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recursion.js
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recursion.js
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import net from 'net';
import dgram from 'dgram';
import assert from 'assert';
import dnspacket from 'dns-packet';
import { dnsObject, dnsParse, dnsBuild } from './dns-utils.js';
import { LOG_ERROR, LOG_DEBUG } from './dns-utils.js';
let GLOBALCACHE = [
{name: "", type: "NS", data: "a.root-servers.net"},
{name: "a.root-servers.net", type: "A", data: "198.41.0.4"},
{name: "a.root-servers.net", type: "AAAA", data: "2001:503:ba3e::2:30"}
];
function dnsNetworkLookup(message, c) {
const udp6 = dgram.createSocket('udp6');
const cb = (resolv, reject) => {
let timer = null;
let time1 = null;
let timerReject = setTimeout(reject, 3000);
const on_message = (data, rinfo) => {
LOG_DEBUG("rinfo " + rinfo.address + " fast " + data.length);
const result = dnsParse(data);
const fire = (result == dnsObject? reject: resolv);
clearTimeout(timerReject);
clearTimeout(time1);
clearTimeout(timer);
fire(result);
};
const oil_msg = dnsBuild(message);
udp6.on("message", on_message.bind(udp6));
const cb = i => udp6.send(oil_msg, c.dnsPort, c.dnsServer, LOG_DEBUG);
time1 = setTimeout(cb, 1800);
timer = setTimeout(cb, 800);
cb();
};
return new Promise(cb).finally(udp6.close.bind(udp6));
}
function getRandomInt(max) {
return Math.floor(Math.random() * max);
}
function checkValidate(records, alias, type) {
LOG_DEBUG("alias = " + alias);
LOG_DEBUG("type = " + type);
LOG_DEBUG("records = " + JSON.stringify(records));
if (records.some(item => item.type == type)) {
return true;
}
return false;
}
function dnsServerLock(server, LOCK) {
if (!LOCK[server]) {
LOCK[server] = true;
return true;
}
return false;
}
function dnsServerUnlock(server, pool) {
delete pool[server];
}
function dnsServerCheck(server, pool) {
return pool[server];
}
function makeQuery(name, type) {
const dnsObjectZero = {
type: 'query',
id: 26858,
flags: dnspacket.RECURSION_DESIRED,
questions: [{
type: 'A',
name: 'google.com'
}],
answers: [],
additionals: [{
name: ".",
type: "OPT",
udpPayloadSize: 1232,
extendedRcode: 0,
ednsVersion: 0,
flags: 0,
flag_do: false,
options:[]
}]
};
dnsObjectZero.questions[0].name = name;
dnsObjectZero.questions[0].type = type;
return dnsObjectZero;
}
async function dnsNetworkUpdate(alias, type, results, pool) {
const message = makeQuery(alias, type);
const temp = [];
const updateCache = item => {
temp.push(item);
};
for (let i = 0; i < results.length; i++) {
if (results[i].type != 'A') continue;
const result = await dnsNetworkLookup(message, {dnsServer: "::ffff:" + results[i].data, dnsPort: 53});
LOG_DEBUG("dnsNetworkLookup: alias = " + alias);
if (result.answers)
result.answers.forEach(updateCache);
if (result.authorities)
result.authorities.forEach(updateCache);
if (result.additionals)
result.additionals.forEach(updateCache);
if (result.flag_aa) {
pool.authorized = result;
};
if (temp.length) {
const arrayNew = GLOBALCACHE.filter(item => !temp.some(it => it.name == item.name && it.type == item.type));
GLOBALCACHE = arrayNew.concat(temp);
return true;
}
}
return false;
}
function getDnsAlias(records, name) {
LOG_DEBUG("getDnsAlias records " + JSON.stringify(records));
if (records && records.length) {
const last = records.at(-1);
if (last.type == "CNAME")
return last.data;
}
return name;
}
function quickCacheLookup(name, type) {
const records = [];
const cb = obj => {
if (obj.name == name && obj.type == type)
records.push(obj);
};
GLOBALCACHE.forEach(cb);
LOG_DEBUG("name=" + name + " records=" + JSON.stringify(records));
return records;
}
function dnsServerLookup(name) {
let suffix = 0;
let records = [];
const cb = obj => {
const domain = "." + name;
const suffiz = "." + obj.name;
if ((domain.endsWith(suffiz) || suffiz == '.')
&& obj.type == "NS" && suffix <= obj.name.length) {
if (suffix != obj.name.length) {
suffix = obj.name.length;
records = [];
}
records.push(obj.data);
}
};
GLOBALCACHE.forEach(cb);
return records;
}
function dnsContains(alias, records) {
return records.some(item => item.name == alias);
}
function dnsCacheLookup(name, type) {
let records = [];
let alias = name, results;
do {
results = quickCacheLookup(alias, type);
if (results.length > 0) {
records = records.concat(results);
break;
}
results = quickCacheLookup(alias, "CNAME");
if (results.length == 0) {
break;
}
assert(results.length == 1);
alias = results[0].data;
if (dnsContains(alias, records)) {
break;
}
records = records.concat(results);
} while ( 1 );
LOG_DEBUG("dnsCacheLookup: records= " + name + " return " + JSON.stringify(records));
return records;
}
const lockGlobal = {}
const globalContext = {}
function registerGlobalCallback(context) {
globalContext[context] = context;
}
function notifiyGlobalCallback(data) {
Object.entries(globalContext).forEach((key, context) => {
LOG_DEBUG("notifiyGlobalCallback " + data);
context.resolv(data);
});
}
function unregisterGlobalCallback(context) {
delete globalContext[context];
}
async function dnsFullQuery(name, type, pool, request) {
let alias = name;
for ( ; ; ) {
const records = dnsCacheLookup(alias, type);
if (checkValidate(records, alias, type)) {
return dnsCacheLookup(name, type);
}
const old = alias;
alias = getDnsAlias(records, alias);
if (request.authorized && old == alias) {
return dnsCacheLookup(name, type);
}
let results = await dnsServerLookup(alias);
delete pool.authorized;
LOG_DEBUG("dnsFullQuery alias " + alias);
LOG_DEBUG("dnsFullQuery results " + results);
if (results && results.length) {
let updated = false;
const offset = getRandomInt(results.length);
for (let index = 0; index < results.length; index++) {
const refer = (index + offset) % results.length;
const server = results[refer];
const results0 = dnsCacheLookup(server, 'A');
if (checkValidate(results0, server, 'A') && dnsServerLock(alias + server, pool)) {
updated = await dnsNetworkUpdate(alias, type, results0, request);
if (updated && pool === lockGlobal)
notifiyGlobalCallback(name);
if (updated) break;
}
}
if (updated) continue;
const context = {};
context.birthtime = new Date();
const promise = new Promise((resolv, reject) => {
context.resolv = resolv;
context.reject = reject;
});
LOG_DEBUG("dnsFullQuery start network lookup " + alias);
for (let index = 0; index < results.length; index++) {
const refer = (index + offset) % results.length;
const server = results[refer];
if (dnsServerCheck(alias + server, pool)) {
continue;
}
LOG_DEBUG("dnsFullQuery network lookup " + server);
if (dnsServerLock(server, lockGlobal)) {
delete lockGlobal.authorized;
const results0 = await dnsFullQuery(server, 'A', lockGlobal, {});
dnsServerUnlock(server, lockGlobal);
LOG_DEBUG("dnsFullQuery network return " + results0);
updated = results0.length > 0;
if (updated) break;
} else if (!context.waiting) {
registerGlobalCallback(context);
context.waiting = true;
}
}
if (updated) {
if (context.waiting)
unregisterGlobalCallback(context);
continue;
}
if (context.waiting) {
await promise;
unregisterGlobalCallback(context);
continue;
}
}
Object.entries(pool).forEach((key, context) => LOG_DEBUG("FAILURE Lookup " + key));
LOG_DEBUG("failure lookup");
return dnsCacheLookup(name, type);
}
}
async function onDnsQuery(segment, rinfo) {
LOG_DEBUG("UDP SERVER rinfo " + rinfo.address);
try {
const query = dnsParse(segment);
const name = query.questions[0].name;
const type = query.questions[0].type;
const context = {};
LOG_DEBUG("query: " + JSON.stringify(query));
const result = await dnsFullQuery(name, type, context, context);
query.answers = result;
query.type = "response";
if (context.authorized)
query.flags = context.authorized.flags;
let out_segment = dnsBuild(query);
this.send(out_segment, rinfo.port, rinfo.address, (err) => { LOG_ERROR("send error " + err); });
} catch (e) {
LOG_ERROR("UDP FAILURE " + e);
e && LOG_ERROR(e.stack);
}
}
function onFailure(e) {
LOG_ERROR(`onFailure ${e}`);
}
const udp6 = dgram.createSocket('udp6');
udp6.bind(5321, '::ffff:127.9.9.9');
udp6.on('message', onDnsQuery.bind(udp6));
udp6.on('error', onFailure);
LOG_DEBUG(dnsServerLookup("www.baidu.com"));
LOG_DEBUG(dnsCacheLookup("a.root-servers.net", 'A'));
LOG_DEBUG(quickCacheLookup("a.root-servers.net", 'A'));