feat: moderation: block executable attachments

src/utils/moderation/blocked_extension.h

@@ -0,0 +1,34 @@
+#ifndef BLOCKED_EXTENSION_H
+#define BLOCKED_EXTENSION_H
+
+#include <algorithm>
+#include <array>
+#include <cctype>
+#include <string_view>
+
+namespace moderation {
+    inline constexpr auto blockedExtensions = std::to_array<std::string_view>({
+        ".exe", ".dll", ".bat", ".cmd", ".scr", ".msi", ".ps1"
+    });
+
+    inline bool hasBlockedExtension(std::string_view filename)
+    {
+        const auto dot = filename.find_last_of('.');
+        if (dot == std::string_view::npos)
+            return false;
+
+        const std::string_view extension = filename.substr(dot);
+
+        return std::ranges::any_of(blockedExtensions,
+            [extension](const std::string_view blocked) {
+                return extension.size() == blocked.size()
+                    && std::ranges::equal(extension, blocked,
+                        [](const char lhs, const char rhs) {
+                            return std::tolower(static_cast<unsigned char>(lhs))
+                                == std::tolower(static_cast<unsigned char>(rhs));
+                        });
+            });
+    }
+}
+
+#endif // BLOCKED_EXTENSION_H

src/utils/moderation/moderation.cpp

@@ -1,6 +1,8 @@
 #include "moderation.h"
 #include "../../globals/globals.h"
 
+#include "blocked_extension.h"
+
 ModerationService::ModerationService(dpp::cluster& bot) : bot(bot) {}
 
 void ModerationService::cleanupOldEntries(const std::chrono::steady_clock::time_point& now)
@@ -38,6 +40,13 @@ std::string ModerationService::makeMessageSignature(const dpp::message& msg)
     return signature;
 }
 
+bool ModerationService::hasBlockedAttachment(const dpp::message& msg)
+{
+    return std::any_of(
+        msg.attachments.begin(), msg.attachments.end(),
+        [](const dpp::attachment& att) { return moderation::hasBlockedExtension(att.filename); });
+}
+
 bool ModerationService::handleMessage(const dpp::message_create_t& event)
 {
     if (event.msg.author.is_bot())
@@ -48,6 +57,19 @@ bool ModerationService::handleMessage(const dpp::message_create_t& event)
         event.msg.embeds.empty())
         return false;
 
+    if (hasBlockedAttachment(event.msg))
+    {
+        bot.message_delete(event.msg.id, event.msg.channel_id);
+
+        dpp::message blockMessage(
+            event.msg.channel_id,
+            dpp::utility::user_mention(event.msg.author.id) + " " + std::string(executableBlockMsg));
+        blockMessage.set_allowed_mentions(false, false, false, false, {event.msg.author.id}, {});
+        bot.message_create(blockMessage);
+
+        return true;
+    }
+
     const auto now = std::chrono::steady_clock::now();
     const auto userId = event.msg.author.id;
     const std::string signature = makeMessageSignature(event.msg);

src/utils/moderation/moderation.h

@@ -35,6 +35,10 @@ class ModerationService
         "You have been jailed as you posted the same message on multiple channels. "
         "Please contact a staff member if you think this is a mistake.";
 
+    static constexpr std::string_view executableBlockMsg =
+        "Your message contained an executable attachment, "
+        "which is not allowed and has been removed.";
+
     struct PostedMessage
     {
         dpp::snowflake channelId{};
@@ -49,6 +53,7 @@ class ModerationService
     };
 
     static std::string makeMessageSignature(const dpp::message& msg);
+    static bool hasBlockedAttachment(const dpp::message& msg);
     void cleanupOldEntries(const std::chrono::steady_clock::time_point& now);
 
     dpp::cluster& bot;