInfo(s.address)
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si.count--
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if si.count == 0 {
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// last one out turns off the lights
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atomic.StoreInt32(&s.closed, 1)
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if si.listener != nil {
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si.listener.Close()
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<-si.done
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}
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delete(solvers, s.address)
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}
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return nil
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}
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// tlsALPNSolver is a type that can solve TLS-ALPN challenges.
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// It must have an associated config and address on which to
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// serve the challenge.
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type tlsALPNSolver struct {
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config *Config
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address string
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}
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// Present adds the certificate to the certificate cache and, if
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// needed, starts a TLS server for answering TLS-ALPN challenges.
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func (s *tlsALPNSolver) Present(ctx context.Context, chal acme.Challenge) error {
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// load the certificate into the cache; this isn't strictly necessary
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// if we're using the distributed solver since our GetCertificate
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// function will check storage for the keyAuth anyway, but it seems
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// like loading it into the cache is the right thing to do
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cert, err := acmez.TLSALPN01ChallengeCert(chal)
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if err != nil {
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return err
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}
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certHash := hashCertificateChain(cert.Certificate)
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s.config.certCache.mu.Lock()
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s.config.certCache.cache[tlsALPNCertKeyName(chal.Identifier.Value)] = Certificate{
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Certificate: *cert,
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Names: []string{chal.Identifier.Value},
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hash: certHash, // perhaps not necesssary
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}
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s.config.certCache.mu.Unlock()
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// the rest of this function increments the
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// challenge count for the solver at this
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// listener address, and if necessary, starts
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// a simple TLS server
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solversMu.Lock()
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defer solversMu.Unlock()
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si := getSolverInfo(s.address)
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si.count++
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if si.listener != nil {
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return nil // already be served by us
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}
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// notice the unusual error handling here; we
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// only continue to start a challenge server if
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// we got a listener; in all other cases return
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ln, err := robustTryListen(s.address)
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if ln == nil {
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return err
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}
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// we were able to bind the socket, so make it into a TLS
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// listener, store it with the solverInfo, and start the
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// challenge server
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si.listener = tls.NewListener(ln, s.config.TLSConfig())
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go func() {
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defer func() {
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if err := recover(); err != nil {
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buf := make([]byte, stackTraceBufferSize)
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buf = buf[:runtime.Stack(buf, false)]
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log.Printf("panic: tls-alpn solver server: %v\n%s", err, buf)
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}
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}()
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defer close(si.done)
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for {
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conn, err := si.listener.Accept()
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if err != nil {
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if atomic.LoadInt32(&si.closed) == 1 {
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return
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}
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log.Printf("[ERROR] TLS-ALPN challenge server: accept: %v", err)
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continue
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}
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go s.handleConn(conn)
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}
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}()
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return nil
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}
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// handleConn completes the TLS handshake and then closes conn.
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func (*tlsALPNSolver) handleConn(conn net.Conn) {
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defer func() {
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if err := recover(); err != nil {
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buf := make([]byte, stackTraceBufferSize)
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buf = buf[:runtime.Stack(buf, false)]
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log.Printf("panic: tls-alpn solver handler: %v\n%s", err, buf)
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}
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}()
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defer conn.Close()
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tlsConn, ok := conn.(*tls.Conn)
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if !ok {
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log.Printf("[ERROR] TLS-ALPN challenge server: expected tls.Conn but got %T: %#v", conn, conn)
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return
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}
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err := tlsConn.Handshake()
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if err != nil {
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log.Printf("[ERROR] TLS-ALPN challenge server: handshake: %v", err)
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return
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}
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}
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// CleanUp removes the challenge certificate from the cache, and if
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// it is the last one to finish, stops the TLS server.
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func (s *tlsALPNSolver) CleanUp(ctx context.Context, chal acme.Challenge) error {
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s.config.certCache.mu.Lock()
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delete(s.config.certCache.cache, tlsALPNCertKeyName(chal.Identifier.Value))
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s.config.certCache.mu.Unlock()
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solversMu.Lock()
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defer solversMu.Unlock()
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si := getSolverInfo(s.address)
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si.count--
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if si.count == 0 {
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// last one out turns off the lights
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atomic.StoreInt32(&si.closed, 1)
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if si.listener != nil {
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si.listener.Close()
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<-si.done
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}
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delete(solvers, s.address)
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}
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return nil
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}
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// tlsALPNCertKeyName returns the key to use when caching a cert
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// for use with the TLS-ALPN ACME challenge. It is simply to help
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// avoid conflicts (although at time of writing, there shouldn't
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// be, since the cert cache is keyed by hash of certificate chain).
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func tlsALPNCertKeyName(sniName string) string {
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return sniName + ":acme-tls-alpn"
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}
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// DNS01Solver is a type that makes libdns providers usable
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// as ACME dns-01 challenge solvers.
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// See https://github.com/libdns/libdns
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type DNS01Solver struct {
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// The implementation that interacts with the DNS
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// provider to set or delete records. (REQUIRED)
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DNSProvider ACMEDNSProvider
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// The TTL for the temporary challenge records.
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TTL time.Duration
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// Maximum time to wait for temporary record to appear.
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PropagationTimeout time.Duration
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// Preferred DNS resolver(s) to use when doing DNS lookups.
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Resolvers []string
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txtRecords map[string]dnsPresentMemory // keyed by domain name
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txtRecordsMu sync.Mutex
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}
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// Present creates the DNS TXT record for the given ACME challenge.
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func (s *DNS01Solver) Present(ctx context.Context, challenge acme.Challenge) error {
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dnsName := challenge.DNS01TXTRecordName()
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keyAuth := challenge.DNS01KeyAuthorization()
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rec := libdns.Record{
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Type: "TXT",
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Name: dnsName,
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Value: keyAuth,
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TTL: s.TTL,
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}
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// multiple identifiers can have the same ACME challenge
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// domain (e.g. example.com and *.example.com) so we need
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// to ensure that we don't solve those concurrently and
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// step on each challenges' metaphorical toes; see
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// https://github.com/caddyserver/caddy/issues/3474
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activeDNSChallenges.Lock(dnsName)
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zone, err := findZoneByFQDN(dnsName, recursiveNameservers(s.Resolvers))
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if err != nil {
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return fmt.Errorf("could not determine zone for domain %q: %v", dnsName, err)
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}
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results, err := s.DNSProvider.AppendRecords(ctx, zone, []libdns.Record{rec})
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if err != nil {
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return fmt.Errorf("adding temporary record for zone %s: %w", zone, err)
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}
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if len(results) != 1 {
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return fmt.Errorf("expected one record, got %d: %v", len(results), results)
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}
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// remember the record and zone we got so we can clean up more efficiently
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s.txtRecordsMu.Lock()
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if s.txtRecords == nil {
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s.txtRecords = make(map[string]dnsPresentMemory)
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}
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s.txtRecords[dnsName] = dnsPresentMemory{dnsZone: zone, rec: results[0]}
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s.txtRecordsMu.Unlock()
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return nil
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}
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// Wait blocks until the TXT record created in Present() appears in
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// authoritative lookups, i.e. until it has propagated, or until
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// timeout, whichever is first.
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func (s *DNS01Solver) Wait(ctx context.Context, challenge acme.Challenge) error {
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dnsName := challenge.DNS01TXTRecordName()
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keyAuth := challenge.DNS01KeyAuthorization()
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timeout := s.PropagationTimeout
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if timeout == 0 {
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timeout = 2 * time.Minute
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}
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const interval = 2 * time.Second
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resolvers := recursiveNameservers(s.Resolvers)
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var err error
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start := time.Now()
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for time.Since(start) < timeout {
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select {
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case <-time.After(interval):
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case <-ctx.Done():
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return ctx.Err()
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}
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var ready bool
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ready, err = checkDNSPropagation(dnsName, keyAuth, resolvers)
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if err != nil {
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return fmt.Errorf("checking DNS propagation of %s: %w", dnsName, err)
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}
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if ready {
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return nil
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}
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}
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return fmt.Errorf("timed out waiting for record to fully propagate; verify DNS provider configuration is correct - last error: %v", err)
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}
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// CleanUp deletes the DNS TXT record created in Present().
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func (s *DNS01Solver) CleanUp(ctx context.Context, challenge acme.Challenge) error {
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dnsName := challenge.DNS01TXTRecordName()
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defer func() {
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// always forget about it so we don't leak memory
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s.txtRecordsMu.Lock()
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delete(s.txtRecords, dnsName)
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s.txtRecordsMu.Unlock()
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// always do this last - but always do it!
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activeDNSChallenges.Unlock(dnsName)
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}()
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// recall the record we created and zone we looked up
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s.txtRecordsMu.Lock()
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memory, ok := s.txtRecords[dnsName]
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if !ok {
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s.txtRecordsMu.Unlock()
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return fmt.Errorf("no memory of presenting a DNS record for %s (probably OK if presenting failed)", challenge.Identifier.Value)
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}
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s.txtRecordsMu.Unlock()
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// clean up the record
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_, err := s.DNSProvider.DeleteRecords(ctx, memory.dnsZone, []libdns.Record{memory.rec})
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if err != nil {
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return fmt.Errorf("deleting temporary record for zone %s: %w", memory.dnsZone, err)
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}
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return nil
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}
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type dnsPresentMemory struct {
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dnsZone string
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rec libdns.Record
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}
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// ACMEDNSProvider defines the set of operations required for
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// ACME challenges. A DNS provider must be able to append and
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// delete records in order to solve ACME challenges. Find one
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// you can use at https://github.com/libdns. If your provider
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// isn't implemented yet, feel free to contribute!
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type ACMEDNSProvider interface {
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libdns.RecordAppender
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libdns.RecordDeleter
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}
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// activeDNSChallenges synchronizes DNS challenges for
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// names to ensure that challenges for the same ACME
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// DNS name do not overlap; for example, the TXT record
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// to make for both example.com and *.example.com are
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// the same; thus we cannot solve them concurrently.
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var activeDNSChallenges = newMapMutex()
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// mapMutex implements named mutexes.
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type mapMutex struct {
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cond *sync.Cond
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set map[interface{}]struct{}
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}
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func newMapMutex() *mapMutex {
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return &mapMutex{
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cond: sync.NewCond(new(sync.Mutex)),
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set: make(map[interface{}]struct{}),
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}
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}
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func (mmu *mapMutex) Lock(key interface{}) {
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mmu.cond.L.Lock()
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defer mmu.cond.L.Unlock()
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for mmu.locked(key) {
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mmu.cond.Wait()
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}
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mmu.set[key] = struct{}{}
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return
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}
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func (mmu *mapMutex) Unlock(key interface{}) {
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mmu.cond.L.Lock()
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defer mmu.cond.L.Unlock()
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delete(mmu.set, key)
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mmu.cond.Broadcast()
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}
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func (mmu *mapMutex) locked(key interface{}) (ok bool) {
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_, ok = mmu.set[key]
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return
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}
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|
// distributedSolver allows the ACME HTTP-01 and TLS-ALPN challenges
|
||
|
// to be solved by an instance other than the one which initiated it.
|
||
|
// This is useful behind load balancers or in other cluster/fleet
|
||
|
// configurations. The only requirement is that the instance which
|
||
|
// initiates the challenge shares the same storage and locker with
|
||
|
// the others in the cluster. The storage backing the certificate
|
||
|
// cache in distributedSolver.config is crucial.
|
||
|
//
|
||
|
// Obviously, the instance which completes the challenge must be
|
||
|
// serving on the HTTPChallengePort for the HTTP-01 challenge or the
|
||
|
// TLSALPNChallengePort for the TLS-ALPN-01 challenge (or have all
|
||
|
// the packets port-forwarded) to receive and handle the request. The
|
||
|
// server which receives the challenge must handle it by checking to
|
||
|
// see if the challenge token exists in storage, and if so, decode it
|
||
|
// and use it to serve up the correct response. HTTPChallengeHandler
|
||
|
// in this package as well as the GetCertificate method implemented
|
||
|
// by a Config support and even require this behavior.
|
||
|
//
|
||
|
// In short: the only two requirements for cluster operation are
|
||
|
// sharing sync and storage, and using the facilities provided by
|
||
|
// this package for solving the challenges.
|
||
|
type distributedSolver struct {
|
||
|
// The config with a certificate cache
|
||
|
// with a reference to the storage to
|
||
|
// use which is shared among all the
|
||
|
// instances in the cluster - REQUIRED.
|
||
|
acmeManager *ACMEManager
|
||
|
|
||
|
// Since the distributedSolver is only a
|
||
|
// wrapper over an actual solver, place
|
||
|
// the actual solver here.
|
||
|
solver acmez.Solver
|
||
|
|
||
|
// The CA endpoint URL associated with
|
||
|
// this solver.
|
||
|
caURL string
|
||
|
}
|
||
|
|
||
|
// Present invokes the underlying solver's Present method
|
||
|
// and also stores domain, token, and keyAuth to the storage
|
||
|
// backing the certificate cache of dhs.acmeManager.
|
||
|
func (dhs distributedSolver) Present(ctx context.Context, chal acme.Challenge) error {
|
||
|
infoBytes, err := json.Marshal(chal)
|
||
|
if err != nil {
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
err = dhs.acmeManager.config.Storage.Store(dhs.challengeTokensKey(chal.Identifier.Value), infoBytes)
|
||
|
if err != nil {
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
err = dhs.solver.Present(ctx, chal)
|
||
|
if err != nil {
|
||
|
return fmt.Errorf("presenting with embedded solver: %v", err)
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
// CleanUp invokes the underlying solver's CleanUp method
|
||
|
// and also cleans up any assets saved to storage.
|
||
|
func (dhs distributedSolver) CleanUp(ctx context.Context, chal acme.Challenge) error {
|
||
|
err := dhs.acmeManager.config.Storage.Delete(dhs.challengeTokensKey(chal.Identifier.Value))
|
||
|
if err != nil {
|
||
|
return err
|
||
|
}
|
||
|
err = dhs.solver.CleanUp(ctx, chal)
|
||
|
if err != nil {
|
||
|
return fmt.Errorf("cleaning up embedded provider: %v", err)
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
// challengeTokensPrefix returns the key prefix for challenge info.
|
||
|
func (dhs distributedSolver) challengeTokensPrefix() string {
|
||
|
return path.Join(dhs.acmeManager.storageKeyCAPrefix(dhs.caURL), "challenge_tokens")
|
||
|
}
|
||
|
|
||
|
// challengeTokensKey returns the key to use to store and access
|
||
|
// challenge info for domain.
|
||
|
func (dhs distributedSolver) challengeTokensKey(domain string) string {
|
||
|
return path.Join(dhs.challengeTokensPrefix(), StorageKeys.Safe(domain)+".json")
|
||
|
}
|
||
|
|
||
|
// solverInfo associates a listener with the
|
||
|
// number of challenges currently using it.
|
||
|
type solverInfo struct {
|
||
|
closed int32 // accessed atomically
|
||
|
count int
|
||
|
listener net.Listener
|
||
|
done chan struct{} // used to signal when our own solver server is done
|
||
|
}
|
||
|
|
||
|
// getSolverInfo gets a valid solverInfo struct for address.
|
||
|
func getSolverInfo(address string) *solverInfo {
|
||
|
si, ok := solvers[address]
|
||
|
if !ok {
|
||
|
si = &solverInfo{done: make(chan struct{})}
|
||
|
solvers[address] = si
|
||
|
}
|
||
|
return si
|
||
|
}
|
||
|
|
||
|
// robustTryListen calls net.Listen for a TCP socket at addr.
|
||
|
// This function may return both a nil listener and a nil error!
|
||
|
// If it was able to bind the socket, it returns the listener
|
||
|
// and no error. If it wasn't able to bind the socket because
|
||
|
// the socket is already in use, then it returns a nil listener
|
||
|
// and nil error. If it had any other error, it returns the
|
||
|
// error. The intended error handling logic for this function
|
||
|
// is to proceed if the returned listener is not nil; otherwise
|
||
|
// return err (which may also be nil). In other words, this
|
||
|
// function ignores errors if the socket is already in use,
|
||
|
// which is useful for our challenge servers, where we assume
|
||
|
// that whatever is already listening can solve the challenges.
|
||
|
func robustTryListen(addr string) (net.Listener, error) {
|
||
|
var listenErr error
|
||
|
for i := 0; i < 2; i++ {
|
||
|
// doesn't hurt to sleep briefly before the second
|
||
|
// attempt in case the OS has timing issues
|
||
|
if i > 0 {
|
||
|
time.Sleep(100 * time.Millisecond)
|
||
|
}
|
||
|
|
||
|
// if we can bind the socket right away, great!
|
||
|
var ln net.Listener
|
||
|
ln, listenErr = net.Listen("tcp", addr)
|
||
|
if listenErr == nil {
|
||
|
return ln, nil
|
||
|
}
|
||
|
|
||
|
// if it failed just because the socket is already in use, we
|
||
|
// have no choice but to assume that whatever is using the socket
|
||
|
// can answer the challenge already, so we ignore the error
|
||
|
connectErr := dialTCPSocket(addr)
|
||
|
if connectErr == nil {
|
||
|
return nil, nil
|
||
|
}
|
||
|
|
||
|
// hmm, we couldn't connect to the socket, so something else must
|
||
|
// be wrong, right? wrong!! we've had reports across multiple OSes
|
||
|
// now that sometimes connections fail even though the OS told us
|
||
|
// that the address was already in use; either the listener is
|
||
|
// fluctuating between open and closed very, very quickly, or the
|
||
|
// OS is inconsistent and contradicting itself; I have been unable
|
||
|
// to reproduce this, so I'm now resorting to hard-coding substring
|
||
|
// matching in error messages as a really hacky and unreliable
|
||
|
// safeguard against this, until we can idenify exactly what was
|
||
|
// happening; see the following threads for more info:
|
||
|
// https://caddy.community/t/caddy-retry-error/7317
|
||
|
// https://caddy.community/t/v2-upgrade-to-caddy2-failing-with-errors/7423
|
||
|
if strings.Contains(listenErr.Error(), "address already in use") ||
|
||
|
strings.Contains(listenErr.Error(), "one usage of each socket address") {
|
||
|
log.Printf("[WARNING] OS reports a contradiction: %v - but we cannot connect to it, with this error: %v; continuing anyway 🤞 (I don't know what causes this... if you do, please help?)", listenErr, connectErr)
|
||
|
return nil, nil
|
||
|
}
|
||
|
}
|
||
|
return nil, fmt.Errorf("could not start listener for challenge server at %s: %v", addr, listenErr)
|
||
|
}
|
||
|
|
||
|
// dialTCPSocket connects to a TCP address just for the sake of
|
||
|
// seeing if it is open. It returns a nil error if a TCP connection
|
||
|
// can successfully be made to addr within a short timeout.
|
||
|
func dialTCPSocket(addr string) error {
|
||
|
conn, err := net.DialTimeout("tcp", addr, 250*time.Millisecond)
|
||
|
if err == nil {
|
||
|
conn.Close()
|
||
|
}
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
// The active challenge solvers, keyed by listener address,
|
||
|
// and protected by a mutex. Note that the creation of
|
||
|
// solver listeners and the incrementing of their counts
|
||
|
// are atomic operations guarded by this mutex.
|
||
|
var (
|
||
|
solvers = make(map[string]*solverInfo)
|
||
|
solversMu sync.Mutex
|
||
|
)
|
||
|
|
||
|
// Interface guards
|
||
|
var (
|
||
|
_ acmez.Solver = (*DNS01Solver)(nil)
|
||
|
_ acmez.Waiter = (*DNS01Solver)(nil)
|
||
|
)
|