From 93cd2d30e484a806982c8318acee4117bea6ea53 Mon Sep 17 00:00:00 2001
From: Neeraj Gupta <254676+ua741@users.noreply.github.com>
Date: Sat, 10 May 2025 07:22:28 +0530
Subject: [PATCH] Improve handling for ott errors

---
 server/pkg/controller/user/user.go     |  3 +++
 server/pkg/controller/user/userauth.go | 24 +++++++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/server/pkg/controller/user/user.go b/server/pkg/controller/user/user.go
index aacb5a64f3..048eaa54df 100644
--- a/server/pkg/controller/user/user.go
+++ b/server/pkg/controller/user/user.go
@@ -59,6 +59,7 @@ type UserController struct {
 	UserCache              *cache2.UserCache
 	UserCacheController    *usercache.Controller
 	SRPLimiter             *limiter.Limiter
+	OTTLimiter             *limiter.Limiter
 }
 
 const (
@@ -125,6 +126,7 @@ func NewUserController(
 	userCacheController *usercache.Controller,
 ) *UserController {
 	srpLimiter := util.NewRateLimiter("100-H")
+	ottLimiter := util.NewRateLimiter("100-H")
 	return &UserController{
 		UserRepo:               userRepo,
 		UsageRepo:              usageRepo,
@@ -151,6 +153,7 @@ func NewUserController(
 		UserCache:              userCache,
 		UserCacheController:    userCacheController,
 		SRPLimiter:             srpLimiter,
+		OTTLimiter:             ottLimiter,
 	}
 }
 
diff --git a/server/pkg/controller/user/userauth.go b/server/pkg/controller/user/userauth.go
index 13be40d6d6..ae20dff124 100644
--- a/server/pkg/controller/user/userauth.go
+++ b/server/pkg/controller/user/userauth.go
@@ -83,7 +83,7 @@ func hardcodedOTTForEmail(hardCodedOTT HardCodedOTT, email string) string {
 
 // SendEmailOTT generates and sends an OTT to the provided email address
 func (c *UserController) SendEmailOTT(context *gin.Context, email string, purpose string) error {
-	if err := c.validateSendOTT(email, purpose); err != nil {
+	if err := c.validateSendOTT(context, email, purpose); err != nil {
 		return err
 	}
 	ott, err := random.GenerateSixDigitOtp()
@@ -142,7 +142,7 @@ func (c *UserController) isEmailAlreadyUsed(email string) error {
 	return nil
 }
 
-func (c *UserController) validateSendOTT(email string, purpose string) error {
+func (c *UserController) validateSendOTT(ctx *gin.Context, email string, purpose string) error {
 	if purpose == ente.ChangeEmailOTTPurpose {
 		if err := c.isEmailAlreadyUsed(email); err != nil {
 			return err
@@ -155,13 +155,27 @@ func (c *UserController) validateSendOTT(email string, purpose string) error {
 	if purpose == ente.SignUpOTTPurpose && viper.GetBool("internal.disable-registration") && !isSignUpComplete {
 		return stacktrace.Propagate(ente.ErrPermissionDenied, "registration is disabled")
 	}
+	//
+	var registrationErr error
 	if purpose == ente.SignUpOTTPurpose && isSignUpComplete {
-		return stacktrace.Propagate(ente.ErrUserAlreadyRegistered, "user has already completed sign up process")
+		registrationErr = stacktrace.Propagate(ente.ErrUserAlreadyRegistered, "user has already completed sign up process")
 	}
 	if purpose == ente.LoginOTTPurpose && !isSignUpComplete {
-		return stacktrace.Propagate(ente.ErrUserNotRegistered, "user has not completed sign up process")
+		registrationErr = stacktrace.Propagate(ente.ErrUserNotRegistered, "user has not completed sign up process")
 	}
-	return nil
+	// if no registration error, return
+	if registrationErr == nil {
+		return registrationErr
+	}
+	// check & swallow registration information error if too many such
+	// errors are generated in a short time
+	if limiter, limitErr := c.OTTLimiter.Get(ctx, "send-ott"); limitErr != nil {
+		if limiter.Reached {
+			go c.DiscordController.NotifyPotentialAbuse("swallowing send-ott registration error")
+			return nil
+		}
+	}
+	return registrationErr
 }
 
 // isSignUpComplete checks if the user has completed the entire signup process.