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net.resolvers.basic: Refactor to remove code duplication

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...and prepare for Happy Eyeballs
This commit is contained in:
Matthew Wild 2022-03-18 16:09:22 +00:00
parent 47dbb92888
commit 668bd38c71
1 changed files with 72 additions and 80 deletions
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152
net/resolvers/basic.lua
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@ -2,13 +2,51 @@ 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 unpack = table.unpack or unpack; -- luacheck: ignore 113
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 };
t_move(ipv6_targets, 1, #ipv6_targets, 1, result);
t_move(ipv4_targets, 1, #ipv4_targets, #result+1, result);
return result;
end
-- Find the next target to connect to, and
-- pass it to cb()
function methods:next(cb)
@ -18,7 +56,7 @@ function methods:next(cb)
return;
end
local next_target = table.remove(self.targets, 1);
cb(unpack(next_target, 1, 4));
cb(next_target[1], next_target[2], next_target[3], next_target[4]);
return;
end
@ -28,91 +66,45 @@ function methods:next(cb)
return;
end
local secure = true;
local tlsa = {};
local targets = {};
local n = 3;
local function ready()
n = n - 1;
if n > 0 then return; end
self.targets = targets;
-- 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.conntype, 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 secure and tlsa[1] then
self.extra.tlsa = tlsa;
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
-- Resolve DNS to target list
local dns_resolver = adns.resolver();
if not self.extra or self.extra.use_ipv4 ~= false then
dns_resolver:lookup(function (answer, err)
if answer then
secure = secure and answer.secure;
for _, record in ipairs(answer) do
table.insert(targets, { self.conn_type.."4", record.a, self.port, self.extra });
end
if answer.bogus then
self.last_error = "Validation error in A lookup";
elseif answer.status then
self.last_error = answer.status .. " in A lookup";
end
else
self.last_error = err;
end
ready();
end, self.hostname, "A", "IN");
else
ready();
end
if not self.extra or self.extra.use_ipv6 ~= false then
dns_resolver:lookup(function (answer, err)
if answer then
secure = secure and answer.secure;
for _, record in ipairs(answer) do
table.insert(targets, { self.conn_type.."6", record.aaaa, self.port, self.extra });
end
if answer.bogus then
self.last_error = "Validation error in AAAA lookup";
elseif answer.status then
self.last_error = answer.status .. " in AAAA lookup";
end
else
self.last_error = err;
end
ready();
end, self.hostname, "AAAA", "IN");
else
ready();
end
if self.extra and self.extra.use_dane == true then
dns_resolver:lookup(function (answer, err)
if answer then
secure = secure and answer.secure;
for _, record in ipairs(answer) do
table.insert(tlsa, record.tlsa);
end
if answer.bogus then
self.last_error = "Validation error in TLSA lookup";
elseif answer.status then
self.last_error = answer.status .. " in TLSA lookup";
end
else
self.last_error = err;
end
ready();
end, ("_%d._tcp.%s"):format(self.port, self.hostname), "TLSA", "IN");
else
ready();
end
end):catch(function (err)
self.last_error = err;
self.targets = {};
end);
end
local function new(hostname, port, conn_type, extra)
@ -137,7 +129,7 @@ local function new(hostname, port, conn_type, extra)
hostname = ascii_host;
port = port;
conn_type = conn_type;
extra = extra;
extra = extra or {};
targets = targets;
}, resolver_mt);
end