File

net/resolvers/basic.lua @ 12471:a3b12eeedd4b

mod_smacks: Improve activation of smacks on outgoing s2s Using a timer was a hack to get around that stream features are not available at the right time and sendq stanzas were stored as strings so could not be counted properly. The later has now been fixed and the former is fixed by recording the relevant stream feature on the session so that the correct version of XEP-0198 can be activated once the connection has been authenticated and is ready to start.
author Kim Alvefur <zash@zash.se>
date Sun, 24 Apr 2022 16:17:32 +0200
parent 12413:e155f4509954
child 12601:72f7bb3f30d3
line wrap: on
line source

local adns = require "net.adns";
local inet_pton = require "util.net".pton;
local inet_ntop = require "util.net".ntop;
local idna_to_ascii = require "util.encodings".idna.to_ascii;
local promise = require "util.promise";
local t_move = require "util.table".move;

local methods = {};
local resolver_mt = { __index = methods };

-- FIXME RFC 6724

local function do_dns_lookup(self, dns_resolver, record_type, name)
	return promise.new(function (resolve, reject)
		local ipv = (record_type == "A" and "4") or (record_type == "AAAA" and "6") or nil;
		if ipv and self.extra["use_ipv"..ipv] == false then
			return reject(("IPv%s disabled - %s lookup skipped"):format(ipv, record_type));
		elseif record_type == "TLSA" and self.extra.use_dane ~= true then
			return reject("DANE disabled - TLSA lookup skipped");
		end
		dns_resolver:lookup(function (answer, err)
			if not answer then
				return reject(err);
			elseif answer.bogus then
				return reject(("Validation error in %s lookup"):format(record_type));
			elseif answer.status and #answer == 0 then
				return reject(("%s in %s lookup"):format(answer.status, record_type));
			end

			local targets = { secure = answer.secure };
			for _, record in ipairs(answer) do
				if ipv then
					table.insert(targets, { self.conn_type..ipv, record[record_type:lower()], self.port, self.extra });
				else
					table.insert(targets, record[record_type:lower()]);
				end
			end
			return resolve(targets);
		end, name, record_type, "IN");
	end);
end

local function merge_targets(ipv4_targets, ipv6_targets)
	local result = { secure = ipv4_targets.secure and ipv6_targets.secure };
	local common_length = math.min(#ipv4_targets, #ipv6_targets);
	for i = 1, common_length do
		table.insert(result, ipv6_targets[i]);
		table.insert(result, ipv4_targets[i]);
	end
	if common_length < #ipv4_targets then
		t_move(ipv4_targets, common_length+1, #ipv4_targets, common_length+1, result);
	elseif common_length < #ipv6_targets then
		t_move(ipv6_targets, common_length+1, #ipv6_targets, common_length+1, result);
	end
	return result;
end

-- Find the next target to connect to, and
-- pass it to cb()
function methods:next(cb)
	if self.targets then
		if #self.targets == 0 then
			cb(nil);
			return;
		end
		local next_target = table.remove(self.targets, 1);
		cb(next_target[1], next_target[2], next_target[3], next_target[4], not not self.targets[1]);
		return;
	end

	if not self.hostname then
		self.last_error = "hostname failed IDNA";
		cb(nil);
		return;
	end

	-- Resolve DNS to target list
	local dns_resolver = adns.resolver();

	local dns_lookups = {
		ipv4 = do_dns_lookup(self, dns_resolver, "A", self.hostname);
		ipv6 = do_dns_lookup(self, dns_resolver, "AAAA", self.hostname);
		tlsa = do_dns_lookup(self, dns_resolver, "TLSA", ("_%d._%s.%s"):format(self.port, self.conn_type, self.hostname));
	};

	promise.all_settled(dns_lookups):next(function (dns_results)
		-- Combine targets, assign to self.targets, self:next(cb)
		local have_ipv4 = dns_results.ipv4.status == "fulfilled";
		local have_ipv6 = dns_results.ipv6.status == "fulfilled";

		if have_ipv4 and have_ipv6 then
			self.targets = merge_targets(dns_results.ipv4.value, dns_results.ipv6.value);
		elseif have_ipv4 then
			self.targets = dns_results.ipv4.value;
		elseif have_ipv6 then
			self.targets = dns_results.ipv6.value;
		else
			self.targets = {};
		end

		if self.extra and self.extra.use_dane then
			if self.targets.secure and dns_results.tlsa.status == "fulfilled" then
				self.extra.tlsa = dns_results.tlsa.value;
				self.extra.dane_hostname = self.hostname;
			else
				self.extra.tlsa = nil;
				self.extra.dane_hostname = nil;
			end
		end

		self:next(cb);
	end):catch(function (err)
		self.last_error = err;
		self.targets = {};
	end);
end

local function new(hostname, port, conn_type, extra)
	local ascii_host = idna_to_ascii(hostname);
	local targets = nil;
	conn_type = conn_type or "tcp";

	local is_ip = inet_pton(hostname);
	if not is_ip and hostname:sub(1,1) == '[' then
		is_ip = inet_pton(hostname:sub(2,-2));
	end
	if is_ip then
		hostname = inet_ntop(is_ip);
		if #is_ip == 16 then
			targets = { { conn_type.."6", hostname, port, extra } };
		elseif #is_ip == 4 then
			targets = { { conn_type.."4", hostname, port, extra } };
		end
	end

	return setmetatable({
		hostname = ascii_host;
		port = port;
		conn_type = conn_type;
		extra = extra or {};
		targets = targets;
	}, resolver_mt);
end

return {
	new = new;
};