302 lines
9.2 KiB
JavaScript
302 lines
9.2 KiB
JavaScript
// mdns-sync.js
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// A single-file mDNS sync tool acting as client or server
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// Uses mdns-server for mDNS and Express for HTTP
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/*********************************
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*
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* 1. LIBRARY FUNCTIONS
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*
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*********************************/
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const os = require('os');
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const mysql = require('mysql2/promise');
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// 0. HELPER FUNCTIONS
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// Extract password from ~/.ssh/id_rsa.pub (last 6 characters of base64)
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function getDbPassword() {
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const pubKeyContent = fs.readFileSync(`${os.homedir()}/.ssh/id_rsa.pub`, "utf8");
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const base64Part = pubKeyContent.split(" ")[1];
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return base64Part.slice(-7,-1);
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}
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// Insert data into MariaDB
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async function insertToMariaDB(record) {
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if (!['A', 'PTR', 'SRV','TXT'].includes(record.Type)) return;
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const dataStr = typeof record.Data === 'object' ? JSON.stringify(record.Data) : record.Data;
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try {
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await dbPool.execute(
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`REPLACE INTO ${DB_TABLE} (Host, Type, Name, Data) VALUES (?, ?, ?, ?);`,
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[DB_USER, record.Type, record.Name, dataStr]
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);
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} catch (err) {
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console.error("DB Insert Error:", err);
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}
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}
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// 1. Database functions
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function saveDbToFile(data, filename) {
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return fs.writeFileSync(filename,typeof data === 'object'?JSON.stringify(data):data);
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}
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function loadDbFromFile(filename) {if (!fs.existsSync(filename)) return {local:{},remote:{}}; else return JSON.parse(fs.readFileSync(filename));}
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// 2. Network functions
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function getLocalNetworkAddressesIPs() {
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const interfaces = os.networkInterfaces();
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const addresses = [];
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for (const name of Object.keys(interfaces)) {
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for (const iface of interfaces[name]) {
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if (iface.family === 'IPv4' && !iface.internal) {
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addresses.push(iface.address);
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}
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}
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}
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return addresses;
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}
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function sniffmDNSLocalPackets() {
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// 1. Listen for responses
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mdns.on('response', async function(response) {
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// console.log("got a new mDNS response.",response);
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let all_answers = response.answers.concat(response.additionals);
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for (let k in all_answers) {
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let answer = all_answers[k];
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// 1. Handle DEVICES for a given SERVICE
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if (answer.type == "PTR") {
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// 1.1 Filter by RELEVANT SERVICE TYPES
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if (!["in-addr.arpa","_googlecast._tcp.local","_tcp.local"].some(suffix => answer.name.endsWith(suffix))) continue;
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// 1.2 Initialize POINTERS (services) sub-database
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if (!db.local.PTR) db.local.PTR = {};
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// 1.3 Initialize this SERVICE TYPE (e.g. _googlecast._tcp.local), if needed
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if (!db.local.PTR[answer.name]) {
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db.local.PTR[answer.name] = [answer.data];
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} else {
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// Add a new DEVICE to this SERVICE TYPE if needed
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if (!db.local.PTR[answer.name].includes(answer.data))
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db.local.PTR[answer.name].push(answer.data);
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}
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}
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// 2. Handle DEVICE IP resolution
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if (answer.type == "A") {
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// 2.1 Initialize ADDRESSES sub-database
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if (!db.local.A) db.local.A = {};
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db.local.A[answer.name] = answer.data;
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}
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if (answer.type == "SRV") {
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// Initialize this device / entry, if needed
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if (db.local[answer.name] === undefined) db.local[answer.name] = {"TXT":null,"SRV":null};
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db.local[answer.name][answer.type] = answer.data;
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}
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if (answer.type == "TXT") {
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// Initialize this device / entry, if needed
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if (db.local[answer.name] === undefined) db.local[answer.name] = {"TXT":null,"SRV":null};
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db.local[answer.name][answer.type] = answer.data;
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}
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await insertToMariaDB({
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Type: answer.type,
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Name: answer.name,
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Data: answer.data
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});
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saveDbToFile(db,DB_FILENAME);
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}
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})
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// 2. Handle the server being destroyed
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mdns.on('destroyed', function () {console.log('Server destroyed.');process.exit(0);});
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// 3. Handle the onReady event
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mdns.on('ready', function () {
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console.log("mDNS server is ready...");
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// mdns.query({questions:[{ name: '_:googlecast._tcp.local', type: 'PTR', class: 'IN'}]} );
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})
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}
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function injectmDNSPacketLocally(type,name,data,flush = true,_class = 'IN',ttl = 120) {
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console.log(`sending packet ${name} of ${type} with data: ${data}`);
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mdns.respond({answers:[
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{
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name: name,
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type: type,
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ttl: ttl,
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class: _class,
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flush: flush,
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data: data
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}
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]});}
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function replyLocallyWithRemoteDevicesData(name,type,query) {
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const answers = [];
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if (!db.remote) db.remote = {};
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if (!db.remote.PTR) db.remote.PTR = {};
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if (!db.remote.A) db.remote.A = {};
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// 1. If the query is asking for a PTR (pointer to a service)
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if (type === 'PTR' && db.remote.PTR && db.remote.PTR[name]) {
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for (let ptrData of db.remote.PTR[name]) {
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answers.push({
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name, // The service name being queried
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type: 'PTR', // Type of DNS record
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class: 'IN', // Internet class
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ttl: 120, // Time-to-live (how long to cache)
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data: ptrData // The actual pointer data (e.g. device instance name)
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});
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}
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}
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// 2. If the query is for an A record (IPv4 address of a device)
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if (type === 'A' && db.remote.A && db.remote.A[name]) {
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answers.push({
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name,
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type: 'A',
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class: 'IN',
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ttl: 120,
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data: db.remote.A[name] // The IPv4 address
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});
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}
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// 3. If the query is for an SRV record (hostname + port of a service)
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if (type === 'SRV' && db.remote.services[name] && db.remote.services[name].SRV !== null) {
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answers.push({
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name,
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type: 'SRV',
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class: 'IN',
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ttl: 120,
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data: db.remote.services[name].SRV // Must be an object like { port, target, priority, weight }
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});
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}
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// 4. If the query is for a TXT record (extra metadata)
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if (type === 'TXT' && db.remote.services[name] && db.remote.services[name].TXT !== null) {
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answers.push({
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name,
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type: 'TXT',
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class: 'IN',
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ttl: 120,
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// Convert plain string to buffer; required by mdns-server
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data: Buffer.from(db.remote.services[name].TXT, 'utf8')
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});
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}
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// 5. Many mDNS tools (like Avahi or Bonjour) send type: 'ANY' queries to discover all records for a name.
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if (type === 'ANY') {
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// Respond with everything you know about this name
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if (db.remote.PTR && db.remote.PTR[name]) {
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for (let ptrData of db.remote.PTR[name]) {
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answers.push({ name, type: 'PTR', class: 'IN', ttl: 120, data: ptrData });
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}
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}
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if (db.remote.A && db.remote.A[name]) {
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answers.push({ name, type: 'A', class: 'IN', ttl: 120, data: db.remote.A[name] });
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}
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if (db.remote.services[name]) {
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const r = db.remote.services[name];
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if (r.SRV) answers.push({ name, type: 'SRV', class: 'IN', ttl: 120, data: r.SRV });
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if (r.TXT) answers.push({ name, type: 'TXT', class: 'IN', ttl: 120, data: r.TXT.map(entry=>Buffer.from(entry.data)) });
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}
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}
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// 6. If we prepared any answers, respond to the query
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if (answers.length > 0) {
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console.log(`Responding with ${answers.length} answer(s) for ${name}`);
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mdns.respond({ answers });
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}
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}
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async function fetchRemoteDevicesData() {
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try {
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const [rows] = await dbPool.execute(
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`SELECT Type, Name, Data FROM ${DB_TABLE} WHERE Host <> ? AND MakeAvailableEverywhere = 1`,
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[DB_USER]
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);
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db.remote = { A: {}, PTR: {}, services: {} };
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rows.forEach(row => {
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const { Type, Name, Data } = row;
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if (Type === 'A') {
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db.remote.A[Name] = Data;
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}
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else if (Type === 'PTR') {
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if (!db.remote.PTR[Name]) db.remote.PTR[Name] = [];
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if (!db.remote.PTR[Name].includes(Data)) db.remote.PTR[Name].push(Data);
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}
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else if (['TXT', 'SRV'].includes(Type)) {
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if (!db.remote.services[Name]) db.remote.services[Name] = { TXT: null, SRV: null };
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db.remote.services[Name][Type] = (Data.substr(0,1)=="{"?JSON.parse(Data):Data);
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}
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});
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console.log(`Remote DB updated. A records: ${Object.keys(db.remote.A).length} PTR records: ${Object.keys(db.remote.PTR).length}`);
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} catch (err) {
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console.error('Error fetching remote DB:', err);
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}
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}
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/*********************************
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*
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* 100. MAIN / IMPERATIVE CODE
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*
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*********************************/
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const fs = require("fs");
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const DB_FILENAME = 'database.json';
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const db = loadDbFromFile(DB_FILENAME);
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const LOCAL_IP_ADDR = getLocalNetworkAddressesIPs()[0];
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const mdns = require('mdns-server')({interface: LOCAL_IP_ADDR,reuseAddr: true,loopback: false,noInit: true});
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// MariaDB Configuration
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const DB_HOST = "10.10.8.1";
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const DB_NAME = "NETWORK";
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const DB_TABLE = "mDNS";
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const DB_USER = os.hostname();
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// Initialize MariaDB connection pool
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const dbPool = mysql.createPool({
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host: DB_HOST,
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user: DB_USER,
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password: getDbPassword(),
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database: DB_NAME,
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connectionLimit: 5
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});
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sniffmDNSLocalPackets();
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mdns.on('query', function (query) {
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// Loop through each question in the mDNS query
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query.questions.forEach(q => {
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const { name, type } = q;
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console.log(`Received mDNS query for ${name} (${type})`);
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replyLocallyWithRemoteDevicesData(name,type,q);
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});
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});
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// every 15 seconds
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setInterval(fetchRemoteDevicesData, 15000);
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fetchRemoteDevicesData(); // initial immediate call
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// initialize the server now that we are watching for events
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mdns.initServer()
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