1 files changed, 18 insertions, 175 deletions

diff --git a/roseh.moe.go b/roseh.moe.go
index e8fb802..54b4ea6 100644
--- a/roseh.moe.go
+++ b/roseh.moe.go
@@ -22,17 +22,12 @@ import (
 	"bytes"
 	"compress/gzip"
 	"context"
-	"crypto"
-	"crypto/ecdsa"
 	"crypto/hmac"
 	"crypto/rand"
-	"crypto/rsa"
 	"crypto/sha256"
-	"crypto/x509"
 	"embed"
 	"encoding/base64"
 	"encoding/binary"
-	"encoding/json/v2"
 	"encoding/xml"
 	"flag"
 	"fmt"
@@ -55,6 +50,7 @@ import (
 	"unicode"
 
 	"github.com/skip2/go-qrcode"
+	"roseh.moe/pkg/roseh.moe/internal/auth"
 	"roseh.moe/pkg/roseh.moe/internal/hole"
 	"roseh.moe/pkg/wordlist"
 )
@@ -104,40 +100,6 @@ func urlFlag(name, def, doc string) *url.URL {
 	return u
 }
 
-func sigVerifier(keyBytes []byte) (func(msg, sig []byte) bool, error) {
-	key, err := x509.ParsePKIXPublicKey(keyBytes)
-	if err != nil {
-		return nil, err
-	}
-	switch key := key.(type) {
-	case *ecdsa.PublicKey:
-		return func(msg, sig []byte) bool {
-			hash := sha256.Sum256(msg)
-			return ecdsa.VerifyASN1(key, hash[:], sig)
-		}, nil
-	case *rsa.PublicKey:
-		return func(msg, sig []byte) bool {
-			hash := sha256.Sum256(msg)
-			return rsa.VerifyPKCS1v15(key, crypto.SHA256, hash[:], sig) == nil
-		}, nil
-	default:
-		return nil, fmt.Errorf("unsupported key type")
-	}
-}
-
-func verifyPubKey(pubKey, msg, sig []byte) error {
-	verify, err := sigVerifier(pubKey)
-	if err != nil {
-		return err
-	}
-	if !verify(msg, sig) {
-		return fmt.Errorf("message failed validation")
-	}
-	return nil
-}
-
-var secretKey []byte
-
 func loadSecrets() error {
 	fileBytes, err := os.ReadFile(*secretsFile)
 	if err != nil {
@@ -152,7 +114,7 @@ func loadSecrets() error {
 	if secretsConfig.SecretKey == "" {
 		return fmt.Errorf("%s: missing SecretKey", *secretsFile)
 	}
-	if secretKey, err = base64.StdEncoding.DecodeString(secretsConfig.SecretKey); err != nil {
+	if auth.SecretKey, err = base64.StdEncoding.DecodeString(secretsConfig.SecretKey); err != nil {
 		return fmt.Errorf("%s: bad SecretKey (try base64)", *secretsFile)
 	}
 	return nil
@@ -173,15 +135,10 @@ type commandConfig struct {
 	Multi       bool   `xml:",attr"`
 }
 
-type passkey struct {
-	ID  string `xml:",attr"`
-	Key string `xml:",attr"`
-}
-
 type serviceConfiguration struct {
 	PackageRedirects []packageConfig `xml:"Redirects>Package"`
 	CommandRedirects []commandConfig `xml:"Redirects>Command"`
-	Passkey          []passkey
+	Passkey          []auth.Passkey
 	passkeys         map[string][]byte
 }
 
@@ -213,35 +170,9 @@ func loadConfig() (*serviceConfiguration, error) {
 	if err := xml.Unmarshal(fileBytes, config); err != nil {
 		return nil, err
 	}
-	names := make(map[string]bool)
-	config.passkeys = make(map[string][]byte)
-	namesByID := make(map[string]string)
-	for _, passkey := range config.Passkey {
-		if names[passkey.ID] {
-			return nil, fmt.Errorf("%s: duplicate name %q", *configFile, passkey.ID)
-		}
-		names[passkey.ID] = true
-		keyBytes, err := base64.RawURLEncoding.DecodeString(strings.Map(func(r rune) rune {
-			if unicode.IsSpace(r) {
-				return -1
-			}
-			return r
-		}, passkey.Key))
-		if err != nil {
-			return nil, fmt.Errorf("%s: invalid key for passkey %q: %s", *configFile, passkey.ID, err)
-		}
-		if len(keyBytes) < 16 {
-			return nil, fmt.Errorf("%s: invalid key for passkey %q: bad user ID: too short", *configFile, passkey.ID)
-		}
-		id, key := keyBytes[:16], keyBytes[16:]
-		if _, err := sigVerifier(key); err != nil {
-			return nil, fmt.Errorf("%s: invalid key for passkey %q: %s", *configFile, passkey.ID, err)
-		}
-		if _, ok := config.passkeys[string(id)]; ok {
-			return nil, fmt.Errorf("%s: passkeys %q and %q have duplicate ID %d", *configFile, namesByID[string(id)], passkey.ID, id)
-		}
-		config.passkeys[string(id)] = key
-		namesByID[string(id)] = passkey.ID
+	config.passkeys, err = auth.LoadPasskeys(config.Passkey)
+	if err != nil {
+		return nil, fmt.Errorf("%s: %s", *configFile, err)
 	}
 	slices.SortFunc(config.PackageRedirects, func(x, y packageConfig) int { return strings.Compare(x.Name, y.Name) })
 	slices.SortFunc(config.CommandRedirects, func(x, y commandConfig) int { return strings.Compare(x.Name, y.Name) })
@@ -407,7 +338,7 @@ func sharedFileHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func qrHandler(w http.ResponseWriter, r *http.Request) {
-	text, ok := verifyHMAC(r.FormValue("t"), "qr")
+	text, ok := auth.VerifyHMAC(r.FormValue("t"), "qr")
 	if !ok {
 		http.Error(w, "Bad signature", http.StatusBadRequest)
 		return
@@ -485,7 +416,7 @@ func wormholeUpload(w http.ResponseWriter, r *http.Request) {
 	downloadURL := selfURL.String() + "/wormhole/" + holeName
 	if err := wormholeSuccessTemplate.Execute(w, wormholeSuccessTemplateArgs{
 		URL: downloadURL,
-		QR:  "/qr.png?t=" + url.QueryEscape(signMsg(downloadURL, "qr")),
+		QR:  "/qr.png?t=" + url.QueryEscape(auth.SignMsg(downloadURL, "qr")),
 	}); err != nil {
 		log.Printf("Warning: wormholeSend: %s", err)
 	}
@@ -517,31 +448,6 @@ func wormholeDownload(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func mac(msg []byte, purpose string) []byte {
-	mac := hmac.New(sha256.New, secretKey)
-	io.WriteString(mac, purpose)
-	io.WriteString(mac, ":")
-	mac.Write(msg)
-	return mac.Sum(nil)
-}
-
-func signMsg(msg, purpose string) string {
-	return msg + base64.RawURLEncoding.EncodeToString(mac([]byte(msg), purpose))
-}
-
-func verifyHMAC(signedMsg, purpose string) (string, bool) {
-	macSize := base64.RawURLEncoding.EncodedLen(sha256.Size)
-	if len(signedMsg) < macSize {
-		return "", false
-	}
-	msg, msgMAC := signedMsg[:len(signedMsg)-macSize], signedMsg[len(signedMsg)-macSize:]
-	expectedMAC := base64.RawURLEncoding.EncodeToString(mac([]byte(msg), purpose))
-	if !hmac.Equal([]byte(msgMAC), []byte(expectedMAC)) {
-		return "", false
-	}
-	return msg, true
-}
-
 const (
 	authVersion    = "authv3"
 	authCookieName = "__Secure-a"
@@ -569,7 +475,7 @@ type authToken struct {
 func attachCookie(w http.ResponseWriter, tok *authToken) {
 	buf := binary.AppendVarint(nil, tok.expiry.Unix())
 	buf = append(buf, tok.userID...)
-	token := signMsg(base64.RawURLEncoding.EncodeToString(buf), authVersion)
+	token := auth.SignMsg(base64.RawURLEncoding.EncodeToString(buf), authVersion)
 	http.SetCookie(w, makeHTTPCookie(token, tok.expiry))
 }
 
@@ -578,7 +484,7 @@ func cookieAuth(r *http.Request) bool {
 	if err != nil {
 		return false
 	}
-	msg, ok := verifyHMAC(cookie.Value, authVersion)
+	msg, ok := auth.VerifyHMAC(cookie.Value, authVersion)
 	if !ok {
 		return false
 	}
@@ -628,13 +534,6 @@ func verifyRedirect(redirect string) bool {
 	return false
 }
 
-const challengeExpiry = 10 * time.Minute
-
-var (
-	challengeMu sync.Mutex
-	challenges  = make(map[string]time.Time)
-)
-
 var (
 	//go:embed templates/login.html.template
 	loginTemplateString string
@@ -654,19 +553,13 @@ func serveLogin(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, redirect, http.StatusSeeOther)
 		return
 	}
-	buf := make([]byte, 32)
-	rand.Read(buf)
-	now := time.Now()
-	challengeMu.Lock()
-	if len(challenges) >= 100 {
-		challengeMu.Unlock()
+	challenge, ok := auth.NewChallenge()
+	if !ok {
 		http.Error(w, "Too many active requests", http.StatusTooManyRequests)
 		return
 	}
-	challenges[string(buf)] = now
-	challengeMu.Unlock()
 	if err := loginTemplate.Execute(w, loginTemplateArgs{
-		Challenge: base64.StdEncoding.EncodeToString(buf),
+		Challenge: base64.StdEncoding.EncodeToString(challenge),
 	}); err != nil {
 		log.Printf("Warning: login: %s", err)
 	}
@@ -699,51 +592,8 @@ func login(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "Internal error", http.StatusInternalServerError)
 		return
 	}
-	pubKey, ok := config.passkeys[string(user)]
-	if !ok {
-		http.Error(w, "No user with the given ID", http.StatusBadRequest)
-		return
-	}
-	clientDataHash := sha256.Sum256(clientData)
-	if err := verifyPubKey(pubKey, slices.Concat(authData, clientDataHash[:]), sig); err != nil {
-		http.Error(w, "Challenge failed", http.StatusBadRequest)
-		return
-	}
-	var cd struct {
-		Type        string `json:"type"`
-		Challenge   string `json:"challenge"`
-		Origin      string `json:"origin"`
-		CrossOrigin bool   `json:"crossOrigin"`
-	}
-	if err := json.Unmarshal(clientData, &cd); err != nil {
-		http.Error(w, "Bad client data: invalid JSON", http.StatusBadRequest)
-		return
-	}
-	challenge, err := base64.RawURLEncoding.DecodeString(cd.Challenge)
-	if err != nil {
-		http.Error(w, "Bad client data: bad challenge", http.StatusBadRequest)
-		return
-	}
-	challengeMu.Lock()
-	initiated, ok := challenges[string(challenge)]
-	delete(challenges, string(challenge))
-	challengeMu.Unlock()
-	if !ok {
-		http.Error(w, "Request already consumed", http.StatusConflict)
-		return
-	}
-	if time.Since(initiated) > challengeExpiry {
-		http.Error(w, "Challenge is too old. Please try again", http.StatusConflict)
-		return
-	}
-	if cd.Type != "webauthn.get" || cd.Origin != selfURL.String() || cd.CrossOrigin {
-		http.Error(w, "Bad client data", http.StatusBadRequest)
-		return
-	}
-	expectedRPHash := sha256.Sum256([]byte(selfURL.Hostname()))
-	const flagUserPresence, flagUserVerification = 0x01, 0x04
-	if len(authData) < 37 || !bytes.Equal(authData[:32], expectedRPHash[:]) || authData[32]&(flagUserPresence|flagUserVerification) != (flagUserPresence|flagUserVerification) {
-		http.Error(w, "Bad authenticator data", http.StatusBadRequest)
+	if err := auth.Login(user, authData, clientData, sig, config.passkeys, selfURL); err != nil {
+		http.Error(w, "Failed challenge", http.StatusBadRequest)
 		return
 	}
 	attachCookie(w, &authToken{
@@ -861,7 +711,7 @@ func serveOTP(w http.ResponseWriter, r *http.Request) {
 	otpURL := selfURL.String() + "/otp/" + l
 	if err := otpTemplate.Execute(w, otpTemplateArgs{
 		URL: otpURL,
-		QR:  "/qr.png?t=" + url.QueryEscape(signMsg(otpURL, "qr")),
+		QR:  "/qr.png?t=" + url.QueryEscape(auth.SignMsg(otpURL, "qr")),
 	}); err != nil {
 		log.Printf("Warning: serveOTP: %s", err)
 	}
@@ -1243,15 +1093,8 @@ func main() {
 	}()
 
 	go func() {
-		for now := range time.NewTicker(time.Hour).C {
-			log.Printf("Cleaning expired challenges")
-			challengeMu.Lock()
-			for challenge, initiated := range challenges {
-				if now.Sub(initiated) > challengeExpiry {
-					delete(challenges, challenge)
-				}
-			}
-			challengeMu.Unlock()
+		for range time.NewTicker(time.Hour).C {
+			auth.CleanChallenges()
 		}
 	}()