feat: introduce 3-tier architecture with relay and exit nodes
This commit is contained in:
426
proxy-exit.js
Normal file
426
proxy-exit.js
Normal file
@@ -0,0 +1,426 @@
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#!/usr/bin/env node
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/**
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* PSK Proxy Exit-Node (Server)
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*
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* Listens for a TLS-PSK tunnel connection from the proxy relay.
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* Receives OPEN(host,port) to create outbound TCP connections to remote servers,
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* then forwards DATA/CLOSE frames bidirectionally.
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*
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* Also supports UDP relaying for SOCKS5 UDP ASSOCIATE via new UDP_* frames.
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*/
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const net = require('net');
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const tls = require('tls');
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const fs = require('fs');
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const dgram = require('dgram');
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const { program } = require('commander');
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program
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.requiredOption('-P, --relay-port <port>', 'Port for proxy relay TLS-PSK tunnel connections')
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.requiredOption('-H, --host <host>', 'Host to bind to (e.g., 0.0.0.0)')
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.requiredOption('--psk-file <path>', 'Path to PSK key file')
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.requiredOption('--identity <identity>', 'Expected PSK identity from relay')
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.option('--connect-timeout <ms>', 'Timeout for outbound TCP connect (ms)', '10000')
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.parse();
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const options = program.opts();
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let pskKey;
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try {
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pskKey = fs.readFileSync(options.pskFile, 'utf8').trim();
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} catch (error) {
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console.error(`Error reading PSK file: ${error.message}`);
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process.exit(1);
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}
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const OUT_CONNECT_TIMEOUT = parseInt(options.connectTimeout, 10) || 10000;
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// Message Types
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const MSG_TYPES = {
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DATA: 2,
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CLOSE: 3,
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OPEN: 4,
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OPEN_RESULT: 5,
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UDP_OPEN: 6,
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UDP_OPEN_RESULT: 7,
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UDP_SEND: 8,
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UDP_RECV: 9,
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UDP_CLOSE: 10,
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};
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function writeMessage(socket, type, connectionId, data = Buffer.alloc(0)) {
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if (!socket || socket.destroyed) return true;
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const buf = Buffer.allocUnsafe(9 + data.length);
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buf.writeUInt8(type, 0);
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buf.writeUInt32BE(connectionId >>> 0, 1);
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buf.writeUInt32BE(data.length >>> 0, 5);
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if (data.length > 0) data.copy(buf, 9);
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return socket.write(buf);
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}
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function createMessageReader() {
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let buffer = Buffer.alloc(0);
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let expectedLength = 9;
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let currentMessage = null;
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return function onData(data, callback) {
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buffer = Buffer.concat([buffer, data]);
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// Parse as many complete frames as possible
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while (buffer.length >= expectedLength) {
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if (!currentMessage) {
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const type = buffer.readUInt8(0);
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const connectionId = buffer.readUInt32BE(1);
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const dataLength = buffer.readUInt32BE(5);
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currentMessage = { type, connectionId, dataLength };
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expectedLength = 9 + dataLength;
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if (dataLength === 0) {
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callback(currentMessage.type, currentMessage.connectionId, Buffer.alloc(0));
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buffer = buffer.subarray(9);
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currentMessage = null;
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expectedLength = 9;
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}
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} else {
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const messageData = buffer.subarray(9, expectedLength);
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callback(currentMessage.type, currentMessage.connectionId, messageData);
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buffer = buffer.subarray(expectedLength);
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currentMessage = null;
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expectedLength = 9;
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}
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}
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};
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}
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function parseOpenPayload(buf) {
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if (buf.length < 4) return null;
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let offset = 0;
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const hostLen = buf.readUInt16BE(offset); offset += 2;
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if (buf.length < 2 + hostLen + 2) return null;
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const host = buf.subarray(offset, offset + hostLen).toString('utf8'); offset += hostLen;
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const port = buf.readUInt16BE(offset); offset += 2;
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return { host, port };
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}
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function buildOpenResultPayload(success) {
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const b = Buffer.allocUnsafe(1);
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b.writeUInt8(success ? 1 : 0, 0);
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return b;
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}
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function parseUdpPayload(buf) {
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// [2B hostLen][host][2B port][2B dataLen][data...]
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if (buf.length < 2) return null;
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let off = 0;
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const hostLen = buf.readUInt16BE(off); off += 2;
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if (buf.length < 2 + hostLen + 2 + 2) return null;
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const host = buf.subarray(off, off + hostLen).toString('utf8'); off += hostLen;
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const port = buf.readUInt16BE(off); off += 2;
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const dataLen = buf.readUInt16BE(off); off += 2;
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if (buf.length < 2 + hostLen + 2 + 2 + dataLen) return null;
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const data = buf.subarray(off, off + dataLen);
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return { host, port, data };
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}
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function buildUdpPayload(host, port, data) {
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const hostBuf = Buffer.from(host, 'utf8');
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const buf = Buffer.allocUnsafe(2 + hostBuf.length + 2 + 2 + data.length);
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let off = 0;
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buf.writeUInt16BE(hostBuf.length, off); off += 2;
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hostBuf.copy(buf, off); off += hostBuf.length;
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buf.writeUInt16BE(port, off); off += 2;
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buf.writeUInt16BE(data.length, off); off += 2;
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data.copy(buf, off);
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return buf;
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}
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function pskCallback(socket, identity) {
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console.log(`Relay client identity: ${identity}`);
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if (identity !== options.identity) {
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console.warn(`PSK identity mismatch. Expected '${options.identity}', got '${identity}'.`);
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// Abort the connection by returning a falsy value.
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// For TLS 1.2, this should cause the handshake to fail.
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return null;
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}
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// For TLS 1.2, the callback should return the PSK as a Buffer.
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return Buffer.from(pskKey, 'hex');
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}
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let relaySocket = null;
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const upstreamConns = new Map(); // connectionId -> net.Socket
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// UDP association mapping: connectionId -> { udp4?: dgram.Socket, udp6?: dgram.Socket }
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const udpAssoc = new Map();
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// Framing and fairness controls
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const FRAME_MAX = 16 * 1024; // 16KiB frames to improve interleaving
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const BYTES_PER_TICK = 64 * 1024; // Limit per processing burst to yield event loop
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// Per-connection TX queues for upstream->relay direction
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const txQueues = new Map(); // connectionId -> { queue: Buffer[], sending: boolean }
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function processTxQueue(connectionId, state) {
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if (!relaySocket || relaySocket.destroyed) {
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// Drop queued data if relay is gone
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state.queue = [];
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state.sending = false;
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return;
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}
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if (state.sending) return;
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state.sending = true;
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let bytesThisTick = 0;
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const run = () => {
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if (!relaySocket || relaySocket.destroyed) {
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state.queue = [];
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state.sending = false;
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return;
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}
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while (state.queue.length) {
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const buf = state.queue[0];
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let offset = buf._offset || 0;
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while (offset < buf.length) {
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const end = Math.min(offset + FRAME_MAX, buf.length);
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const slice = buf.subarray(offset, end);
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const ok = writeMessage(relaySocket, MSG_TYPES.DATA, connectionId, slice);
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if (!ok) {
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// Backpressure: remember progress and resume on drain
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buf._offset = end;
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relaySocket.once('drain', () => {
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// Reset flag to allow re-entry
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state.sending = false;
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run();
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});
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return;
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}
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offset = end;
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bytesThisTick += slice.length;
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if (bytesThisTick >= BYTES_PER_TICK) {
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// Yield to allow other I/O
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buf._offset = offset;
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bytesThisTick = 0;
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setImmediate(() => {
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state.sending = false;
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run();
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});
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return;
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}
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}
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// Finished this buffer
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delete buf._offset;
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state.queue.shift();
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}
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state.sending = false;
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};
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run();
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}
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function enqueueToRelay(connectionId, data) {
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let state = txQueues.get(connectionId);
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if (!state) {
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state = { queue: [], sending: false };
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txQueues.set(connectionId, state);
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}
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state.queue.push(data);
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// Attempt to process immediately
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if (!state.sending) {
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state.sending = false; // ensure process can start
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processTxQueue(connectionId, state);
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}
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}
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function closeAllUpstreams() {
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for (const [, s] of upstreamConns) {
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try { s.destroy(); } catch (_) {}
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}
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upstreamConns.clear();
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}
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function closeAllUdp() {
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for (const [, obj] of udpAssoc) {
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try { obj.udp4 && obj.udp4.close(); } catch (_) {}
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try { obj.udp6 && obj.udp6.close(); } catch (_) {}
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}
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udpAssoc.clear();
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}
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function ensureUdpSocketsForAssoc(connectionId) {
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if (udpAssoc.has(connectionId)) return udpAssoc.get(connectionId);
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const onMessage = (msg, rinfo) => {
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// Forward incoming datagrams to client
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writeMessage(relaySocket, MSG_TYPES.UDP_RECV, connectionId, buildUdpPayload(rinfo.address, rinfo.port, msg));
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};
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// Create both IPv4 and IPv6 sockets to support all targets
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const u4 = dgram.createSocket('udp4');
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const u6 = dgram.createSocket('udp6');
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u4.on('message', onMessage);
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u6.on('message', onMessage);
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u4.on('error', (err) => { /* log but keep running */ console.warn(`UDP4 error (conn ${connectionId}): ${err.message}`); });
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u6.on('error', (err) => { /* log but keep running */ console.warn(`UDP6 error (conn ${connectionId}): ${err.message}`); });
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// Bind to ephemeral ports to receive replies
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try { u4.bind(0); } catch (_) {}
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try { u6.bind(0); } catch (_) {}
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const entry = { udp4: u4, udp6: u6 };
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udpAssoc.set(connectionId, entry);
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return entry;
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}
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const server = tls.createServer(
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{
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pskCallback,
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ciphers: 'PSK-AES256-GCM-SHA384:PSK-AES128-GCM-SHA256',
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},
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(socket) => {
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console.log('Proxy relay connected');
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relaySocket = socket;
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socket.setNoDelay(true);
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socket.setKeepAlive(true, 30000);
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const reader = createMessageReader();
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socket.on('data', (data) => {
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reader(data, (type, connectionId, payload) => {
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if (type === MSG_TYPES.OPEN) {
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const spec = parseOpenPayload(payload);
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if (!spec) {
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console.warn(`Invalid OPEN payload for connection ${connectionId}`);
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writeMessage(relaySocket, MSG_TYPES.OPEN_RESULT, connectionId, buildOpenResultPayload(false));
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return;
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}
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const { host, port } = spec;
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// Create outbound TCP connection
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const upstream = net.createConnection({ host, port });
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upstream.setNoDelay(true);
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upstream.setKeepAlive(true, 30000);
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let connected = false;
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const connectTimer = setTimeout(() => {
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if (!connected) {
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upstream.destroy(new Error('Connect timeout'));
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}
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}, OUT_CONNECT_TIMEOUT);
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upstream.once('connect', () => {
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connected = true;
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clearTimeout(connectTimer);
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upstreamConns.set(connectionId, upstream);
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// Notify open success
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writeMessage(relaySocket, MSG_TYPES.OPEN_RESULT, connectionId, buildOpenResultPayload(true));
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});
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upstream.on('data', (chunk) => {
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// Queue data with framing and backpressure-aware sending
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enqueueToRelay(connectionId, chunk);
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});
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const cleanup = () => {
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clearTimeout(connectTimer);
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if (upstreamConns.get(connectionId) === upstream) {
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upstreamConns.delete(connectionId);
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}
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// Drop any pending TX data for this connection
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txQueues.delete(connectionId);
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writeMessage(relaySocket, MSG_TYPES.CLOSE, connectionId);
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};
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upstream.on('error', (err) => {
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if (!connected) {
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clearTimeout(connectTimer);
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writeMessage(relaySocket, MSG_TYPES.OPEN_RESULT, connectionId, buildOpenResultPayload(false));
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} else {
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// Upstream error after established
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cleanup();
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}
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});
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upstream.on('close', () => {
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cleanup();
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});
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} else if (type === MSG_TYPES.DATA) {
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const upstream = upstreamConns.get(connectionId);
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if (upstream && !upstream.destroyed) {
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upstream.write(payload);
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}
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} else if (type === MSG_TYPES.CLOSE) {
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const upstream = upstreamConns.get(connectionId);
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if (upstream) {
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upstream.destroy();
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upstreamConns.delete(connectionId);
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}
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// UDP handling
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} else if (type === MSG_TYPES.UDP_OPEN) {
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try {
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ensureUdpSocketsForAssoc(connectionId);
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writeMessage(relaySocket, MSG_TYPES.UDP_OPEN_RESULT, connectionId, buildOpenResultPayload(true));
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} catch (e) {
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console.warn(`Failed to create UDP association for ${connectionId}: ${e.message}`);
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writeMessage(relaySocket, MSG_TYPES.UDP_OPEN_RESULT, connectionId, buildOpenResultPayload(false));
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}
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} else if (type === MSG_TYPES.UDP_SEND) {
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const parsed = parseUdpPayload(payload);
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if (!parsed) {
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console.warn(`Invalid UDP_SEND payload for ${connectionId}`);
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return;
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}
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const { host, port, data } = parsed;
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const entry = udpAssoc.get(connectionId) || ensureUdpSocketsForAssoc(connectionId);
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// Choose v6 socket if IPv6 literal detected
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const isV6 = host.includes(':');
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const sock = isV6 ? entry.udp6 : entry.udp4;
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try {
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sock.send(data, port, host);
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} catch (e) {
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console.warn(`UDP send failed (conn ${connectionId}) to ${host}:${port} - ${e.message}`);
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}
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} else if (type === MSG_TYPES.UDP_CLOSE) {
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const entry = udpAssoc.get(connectionId);
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if (entry) {
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try { entry.udp4 && entry.udp4.close(); } catch (_) {}
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try { entry.udp6 && entry.udp6.close(); } catch (_) {}
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udpAssoc.delete(connectionId);
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}
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} else {
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// ignore unknown types
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}
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});
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});
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socket.on('close', () => {
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console.log('Proxy relay disconnected');
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relaySocket = null;
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closeAllUpstreams();
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closeAllUdp();
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});
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socket.on('error', (err) => {
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console.error('Relay socket error:', err.message);
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});
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}
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);
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server.listen(parseInt(options.relayPort, 10), options.host, () => {
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console.log(`PSK Proxy Exit-Node listening on ${options.host}:${options.relayPort}`);
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});
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process.on('SIGINT', () => {
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console.log('Shutting down...');
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try { server.close(); } catch (_) {}
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closeAllUpstreams();
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closeAllUdp();
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process.exit(0);
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});
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