134 lines
4.3 KiB
Go
134 lines
4.3 KiB
Go
// Copyright 2015 Matthew Holt
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package certmagic
|
|
|
|
import (
|
|
"encoding/json"
|
|
"net/http"
|
|
"strings"
|
|
|
|
"github.com/mholt/acmez/acme"
|
|
"go.uber.org/zap"
|
|
)
|
|
|
|
// HTTPChallengeHandler wraps h in a handler that can solve the ACME
|
|
// HTTP challenge. cfg is required, and it must have a certificate
|
|
// cache backed by a functional storage facility, since that is where
|
|
// the challenge state is stored between initiation and solution.
|
|
//
|
|
// If a request is not an ACME HTTP challenge, h will be invoked.
|
|
func (am *ACMEManager) HTTPChallengeHandler(h http.Handler) http.Handler {
|
|
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
|
|
if am.HandleHTTPChallenge(w, r) {
|
|
return
|
|
}
|
|
h.ServeHTTP(w, r)
|
|
})
|
|
}
|
|
|
|
// HandleHTTPChallenge uses am to solve challenge requests from an ACME
|
|
// server that were initiated by this instance or any other instance in
|
|
// this cluster (being, any instances using the same storage am does).
|
|
//
|
|
// If the HTTP challenge is disabled, this function is a no-op.
|
|
//
|
|
// If am is nil or if am does not have a certificate cache backed by
|
|
// usable storage, solving the HTTP challenge will fail.
|
|
//
|
|
// It returns true if it handled the request; if so, the response has
|
|
// already been written. If false is returned, this call was a no-op and
|
|
// the request has not been handled.
|
|
func (am *ACMEManager) HandleHTTPChallenge(w http.ResponseWriter, r *http.Request) bool {
|
|
if am == nil {
|
|
return false
|
|
}
|
|
if am.DisableHTTPChallenge {
|
|
return false
|
|
}
|
|
if !LooksLikeHTTPChallenge(r) {
|
|
return false
|
|
}
|
|
return am.distributedHTTPChallengeSolver(w, r)
|
|
}
|
|
|
|
// distributedHTTPChallengeSolver checks to see if this challenge
|
|
// request was initiated by this or another instance which uses the
|
|
// same storage as am does, and attempts to complete the challenge for
|
|
// it. It returns true if the request was handled; false otherwise.
|
|
func (am *ACMEManager) distributedHTTPChallengeSolver(w http.ResponseWriter, r *http.Request) bool {
|
|
if am == nil {
|
|
return false
|
|
}
|
|
|
|
host := hostOnly(r.Host)
|
|
|
|
tokenKey := distributedSolver{acmeManager: am, caURL: am.CA}.challengeTokensKey(host)
|
|
chalInfoBytes, err := am.config.Storage.Load(tokenKey)
|
|
if err != nil {
|
|
if _, ok := err.(ErrNotExist); !ok {
|
|
if am.Logger != nil {
|
|
am.Logger.Error("opening distributed HTTP challenge token file",
|
|
zap.String("host", host),
|
|
zap.Error(err))
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
var challenge acme.Challenge
|
|
err = json.Unmarshal(chalInfoBytes, &challenge)
|
|
if err != nil {
|
|
if am.Logger != nil {
|
|
am.Logger.Error("decoding HTTP challenge token file (corrupted?)",
|
|
zap.String("host", host),
|
|
zap.String("token_key", tokenKey),
|
|
zap.Error(err))
|
|
}
|
|
return false
|
|
}
|
|
|
|
return am.answerHTTPChallenge(w, r, challenge)
|
|
}
|
|
|
|
// answerHTTPChallenge solves the challenge with chalInfo.
|
|
// Most of this code borrowed from xenolf's built-in HTTP-01
|
|
// challenge solver in March 2018.
|
|
func (am *ACMEManager) answerHTTPChallenge(w http.ResponseWriter, r *http.Request, challenge acme.Challenge) bool {
|
|
challengeReqPath := challenge.HTTP01ResourcePath()
|
|
if r.URL.Path == challengeReqPath &&
|
|
strings.EqualFold(hostOnly(r.Host), challenge.Identifier.Value) && // mitigate DNS rebinding attacks
|
|
r.Method == "GET" {
|
|
w.Header().Add("Content-Type", "text/plain")
|
|
w.Write([]byte(challenge.KeyAuthorization))
|
|
r.Close = true
|
|
if am.Logger != nil {
|
|
am.Logger.Info("served key authentication",
|
|
zap.String("identifier", challenge.Identifier.Value),
|
|
zap.String("challenge", "http-01"),
|
|
zap.String("remote", r.RemoteAddr))
|
|
}
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// LooksLikeHTTPChallenge returns true if r looks like an ACME
|
|
// HTTP challenge request from an ACME server.
|
|
func LooksLikeHTTPChallenge(r *http.Request) bool {
|
|
return r.Method == "GET" && strings.HasPrefix(r.URL.Path, challengeBasePath)
|
|
}
|
|
|
|
const challengeBasePath = "/.well-known/acme-challenge"
|