Add helper for permission calculations

d2m/converters/remove-reaction.js

@@ -12,7 +12,7 @@ const utils = sync.require("../../m2d/converters/utils")
  * @typedef ReactionRemoveRequest
  * @prop {string} eventID
  * @prop {string | null} mxid
- * @prop {BigInt} [hash]
+ * @prop {bigint} [hash]
  */
 
 /**

d2m/event-dispatcher.js

@@ -115,8 +115,7 @@ module.exports = {
 			if (!member) return
 			if (!("permission_overwrites" in channel)) continue
 			const permissions = dUtils.getPermissions(member.roles, guild.roles, client.user.id, channel.permission_overwrites)
-			const wants = BigInt(1 << 10) | BigInt(1 << 16) // VIEW_CHANNEL + READ_MESSAGE_HISTORY
-			if ((permissions & wants) !== wants) continue // We don't have permission to look back in this channel
+			if (!dUtils.hasAllPermissions(permissions, ["ViewChannel", "ReadMessageHistory"])) continue // We don't have permission to look back in this channel
 
 			/** More recent messages come first. */
 			// console.log(`[check missed messages] in ${channel.id} (${guild.name} / ${channel.name}) because its last message ${channel.last_message_id} is not in the database`)
@@ -164,8 +163,7 @@ module.exports = {
 
 			// Permissions check
 			const permissions = dUtils.getPermissions(member.roles, guild.roles, client.user.id, channel.permission_overwrites)
-			const wants = BigInt(1 << 10) | BigInt(1 << 16) // VIEW_CHANNEL + READ_MESSAGE_HISTORY
-			if ((permissions & wants) !== wants) continue // We don't have permission to look up the pins in this channel
+			if (!dUtils.hasAllPermissions(permissions, ["ViewChannel", "ReadMessageHistory"])) continue // We don't have permission to look up the pins in this channel
 
 			const row = select("channel_room", ["room_id", "last_bridged_pin_timestamp"], {channel_id: channel.id}).get()
 			if (!row) continue // Only care about already bridged channels

discord/discord-command-handler.js

@@ -137,7 +137,7 @@ const commands = [{
 			// Check CREATE_INSTANT_INVITE permission
 			assert(message.member)
 			const guildPermissions = utils.getPermissions(message.member.roles, guild.roles)
-			if (!(guildPermissions & BigInt(1))) {
+			if (!(guildPermissions & DiscordTypes.PermissionFlagsBits.CreateInstantInvite)) {
 				return discord.snow.channel.createMessage(channel.id, {
 					...ctx,
 					content: "You don't have permission to invite people to this Discord server."

discord/utils.js

@@ -1,6 +1,7 @@
 // @ts-check
 
 const DiscordTypes = require("discord-api-types/v10")
+const assert = require("assert").strict
 
 const EPOCH = 1420070400000
 
@@ -49,6 +50,48 @@ function getPermissions(userRoles, guildRoles, userID, channelOverwrites) {
 	return allowed
 }
 
+/**
+ * Note: You can only provide one permission bit to permissionToCheckFor. To check multiple permissions, call `hasAllPermissions` or `hasSomePermissions`.
+ * It is designed like this to avoid developer error with bit manipulations.
+ *
+ * @param {bigint} resolvedPermissions
+ * @param {bigint} permissionToCheckFor
+ * @returns {boolean} whether the user has the requested permission
+ * @example
+ * const permissions = getPermissions(userRoles, guildRoles, userID, channelOverwrites)
+ * hasPermission(permissions, DiscordTypes.PermissionFlagsBits.ViewChannel)
+ */
+function hasPermission(resolvedPermissions, permissionToCheckFor) {
+	// Make sure permissionToCheckFor has exactly one permission in it
+	assert.equal(permissionToCheckFor.toString(2).match(/1/g), 1)
+	// Do the actual calculation
+	return (resolvedPermissions & permissionToCheckFor) === permissionToCheckFor
+}
+
+/**
+ * @param {bigint} resolvedPermissions
+ * @param {(keyof DiscordTypes.PermissionFlagsBits)[]} permissionsToCheckFor
+ * @returns {boolean} whether the user has any of the requested permissions
+ * @example
+ * const permissions = getPermissions(userRoles, guildRoles, userID, channelOverwrites)
+ * hasSomePermissions(permissions, ["ViewChannel", "ReadMessageHistory"])
+ */
+function hasSomePermissions(resolvedPermissions, permissionsToCheckFor) {
+	return permissionsToCheckFor.some(x => hasPermission(resolvedPermissions, DiscordTypes.PermissionFlagsBits[x]))
+}
+
+/**
+ * @param {bigint} resolvedPermissions
+ * @param {(keyof DiscordTypes.PermissionFlagsBits)[]} permissionsToCheckFor
+ * @returns {boolean} whether the user has all of the requested permissions
+ * @example
+ * const permissions = getPermissions(userRoles, guildRoles, userID, channelOverwrites)
+ * hasAllPermissions(permissions, ["ViewChannel", "ReadMessageHistory"])
+ */
+function hasAllPermissions(resolvedPermissions, permissionsToCheckFor) {
+	return permissionsToCheckFor.every(x => hasPermission(resolvedPermissions, DiscordTypes.PermissionFlagsBits[x]))
+}
+
 /**
  * Command interaction responses have a webhook_id for some reason, but still have real author info of a real bot user in the server.
  * @param {DiscordTypes.APIMessage} message
@@ -69,6 +112,9 @@ function timestampToSnowflakeInexact(timestamp) {
 }
 
 module.exports.getPermissions = getPermissions
+module.exports.hasPermission = hasPermission
+module.exports.hasSomePermissions = hasSomePermissions
+module.exports.hasAllPermissions = hasAllPermissions
 module.exports.isWebhookMessage = isWebhookMessage
 module.exports.snowflakeToTimestampExact = snowflakeToTimestampExact
 module.exports.timestampToSnowflakeInexact = timestampToSnowflakeInexact