From c99dbb34ce8030f7975117c30af5f2eb7569b2b6 Mon Sep 17 00:00:00 2001
From: Moritz Marquardt <git@momar.de>
Date: Sat, 20 Nov 2021 21:10:46 +0100
Subject: [PATCH] Implement HTTP-01 challenge

---
 README.md       |  1 +
 certificates.go | 20 ++++++++++++++++++--
 main.go         | 21 +++++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 81f12c7..85d47ad 100644
--- a/README.md
+++ b/README.md
@@ -11,5 +11,6 @@
 - `ACME_EMAIL` (default: `noreply@example.email`): Set this to "true" to accept the Terms of Service of your ACME provider.
 - `ACME_EAB_KID` &  `ACME_EAB_HMAC` (default: don't use EAB): EAB credentials, for example for ZeroSSL.
 - `ACME_ACCEPT_TERMS` (default: use self-signed certificate): Set this to "true" to accept the Terms of Service of your ACME provider.
+- `ENABLE_HTTP_SERVER` (default: false): Set this to true to enable the HTTP-01 challenge and redirect all other HTTP requests to HTTPS. Currently only works with port 80.
 - `DNS_PROVIDER` (default: use self-signed certificate): Code of the ACME DNS provider for the main domain wildcard.  
   See https://go-acme.github.io/lego/dns/ for available values & additional environment variables.
diff --git a/certificates.go b/certificates.go
index 501ae37..89961b1 100644
--- a/certificates.go
+++ b/certificates.go
@@ -131,7 +131,6 @@ var tlsConfig = &tls.Config{
 	},
 }
 
-var challengeCache = mcache.New()
 var keyCache = mcache.New()
 var keyDatabase *pogreb.DB
 
@@ -189,6 +188,7 @@ var acmeClientOrderLimit = equalizer.NewTokenBucket(25, 15 * time.Minute)
 // rate limit is 20 / second, we want 10 / second
 var acmeClientRequestLimit = equalizer.NewTokenBucket(10, 1 * time.Second)
 
+var challengeCache = mcache.New()
 type AcmeTLSChallengeProvider struct{}
 var _ challenge.Provider = AcmeTLSChallengeProvider{}
 func (a AcmeTLSChallengeProvider) Present(domain, _, keyAuth string) error {
@@ -198,6 +198,15 @@ func (a AcmeTLSChallengeProvider) CleanUp(domain, _, _ string) error {
 	challengeCache.Remove(domain)
 	return nil
 }
+type AcmeHTTPChallengeProvider struct{}
+var _ challenge.Provider = AcmeHTTPChallengeProvider{}
+func (a AcmeHTTPChallengeProvider) Present(domain, token, keyAuth string) error {
+	return challengeCache.Set(domain + "/" + token, keyAuth, 1*time.Hour)
+}
+func (a AcmeHTTPChallengeProvider) CleanUp(domain, token, _ string) error {
+	challengeCache.Remove(domain + "/" + token)
+	return nil
+}
 
 func retrieveCertFromDB(sni []byte) (tls.Certificate, bool) {
 	// parse certificate from database
@@ -383,7 +392,14 @@ func setupCertificates() {
 	}
 
 	acmeClient = newAcmeClient(func(challenge *resolver.SolverManager) error {
-		return challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{})
+		err = challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{})
+		if err != nil {
+			return err
+		}
+		if os.Getenv("ENABLE_HTTP_SERVER") == "true" {
+			return challenge.SetHTTP01Provider(AcmeHTTPChallengeProvider{})
+		}
+		return err
 	})
 	mainDomainAcmeClient = newAcmeClient(func(challenge *resolver.SolverManager) error {
 		if os.Getenv("DNS_PROVIDER") == "" {
diff --git a/main.go b/main.go
index c795f1f..c181977 100644
--- a/main.go
+++ b/main.go
@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"log"
 	"net"
+	"net/http"
 	"os"
 	"time"
 
@@ -103,6 +104,26 @@ func main() {
 	listener = tls.NewListener(listener, tlsConfig)
 
 	setupCertificates()
+	if os.Getenv("ENABLE_HTTP_SERVER") == "true" {
+		go (func() {
+			challengePath := []byte("/.well-known/acme-challenge/")
+			err := fasthttp.ListenAndServe("[::]:80", func(ctx *fasthttp.RequestCtx) {
+				if bytes.HasPrefix(ctx.Path(), challengePath) {
+					challenge, ok := challengeCache.Get(string(TrimHostPort(ctx.Host())) + "/" + string(bytes.TrimPrefix(ctx.Path(), challengePath)))
+					if !ok {
+						ctx.SetStatusCode(http.StatusNotFound)
+						ctx.SetBodyString("no challenge for this token")
+					}
+					ctx.SetBodyString(challenge.(string))
+				} else {
+					ctx.Redirect("https://" + string(ctx.Host()) + string(ctx.RequestURI()), http.StatusMovedPermanently)
+				}
+			})
+			if err != nil {
+				log.Fatalf("Couldn't start HTTP server: %s", err)
+			}
+		})()
+	}
 
 	// Start the web server
 	err = server.Serve(listener)