Revert "feat: Add 3-strike anti-spam system for captchas"

src/ban.go

@@ -5,7 +5,6 @@ import (
 	"log"
 	"strings"
 	"sync"
-	"time"
 
 	tgbotapi "github.com/osprogramadores/telegram-bot-api"
 )
@@ -325,13 +324,3 @@ func kickUser(bot kickChatMemberer, chatID int64, userID int) error {
 	_, err := bot.KickChatMember(tgbotapi.KickChatMemberConfig{ChatMemberConfig: memberConfig})
 	return err
 }
-
-// kickUserUntil bans a user until a specific time.
-func kickUserUntil(bot kickChatMemberer, chatID int64, userID int, until time.Time) error {
-	memberConfig := tgbotapi.ChatMemberConfig{ChatID: chatID, UserID: userID}
-	_, err := bot.KickChatMember(tgbotapi.KickChatMemberConfig{
-		ChatMemberConfig: memberConfig,
-		UntilDate:        until.Unix(),
-	})
-	return err
-}

src/bot.go

@@ -33,9 +33,6 @@ type opBot struct {
 	// List of users not yet validated by captcha.
 	pendingCaptcha *pendingCaptchaType
 
-	// Track captcha failures across sessions
-	captchaFails *captchaFailures
-
 	// Don't send warning messages to new users on every infraction.
 	newUserWarningCache *cache.Cache
 
@@ -86,7 +83,6 @@ func newOpBot(config botConfig) (opBot, error) {
 
 		newUserCache:   cache.New(duration, duration),
 		pendingCaptcha: newPendingCaptchaType(),
-		captchaFails:   newCaptchaFailures(),
 
 		// How often will re-send warning messages to offending new users.
 		newUserWarningCache: cache.New(30*time.Minute, time.Hour),
@@ -225,11 +221,7 @@ func (x *opBot) Run(bot *tgbotapi.BotAPI) {
 						// and exit normally.
 						promCaptchaValidatedCount.Inc()
 						x.pendingCaptcha.del(userid)
-						x.captchaFails.reset(userid)
 						x.sendWelcome(bot, update, *update.Message.From)
-					} else {
-						promCaptchaFailedCount.Inc()
-						x.handleCaptchaFailure(bot, chatid, msgid, *update.Message.From)
 					}
 					continue
 				}

src/captcha.go

@@ -143,7 +143,7 @@ func (x *opBot) captchaReaper(bot tgbotInterface, chatID int64, user tgbotapi.Us
 		name := nameRef(user)
 
 		// check if this user is already banned and possibly skip some of the following steps.
-		_, err := isBanned(bot, chatID, user.ID)
+		banned, err := isBanned(bot, chatID, user.ID)
 		if err != nil {
 			log.Printf("Warning: Unable to get information for user %s (uid=%d): %v", name, user.ID, err)
 		}
@@ -152,7 +152,29 @@ func (x *opBot) captchaReaper(bot tgbotInterface, chatID int64, user tgbotapi.Us
 		// in the pending captcha list, meaning they didn't confirm the
 		// captcha.
 
-		x.handleCaptchaFailure(bot, chatID, 0, user)
+		// Let's remove the pending request.
+		defer x.pendingCaptcha.del(user.ID)
+
+		// Do nothing if user is already kicked (probably by an admin).
+		if banned {
+			log.Printf("User %s (uid=%d) has already been banned (by admin?) Not unbanning.", name, user.ID)
+			return
+		}
+
+		// As the user is not yet banned, proceed to kick+unban.
+		// Kick user and remove from list.
+		_, err = sendMessage(bot, chatID, fmt.Sprintf(T("no_captcha_received"), name))
+		if err != nil {
+			log.Printf("Warning: Unable to send 'invalid captcha' message.")
+		}
+
+		if err = kickUser(bot, chatID, user.ID); err != nil {
+			log.Printf("Warning: Unable to kick user %s (uid=%d) out of the channel.", name, user.ID)
+		}
+
+		if err = unBanUser(bot, chatID, user.ID); err != nil {
+			log.Printf("Warning: Unable to UNBAN user %s (uid=%d) (May be locked out.)", name, user.ID)
+		}
 	})
 }
 
@@ -221,85 +243,3 @@ func bincode(s string) []byte {
 func captchaResendRequest(s string) bool {
 	return strings.EqualFold(s, T("another_captcha"))
 }
-
-// handleCaptchaFailure deals with users who failed the captcha (timeout or wrong answer).
-func (x *opBot) handleCaptchaFailure(bot tgbotInterface, chatID int64, messageID int, user tgbotapi.User) {
-	name := nameRef(user)
-	fails := x.captchaFails.increment(user.ID)
-
-	log.Printf("User %s (uid=%d) failed captcha. Total fails: %d", name, user.ID, fails)
-
-	// Remove from pending
-	x.pendingCaptcha.del(user.ID)
-
-	banned, err := isBanned(bot, chatID, user.ID)
-	if err != nil {
-		log.Printf("Warning: Unable to get information for user %s (uid=%d): %v", name, user.ID, err)
-	}
-
-	if banned {
-		log.Printf("User %s (uid=%d) has already been banned. Not doing anything.", name, user.ID)
-		return
-	}
-
-	switch fails {
-	case 1:
-		sendMessage(bot, chatID, fmt.Sprintf(T("captcha_fail_1"), name))
-		kickUser(bot, chatID, user.ID)
-		unBanUser(bot, chatID, user.ID)
-	case 2:
-		sendMessage(bot, chatID, fmt.Sprintf(T("captcha_fail_2"), name))
-		kickUser(bot, chatID, user.ID)
-		unBanUser(bot, chatID, user.ID)
-	case 3:
-		sendMessage(bot, chatID, fmt.Sprintf(T("captcha_fail_3"), name))
-		kickUserUntil(bot, chatID, user.ID, time.Now().Add(24*time.Hour))
-	default:
-		sendMessage(bot, chatID, fmt.Sprintf(T("captcha_fail_max"), name))
-		banUser(bot, chatID, user.ID)
-	}
-}
-
-const captchaFailuresDB = "captcha_failures.json"
-
-type captchaFailures struct {
-	sync.RWMutex
-	Failures map[int]int `json:"failures"`
-}
-
-func newCaptchaFailures() *captchaFailures {
-	cf := &captchaFailures{
-		Failures: map[int]int{},
-	}
-	cf.load()
-	return cf
-}
-
-func (c *captchaFailures) load() {
-	c.Lock()
-	defer c.Unlock()
-	readJSONFromDataDir(&c.Failures, captchaFailuresDB)
-	if c.Failures == nil {
-		c.Failures = map[int]int{}
-	}
-}
-
-func (c *captchaFailures) save() error {
-	return safeWriteJSON(c.Failures, captchaFailuresDB)
-}
-
-func (c *captchaFailures) increment(userID int) int {
-	c.Lock()
-	defer c.Unlock()
-	c.Failures[userID]++
-	fails := c.Failures[userID]
-	c.save()
-	return fails
-}
-
-func (c *captchaFailures) reset(userID int) {
-	c.Lock()
-	defer c.Unlock()
-	delete(c.Failures, userID)
-	c.save()
-}