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local adns = require "prosody.net.adns";
local inet_pton = require "prosody.util.net".pton;
local inet_ntop = require "prosody.util.net".ntop;
local idna_to_ascii = require "prosody.util.encodings".idna.to_ascii;
local promise = require "prosody.util.promise";
local t_move = require "prosody.util.table".move;
local methods = {};
local resolver_mt = { __index = methods };
-- FIXME RFC 6724
local function do_dns_lookup(self, dns_resolver, record_type, name, allow_insecure)
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 not (answer.secure or allow_insecure) then
return reject(("Insecure response 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, true);
ipv6 = do_dns_lookup(self, dns_resolver, "AAAA", self.hostname, true);
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
elseif self.extra and self.extra.srv_secure then
self.extra.secure_hostname = self.hostname;
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;
};
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