--- a/mod_spam_report_forwarder/mod_spam_report_forwarder.lua	Fri Feb 23 22:50:57 2024 +0000
+++ b/mod_spam_report_forwarder/mod_spam_report_forwarder.lua	Sun Feb 25 15:28:45 2024 +0000
@@ -1,18 +1,133 @@
+local dt = require "util.datetime";
+local jid = require "util.jid";
 local st = require "util.stanza";
+local url = require "socket.url";
+
+local new_id = require "util.id".short;
+local render = require"util.interpolation".new("%b{}", function (s) return s; end);
 
 local destinations = module:get_option_set("spam_report_destinations", {});
 
+local archive = module:open("archive");
+
+local cache_size = module:get_option_number("spam_report_forwarder_contact_cache_size", 256);
+local report_to_origin = module:get_option_boolean("spam_report_forwarder_to_origin", true);
+local contact_lookup_timeout = module:get_option_number("spam_report_forwarder_contact_lookup_timeout", 180);
+
+local body_template = module:get_option_string("spam_report_forwarder_body_template", [[
+SPAM/ABUSE REPORT
+-----------------
+
+Reported JID: {reported_jid}
+
+A user on our service has reported a message originating from the above JID on
+your server.
+
+{reported_message_time&The reported message was sent at: {reported_message_time}}
+
+--
+This message contains also machine-readable payloads, including XEP-0377, in case
+you want to automate handling of these reports. You can receive these reports
+to a different address by setting 'spam-report-addresses' in your server
+contact info configuration. For more information, see https://xmppbl.org/reports/
+]]):gsub("^%s+", ""):gsub("(%S)\n(%S)", "%1 %2");
+
+local report_addresses = require "util.cache".new(cache_size);
+
+local function get_address(form, ...)
+	for i = 1, select("#", ...) do
+		local field_var = select(i, ...);
+		local field = form:get_child_with_attr("field", "jabber:x:data", "var", field_var);
+		if field then
+			return url.parse(field:get_child_text("value")).path;
+		end
+	end
+end
+
+local function get_origin_report_address(reported_jid)
+	local host = jid.host(reported_jid);
+	local address = report_addresses:get(host);
+	if address then return address; end
+
+	local contact_query = st.iq({ to = host, from = module.host, id = new_id() })
+		:query("http://jabber.org/protocol/disco#info");
+
+	return module:send_iq(contact_query, prosody.hosts[module.host], contact_lookup_timeout)
+		:next(function (response)
+			if response.attr.type ~= "result" then return; end
+
+			for form in response.tags[1]:childtags("x", "jabber:x:data") do
+				local form_type = form:get_child_with_attr("field", nil, "var", "FORM_TYPE");
+				if form_type == "http://jabber.org/network/serverinfo" then
+					address = get_address(form, "spam-report-addresses", "abuse-addresses");
+					break;
+				end
+			end
+			return address;
+		end);
+end
+
+local function send_report(to, message)
+	local m = st.clone(message);
+	m.attr.to = to;
+	module:send(m);
+end
+
 function forward_report(event)
+	local reporter_username = event.origin.username;
+	local reporter_jid = jid.join(reporter_username, module.host);
+	local reported_jid = event.jid;
+
 	local report = st.clone(event.report);
-	report:text_tag("jid", event.jid, { xmlns = "urn:xmpp:jid:0" });
+	report:text_tag("jid", reported_jid, { xmlns = "urn:xmpp:jid:0" });
+
+	local reported_message_id = report:get_child_with_attr(
+		"stanza-id",
+		"urn:xmpp:sid:0",
+		"by",
+		reported_jid,
+		jid.prep
+	);
+
+	local reported_message, reported_message_time, reported_message_with;
+	if reported_message_id then
+		reported_message, reported_message_time, reported_message_with = archive:get(reporter_username, reported_message_id);
+		if jid.bare(reported_message_with) ~= event.jid then
+			reported_message = nil;
+		end
+	end
+
+	local body_text = render(body_template, {
+		reporter_jid = reporter_jid;
+		reported_jid = event.jid;
+		reported_message_time = dt.datetime(reported_message_time);
+	});
 
 	local message = st.message({ from = module.host })
+		:text_tag("body", body_text)
 		:add_child(report);
 
+	if reported_message then
+		reported_message.attr.xmlns = "jabber:client";
+		local fwd = st.stanza("forwarded", { xmlns = "urn:xmpp:forward:0" })
+			:tag("delay", { xmlns = "urn:xmpp:delay", stamp = dt.datetime(reported_message_time) }):up()
+			:add_child(reported_message);
+		message:add_child(fwd);
+	end
+
 	for destination in destinations do
-		local m = st.clone(message);
-		m.attr.to = destination;
-		module:send(m);
+		send_report(destination, message);
+	end
+
+	if report_to_origin then
+		module:log("debug", "Sending report to origin server...");
+		get_origin_report_address(event.jid):next(function (origin_report_address)
+			if not origin_report_address then
+				module:log("warn", "Couldn't report to origin: no contact address found for %s", jid.host(event.jid));
+				return;
+			end
+			send_report(origin_report_address, message);
+		end);
 	end
 end