internal/db/initialize.go

@@ -46,6 +46,11 @@ func InitializeDB() error {
 		return fmt.Errorf("[DB] couldn't create database: [%w]", err)
 	}
 
+	_, err = models.DB.NewCreateTable().IfNotExists().Model((*models.MFAScratchCode)(nil)).Exec(context.Background())
+	if err != nil {
+		return fmt.Errorf("[DB] couldn't create database: [%w]", err)
+	}
+
 	err = doMigrations()
 	if err != nil {
 		return fmt.Errorf("[DB] Error during Migrations: [%w]", err)

internal/db/multifactor.go

@@ -18,3 +18,18 @@ func UserHasMFA(user models.User) (bool, error) {
 	}
 	return false, nil
 }
+
+// ScratchCodeUnique checks the database if the generated scratch code
+// is unique (not in the database yet)
+func ScratchCodeIsUnique(scratchcode string) bool {
+	var dbitem models.MFAScratchCode
+	numrows, err := models.DB.NewSelect().Model(&dbitem).Where("code = ?", scratchcode).Count(context.Background())
+	if err != nil {
+		return false
+	}
+
+	if numrows != 0 {
+		return false
+	}
+	return true
+}

internal/web/multifactor-login.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"slices"
 
@@ -45,20 +46,28 @@ func HandleAdminLoginMFAPost(c *fiber.Ctx) error {
 	}
 
 	// check token/scratch validity
-	var passcodeIsValid bool
+	var scratchcodeIsValid bool
 	if istotp {
-		passcodeIsValid = checkTotpIsValid(token.Token, user)
+		scratchcodeIsValid = checkTotpIsValid(token.Token, user)
 	} else {
-		passcodeIsValid = checkScratchIsValid(token.Token, user)
+		scratchcodeIsValid = checkScratchIsValid(token.Token, user)
 	}
 
-	if passcodeIsValid {
+	if scratchcodeIsValid {
 		err = misc.SetLoginCookie(c, user, constants.LoginCookieExpiryDuration)
 		if err != nil {
 			log.Printf("[HandleAdminLoginPost] Error setting cookie: %q\n", err)
 			return misc.New500Error()
 		}
 
+		_, err = models.DB.NewUpdate().
+			Model(&models.MFAScratchCode{Code: token.Token, IsUsed: true}).
+			OmitZero().WherePK().Exec(context.Background())
+		if err != nil {
+			fmt.Printf("[HandleAdminLoginMFAPost] Error marking scratch code as used: %v\n", err.Error())
+			return fiber.NewError(fiber.StatusInternalServerError, "500 Internal Server Error")
+		}
+
 		c.Status(fiber.StatusOK)
 		return nil
 	}
@@ -81,16 +90,21 @@ func checkTotpIsValid(passcode string, user models.User) bool {
 }
 
 func checkScratchIsValid(scratch string, user models.User) bool {
-	var mfaconfig models.MFAConfig
+	var scratchcodes []models.MFAScratchCode
 
-	err := models.DB.NewSelect().Model(&mfaconfig).Where("username = ?", user.UserName).Scan(context.Background())
+	err := models.DB.NewSelect().Model(&scratchcodes).Where("username = ?", user.UserName).Where("is_used = ?", false).Scan(context.Background())
 	if err != nil {
 		log.Printf("Error getting MFA config for %v from DB: %v\n", user.UserName, err.Error())
 		// TODO: Debug logging
 		return false
 	}
 
-	return slices.Contains(mfaconfig.RecoveryCodes, scratch)
+	var scratchcodeSlice []string
+	for _, code := range scratchcodes {
+		scratchcodeSlice = append(scratchcodeSlice, code.Code)
+	}
+
+	return slices.Contains(scratchcodeSlice, scratch)
 }
 
 func HandleAdminLoginMFAGet(c *fiber.Ctx) error {

internal/web/setup-multifactor.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/base64"
 	"encoding/json"
+	"fmt"
 	"image/png"
 	"log"
 	"strconv"
@@ -18,12 +19,6 @@ import (
 	"github.com/pquerna/otp/totp"
 )
 
-type mfaSetupResponse struct {
-	Error          bool     `json:"error"`
-	Message        string   `json:"message,omitempty"`
-	RecoveryTokens []string `json:"recoverytokens,omitempty"`
-}
-
 func HandleAdminAccountMFASetupGet(c *fiber.Ctx) error {
 	if !db.IsCookieValid(c.Cookies(constants.LoginCookieName, "")) {
 		c.Location("/admin/")
@@ -36,15 +31,33 @@ func HandleAdminAccountMFASetupGet(c *fiber.Ctx) error {
 	mfaconfig.Active = false
 	mfaconfig.ExpiresAt = time.Now().Add(15 * time.Minute)
 
-	for i := 0; i < 6; i++ {
-		mfaconfig.RecoveryCodes = append(mfaconfig.RecoveryCodes, misc.RandomString(8))
-	}
-
 	user, err := db.GetUserFromCookie(c.Cookies(constants.LoginCookieName))
 	if err != nil {
 		log.Println(err)
 		fiber.NewError(fiber.StatusInternalServerError, "500 Internal Server Error")
 	}
+
+	scratchcodes := []models.MFAScratchCode{}
+	scratchcodeFailed := 0
+
+	// generate four unique(!) scratch codes for the user
+	for len(scratchcodes) != 4 {
+		if scratchcodeFailed > 15 {
+			//TODO: structurized error logging
+			fmt.Println("[HandleAdminAccountMFASetupPost] Failed to generate unique scratch code 15 times! Aborting")
+			return misc.New500Error()
+		}
+
+		code := misc.RandomString(8)
+
+		if db.ScratchCodeIsUnique(code) {
+			scratchcodes = append(scratchcodes, models.MFAScratchCode{
+				IsUsed: false, Code: code, UserName: user.UserName})
+		} else {
+			scratchcodeFailed++
+		}
+	}
+
 	mfaconfig.UserName = user.UserName
 
 	key, err := totp.Generate(totp.GenerateOpts{
@@ -71,6 +84,12 @@ func HandleAdminAccountMFASetupGet(c *fiber.Ctx) error {
 
 	mfaobject.Image = base64img
 
+	_, err = models.DB.NewInsert().Model(&scratchcodes).Exec(context.Background())
+	if err != nil {
+		log.Printf("[HandleAdminAccountMFASetupGet] Error inserting scratch codes to DB: %q\n", err)
+		fiber.NewError(fiber.StatusInternalServerError, "500 Internal Server Error")
+	}
+
 	_, err = models.DB.NewInsert().Model(&mfaconfig).Exec(context.Background())
 	if err != nil {
 		log.Printf("[HandleAdminAccountMFASetupGet] Error inserting mfaconfig to DB: %q\n", err)
@@ -88,11 +107,12 @@ func HandleAdminAccountMFASetupPost(c *fiber.Ctx) error {
 		return nil
 	}
 
-	var response mfaSetupResponse
+	var response models.MFASetupResponse
 	response.Error = true
 
 	var token models.TokenRequest
 	var config models.MFAConfig
+	var scratchcodes []models.MFAScratchCode
 	//var user models.User
 
 	err := json.Unmarshal(c.Body(), &token)
@@ -115,7 +135,7 @@ func HandleAdminAccountMFASetupPost(c *fiber.Ctx) error {
 
 	err = models.DB.NewSelect().Model(&config).Where("id = ?", setupcookie).Scan(context.Background())
 	if err != nil {
-		log.Printf("[HandleAdminAccountMFASetupGet] Error getting MFAConfig from DB: %q\n", err)
+		log.Printf("[HandleAdminAccountMFASetupPost] Error getting MFAConfig from DB: %q\n", err)
 		return fiber.NewError(fiber.StatusInternalServerError, "500 Internal Server Error")
 	}
 
@@ -123,7 +143,19 @@ func HandleAdminAccountMFASetupPost(c *fiber.Ctx) error {
 	if totpvalid {
 		response.Error = false
 		response.Message = "Multifactor authentication was successfully set up!"
-		response.RecoveryTokens = config.RecoveryCodes
+
+		err = models.DB.NewSelect().Model(&scratchcodes).Where("username = ?", config.UserName).Scan(context.Background())
+		if err != nil {
+			log.Printf("[HandleAdminAccountMFASetupPost] Error getting MFA scratch codes from DB: %q\n", err)
+			return fiber.NewError(fiber.StatusInternalServerError, "500 Internal Server Error")
+		}
+
+		var scratchcodeSlice []string
+		for _, code := range scratchcodes {
+			scratchcodeSlice = append(scratchcodeSlice, code.Code)
+		}
+
+		response.RecoveryTokens = scratchcodeSlice
 
 		config.Active = true
 

models/multifactor.go

@@ -26,12 +26,24 @@ type MFAConfig struct {
 	ID            int64     `bun:"id,pk,autoincrement"`
 	UserName      string    `bun:"username,notnull"`
 	TOTPSecret    string    `bun:"totpurl,notnull"`
-	RecoveryCodes []string  `bun:"recoverycodes,notnull,array"`
 	ExpiresAt     time.Time `bun:"expiresat,notnull"`
 	Active        bool      `bun:"active,notnull"`
 }
 
+type MFAScratchCode struct {
+	bun.BaseModel `bun:"table:multifactor_scratchcodes"`
+	Code          string `bun:"code,pk"`
+	UserName      string `bun:"username,notnull"`
+	IsUsed        bool   `bun:"is_used,notnull"`
+}
+
 type MFATemplateObject struct {
 	Key   string
 	Image string
 }
+
+type MFASetupResponse struct {
+	Error          bool     `json:"error"`
+	Message        string   `json:"message,omitempty"`
+	RecoveryTokens []string `json:"recovery_tokens,omitempty"`
+}

views/account.tmpl

@@ -50,11 +50,11 @@
     <p>Created at: {{ .Created }}</p>
 
     <h2>Security</h2>
-    {{if not .HasMFA}}
+    {{if .MFAEnabled}}
-      <a href="/admin/account/mfasetup" role="button">Setup 2fa</a>
-    {{else}}
       <a role="button" class="secondary">2fa already enabled</a>
-    {{end}}
+    {{else}}
+      <a href="/admin/account/mfasetup" role="button">Setup 2fa</a>
+      {{end}}
     <dialog id="dialog-info">
       <h2 id="dialog-heading"></h2>
       <p id="dialog-text"></p>

web/main.js

@@ -134,7 +134,7 @@ async function HandleMFASetupTokenSubmit() {
     if (response.ok) {
         let data = await response.json()
 
-        document.getElementById("dialog-tokens").textContent = data["recoverytokens"].join(" ")
+        document.getElementById("dialog-tokens").textContent = data["recovery_tokens"].join(" ")
         document.getElementById('dialog-success').showModal()
     } else {
         document.cookie = 'gourlsh_mfa_setup=; Max-Age=-1; path=/; domain=' + location.hostname;