--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_report_tracker/mod_report_tracker.lua	Sun Jan 05 17:50:02 2025 +0100
@@ -0,0 +1,93 @@
+local um = require "core.usermanager";
+local cache = require "util.cache";
+local jid = require "util.jid";
+local trusted_reporters = module:get_option_inherited_set("trusted_reporters", {});
+
+local reports_received = module:open_store("reports_received");
+
+local xmlns_reporting = "urn:xmpp:reporting:1";
+
+local reported_users = cache.new(256);
+
+local function is_trusted_reporter(reporter_jid)
+	return trusted_reporters:contains(reporter_jid);
+end
+
+function handle_report(event)
+	local stanza = event.stanza;
+	local report = stanza:get_child("report", xmlns_reporting);
+	if not report then
+		return;
+	end
+	local reported_jid = report:get_child_text("jid", "urn:xmpp:jid:0")
+		or stanza:find("{urn:xmpp:forward:0}forwarded/{jabber:client}message@from");
+	if not reported_jid then
+		module:log("debug", "Discarding report with no JID");
+		return;
+	elseif jid.host(reported_jid) ~= module.host then
+		module:log("debug", "Discarding report about non-local user");
+		return;
+	end
+
+	local reporter_jid = stanza.attr.from;
+	if jid.node(reporter_jid) then
+		module:log("debug", "Discarding report from non-server JID");
+		return;
+	end
+
+	local reported_user = jid.node(reported_jid);
+	if not um.user_exists(reported_user, module.host) then
+		module:log("debug", "Discarding report about non-existent user");
+		return;
+	end
+
+	if is_trusted_reporter(reporter_jid) then
+		local current_reports = reports_received:get(reported_user, reporter_jid);
+
+		if not current_reports then
+			current_reports = {
+				first = os.time();
+				last = os.time();
+				count = 1;
+			};
+		else
+			current_reports.last = os.time();
+			current_reports.count = current_reports.count + 1;
+		end
+
+		reports_received:set(reported_user, reporter_jid, current_reports);
+		reported_users:set(reported_user, true);
+
+		module:log("info", "Received abuse report about <%s> from <%s>", reported_jid, reporter_jid);
+
+		module:fire_event(module.name.."/account-reported", {
+			report_from = reporter_jid;
+			reported_user = reported_user;
+			report = report;
+		});
+	else
+		module:log("warn", "Discarding abuse report about <%s> from untrusted source <%s>", reported_jid, reporter_jid);
+	end
+
+	-- Message was handled
+	return true;
+end
+
+module:hook("message/host", handle_report);
+
+module:add_item("account-trait", {
+	name = "reported-by-trusted-server";
+	prob_bad_true = 0.80;
+	prob_bad_false = 0.50;
+});
+
+module:hook("get-account-traits", function (event)
+	local username = event.username;
+	local reported = reported_users:get(username);
+	if reported == nil then
+		-- Check storage, update cache
+		reported = not not reports_received:get(username);
+		reported_users:set(username, reported);
+	end
+	event.traits["reported-by-trusted-server"] = reported;
+end);