Completely refactor certificates and implement renewal & cleanup

2024-11-18 10:29:43 +00:00 · 2021-11-20 15:30:58 +01:00 · 2021-11-20 15:30:58 +01:00 · 2aaac2c52b
commit 2aaac2c52b
parent 33f7a5d0df
7 changed files with 242 additions and 247 deletions
--- a/404.html
+++ b/404.html
@ -5,7 +5,7 @@
    <meta name="viewport" content="width=device-width">
    <title>%status</title>

-    <link rel="stylesheet" href="https://design.codeberg-test.org/design-kit/codeberg.css" />
+    <link rel="stylesheet" href="https://design.codeberg.org/design-kit/codeberg.css" />
    <link href="https://fonts.codeberg.org/dist/inter/Inter%20Web/inter.css" rel="stylesheet" />
    <link href="https://fonts.codeberg.org/dist/fontawesome5/css/all.min.css" rel="stylesheet" />

@ -29,7 +29,7 @@
    	Sorry, this page doesn't exist or is inaccessible for other reasons (%status)
    </h5>
    <small class="text-muted">
-        <img src="https://design.codeberg-test.org/logo-kit/icon.svg" class="align-top">
+        <img src="https://design.codeberg.org/logo-kit/icon.svg" class="align-top">
        Static pages made easy - <a href="https://codeberg.page">Codeberg Pages</a>
    </small>
 </body>
--- a/README.md
+++ b/README.md
@ -1,11 +1,13 @@
 ## Environment

+- `HOST` & `PORT` (default: `[::]` & `443`): listen address.
 - `PAGES_DOMAIN` (default: `codeberg.page`): main domain for pages.
 - `RAW_DOMAIN` (default: `raw.codeberg.org`): domain for raw resources.
 - `GITEA_ROOT` (default: `https://codeberg.org`): root of the upstream Gitea instance.
- `REDIRECT_BROKEN_DNS` (default: "https://docs.codeberg.org/pages/custom-domains/"): info page for setting up DNS, shown for invalid DNS setups.
+- `REDIRECT_BROKEN_DNS` (default: https://docs.codeberg.org/pages/custom-domains/): info page for setting up DNS, shown for invalid DNS setups.
 - `REDIRECT_RAW_INFO` (default: https://docs.codeberg.org/pages/raw-content/): info page for raw resources, shown if no resource is provided.
- `ACME_API` (default: https://acme-v02.api.letsencrypt.org/directory): Set this to "https://acme-staging-v02.api.letsencrypt.org/directory" to use the staging API of Let's Encrypt instead.
+- `ACME_API` (default: https://acme.zerossl.com/v2/DV90): set this to https://acme.mock.director to use invalid certificates without any verification (great for debugging). ZeroSSL is used as it doesn't have rate limits and doesn't clash with the official Codeberg certificates (which are using Let's Encrypt).
+- `ACME_EMAIL` (default: `noreply@example.email`): Set this to "true" to accept the Terms of Service of your ACME provider.
 - `ACME_ACCEPT_TERMS` (default: use self-signed certificate): Set this to "true" to accept the Terms of Service of your ACME provider.
 - `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.
--- a/certificates.go
+++ b/certificates.go
@ -6,20 +6,17 @@ import (
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/rand"
-	"crypto/rsa"
 	"crypto/tls"
 	"crypto/x509"
-	"crypto/x509/pkix"
-	"encoding/pem"
 	"errors"
 	"github.com/OrlovEvgeny/go-mcache"
 	"github.com/akrylysov/pogreb/fs"
 	"github.com/go-acme/lego/v4/certificate"
 	"github.com/go-acme/lego/v4/challenge"
+	"github.com/go-acme/lego/v4/challenge/resolver"
 	"github.com/go-acme/lego/v4/challenge/tlsalpn01"
 	"github.com/go-acme/lego/v4/providers/dns"
 	"log"
-	"math/big"
 	"os"
 	"strings"
 	"time"
@ -36,10 +33,6 @@ import (
 var tlsConfig = &tls.Config{
 	// check DNS name & get certificate from Let's Encrypt
 	GetCertificate: func(info *tls.ClientHelloInfo) (*tls.Certificate, error) {
-		if os.Getenv("ACME_ACCEPT_TERMS") != "true" {
-			return FallbackCertificate(), nil
-		}
-
 		sni := strings.ToLower(strings.TrimSpace(info.ServerName))
 		sniBytes := []byte(sni)
 		if len(sni) < 1 {
@ -63,7 +56,7 @@ var tlsConfig = &tls.Config{
 		}

 		targetOwner := ""
-		if bytes.HasSuffix(sniBytes, MainDomainSuffix) {
+		if bytes.HasSuffix(sniBytes, MainDomainSuffix) || bytes.Equal(sniBytes, MainDomainSuffix[1:]) {
 			// deliver default certificate for the main domain (*.codeberg.page)
 			sniBytes = MainDomainSuffix
 			sni = string(sniBytes)
@ -71,90 +64,68 @@ var tlsConfig = &tls.Config{
 			var targetRepo, targetBranch string
 			targetOwner, targetRepo, targetBranch = getTargetFromDNS(sni)
 			if targetOwner == "" {
-				// DNS not set up, return a self-signed certificate to redirect to the docs
-				return FallbackCertificate(), nil
-			}
-
-			// TODO: use .domains file to list all domains, to keep users from getting rate-limited
+				// DNS not set up, return main certificate to redirect to the docs
+				sniBytes = MainDomainSuffix
+				sni = string(sniBytes)
+			} else {
 				_, _ = targetRepo, targetBranch
-			/*canonicalDomain := checkCanonicalDomain(targetOwner, targetRepo, targetBranch)
-			if sni != canonicalDomain {
-				return FallbackCertificate(), nil
-			}*/
+				_, valid := checkCanonicalDomain(targetOwner, targetRepo, targetBranch, sni)
+				if !valid {
+					sniBytes = MainDomainSuffix
+					sni = string(sniBytes)
+				}
+			}
 		}

-		// limit users to 1 certificate per week
-
-		var cert, key []byte
 		if tlsCertificate, ok := keyCache.Get(sni); ok {
 			// we can use an existing certificate object
 			return tlsCertificate.(*tls.Certificate), nil
-		} else if ok, err := keyDatabase.Has(sniBytes); err != nil {
+		}
+
+		var tlsCertificate tls.Certificate
+		if ok, err := keyDatabase.Has(sniBytes); err != nil {
 			// key database is not working
 			panic(err)
 		} else if ok {
 			// parse certificate from database
-
-			cert, err = keyDatabase.Get(sniBytes)
+			certPem, err := keyDatabase.Get(sniBytes)
 			if err != nil {
 				// key database is not working
 				panic(err)
 			}
-			key, err = keyDatabase.Get(append(sniBytes, '/', 'k', 'e', 'y'))
+			keyPem, err := keyDatabase.Get(append(sniBytes, '/', 'k', 'e', 'y'))
 			if err != nil {
 				// key database is not working or key doesn't exist
 				panic(err)
 			}
-		} else {
-			// request a new certificate

+			tlsCertificate, err = tls.X509KeyPair(certPem, keyPem)
+			if err != nil {
+				panic(err)
+			}
+			tlsCertificate.Leaf, err = x509.ParseCertificate(tlsCertificate.Certificate[0])
+			if err != nil {
+				panic(err)
+			}
+		}
+		if tlsCertificate.Certificate == nil || !tlsCertificate.Leaf.NotAfter.After(time.Now().Add(-24 * time.Hour)) {
+			// request a new certificate
 			if bytes.Equal(sniBytes, MainDomainSuffix) {
 				return nil, errors.New("won't request certificate for main domain, something really bad has happened")
 			}

-			log.Printf("Requesting new certificate for %s", sni)
-			privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
+			err := CheckUserLimit(targetOwner)
 			if err != nil {
 				return nil, err
 			}
-			key = x509.MarshalPKCS1PrivateKey(privateKey)
-			acmeClient, err := acmeClientFromPool(targetOwner)
-			if err != nil {
-				// TODO
-			}
-			res, err := acmeClient.Certificate.Obtain(certificate.ObtainRequest{
-				Domains:        []string{sni},
-				PrivateKey:     key,
-				Bundle:         true,
-				MustStaple:     true,
-			})
-			if err != nil {
-				return nil, err
-			}
-			log.Printf("Obtained certificate for %s", sni)
-			err = keyDatabase.Put(append(sniBytes, '/', 'k', 'e', 'y'), key)
-			if err != nil {
-				return nil, err
-			}
-			err = keyDatabase.Put(sniBytes, res.Certificate)
-			if err != nil {
-				_ = keyDatabase.Delete(append(sniBytes, '/', 'k', 'e', 'y'))
-				return nil, err
-			}
-			cert = res.Certificate
-		}
-		tlsCertificate, err := tls.X509KeyPair(pem.EncodeToMemory(&pem.Block{
-			Bytes: cert,
-			Type: "CERTIFICATE",
-		}), pem.EncodeToMemory(&pem.Block{
-			Bytes: key,
-			Type: "RSA PRIVATE KEY",
-		}))
-		if err != nil {
-			panic(err)
-		}

-		err = keyCache.Set(sni, &tlsCertificate, 15 * time.Minute)
+			tlsCertificate, err = obtainCert(acmeClient, []string{sni})
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		err := keyCache.Set(sni, &tlsCertificate, 15 * time.Minute)
 		if err != nil {
 			panic(err)
 		}
@ -178,76 +149,28 @@ var tlsConfig = &tls.Config{
 	},
 }

-// GetHSTSHeader returns a HSTS header with includeSubdomains & preload for MainDomainSuffix and RawDomain, or an empty
-// string for custom domains.
-func GetHSTSHeader(host []byte) string {
-	if bytes.HasSuffix(host, MainDomainSuffix) || bytes.Equal(host, RawDomain) {
-		return "max-age=63072000; includeSubdomains; preload"
-	} else {
-		return ""
-	}
-}
-
 var challengeCache = mcache.New()
 var keyCache = mcache.New()
 var keyDatabase *pogreb.DB

-var fallbackCertificate *tls.Certificate
-// FallbackCertificate generates a new self-signed TLS certificate on demand.
-func FallbackCertificate() *tls.Certificate {
-	if fallbackCertificate != nil {
-		return fallbackCertificate
+func CheckUserLimit(user string) (error) {
+	userLimit, ok := acmeClientCertificateLimitPerUser[user]
+	if !ok {
+		// Each Codeberg user can only add 10 new domains per day.
+		userLimit = equalizer.NewTokenBucket(10, time.Hour * 24)
+		acmeClientCertificateLimitPerUser[user] = userLimit
 	}
-
-	fallbackSerial, err := rand.Int(rand.Reader, (&big.Int{}).Lsh(big.NewInt(1), 159))
-	if err != nil {
-		panic(err)
+	if !userLimit.Ask() {
+		return errors.New("rate limit exceeded: 10 certificates per user per 24 hours")
 	}
-
-	fallbackCertKey, err := rsa.GenerateKey(rand.Reader, 1024)
-	if err != nil {
-		panic(err)
-	}
-
-	fallbackCertSpecification := &x509.Certificate{
-		Subject: pkix.Name{
-			CommonName: strings.TrimPrefix(string(MainDomainSuffix), "."),
-		},
-		SerialNumber: fallbackSerial,
-		NotBefore: time.Now(),
-		NotAfter: time.Now().AddDate(100, 0, 0),
-	}
-
-	fallbackCertBytes, err := x509.CreateCertificate(
-		rand.Reader,
-		fallbackCertSpecification,
-		fallbackCertSpecification,
-		fallbackCertKey.Public(),
-		fallbackCertKey,
-	)
-	if err != nil {
-		panic(err)
-	}
-
-	fallbackCert, err := tls.X509KeyPair(pem.EncodeToMemory(&pem.Block{
-		Bytes: fallbackCertBytes,
-		Type: "CERTIFICATE",
-	}), pem.EncodeToMemory(&pem.Block{
-		Bytes: x509.MarshalPKCS1PrivateKey(fallbackCertKey),
-		Type: "RSA PRIVATE KEY",
-	}))
-	if err != nil {
-		panic(err)
-	}
-
-	fallbackCertificate = &fallbackCert
-	return fallbackCertificate
+	return nil
 }

 type AcmeAccount struct {
 	Email        string
 	Registration *registration.Resource
 	key          crypto.PrivateKey
+	limit        equalizer.Limiter
 }
 func (u *AcmeAccount) GetEmail() string {
 	return u.Email
@ -259,17 +182,54 @@ func (u *AcmeAccount) GetPrivateKey() crypto.PrivateKey {
 	return u.key
 }

-// rate-limit certificates per owner, based on LE Rate Limits:
-// - 300 new orders per account per 3 hours
-// - 20 requests per second
-// - 10 Accounts per IP per 3 hours
-var acmeClientPool []*lego.Client
-var lastAcmeClient = 0
-var acmeClientRequestLimit = equalizer.NewTokenBucket(10, time.Second) // LE allows 20 requests per second, but we want to give other applications a chancem so we want 10 here at most.
-var acmeClientRegistrationLimit = equalizer.NewTokenBucket(5, time.Hour * 3) // LE allows 10 registrations in 3 hours per IP, we want at most 5 of them.
-var acmeClientCertificateLimitPerRegistration = []*equalizer.TokenBucket{}
+func newAcmeClient(configureChallenge func(*resolver.SolverManager) error) *lego.Client {
+	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		panic(err)
+	}
+	myUser := AcmeAccount{
+		Email: envOr("ACME_EMAIL", "noreply@example.email"),
+		key:   privateKey,
+	}
+	config := lego.NewConfig(&myUser)
+	config.CADirURL = envOr("ACME_API", "https://acme.zerossl.com/v2/DV90")
+	config.Certificate.KeyType = certcrypto.RSA2048
+	acmeClient, err := lego.NewClient(config)
+	if err != nil {
+		panic(err)
+	}
+	err = configureChallenge(acmeClient.Challenge)
+	if err != nil {
+		panic(err)
+	}
+
+	// accept terms
+	reg, err := acmeClient.Registration.Register(registration.RegisterOptions{TermsOfServiceAgreed: os.Getenv("ACME_ACCEPT_TERMS") == "true"})
+	if err != nil {
+		panic(err)
+	}
+	myUser.Registration = reg
+
+	return acmeClient
+}
+
+var acmeClient = newAcmeClient(func(challenge *resolver.SolverManager) error {
+	return challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{})
+})
 var acmeClientCertificateLimitPerUser = map[string]*equalizer.TokenBucket{}

+var mainDomainAcmeClient = newAcmeClient(func(challenge *resolver.SolverManager) error {
+	if os.Getenv("DNS_PROVIDER") == "" {
+		// using mock server, don't use wildcard certs
+		return challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{})
+	}
+	provider, err := dns.NewDNSChallengeProviderByName(os.Getenv("DNS_PROVIDER"))
+	if err != nil {
+		return err
+	}
+	return challenge.SetDNS01Provider(provider)
+})
+
 type AcmeTLSChallengeProvider struct{}
 var _ challenge.Provider = AcmeTLSChallengeProvider{}
 func (a AcmeTLSChallengeProvider) Present(domain, _, keyAuth string) error {
@ -280,67 +240,42 @@ func (a AcmeTLSChallengeProvider) CleanUp(domain, _, _ string) error {
 	return nil
 }

-func acmeClientFromPool(user string) (*lego.Client, error) {
-	userLimit, ok := acmeClientCertificateLimitPerUser[user]
-	if !ok {
-		// Each Codeberg user can only add 10 new domains per day.
-		userLimit = equalizer.NewTokenBucket(10, time.Hour * 24)
-		acmeClientCertificateLimitPerUser[user] = userLimit
-
-	}
-	if !userLimit.Ask() {
-		return nil, errors.New("rate limit exceeded: 10 certificates per user per 24 hours")
+func obtainCert(acmeClient *lego.Client, domains []string) (tls.Certificate, error) {
+	name := domains[0]
+	if os.Getenv("DNS_PROVIDER") == "" && len(domains[0]) > 0 && domains[0][0] == '*' {
+		domains = domains[1:]
 	}

-	if len(acmeClientPool) < 1 {
-		acmeClientPool = append(acmeClientPool, newAcmeClient())
-		acmeClientCertificateLimitPerRegistration = append(acmeClientCertificateLimitPerRegistration, equalizer.NewTokenBucket(290, time.Hour * 3))
+		log.Printf("Requesting new certificate for %v", domains)
+	res, err := acmeClient.Certificate.Obtain(certificate.ObtainRequest{
+		Domains:    domains,
+		Bundle:     true,
+		MustStaple: true,
+	})
+	if err != nil {
+		log.Printf("Couldn't obtain certificate for %v: %s", domains, err)
+		return tls.Certificate{}, err
 	}
-	if !acmeClientCertificateLimitPerRegistration[(lastAcmeClient + 1) % len(acmeClientPool)].Ask() {
+	log.Printf("Obtained certificate for %v", domains)

-	}
-	equalizer.NewTokenBucket(290, time.Hour * 3) // LE allows 300 certificates per account, to be sure to catch it earlier, we limit that to 290.
-
-	// TODO: limit domains by file in repo
-}
-
-func newAcmeClient() *lego.Client {
-	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	err = keyDatabase.Put([]byte(name + "/key"), res.PrivateKey)
 	if err != nil {
 		panic(err)
 	}
-	myUser := AcmeAccount{
-		Email: "",
-		key:   privateKey,
-	}
-	config := lego.NewConfig(&myUser)
-	config.CADirURL = envOr("ACME_API", "https://acme-v02.api.letsencrypt.org/directory")
-	config.Certificate.KeyType = certcrypto.RSA2048
-	acmeClient, err := lego.NewClient(config)
-	if err != nil {
-		panic(err)
-	}
-	err = acmeClient.Challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{})
+	err = keyDatabase.Put([]byte(name), res.Certificate)
 	if err != nil {
+		_ = keyDatabase.Delete([]byte(name + "/key"))
 		panic(err)
 	}

-	// accept terms
-	if os.Getenv("ACME_ACCEPT_TERMS") == "true" {
-		reg, err := acmeClient.Registration.Register(registration.RegisterOptions{TermsOfServiceAgreed: os.Getenv("ACME_ACCEPT_TERMS") == "true"})
+	tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey)
 	if err != nil {
 		panic(err)
 	}
-		myUser.Registration = reg
-	} else {
-		log.Printf("Warning: not using ACME certificates as ACME_ACCEPT_TERMS is false!")
-	}
-	return acmeClient
+	return tlsCertificate, nil
 }

 func init() {
-	FallbackCertificate()
-
 	var err error
 	keyDatabase, err = pogreb.Open("key-database.pogreb", &pogreb.Options{
 		BackgroundSyncInterval:       30 * time.Second,
@ -351,50 +286,62 @@ func init() {
 		panic(err)
 	}

-	// generate certificate for main domain
-	if os.Getenv("ACME_ACCEPT_TERMS") != "true" || os.Getenv("DNS_PROVIDER") == "" {
-		err = keyCache.Set(string(MainDomainSuffix), FallbackCertificate(), mcache.TTL_FOREVER)
-		if err != nil {
-			panic(err)
-		}
-	} else {
-		log.Printf("Requesting new certificate for *%s", MainDomainSuffix)
-		dnsAcmeClient, err := lego.NewClient(config)
-		if err != nil {
-			panic(err)
-		}
-		provider, err := dns.NewDNSChallengeProviderByName(os.Getenv("DNS_PROVIDER"))
-		if err != nil {
-			panic(err)
-		}
-		err = dnsAcmeClient.Challenge.SetDNS01Provider(provider)
-		if err != nil {
-			panic(err)
-		}
-		mainPrivateKey, err := rsa.GenerateKey(rand.Reader, 2048)
-		if err != nil {
-			panic(err)
-		}
-		mainKey := x509.MarshalPKCS1PrivateKey(mainPrivateKey)
-		res, err := dnsAcmeClient.Certificate.Obtain(certificate.ObtainRequest{
-			Domains:    []string{"*" + string(MainDomainSuffix), string(MainDomainSuffix[1:])},
-			PrivateKey: mainKey,
-			Bundle:     true,
-			MustStaple: true,
-		})
-		if err != nil {
-			panic(err)
-		}
-		err = keyDatabase.Put(append(MainDomainSuffix, '/', 'k', 'e', 'y'), mainKey)
-		if err != nil {
-			panic(err)
-		}
-		err = keyDatabase.Put(MainDomainSuffix, res.Certificate)
-		if err != nil {
-			_ = keyDatabase.Delete(append(MainDomainSuffix, '/', 'k', 'e', 'y'))
-			panic(err)
-		}
-	}
+	if os.Getenv("ACME_ACCEPT_TERMS") != "true" || (os.Getenv("DNS_PROVIDER") == "" && os.Getenv("ACME_API") != "https://acme.mock.directory") {
+		panic(errors.New("you must set ACME_ACCEPT_TERMS and DNS_PROVIDER, unless ACME_API is set to https://acme.mock.directory"))
 	}

-// TODO: renew & revoke
+	go (func() {
+		for {
+			err := keyDatabase.Sync()
+			if err != nil {
+				log.Printf("Syncinc key database failed: %s", err)
+			}
+			time.Sleep(5 * time.Minute)
+		}
+	})()
+	go (func() {
+		for {
+			// clean up expired certs
+			keySuffix := []byte("/key")
+			now := time.Now()
+			expiredCertCount := 0
+			key, value, err := keyDatabase.Items().Next()
+			for err == nil {
+				if !bytes.HasSuffix(key, keySuffix) {
+					tlsCertificates, err := certcrypto.ParsePEMBundle(value)
+					if err != nil || !tlsCertificates[0].NotAfter.After(now) {
+						err := keyDatabase.Delete(key)
+						if err != nil {
+							log.Printf("Deleting expired certificate for %s failed: %s", string(key), err)
+						} else {
+							expiredCertCount++
+						}
+					}
+				}
+				key, value, err = keyDatabase.Items().Next()
+			}
+			log.Printf("Removed %d expired certificates from the database", expiredCertCount)
+
+			// compact the database
+			result, err := keyDatabase.Compact()
+			if err != nil {
+				log.Printf("Compacting key database failed: %s", err)
+			} else {
+				log.Printf("Compacted key database (%+v)", result)
+			}
+
+			// update main cert
+			certPem, err := keyDatabase.Get(MainDomainSuffix)
+			if err != nil {
+				// key database is not working
+				panic(err)
+			}
+			tlsCertificates, err := certcrypto.ParsePEMBundle(certPem)
+			if err != nil || !tlsCertificates[0].NotAfter.After(time.Now().Add(-48 * time.Hour)) {
+				_, _ = obtainCert(mainDomainAcmeClient, []string{"*" + string(MainDomainSuffix), string(MainDomainSuffix[1:])})
+			}
+
+			time.Sleep(12 * time.Hour)
+		}
+	})()
+}
--- a/domains.go
+++ b/domains.go
@ -68,10 +68,16 @@ var CanonicalDomainCacheTimeout = 15*time.Minute
 var canonicalDomainCache = mcache.New()

 // checkCanonicalDomain returns the canonical domain specified in the repo (using the file `.canonical-domain`).
-func checkCanonicalDomain(targetOwner, targetRepo, targetBranch string) (canonicalDomain string) {
-	// Check if the canonical domain matches
+func checkCanonicalDomain(targetOwner, targetRepo, targetBranch, actualDomain string) (canonicalDomain string, valid bool) {
+	domains := []string{}
 	if cachedValue, ok := canonicalDomainCache.Get(targetOwner + "/" + targetRepo + "/" + targetBranch); ok {
-		canonicalDomain = cachedValue.(string)
+		domains = cachedValue.([]string)
+		for _, domain := range domains {
+			if domain == actualDomain {
+				valid = true
+				break
+			}
+		}
 	} else {
 		req := fasthttp.AcquireRequest()
 		req.SetRequestURI(string(GiteaRoot) + "/api/v1/repos/" + targetOwner + "/" + targetRepo + "/raw/" + targetBranch + "/.domains")
@ -79,18 +85,28 @@ func checkCanonicalDomain(targetOwner, targetRepo, targetBranch string) (canonic

 		err := upstreamClient.Do(req, res)
 		if err == nil && res.StatusCode() == fasthttp.StatusOK {
-			canonicalDomain = strings.TrimSpace(string(res.Body()))
-			if strings.Contains(canonicalDomain, "/") {
-				canonicalDomain = ""
+			for _, domain := range strings.Split(string(res.Body()), "\n") {
+				domain = strings.ToLower(domain)
+				domain = strings.TrimSpace(domain)
+				domain = strings.TrimPrefix(domain, "http://")
+				domain = strings.TrimPrefix(domain, "https://")
+				if len(domain) > 0 && !strings.HasPrefix(domain, "#") && !strings.ContainsAny(domain, "\t /") && strings.ContainsRune(domain, '.') {
+					domains = append(domains, domain)
+				}
+				if domain == actualDomain {
+					valid = true
 				}
 			}
-		if canonicalDomain == "" {
-			canonicalDomain = targetOwner + string(MainDomainSuffix)
+		}
+		domains = append(domains, targetOwner + string(MainDomainSuffix))
+		if domains[len(domains) - 1] == actualDomain {
+			valid = true
+		}
 		if targetRepo != "" && targetRepo != "pages" {
-				canonicalDomain += "/" + targetRepo
+			domains[len(domains) - 1] += "/" + targetRepo
 		}
+		_ = canonicalDomainCache.Set(targetOwner + "/" + targetRepo + "/" + targetBranch, domains, CanonicalDomainCacheTimeout)
 	}
-		_ = canonicalDomainCache.Set(targetOwner + "/" + targetRepo + "/" + targetBranch, canonicalDomain, CanonicalDomainCacheTimeout)
-	}
+	canonicalDomain = domains[0]
 	return
 }
--- a/handler.go
+++ b/handler.go
@ -28,8 +28,10 @@ func handler(ctx *fasthttp.RequestCtx) {
 	// Enable caching, but require revalidation to reduce confusion
 	ctx.Response.Header.Set("Cache-Control", "must-revalidate")

+	trimmedHost := TrimHostPort(ctx.Request.Host())
+
 	// Add HSTS for RawDomain and MainDomainSuffix
-	if hsts := GetHSTSHeader(ctx.Host()); hsts != "" {
+	if hsts := GetHSTSHeader(trimmedHost); hsts != "" {
 		ctx.Response.Header.Set("Strict-Transport-Security", hsts)
 	}

@ -52,7 +54,7 @@ func handler(ctx *fasthttp.RequestCtx) {
 	if ctx.IsOptions() {
 		allowCors := false
 		for _, allowedCorsDomain := range AllowedCorsDomains {
-			if bytes.Equal(ctx.Request.Host(), allowedCorsDomain) {
+			if bytes.Equal(trimmedHost, allowedCorsDomain) {
 				allowCors = true
 				break
 			}
@ -109,8 +111,8 @@ func handler(ctx *fasthttp.RequestCtx) {
 	// tryUpstream forwards the target request to the Gitea API, and shows an error page on failure.
 	var tryUpstream = func() {
 		// check if a canonical domain exists on a request on MainDomain
-		if bytes.HasSuffix(ctx.Request.Host(), MainDomainSuffix) {
-			canonicalDomain := checkCanonicalDomain(targetOwner, targetRepo, targetBranch)
+		if bytes.HasSuffix(trimmedHost, MainDomainSuffix) {
+			canonicalDomain, _ := checkCanonicalDomain(targetOwner, targetRepo, targetBranch, "")
 			if !strings.HasSuffix(strings.SplitN(canonicalDomain, "/", 2)[0], string(MainDomainSuffix)) {
 				canonicalPath := string(ctx.RequestURI())
 				if targetRepo != "pages" {
@ -129,7 +131,7 @@ func handler(ctx *fasthttp.RequestCtx) {

 	s.Step("preparations")

-	if RawDomain != nil && bytes.Equal(ctx.Request.Host(), RawDomain) {
+	if RawDomain != nil && bytes.Equal(trimmedHost, RawDomain) {
 		// Serve raw content from RawDomain
 		s.Debug("raw domain")

@ -169,12 +171,12 @@ func handler(ctx *fasthttp.RequestCtx) {
 			return
 		}

-	} else if bytes.HasSuffix(ctx.Request.Host(), MainDomainSuffix) {
+	} else if bytes.HasSuffix(trimmedHost, MainDomainSuffix) {
 		// Serve pages from subdomains of MainDomainSuffix
 		s.Debug("main domain suffix")

 		pathElements := strings.Split(string(bytes.Trim(ctx.Request.URI().Path(), "/")), "/")
-		targetOwner = string(bytes.TrimSuffix(ctx.Request.Host(), MainDomainSuffix))
+		targetOwner = string(bytes.TrimSuffix(trimmedHost, MainDomainSuffix))
 		targetRepo = pathElements[0]
 		targetPath = strings.Trim(strings.Join(pathElements[1:], "/"), "/")

@ -235,8 +237,10 @@ func handler(ctx *fasthttp.RequestCtx) {
 		returnErrorPage(ctx, fasthttp.StatusFailedDependency)
 		return
 	} else {
+		trimmedHostStr := string(trimmedHost)
+
 		// Serve pages from external domains
-		targetOwner, targetRepo, targetBranch = getTargetFromDNS(string(ctx.Request.Host()))
+		targetOwner, targetRepo, targetBranch = getTargetFromDNS(trimmedHostStr)
 		if targetOwner == "" {
 			ctx.Redirect(BrokenDNSPage, fasthttp.StatusTemporaryRedirect)
 			return
@ -253,8 +257,11 @@ func handler(ctx *fasthttp.RequestCtx) {
 		// Try to use the given repo on the given branch or the default branch
 		s.Step("custom domain preparations, now trying with details from DNS")
 		if tryBranch(targetRepo, targetBranch, pathElements, canonicalLink) {
-			canonicalDomain := checkCanonicalDomain(targetOwner, targetRepo, targetBranch)
-			if canonicalDomain != string(ctx.Request.Host()) {
+			canonicalDomain, valid := checkCanonicalDomain(targetOwner, targetRepo, targetBranch, trimmedHostStr)
+			if !valid {
+				returnErrorPage(ctx, fasthttp.StatusMisdirectedRequest)
+				return
+			} else if canonicalDomain != trimmedHostStr {
 				// only redirect if the target is also a codeberg page!
 				targetOwner, _, _ = getTargetFromDNS(strings.SplitN(canonicalDomain, "/", 2)[0])
 				if targetOwner != "" {
@ -282,6 +289,9 @@ func returnErrorPage(ctx *fasthttp.RequestCtx, code int) {
 	ctx.Response.SetStatusCode(code)
 	ctx.Response.Header.SetContentType("text/html; charset=utf-8")
 	message := fasthttp.StatusMessage(code)
+	if code == fasthttp.StatusMisdirectedRequest {
+		message += " - domain not specified in <code>.domains</code> file"
+	}
 	if code == fasthttp.StatusFailedDependency {
 		message += " - owner, repo or branch doesn't exist"
 	}
--- a/helpers.go
+++ b/helpers.go
@ -0,0 +1,21 @@
+package main
+
+import "bytes"
+
+// GetHSTSHeader returns a HSTS header with includeSubdomains & preload for MainDomainSuffix and RawDomain, or an empty
+// string for custom domains.
+func GetHSTSHeader(host []byte) string {
+	if bytes.HasSuffix(host, MainDomainSuffix) || bytes.Equal(host, RawDomain) {
+		return "max-age=63072000; includeSubdomains; preload"
+	} else {
+		return ""
+	}
+}
+
+func TrimHostPort(host []byte) []byte {
+	i := bytes.IndexByte(host, ':')
+	if i >= 0 {
+		return host[:i]
+	}
+	return host
+}
--- a/main.go
+++ b/main.go
@ -94,7 +94,6 @@ func main() {
 		Concurrency:                  1024 * 32, // TODO: adjust bottlenecks for best performance with Gitea!
 		MaxConnsPerIP:                100,
 	}
-	//fasthttp2.ConfigureServerAndConfig(server, tlsConfig)

 	// Setup listener and TLS
 	listener, err := net.Listen("tcp", address)