view mod_bob/mod_bob.lua @ 3866:c0df50ce96f0

mod_rest: Handle internal http request errors early and then return Skips over attempted parsing of the payload which usually failed since the body is an error string like "connection refused", so this produced useless errors.
author Kim Alvefur <zash@zash.se>
date Sat, 25 Jan 2020 20:22:12 +0100
parents 76fc915647ab
children 41fbed2de482
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module:depends("cache_c2s_caps");

local st = require "util.stanza";
local encodings = require "util.encodings";
local b64_encode = encodings.base64.encode;
local b64_decode = encodings.base64.decode;
local sha1 = require"util.hashes".sha1;

-- TODO: Move that to storage.
local cache = {};
-- TODO: use util.cache for this.
local in_flight = {};

local function check_cid(src)
	return src:match("^cid:(%w+%+%w+@bob%.xmpp%.org)$");
end

local function handle_data_carrier(tag)
	if tag.name ~= "data" or tag.attr.xmlns ~= "urn:xmpp:bob" then
		return tag;
	end
	local cid = tag.attr.cid;
	local media_type = tag.attr.type;
	local max_age = tag.attr['max-age'];
	local b64_content = tag:get_text();
	local content = b64_decode(b64_content);
	local hash = sha1(content, true);
	if cid ~= "sha1+"..hash.."@bob.xmpp.org" then
		module:log("debug", "Invalid BoB cid, %s ~= %s", cid, "sha1+"..hash.."@bob.xmpp.org");
		return nil;
	end
	cache[cid] = { media_type = media_type, max_age = max_age, content = content };
	if in_flight[cid] then
		local iq = st.iq({ type = "result", id = "fixme" });
		iq:add_direct_child(tag);
		for jid, data in pairs(in_flight[cid]) do
			iq.attr.from = data.from;
			iq.attr.to = jid;
			iq.attr.id = data.id;
			module:send(iq);
		end
		in_flight[cid] = nil;
	end
	return nil;
end

local current_id = 0;
local function send_iq(room_jid, jid, cid, log)
	local iq = st.iq({ type = "get", from = room_jid, to = jid, id = "bob-"..current_id })
		:tag("data", { xmlns = "urn:xmpp:bob", cid = cid });
	log("debug", "found BoB image in XHTML-IM, asking %s for cid %s", jid, cid);
	module:send(iq);
	in_flight[cid] = {};
end

local function find_images(tag, jid, room_jid, log)
	if tag.name == "img" and tag.attr.xmlns == "http://www.w3.org/1999/xhtml" then
		local src = tag.attr.src;
		local cid = check_cid(src);
		if not cid then
			return;
		end
		if cache[cid] then
			log("debug", "cid %s already found in cache", cid);
			return;
		end
		if in_flight[cid] then
			log("debug", "cid %s already queried", cid);
			return;
		end
		send_iq(room_jid, jid, cid, log);
		return;
	end
	for child in tag:childtags(nil, "http://www.w3.org/1999/xhtml") do
		find_images(child, jid, room_jid, log);
	end
end

local function message_handler(event)
	local stanza, origin = event.stanza, event.origin;
	local jid = stanza.attr.from;
	local room_jid = stanza.attr.to;
	local log = origin.log or module._log;

	-- Remove and cache all <data/> elements embedded here.
	stanza:maptags(handle_data_carrier);

	-- Find and query all of the cids not already cached.
	local tag = stanza:get_child("html", "http://jabber.org/protocol/xhtml-im");
	if not tag then
		return;
	end
	for body in tag:childtags("body", "http://www.w3.org/1999/xhtml") do
		find_images(body, jid, room_jid, log);
	end
end

local function handle_data_get(stanza, cid, log)
	local data = cache[cid];
	if not data then
		log("debug", "BoB requested for data not in cache (cid %s), falling through.", cid);
		if in_flight[cid] then
			log("debug", "But an iq has already been sent, let’s wait…");
			in_flight[cid][stanza.attr.from] = { id = stanza.attr.id, from = stanza.attr.to };
			return true;
		end
		return nil;
	end

	local iq = st.reply(stanza);
	iq:text_tag("data", b64_encode(data.content), {
		xmlns = "urn:xmpp:bob",
		cid = cid,
		type = data.media_type,
		['max-age'] = data.max_age,
	});
	log("debug", "Answering BoB request for cid %s on the behalf of %s", cid, stanza.attr.to);
	module:send(iq);
	return true;
end

local function iq_handler(event)
	local stanza, origin = event.stanza, event.origin;
	local tag = stanza.tags[1];
	if tag.name ~= "data" or tag.attr.xmlns ~= "urn:xmpp:bob" then
		return nil;
	end
	local log = origin.log or module._log;
	local cid = tag.attr.cid;
	if not cid then
		log("debug", "BoB iq doesn’t contain a cid attribute.");
		return;
	end
	if stanza.attr.type == "get" then
		return handle_data_get(stanza, cid, log);
	elseif stanza.attr.type == "result" then
		handle_data_carrier(tag);
		return true;
	end
	-- TODO: also handle error iqs.
end

module:hook("message/bare", message_handler, 1);
module:hook("iq/full", iq_handler, 1);
module:hook("iq/bare", iq_handler, 1);