PluralKit/PluralKit.Bot/Proxy/ProxyService.cs

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using System.Text;
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using System.Text.RegularExpressions;
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using App.Metrics;
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using Myriad.Cache;
using Myriad.Extensions;
using Myriad.Gateway;
using Myriad.Rest;
using Myriad.Rest.Exceptions;
using Myriad.Rest.Types.Requests;
using Myriad.Types;
using PluralKit.Core;
using Serilog;
namespace PluralKit.Bot;
public class ProxyService
{
private static readonly TimeSpan MessageDeletionDelay = TimeSpan.FromMilliseconds(1000);
private readonly IDiscordCache _cache;
private readonly IDatabase _db;
private readonly DispatchService _dispatch;
private readonly LastMessageCacheService _lastMessage;
private readonly LogChannelService _logChannel;
private readonly ILogger _logger;
private readonly ProxyMatcher _matcher;
private readonly IMetrics _metrics;
private readonly ModelRepository _repo;
private readonly DiscordApiClient _rest;
private readonly WebhookExecutorService _webhookExecutor;
public ProxyService(LogChannelService logChannel, ILogger logger, WebhookExecutorService webhookExecutor,
DispatchService dispatch, IDatabase db, ProxyMatcher matcher, IMetrics metrics, ModelRepository repo,
IDiscordCache cache, DiscordApiClient rest, LastMessageCacheService lastMessage)
{
_logChannel = logChannel;
_webhookExecutor = webhookExecutor;
_dispatch = dispatch;
_db = db;
_matcher = matcher;
_metrics = metrics;
_repo = repo;
_cache = cache;
_lastMessage = lastMessage;
_rest = rest;
_logger = logger.ForContext<ProxyService>();
}
public async Task<bool> HandleIncomingMessage(Shard shard, MessageCreateEvent message, MessageContext ctx,
Guild guild, Channel channel, bool allowAutoproxy, PermissionSet botPermissions)
{
if (!ShouldProxy(channel, message, ctx))
return false;
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var rootChannel = await _cache.GetRootChannel(message.ChannelId);
List<ProxyMember> members;
// Fetch members and try to match to a specific member
using (_metrics.Measure.Timer.Time(BotMetrics.ProxyMembersQueryTime))
members = (await _repo.GetProxyMembers(message.Author.Id, message.GuildId!.Value)).ToList();
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if (!_matcher.TryMatch(ctx, members, out var match, message.Content, message.Attachments.Length > 0,
allowAutoproxy)) return false;
// this is hopefully temporary, so not putting it into a separate method
if (message.Content != null && message.Content.Length > 2000)
throw new PKError("PluralKit cannot proxy messages over 2000 characters in length.");
// Permission check after proxy match so we don't get spammed when not actually proxying
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if (!CheckBotPermissionsOrError(botPermissions, rootChannel.Id))
return false;
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// this method throws, so no need to wrap it in an if statement
CheckProxyNameBoundsOrError(match.Member.ProxyName(ctx));
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// Check if the sender account can mention everyone/here + embed links
// we need to "mirror" these permissions when proxying to prevent exploits
var senderPermissions = PermissionExtensions.PermissionsFor(guild, rootChannel, message);
var allowEveryone = senderPermissions.HasFlag(PermissionSet.MentionEveryone);
var allowEmbeds = senderPermissions.HasFlag(PermissionSet.EmbedLinks);
// Everything's in order, we can execute the proxy!
await ExecuteProxy(shard, message, ctx, match, allowEveryone, allowEmbeds);
return true;
}
public bool ShouldProxy(Channel channel, Message msg, MessageContext ctx)
{
// Make sure author has a system
if (ctx.SystemId == null)
throw new ProxyChecksFailedException(Errors.NoSystemError.Message);
// Make sure channel is a guild text channel and this is a normal message
if (!DiscordUtils.IsValidGuildChannel(channel))
throw new ProxyChecksFailedException("This channel is not a text channel.");
if (msg.Type != Message.MessageType.Default && msg.Type != Message.MessageType.Reply)
throw new ProxyChecksFailedException("This message is not a normal message.");
// Make sure author is a normal user
if (msg.Author.System == true || msg.Author.Bot || msg.WebhookId != null)
throw new ProxyChecksFailedException("This message was not sent by a normal user.");
// Make sure proxying is enabled here
if (ctx.InBlacklist)
throw new ProxyChecksFailedException(
"Proxying was disabled in this channel by a server administrator (via the proxy blacklist).");
// Make sure the system has proxying enabled in the server
if (!ctx.ProxyEnabled)
throw new ProxyChecksFailedException(
"Your system has proxying disabled in this server. Type `pk;proxy on` to enable it.");
// Make sure we have either an attachment or message content
var isMessageBlank = msg.Content == null || msg.Content.Trim().Length == 0;
if (isMessageBlank && msg.Attachments.Length == 0)
throw new ProxyChecksFailedException("Message cannot be blank.");
// All good!
return true;
}
private async Task ExecuteProxy(Shard shard, Message trigger, MessageContext ctx,
ProxyMatch match, bool allowEveryone, bool allowEmbeds)
{
// Create reply embed
var embeds = new List<Embed>();
if (trigger.Type == Message.MessageType.Reply && trigger.MessageReference?.ChannelId == trigger.ChannelId)
{
var repliedTo = trigger.ReferencedMessage.Value;
if (repliedTo != null)
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{
var (nickname, avatar) = await FetchReferencedMessageAuthorInfo(trigger, repliedTo);
var embed = CreateReplyEmbed(match, trigger, repliedTo, nickname, avatar);
if (embed != null)
embeds.Add(embed);
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}
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// TODO: have a clean error for when message can't be fetched instead of just being silent
}
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// Send the webhook
var content = match.ProxyContent;
if (!allowEmbeds) content = content.BreakLinkEmbeds();
var messageChannel = await _cache.GetChannel(trigger.ChannelId);
var rootChannel = await _cache.GetRootChannel(trigger.ChannelId);
var threadId = messageChannel.IsThread() ? messageChannel.Id : (ulong?)null;
var guild = await _cache.GetGuild(trigger.GuildId.Value);
var proxyMessage = await _webhookExecutor.ExecuteWebhook(new ProxyRequest
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{
GuildId = trigger.GuildId!.Value,
ChannelId = rootChannel.Id,
ThreadId = threadId,
Name = await FixSameName(messageChannel.Id, ctx, match.Member),
AvatarUrl = AvatarUtils.TryRewriteCdnUrl(match.Member.ProxyAvatar(ctx)),
Content = content,
Attachments = trigger.Attachments,
FileSizeLimit = guild.FileSizeLimit(),
Embeds = embeds.ToArray(),
AllowEveryone = allowEveryone
});
await HandleProxyExecutedActions(shard, ctx, trigger, proxyMessage, match);
}
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private async Task<(string?, string?)> FetchReferencedMessageAuthorInfo(Message trigger, Message referenced)
{
if (referenced.WebhookId != null)
return (null, null);
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try
{
var member = await _rest.GetGuildMember(trigger.GuildId!.Value, referenced.Author.Id);
return (member?.Nick, member?.Avatar);
}
catch (ForbiddenException)
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{
_logger.Warning(
"Failed to fetch member {UserId} in guild {GuildId} when getting reply nickname, falling back to username",
referenced.Author.Id, trigger.GuildId!.Value);
return (null, null);
}
}
private Embed CreateReplyEmbed(ProxyMatch match, Message trigger, Message repliedTo, string? nickname,
string? avatar)
{
// repliedTo doesn't have a GuildId field :/
var jumpLink = $"https://discord.com/channels/{trigger.GuildId}/{repliedTo.ChannelId}/{repliedTo.Id}";
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var content = new StringBuilder();
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var hasContent = !string.IsNullOrWhiteSpace(repliedTo.Content);
if (hasContent)
{
var msg = repliedTo.Content;
if (msg.Length > 100)
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{
msg = repliedTo.Content.Substring(0, 100);
var endsWithOpenMention = Regex.IsMatch(msg, @"<[at]?[@#:][!&]?(\w+:)?(\d+)?(:[tTdDfFR])?$");
if (endsWithOpenMention)
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{
var mentionTail = repliedTo.Content.Substring(100).Split(">")[0];
if (repliedTo.Content.Contains(msg + mentionTail + ">"))
msg += mentionTail + ">";
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}
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var endsWithUrl = Regex.IsMatch(msg,
@"(http|https)(:\/\/)?(www\.)?([-a-zA-Z0-9@:%._\+~#=]{1,256})?\.?([a-zA-Z0-9()]{1,6})?\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$");
if (endsWithUrl)
{
var urlTail = repliedTo.Content.Substring(100).Split(" ")[0];
msg += urlTail + " ";
}
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var spoilersInOriginalString = Regex.Matches(repliedTo.Content, @"\|\|").Count;
var spoilersInTruncatedString = Regex.Matches(msg, @"\|\|").Count;
if (spoilersInTruncatedString % 2 == 1 && spoilersInOriginalString % 2 == 0)
msg += "||";
if (msg != repliedTo.Content)
msg += "…";
}
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content.Append($"**[Reply to:]({jumpLink})** ");
content.Append(msg);
if (repliedTo.Attachments.Length > 0 || repliedTo.Embeds.Length > 0)
content.Append($" {Emojis.Paperclip}");
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}
else
{
content.Append($"*[(click to see attachment)]({jumpLink})*");
}
var username = nickname ?? repliedTo.Author.Username;
var avatarUrl = avatar != null
? $"https://cdn.discordapp.com/guilds/{trigger.GuildId}/users/{repliedTo.Author.Id}/avatars/{avatar}.png"
: $"https://cdn.discordapp.com/avatars/{repliedTo.Author.Id}/{repliedTo.Author.Avatar}.png";
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return new Embed
{
// unicodes: [three-per-em space] [left arrow emoji] [force emoji presentation]
Author = new Embed.EmbedAuthor($"{username}\u2004\u21a9\ufe0f", IconUrl: avatarUrl),
Description = content.ToString(),
Color = match.Member.Color?.ToDiscordColor()
};
}
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private async Task<string> FixSameName(ulong channelId, MessageContext ctx, ProxyMember member)
{
var proxyName = member.ProxyName(ctx);
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var lastMessage = _lastMessage.GetLastMessage(channelId)?.Previous;
if (lastMessage == null)
// cache is out of date or channel is empty.
return proxyName;
var pkMessage = await _db.Execute(conn => _repo.GetMessage(conn, lastMessage.Id));
if (lastMessage.AuthorUsername == proxyName)
{
// last message wasn't proxied by us, but somehow has the same name
// it's probably from a different webhook (Tupperbox?) but let's fix it anyway!
if (pkMessage == null)
return FixSameNameInner(proxyName);
// last message was proxied by a different member
if (pkMessage.Member.Id != member.Id)
return FixSameNameInner(proxyName);
}
// if we fixed the name last message and it's the same member proxying, we want to fix it again
if (lastMessage.AuthorUsername == FixSameNameInner(proxyName) && pkMessage?.Member.Id == member.Id)
return FixSameNameInner(proxyName);
// No issues found, current proxy name is fine.
return proxyName;
}
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private string FixSameNameInner(string name)
=> $"{name}\u17b5";
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private async Task HandleProxyExecutedActions(Shard shard, MessageContext ctx,
Message triggerMessage, Message proxyMessage, ProxyMatch match)
{
var sentMessage = new PKMessage
{
Channel = triggerMessage.ChannelId,
Guild = triggerMessage.GuildId,
Member = match.Member.Id,
Mid = proxyMessage.Id,
OriginalMid = triggerMessage.Id,
Sender = triggerMessage.Author.Id
};
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Task SaveMessageInDatabase()
=> _repo.AddMessage(sentMessage);
Task LogMessageToChannel() =>
_logChannel.LogMessage(ctx, sentMessage, triggerMessage, proxyMessage).AsTask();
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Task DispatchWebhook() => _dispatch.Dispatch(ctx.SystemId.Value, sentMessage);
async Task DeleteProxyTriggerMessage()
{
// Wait a second or so before deleting the original message
await Task.Delay(MessageDeletionDelay);
try
{
await _rest.DeleteMessage(triggerMessage.ChannelId, triggerMessage.Id);
}
catch (NotFoundException)
{
_logger.Debug(
"Trigger message {TriggerMessageId} was already deleted when we attempted to; deleting proxy message {ProxyMessageId} also",
triggerMessage.Id, proxyMessage.Id);
await HandleTriggerAlreadyDeleted(proxyMessage);
// Swallow the exception, we don't need it
}
}
// Run post-proxy actions (simultaneously; order doesn't matter)
await Task.WhenAll(
DeleteProxyTriggerMessage(),
SaveMessageInDatabase(),
LogMessageToChannel(),
DispatchWebhook()
);
}
private async Task HandleTriggerAlreadyDeleted(Message proxyMessage)
{
// If a trigger message is deleted before we get to delete it, we can assume a mod bot or similar got to it
// In this case we should also delete the now-proxied message.
// This is going to hit the message delete event handler also, so that'll do the cleanup for us
try
{
await _rest.DeleteMessage(proxyMessage.ChannelId, proxyMessage.Id);
}
catch (NotFoundException) { }
catch (UnauthorizedException) { }
}
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private bool CheckBotPermissionsOrError(PermissionSet permissions, ulong responseChannel)
{
// If we can't send messages at all, just bail immediately.
// 2020-04-22: Manage Messages does *not* override a lack of Send Messages.
if (!permissions.HasFlag(PermissionSet.SendMessages))
return false;
if (!permissions.HasFlag(PermissionSet.ManageWebhooks))
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throw new PKError("PluralKit does not have the *Manage Webhooks* permission in this channel, and thus cannot proxy messages."
+ " Please contact a server administrator to remedy this.");
if (!permissions.HasFlag(PermissionSet.ManageMessages))
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throw new PKError("PluralKit does not have the *Manage Messages* permission in this channel, and thus cannot delete the original trigger message."
+ " Please contact a server administrator to remedy this.");
return true;
}
private void CheckProxyNameBoundsOrError(string proxyName)
{
if (proxyName.Length > Limits.MaxProxyNameLength) throw Errors.ProxyNameTooLong(proxyName);
}
public class ProxyChecksFailedException: Exception
{
public ProxyChecksFailedException(string message) : base(message) { }
}
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}