File

mod_rest/mod_rest.lua @ 4249:64aa1d9d70ac

mod_rest: Catch and log errors in callback promise chain From the code it looks like it should be possible to reply to an error stanza, but it did not. Turns out I was saved by my local developer mode module which throws errors if an attempt is made to create an errror reply to an error stanza. However nothing collects this error from the promise, so all I got was confusion.
author Kim Alvefur <zash@zash.se>
date Sun, 15 Nov 2020 16:25:49 +0100
parent 4247:1f93fa24611d
child 4250:8b489203e4d3
line wrap: on
line source

-- RESTful API
--
-- Copyright (c) 2019-2020 Kim Alvefur
--
-- This file is MIT/X11 licensed.

local encodings = require "util.encodings";
local base64 = encodings.base64;
local errors = require "util.error";
local http = require "net.http";
local id = require "util.id";
local jid = require "util.jid";
local json = require "util.json";
local st = require "util.stanza";
local um = require "core.usermanager";
local xml = require "util.xml";
local have_cbor, cbor = pcall(require, "cbor");

local jsonmap = module:require"jsonmap";

local tokens = module:depends("tokenauth");

local auth_mechanisms = module:get_option_set("rest_auth_mechanisms", { "Basic", "Bearer" });

local www_authenticate_header;
do
	local header, realm = {}, module.host.."/"..module.name;
	for mech in auth_mechanisms do
		header[#header+1] = ("%s realm=%q"):format(mech, realm);
	end
	www_authenticate_header = table.concat(header, ", ");
end

-- Bearer token
local function check_credentials(request)
	local auth_type, auth_data = string.match(request.headers.authorization, "^(%S+)%s(.+)$");
	if not (auth_type and auth_data) or not auth_mechanisms:contains(auth_type) then
		return false;
	end

	if auth_type == "Basic" then
		local creds = base64.decode(auth_data);
		if not creds then return false; end
		local username, password = string.match(creds, "^([^:]+):(.*)$");
		if not username then return false; end
		username, password = encodings.stringprep.nodeprep(username), encodings.stringprep.saslprep(password);
		if not username then return false; end
		if not um.test_password(username, module.host, password) then
			return false;
		end
		return { username = username, host = module.host };
	elseif auth_type == "Bearer" then
		local token_info = tokens.get_token_info(auth_data);
		if not token_info or not token_info.session then
			return false;
		end
		return token_info.session;
	end
	return nil;
end

local function parse(mimetype, data)
	mimetype = mimetype and mimetype:match("^[^; ]*");
	if mimetype == "application/xmpp+xml" then
		return xml.parse(data);
	elseif mimetype == "application/json" then
		local parsed, err = json.decode(data);
		if not parsed then
			return parsed, err;
		end
		return jsonmap.json2st(parsed);
	elseif mimetype == "application/cbor" and have_cbor then
		local parsed, err = cbor.decode(data);
		if not parsed then
			return parsed, err;
		end
		return jsonmap.json2st(parsed);
	elseif mimetype == "application/x-www-form-urlencoded"then
		local parsed = http.formdecode(data);
		if type(parsed) == "string" then
			return parse("text/plain", parsed);
		end
		for i = #parsed, 1, -1 do
			parsed[i] = nil;
		end
		return jsonmap.json2st(parsed);
	elseif mimetype == "text/plain" then
		return st.message({ type = "chat" }, data);
	end
	return nil, "unknown-payload-type";
end

local function decide_type(accept, supported_types)
	-- assumes the accept header is sorted
	local ret = supported_types[1];
	for i = 2, #supported_types do
		if (accept:find(supported_types[i], 1, true) or 1000) < (accept:find(ret, 1, true) or 1000) then
			ret = supported_types[i];
		end
	end
	return ret;
end

local supported_inputs = {
	"application/xmpp+xml",
	"application/json",
	"application/x-www-form-urlencoded",
	"text/plain",
};

local supported_outputs = {
	"application/xmpp+xml",
	"application/json",
	"application/x-www-form-urlencoded",
};

if have_cbor then
	table.insert(supported_inputs, "application/cbor");
	table.insert(supported_outputs, "application/cbor");
end

-- Only { string : string } can be form-encoded, discard the rest
-- (jsonmap also discards anything unknown or unsupported)
local function flatten(t)
	local form = {};
	for k, v in pairs(t) do
		if type(v) == "string" then
			form[k] = v;
		elseif type(v) == "number" then
			form[k] = tostring(v);
		elseif v == true then
			form[k] = "";
		end
	end
	return form;
end

local function encode(type, s)
	if type == "application/json" then
		return json.encode(jsonmap.st2json(s));
	elseif type == "application/x-www-form-urlencoded" then
		return http.formencode(flatten(jsonmap.st2json(s)));
	elseif type == "application/cbor" then
		return cbor.encode(jsonmap.st2json(s));
	elseif type == "text/plain" then
		return s:get_child_text("body") or "";
	end
	return tostring(s);
end

local post_errors = errors.init("mod_rest", {
	noauthz = { code = 401, type = "auth", condition = "not-authorized", text = "No credentials provided" },
	unauthz = { code = 403, type = "auth", condition = "not-authorized", text = "Credentials not accepted" },
	parse = { code = 400, condition = "not-well-formed", text = "Failed to parse payload", },
	xmlns = { code = 422, condition = "invalid-namespace", text = "'xmlns' attribute must be empty", },
	name = { code = 422, condition = "unsupported-stanza-type", text = "Invalid stanza, must be 'message', 'presence' or 'iq'.", },
	to = { code = 422, condition = "improper-addressing", text = "Invalid destination JID", },
	from = { code = 422, condition = "invalid-from", text = "Invalid source JID", },
	post_auth = { code = 403, condition = "not-authorized", text = "Not authorized to send stanza with requested 'from'", },
	iq_type = { code = 422, condition = "invalid-xml", text = "'iq' stanza must be of type 'get' or 'set'", },
	iq_tags = { code = 422, condition = "bad-format", text = "'iq' stanza must have exactly one child tag", },
	mediatype = { code = 415, condition = "bad-format", text = "Unsupported media type" },
});

local function handle_post(event)
	local request, response = event.request, event.response;
	local from;
	local origin;

	if not request.headers.authorization then
		response.headers.www_authenticate = www_authenticate_header;
		return post_errors.new("noauthz");
	else
		origin = check_credentials(request);
		if not origin then
			return post_errors.new("unauthz");
		end
		from = jid.join(origin.username, origin.host, origin.resource);
	end
	local payload, err = parse(request.headers.content_type, request.body);
	if not payload then
		-- parse fail
		local ctx = { error = err, type = request.headers.content_type, data = request.body, };
		if err == "unknown-payload-type" then
			return post_errors.new("mediatype", ctx);
		end
		return post_errors.new("parse", ctx);
	end

	if payload.attr.xmlns then
		return post_errors.new("xmlns");
	elseif payload.name ~= "message" and payload.name ~= "presence" and payload.name ~= "iq" then
		return post_errors.new("name");
	end

	local to = jid.prep(payload.attr.to);
	if not to then
		return post_errors.new("to");
	end

	if payload.attr.from then
		local requested_from = jid.prep(payload.attr.from);
		if not requested_from then
			return post_errors.new("from");
		end
		if jid.compare(requested_from, from) then
			from = requested_from;
		else
			return post_errors.new("from_auth");
		end
	end

	payload.attr = {
		from = from,
		to = to,
		id = payload.attr.id or id.medium(),
		type = payload.attr.type,
		["xml:lang"] = payload.attr["xml:lang"],
	};

	module:log("debug", "Received[rest]: %s", payload:top_tag());
	local send_type = decide_type((request.headers.accept or "") ..",".. request.headers.content_type, supported_outputs)
	if payload.name == "iq" then
		function origin.send(stanza)
			module:send(stanza);
		end

		if payload.attr.type ~= "get" and payload.attr.type ~= "set" then
			return post_errors.new("iq_type");
		elseif #payload.tags ~= 1 then
			return post_errors.new("iq_tags");
		end

		return module:send_iq(payload, origin):next(
			function (result)
				module:log("debug", "Sending[rest]: %s", result.stanza:top_tag());
				response.headers.content_type = send_type;
				return encode(send_type, result.stanza);
			end,
			function (error)
				if not errors.is_err(error) then
					module:log("error", "Uncaught native error: %s", error);
					return select(2, errors.coerce(nil, error));
				elseif error.context and error.context.stanza then
					response.headers.content_type = send_type;
					module:log("debug", "Sending[rest]: %s", error.context.stanza:top_tag());
					return encode(send_type, error.context.stanza);
				else
					return error;
				end
			end);
	else
		function origin.send(stanza)
			module:log("debug", "Sending[rest]: %s", stanza:top_tag());
			response.headers.content_type = send_type;
			response:send(encode(send_type, stanza));
			return true;
		end

		module:send(payload, origin);
		return 202;
	end
end

-- Handle stanzas submitted via HTTP
module:depends("http");
module:provides("http", {
		route = {
			POST = handle_post;
		};
	});

-- Forward stanzas from XMPP to HTTP and return any reply
local rest_url = module:get_option_string("rest_callback_url", nil);
if rest_url then
	local send_type = module:get_option_string("rest_callback_content_type", "application/xmpp+xml");
	if send_type == "json" then
		send_type = "application/json";
	end

	module:set_status("info", "Not yet connected");
	http.request(rest_url, {
			method = "OPTIONS",
		}, function (body, code, response)
			if code == 0 then
				return module:log_status("error", "Could not connect to callback URL %q: %s", rest_url, body);
			else
				module:set_status("info", "Connected");
			end
			if code == 200 and response.headers.accept then
				send_type = decide_type(response.headers.accept, supported_outputs);
				module:log("debug", "Set 'rest_callback_content_type' = %q based on Accept header", send_type);
			end
		end);

	local code2err = require "net.http.errors".registry;

	local function handle_stanza(event)
		local stanza, origin = event.stanza, event.origin;
		local reply_needed = stanza.name == "iq";
		local receipt;

		if stanza.attr.type == "error" then
			reply_needed = false;
		end

		if stanza.name == "message" and stanza.attr.id and stanza:get_child("urn:xmpp:receipts", "request") then
			reply_needed = true;
			receipt = st.stanza("received", { xmlns = "urn:xmpp:receipts", id = stanza.id });
		end

		local request_body = encode(send_type, stanza);

		-- Keep only the top level element and let the rest be GC'd
		stanza = st.clone(stanza, true);

		module:log("debug", "Sending[rest]: %s", stanza:top_tag());
		http.request(rest_url, {
				body = request_body,
				headers = {
					["Content-Type"] = send_type,
					["Content-Language"] = stanza.attr["xml:lang"],
					Accept = table.concat(supported_inputs, ", ");
				},
			}):next(function (response)
				module:set_status("info", "Connected");
				local reply;

				local code, body = response.code, response.body;
				if code == 202 or code == 204 then
					if not reply_needed then
						-- Delivered, no reply
						return;
					end
				else
					local parsed, err = parse(response.headers["content-type"], body);
					if not parsed then
						module:log("warn", "Failed parsing data from REST callback: %s, %q", err, body);
					elseif parsed.name ~= stanza.name then
						module:log("warn", "REST callback responded with the wrong stanza type, got %s but expected %s", parsed.name, stanza.name);
					else
						parsed.attr = {
							from = stanza.attr.to,
							to = stanza.attr.from,
							id = parsed.attr.id or id.medium();
							type = parsed.attr.type,
							["xml:lang"] = parsed.attr["xml:lang"],
						};
						if parsed.name == "message" and parsed.attr.type == "groupchat" then
							parsed.attr.to = jid.bare(stanza.attr.from);
						end
						if not stanza.attr.type and parsed:get_child("error") then
							parsed.attr.type = "error";
						end
						if parsed.attr.type == "error" then
							parsed.attr.id = stanza.attr.id;
						elseif parsed.name == "iq" then
							parsed.attr.id = stanza.attr.id;
							parsed.attr.type = "result";
						end
						reply = parsed;
					end
				end

				if not reply then
					local code_hundreds = code - (code % 100);
					if code_hundreds == 200 then
						reply = st.reply(stanza);
						if stanza.name ~= "iq" then
							reply.attr.id = id.medium();
						end
						-- TODO presence/status=body ?
					elseif code2err[code] then
						reply = st.error_reply(stanza, errors.new(code, nil, code2err));
					elseif code_hundreds == 400 then
						reply = st.error_reply(stanza, "modify", "bad-request", body);
					elseif code_hundreds == 500 then
						reply = st.error_reply(stanza, "cancel", "internal-server-error", body);
					else
						reply = st.error_reply(stanza, "cancel", "undefined-condition", body);
					end
				end

				if receipt then
					reply:add_direct_child(receipt);
				end

				module:log("debug", "Received[rest]: %s", reply:top_tag());

				origin.send(reply);
			end,
			function (err)
				module:log_status("error", "Could not connect to callback URL %q: %s", rest_url, err);
				origin.send(st.error_reply(stanza, "wait", "recipient-unavailable", err.text));
			end):catch(function (err)
				module:log("error", "Error[rest]: %s", err);
			end);

		return true;
	end

	if module:get_host_type() == "component" then
		module:hook("iq/bare", handle_stanza, -1);
		module:hook("message/bare", handle_stanza, -1);
		module:hook("presence/bare", handle_stanza, -1);
		module:hook("iq/full", handle_stanza, -1);
		module:hook("message/full", handle_stanza, -1);
		module:hook("presence/full", handle_stanza, -1);
		module:hook("iq/host", handle_stanza, -1);
		module:hook("message/host", handle_stanza, -1);
		module:hook("presence/host", handle_stanza, -1);
	else
		-- Don't override everything on normal VirtualHosts
		module:hook("iq/host", handle_stanza, -1);
		module:hook("message/host", handle_stanza, -1);
		module:hook("presence/host", handle_stanza, -1);
	end
end

local supported_errors = {
	"text/html",
	"application/xmpp+xml",
	"application/json",
};

local http_server = require "net.http.server";
module:hook_object_event(http_server, "http-error", function (event)
	local request, response = event.request, event.response;
	local response_as = decide_type(request and request.headers.accept or "", supported_errors);
	if response_as == "application/xmpp+xml" then
		if response then
			response.headers.content_type = "application/xmpp+xml";
		end
		local stream_error = st.stanza("error", { xmlns = "http://etherx.jabber.org/streams" });
		if event.error then
			stream_error:tag(event.error.condition, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' }):up();
			if event.error.text then
				stream_error:text_tag("text", event.error.text, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' });
			end
		end
		return tostring(stream_error);
	elseif response_as == "application/json" then
		if response then
			response.headers.content_type = "application/json";
		end
		return json.encode({
				type = "error",
				error = event.error,
				code = event.code,
			});
	end
end, 1);