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mod_pubsub_feeds/mod_pubsub_feeds.lua @ 5383:df11a2cbc7b7

mod_http_oauth2: Implement RFC 7628 Proof Key for Code Exchange Likely to become mandatory in OAuth 2.1. Backwards compatible since the default 'plain' verifier would compare nil with nil if the relevant parameters are left out.
author Kim Alvefur <zash@zash.se>
date Sat, 29 Apr 2023 13:09:46 +0200
parent 4883:68bd8ae9b827
child 5569:1f8c9e27b625
line wrap: on
line source

-- Fetches Atom feeds and publishes to PubSub nodes
--
-- Config:
-- Component "pubsub.example.com" "pubsub"
-- modules_enabled = {
--   "pubsub_feeds";
-- }
-- feeds = { -- node -> url
--   prosody_blog = "http://blog.prosody.im/feed/atom.xml";
-- }
-- feed_pull_interval = 20 -- minutes
--
-- Reference
-- http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.4.html

local pubsub = module:depends"pubsub";

local time = os.time;
local dt_parse, dt_datetime = require "util.datetime".parse, require "util.datetime".datetime;
local uuid = require "util.uuid".generate;
local hmac_sha1 = require "util.hashes".hmac_sha1;
local parse_xml = require "util.xml".parse;
local st = require "util.stanza";
local translate_rss = module:require("feeds").translate_rss;

local xmlns_atom = "http://www.w3.org/2005/Atom";

local function parse_feed(data)
	local feed, err = parse_xml(data, { allow_processing_instructions = true; allow_comments = true });
	if not feed then return feed, err; end
	if feed.attr.xmlns == xmlns_atom then
		return feed;
	elseif feed.attr.xmlns == nil and feed.name == "rss" then
		return translate_rss(feed);
	end
	return nil, "unsupported-format";
end

local use_pubsubhubub = module:get_option_boolean("use_pubsubhubub", true);
if use_pubsubhubub then
	module:depends"http";
end

local http = require "net.http";
local formdecode = http.formdecode;
local formencode = http.formencode;

local feed_list = module:shared("feed_list");
local refresh_interval = module:get_option_number("feed_pull_interval", 15) * 60;
local lease_length = tostring(math.floor(module:get_option_number("feed_lease_length", 86400)));

function module.load()
	local config = module:get_option("feeds", { });
	local ok, nodes = pubsub.service:get_nodes(true);
	if not ok then nodes = {}; end
	local new_feed_list = {};
	for node, url in pairs(config) do
		if type(node) == "number" then
			node = url;
		end
		new_feed_list[node] = true;
		if not feed_list[node] then
			feed_list[node] = { url = url; node = node; last_update = 0 };
		else
			feed_list[node].url = url;
		end
		if not nodes[node] then
			feed_list[node].last_update = 0;
		end
	end
	for node in pairs(feed_list) do
		if not new_feed_list[node] then
			feed_list[node] = nil;
		end
	end
end

function update_entry(item)
	local node = item.node;
	module:log("debug", "parsing %d bytes of data in node %s", #item.data or 0, node)
	local feed, err = parse_feed(item.data);
	if not feed then
		module:log("error", "Could not parse feed %q: %s", item.url, err);
		module:log("debug", "Feed data:\n%s\n.", item.data);
		return;
	end
	local entries = {};
	for entry in feed:childtags("entry") do
		table.insert(entries, entry);
	end
	local ok, items = pubsub.service:get_items(node, true);
	if not ok then
		local ok, err = pubsub.service:create(node, true);
		if not ok then
			module:log("error", "Could not create node %s: %s", node, err);
			return;
		end
		items = {};
	end
	for i = #entries, 1, -1 do -- Feeds are usually in reverse order
		local entry = entries[i];
		entry.attr.xmlns = xmlns_atom;

		local e_published = entry:get_child_text("published");
		e_published = e_published and dt_parse(e_published);
		local e_updated = entry:get_child_text("updated");
		e_updated = e_updated and dt_parse(e_updated);

		local timestamp = e_updated or e_published or nil;
		--module:log("debug", "timestamp is %s, item.last_update is %s", tostring(timestamp), tostring(item.last_update));
		if not timestamp or not item.last_update or timestamp > item.last_update then
			local id = entry:get_child_text("id");
			if not id then
				local link = entry:get_child("link");
				id = link and link.attr.href;
			end
			if not id then
				-- Sigh, no link?
				id = feed.url .. "#" .. hmac_sha1(feed.url, tostring(entry), true) .. "@" .. dt_datetime(timestamp);
			end
			if not items[id] then
				local xitem = st.stanza("item", { id = id, xmlns = "http://jabber.org/protocol/pubsub" }):add_child(entry);
				-- TODO Put data from /feed into item/source

				--module:log("debug", "publishing to %s, id %s", node, id);
				local ok, err = pubsub.service:publish(node, true, id, xitem);
				if not ok then
					module:log("error", "Publishing to node %s failed: %s", node, err);
				end
			end
		end
	end

	if item.lease_expires and item.lease_expires > time() then
		item.subscription = nil;
		item.lease_expires = nil;
	end
	if use_pubsubhubub and not item.subscription then
		--module:log("debug", "check if %s has a hub", item.node);
		for link in feed:childtags("link") do
			if link.attr.rel == "hub" then
				item.hub = link.attr.href;
				module:log("debug", "Node %s has a hub: %s", item.node, item.hub);
				return subscribe(item);
			end
		end
	end
end

function fetch(item, callback) -- HTTP Pull
	local headers = { };
	if item.data and item.etag then
		headers["If-None-Match"] = item.etag;
	end
	http.request(item.url, { headers = headers }, function(data, code, resp)
		if code == 200 then
			item.data = data;
			if callback then callback(item) end
			item.last_update = time();
			if resp.headers then
				item.etag = resp.headers.etag
			end
		elseif code == 304 then
			item.last_update = time();
		elseif code == 301 and resp.headers.location then
			module:log("info", "Feed %q has moved to %q", item.url, resp.headers.location);
		elseif code <= 100 then
			module:log("error", "Error fetching %q: %q[%d]", item.url, data, code);
		else
			module:log("debug", "Unhandled status code %d when fetching %q", code, item.url);
		end
	end);
end

function refresh_feeds(now)
	--module:log("debug", "Refreshing feeds");
	for _, item in pairs(feed_list) do
		if item.subscription ~= "subscribe" and item.last_update + refresh_interval < now then
			--module:log("debug", "checking %s", item.node);
			fetch(item, update_entry);
		end
	end
	return refresh_interval;
end

local function format_url(node)
	return module:http_url(nil, "/callback") .. "?" .. formencode({ node = node });
end

function subscribe(feed, want)
	want = want or "subscribe";
	feed.secret = feed.secret or uuid();
	local body = formencode{
		["hub.callback"] = format_url(feed.node);
		["hub.mode"] = want;
		["hub.topic"] = feed.url;
		["hub.verify"] = "async"; -- COMPAT this is REQUIRED in the 0.3 draft but removed in 0.4
		["hub.secret"] = feed.secret;
		["hub.lease_seconds"] = lease_length;
	};

	--module:log("debug", "subscription request, body: %s", body);

	--FIXME The subscription states and related stuff
	feed.subscription = want;
	http.request(feed.hub, { body = body }, function(data, code)
		module:log("debug", "subscription to %s submitted, status %s", feed.node, tostring(code));
		if code >= 400 then
			module:log("error", "There was something wrong with our subscription request, body: %s", tostring(data));
			feed.subscription = "failed";
		end
	end);
end

function handle_http_request(event)
	local request = event.request;
	local method = request.method;
	local body = request.body;

	local query = request.url.query or {}; --FIXME
	if query and type(query) == "string" then
		query = formdecode(query);
	end

	local feed = feed_list[query.node];
	if not feed then
		if query["hub.mode"] == "unsubscribe" then
			-- Unsubscribe from unknown feed
			module:log("debug", "Unsubscribe from unknown feed %s -- %s", query["hub.topic"], formencode(query));
			return query["hub.challenge"];
		end
		module:log("debug", "Push for unknown feed %s -- %s", query["hub.topic"], formencode(query));
		return 404;
	end

	if method == "GET" then
		if query.node then
			if query["hub.topic"] ~= feed.url then
				module:log("debug", "Invalid topic: %s", tostring(query["hub.topic"]))
				return 404
			end
			if query["hub.mode"] == "denied" then
				module:log("info", "Subscription denied: %s", tostring(query["hub.reason"] or "No reason given"))
				feed.subscription = "denied";
				return "Ok then :(";
			elseif query["hub.mode"] == feed.subscription then
				module:log("debug", "Confirming %s request to %s", feed.subscription, feed.url)
			else
				module:log("debug", "Invalid mode: %s", tostring(query["hub.mode"]))
				return 400
			end
			local lease_seconds = tonumber(query["hub.lease_seconds"]);
			if lease_seconds then
				feed.lease_expires = time() + lease_seconds - refresh_interval * 2;
			end
			return query["hub.challenge"];
		end
		return 400;
	elseif method == "POST" then
		if #body > 0 then
			module:log("debug", "got %d bytes PuSHed for %s", #body, query.node);
			local signature = request.headers.x_hub_signature;
			if feed.secret then
				local localsig = "sha1=" .. hmac_sha1(feed.secret, body, true);
				if localsig ~= signature then
					module:log("debug", "Invalid signature, got %s but wanted %s", tostring(signature), tostring(localsig));
					return 401;
				end
				module:log("debug", "Valid signature");
			end
			feed.data = body;
			update_entry(feed);
			feed.last_update = time();
			return 202;
		end
		return 400;
	end
	return 501;
end

if use_pubsubhubub then
	module:provides("http", {
		default_path = "/callback";
		route = {
			GET = handle_http_request;
			POST = handle_http_request;
			-- This all?
		};
	});
end

module:add_timer(1, refresh_feeds);