Return 403 on join if banned from a group

telegram/utils.go

@@ -2857,6 +2857,39 @@ func (c *Client) IsMessageSendingPermitted(permissions *client.ChatPermissions)
 		permissions.CanSendOtherMessages
 }
 
+// GetMyStatusInChat checks the membership status of current account in the given chat
+func (c *Client) GetMyStatusInChat(chatID int64) ChatMemberStatus {
+	if c.me == nil {
+		return ChatMemberStatusIllegal
+	}
+
+	member, err := c.client.GetChatMember(&client.GetChatMemberRequest{
+		ChatId:   chatID,
+		MemberId: &client.MessageSenderUser{UserId: c.me.Id},
+	})
+	if err != nil {
+		return ChatMemberStatusIllegal
+	}
+	return c.getChatMemberStatus(member.Status)
+}
+
+func (c *Client) getChatMemberStatus(status client.ChatMemberStatus) ChatMemberStatus {
+	switch status.ChatMemberStatusType() {
+	case client.TypeChatMemberStatusCreator, client.TypeChatMemberStatusAdministrator:
+		return ChatMemberStatusPromoted
+	case client.TypeChatMemberStatusMember:
+		return ChatMemberStatusUnbanned
+	case client.TypeChatMemberStatusRestricted:
+		return ChatMemberStatusMuted
+	case client.TypeChatMemberStatusLeft:
+		return ChatMemberStatusKicked
+	case client.TypeChatMemberStatusBanned:
+		return ChatMemberStatusBanned
+	}
+
+	return ChatMemberStatusIllegal
+}
+
 // GetErrorCode obtains an error code from a Telegram response error
 func GetErrorCode(err error) (int32, bool) {
 	responseError, ok := err.(client.ResponseError)

xmpp/handlers.go

@@ -595,6 +595,13 @@ func handleMUCPresence(s xmpp.Sender, p stanza.Presence, mucExt stanza.MucPresen
 				return
 			}
 
+			status := session.GetMyStatusInChat(chatId)
+			// TODO: seems to be impossible for basic groups, check back when supergroups are supported
+			if status == telegram.ChatMemberStatusBanned {
+				presenceReplySetError(reply, 403)
+				return
+			}
+
 			log.Debugf("%#v", mucExt)
 			maxStanzas, maxStanzasOk := mucExt.History.MaxStanzas.Get()
 			maxChars, maxCharsOk := mucExt.History.MaxChars.Get()