File

+
−local ip = require "util.ip";
+
−local jid_bare = require "util.jid".bare;
+
−local jid_split = require "util.jid".split;
+
−local set = require "util.set";
+
−local sha256 = require "util.hashes".sha256;
+
−local st = require"util.stanza";
+
−local rm = require "core.rostermanager";
+
−local full_sessions = prosody.full_sessions;
+
−
+
−local user_exists = require "core.usermanager".user_exists;
+
−
+
−local new_rtbl_subscription = module:require("rtbl").new_rtbl_subscription;
+
−local trie = module:require("trie");
+
−
+
−local spam_source_domains = set.new();
+
−local spam_source_ips = trie.new();
+
−local spam_source_jids = set.new();
+
−local default_spam_action = module:get_option("anti_spam_default_action", "bounce");
+
−local custom_spam_actions = module:get_option("anti_spam_actions", {});
+
−
+
−local spam_actions = setmetatable({}, {
+
−	__index = function (t, reason)
+
−		local action = rawget(custom_spam_actions, reason) or default_spam_action;
+
−		rawset(t, reason, action);
+
−		return action;
+
−	end;
+
−});
+
−
+
−local count_spam_blocked = module:metric("counter", "anti_spam_blocked", "stanzas", "Stanzas blocked as spam", {"reason"});
+
−
+
−local hosts = prosody.hosts;
+
−
+
−local reason_messages = {
+
−	default = "Rejected as spam";
+
−	["known-spam-source"] = "Rejected as spam. Your server is listed as a known source of spam. Please contact your server operator.";
+
−};
+
−
+
−function block_spam(event, reason, action)
+
−	if not action then
+
−		action = spam_actions[reason];
+
−	end
+
−	event.spam_reason = reason;
+
−	event.spam_action = action;
+
−	if module:fire_event("spam-blocked", event) == false then
+
−		module:log("debug", "Spam allowed by another module");
+
−		return;
+
−	end
+
−
+
−	count_spam_blocked:with_labels(reason):add(1);
+
−
+
−	if action == "bounce" then
+
−		module:log("debug", "Bouncing likely spam %s from %s (%s)", event.stanza.name, event.stanza.attr.from, reason);
+
−		event.origin.send(st.error_reply(event.stanza, "cancel", "policy-violation", reason_messages[reason] or reason_messages.default));
+
−	else
+
−		module:log("debug", "Discarding likely spam %s from %s (%s)", event.stanza.name, event.stanza.attr.from, reason);
+
−	end
+
−
+
−	return true;
+
−end
+
−
+
−function is_from_stranger(from_jid, event)
+
−	local stanza = event.stanza;
+
−	local to_user, to_host, to_resource = jid_split(stanza.attr.to);
+
−
+
−	if not to_user then return false; end
+
−
+
−	local to_session = full_sessions[stanza.attr.to];
+
−	if to_session then return false; end
+
−
+
−	if not (
+
−		rm.is_contact_subscribed(to_user, to_host, from_jid) or
+
−		rm.is_user_subscribed(to_user, to_host, from_jid) or
+
−		rm.is_contact_pending_out(to_user, to_host, from_jid) or
+
−		rm.is_contact_preapproved(to_user, to_host, from_jid)
+
−	) then
+
−		local from_user, from_host = jid_split(from_jid);
+
−
+
−		-- Allow all messages from your own jid
+
−		if from_user == to_user and from_host == to_host then
+
−			return false; -- Pass through
+
−		end
+
−		if to_resource and stanza.attr.type == "groupchat" then
+
−			return false; -- Pass through group chat messages
+
−		end
+
−		if rm.is_contact_subscribed(to_user, to_host, from_host) then
+
−			-- If you have the sending domain in your roster,
+
−			-- allow through (probably a gateway)
+
−			return false;
+
−		end
+
−		return true; -- Stranger danger
+
−	end
+
−end
+
−
+
−function is_spammy_server(session)
+
−	if spam_source_domains:contains(session.from_host) then
+
−		return true;
+
−	end
+
−	local raw_ip = session.ip;
+
−	local parsed_ip = raw_ip and ip.new_ip(session.ip);
+
−	-- Not every session has an ip - for example, stanzas sent from a
+
−	-- local host session
+
−	if parsed_ip and spam_source_ips:contains_ip(parsed_ip) then
+
−		return true;
+
−	end
+
−end
+
−
+
−function is_spammy_sender(sender_jid)
+
−	return spam_source_jids:contains(sha256(sender_jid, true));
+
−end
+
−
+
−local spammy_strings = module:get_option_array("anti_spam_block_strings");
+
−local spammy_patterns = module:get_option_array("anti_spam_block_patterns");
+
−
+
−function is_spammy_content(stanza)
+
−	-- Only support message content
+
−	if stanza.name ~= "message" then return; end
+
−	if not (spammy_strings or spammy_patterns) then return; end
+
−
+
−	local body = stanza:get_child_text("body");
+
−	if not body then return; end
+
−
+
−	if spammy_strings then
+
−		for _, s in ipairs(spammy_strings) do
+
−			if body:find(s, 1, true) then
+
−				return true;
+
−			end
+
−		end
+
−	end
+
−	if spammy_patterns then
+
−		for _, s in ipairs(spammy_patterns) do
+
−			if body:find(s) then
+
−				return true;
+
−			end
+
−		end
+
−	end
+
−end
+
−
+
−-- Set up RTBLs
+
−
+
−local anti_spam_services = module:get_option_array("anti_spam_services", {});
+
−
+
−for _, rtbl_service_jid in ipairs(anti_spam_services) do
+
−	new_rtbl_subscription(rtbl_service_jid, "spam_source_domains", {
+
−		added = function (item)
+
−			spam_source_domains:add(item);
+
−		end;
+
−		removed = function (item)
+
−			spam_source_domains:remove(item);
+
−		end;
+
−	});
+
−	new_rtbl_subscription(rtbl_service_jid, "spam_source_ips", {
+
−		added = function (item)
+
−			local subnet_ip, subnet_bits = ip.parse_cidr(item);
+
−			if not subnet_ip then
+
−				return;
+
−			end
+
−			spam_source_ips:add_subnet(subnet_ip, subnet_bits);
+
−		end;
+
−		removed = function (item)
+
−			local subnet_ip, subnet_bits = ip.parse_cidr(item);
+
−			if not subnet_ip then
+
−				return;
+
−			end
+
−			spam_source_ips:remove_subnet(subnet_ip, subnet_bits);
+
−		end;
+
−	});
+
−	new_rtbl_subscription(rtbl_service_jid, "spam_source_jids_sha256", {
+
−		added = function (item)
+
−			spam_source_jids:add(item);
+
−		end;
+
−		removed = function (item)
+
−			spam_source_jids:remove(item);
+
−		end;
+
−	});
+
−end
+
−
+
−module:hook("message/bare", function (event)
+
−	local to_user, to_host = jid_split(event.stanza.attr.to);
+
−
+
−	if not hosts[to_host] then
+
−		module:log("warn", "Skipping filtering of message to unknown host <%s>", to_host);
+
−		return;
+
−	end
+
−
+
−	local from_bare = jid_bare(event.stanza.attr.from);
+
−	if user_exists(to_user, to_host) then
+
−		if not is_from_stranger(from_bare, event) then
+
−			return;
+
−		end
+
−	end
+
−
+
−	module:log("debug", "Processing message from stranger...");
+
−
+
−	if is_spammy_server(event.origin) then
+
−		return block_spam(event, "known-spam-source");
+
−	end
+
−
+
−	if is_spammy_sender(from_bare) then
+
−		return block_spam(event, "known-spam-jid");
+
−	end
+
−
+
−	if is_spammy_content(event.stanza) then
+
−		return block_spam(event, "spam-content");
+
−	end
+
−
+
−	module:log("debug", "Allowing message through");
+
−end, 500);
+
−
+
−module:hook("presence/bare", function (event)
+
−	if event.stanza.attr.type ~= "subscribe" then
+
−		return;
+
−	end
+
−
+
−
+
−	local to_user, to_host = jid_split(event.stanza.attr.to);
+
−	local from_bare = jid_bare(event.stanza.attr.from);
+
−
+
−	if user_exists(to_user, to_host) then
+
−		if not is_from_stranger(from_bare, event) then
+
−			return;
+
−		end
+
−	end
+
−
+
−	module:log("debug", "Processing subscription request from stranger...");
+
−
+
−	if is_spammy_server(event.origin) then
+
−		return block_spam(event, "known-spam-source");
+
−	end
+
−
+
−	module:log("debug", "Not from known spam source server");
+
−
+
−	if is_spammy_sender(jid_bare(event.stanza.attr.from)) then
+
−		return block_spam(event, "known-spam-jid");
+
−	end
+
−
+
−	module:log("debug", "Not from known spam source JID");
+
−
+
−	module:log("debug", "Allowing subscription request through");
+
−end, 500);