From 1b5987275a069dfb075a9699247f0b27903043e2 Mon Sep 17 00:00:00 2001
From: Matthieu Lalonde <matth@noreply.git.lalonde.me>
Date: Wed, 27 Jan 2021 20:30:28 +0000
Subject: [PATCH] Verify discord channel type on join, fixes issue #8

---
 pkg/discord/discord.go | 14 ++++++++++++++
 pkg/utils/utils.go     | 12 ++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/pkg/discord/discord.go b/pkg/discord/discord.go
index 5d8fd0a..d016547 100644
--- a/pkg/discord/discord.go
+++ b/pkg/discord/discord.go
@@ -12,6 +12,7 @@ import (
 	"os"
 
 	"git.lalonde.me/matth/AltVRBot/pkg/discord/mux"
+	"git.lalonde.me/matth/AltVRBot/pkg/utils"
 	"github.com/bwmarrin/discordgo"
 )
 
@@ -27,6 +28,10 @@ type Discord struct {
 	User       *discordgo.User
 }
 
+var (
+	allowedChannelTypes = []discordgo.ChannelType{discordgo.ChannelTypeGuildText, discordgo.ChannelTypeDM, discordgo.ChannelTypeGroupDM}
+)
+
 // New instanciates a new discord bot
 func New(token, sID, cID string) (*Discord, error) {
 	dg := &Discord{
@@ -49,6 +54,15 @@ func New(token, sID, cID string) (*Discord, error) {
 
 	dg.Session = session
 
+	c, err := dg.Session.Channel(cID)
+	if err != nil {
+		log.Fatalf("Invalid channel ID: %+v\n", err)
+	}
+
+	if !utils.SliceContainsChannelType(allowedChannelTypes, c.Type) {
+		log.Fatalf("Cannot join channel, invalid channel type")
+	}
+
 	dg.addHandlers()
 
 	// Open a websocket connection to Discord
diff --git a/pkg/utils/utils.go b/pkg/utils/utils.go
index 5fa7ff7..dd005e1 100644
--- a/pkg/utils/utils.go
+++ b/pkg/utils/utils.go
@@ -1,5 +1,7 @@
 package utils
 
+import "github.com/bwmarrin/discordgo"
+
 // TruncateString UTF8 truncation of string to `i` length
 func TruncateString(s string, i int) string {
 	runes := []rune(s)
@@ -8,3 +10,13 @@ func TruncateString(s string, i int) string {
 	}
 	return s
 }
+
+// SliceContainsChannelType looks for int value in a slice
+func SliceContainsChannelType(s []discordgo.ChannelType, e discordgo.ChannelType) bool {
+	for _, a := range s {
+		if a == e {
+			return true
+		}
+	}
+	return false
+}