Emoji only mode WIP

prosody-modules/mod_muc_peertubelivechat_restrict_message/README.markdown

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+<!--
+SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+# mod_muc_peertubelivechat_restrict_message
+
+This module is a custom module designed for the peertube-plugin-livechat project, that can restrict message content to 
+given regular expression.
+
+This module is part of peertube-plugin-livechat, and is under the same LICENSE (AGPL-v3).
+
+## Prerequisites
+
+This modules needs lrexlib instlaled (available as lua-rex-pcre2 package on Debian).

prosody-modules/mod_muc_peertubelivechat_restrict_message/mod_muc_peertubelivechat_restrict_message.lua

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+-- mod_muc_peertubelivechat_roles
+--
+-- SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
+-- SPDX-License-Identifier: AGPL-3.0-only
+--
+-- This file is AGPL-v3 licensed.
+-- Please see the Peertube livechat plugin copyright information.
+-- https://livingston.frama.io/peertube-plugin-livechat/credits/
+--
+
+local st = require "util.stanza";
+local jid_bare = require "util.jid".bare;
+
+local rex = require "rex_pcre2"; -- We are using PCRE2 (Perl Compatible Regular Expression)
+
+-- Plugin dependencies
+local mod_muc = module:depends "muc";
+local muc_util = module:require "muc/util";
+local valid_roles = muc_util.valid_roles;
+
+
+function get_peertubelivechat_emoji_only_mode(room)
+  return room._data.x_peertubelivechat_emoji_only_mode;
+end
+
+function set_peertubelivechat_emoji_only_mode(room, emoji_only)
+  emoji_only = emoji_only and true or nil;
+  if get_peertubelivechat_emoji_only_mode(room) == emoji_only then return false; end
+  room._data.x_peertubelivechat_emoji_only_mode = emoji_only;
+  return true;
+end
+
+function get_peertubelivechat_emoji_only_regexp(room)
+  return room._data.x_peertubelivechat_emoji_only_regexp;
+end
+
+function set_peertubelivechat_emoji_only_regexp(room, emoji_only_regexp)
+  if (emoji_only_regexp ~= nil and type(emoji_only_regexp) ~= "string") then
+    return false;
+  end
+  if emoji_only_regexp == "" then emoji_only_regexp = nil; end
+  if get_peertubelivechat_emoji_only_regexp(room) == emoji_only_regexp then return false; end
+  room._data.x_peertubelivechat_emoji_only_regexp = emoji_only_regexp;
+
+  -- and we must decache the compile regexp
+  room.x_peertubelivechat_emoji_only_compiled_regexp = nil;
+  return true;
+end
+
+module:hook("muc-disco#info", function(event)
+  if get_peertubelivechat_emoji_only_mode(event.room) and get_peertubelivechat_emoji_only_regexp(event.room) ~= nil then
+    event.reply:tag("feature", {var = "x_peertubelivechat_emoji_only_mode"}):up();
+  end
+end);
+
+module:hook("muc-config-form", function(event)
+  if (get_peertubelivechat_emoji_only_regexp(event.room) ~= nil) then
+    table.insert(event.form, {
+      name = "muc#roomconfig_x_peertubelivechat_emoji_only_mode";
+      type = "boolean";
+      label = "Emoji only mode";
+      desc = "Occupants will only be able to send emoji. This does not affect moderators.";
+      value = get_peertubelivechat_emoji_only_mode(event.room);
+    });
+  end
+end, 121);
+
+module:hook("muc-config-submitted/muc#roomconfig_x_peertubelivechat_emoji_only_mode", function(event)
+  if get_peertubelivechat_emoji_only_regexp(event.room) ~= nil and set_peertubelivechat_emoji_only_mode(event.room, event.value) then
+    event.status_codes["104"] = true;
+  end
+end);
+
+
+-- handling groupchat messages
+function handle_groupchat(event)
+  local origin, stanza = event.origin, event.stanza;
+  local room = event.room;
+
+  if (not get_peertubelivechat_emoji_only_mode(room)) then
+    return;
+  end
+
+  if not room.x_peertubelivechat_emoji_only_compiled_regexp then
+    -- compute the regexp on first access
+    local r = get_peertubelivechat_emoji_only_regexp(room);
+    if (r == nil) then
+      return;
+    end
+    room.x_peertubelivechat_emoji_only_compiled_regexp = rex.new(r, "i");
+  end
+
+  -- only consider messages with body (ie: ignore chatstate and other non-text xmpp messages)
+  local body = stanza:get_child_text("body")
+  if not body or #body < 1 then
+    -- module:log("debug", "No body, message accepted");
+    return;
+  end
+
+  -- Checking user's permissions (moderators are not subject to restrictions)
+  local actor = stanza.attr.from;
+  local actor_nick = room:get_occupant_jid(actor);
+  local actor_jid = jid_bare(actor);
+  -- Only checking role, not affiliation (restrictions only applies on users currently connected to the room)
+  local role = room:get_role(actor_nick);
+  if valid_roles[role or "none"] >= valid_roles.moderator then
+    -- user bypasses
+    -- module:log("debug", "User is moderator, bypassing restrictions");
+    return;
+  end
+
+  -- testing the content
+  if (room.x_peertubelivechat_emoji_only_compiled_regexp:match(body) ~= nil) then
+    -- module:log("debug", "Message accepted");
+    return;
+  end
+
+  module:log("debug", "Bouncing message for user %s", actor_nick);
+  local reply = st.error_reply(
+    stanza,
+    -- error_type = 'modify' (see descriptions in RFC 6120 https://xmpp.org/rfcs/rfc6120.html#stanzas-error-syntax)
+    "modify",
+    -- error_condition = 'policy-violation' (see RFC 6120 Defined Error Conditions https://xmpp.org/rfcs/rfc6120.html#stanzas-error-conditions)
+    "policy-violation",
+    "Emoji only mode enabled"
+  );
+
+  origin.send(reply);
+  return true; -- stoping propagation
+end
+module:hook("muc-occupant-groupchat", handle_groupchat);