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| /* | |
| Copyright 2019-2024 Aaron Suen <warr1024@gmail.com> | |
| Permission is hereby granted, free of charge, to any person obtaining a copy of this | |
| software and associated documentation files (the "Software"), to deal in the Software | |
| without restriction, including without limitation the rights to use, copy, modify, | |
| merge, publish, distribute, sublicense, and/or sell copies of the Software, and to | |
| permit persons to whom the Software is furnished to do so. | |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, | |
| INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A | |
| PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT | |
| HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION | |
| OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE | |
| SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
| */ | |
| "use strict"; | |
| const process = require("process"); | |
| const dgram = require("dgram"); | |
| // Command line args: | |
| let [listenport, fwdport, fwdaddr, mindelay, maxdelay] = process.argv.slice(2); | |
| // It will listen on <listenport> and act as a reverse proxy for the UDP service | |
| // at <fwdaddr>:<fwdport>. All packets will be delayed by a uniformly | |
| // distributed random value between <mindelay> and <maxdelay> in milleseconds. | |
| // Defaults: | |
| listenport = Number(listenport) || 30001; | |
| fwdport = Number(fwdport) || 30000; | |
| fwdaddr = fwdaddr || "127.0.0.1"; | |
| mindelay = Number(mindelay) || 400; | |
| maxdelay = Number(maxdelay) || mindelay * 1.25; | |
| console.log( | |
| `${listenport}->${fwdaddr}:${fwdport} min ${mindelay} max ${maxdelay}` | |
| ); | |
| function delaysend(sock, msg, toport, toaddr, fromport, fromaddr) { | |
| const delay = Math.floor(Math.random() * (maxdelay - mindelay) + mindelay); | |
| setTimeout(() => sock.send(msg, toport, toaddr), delay); | |
| } | |
| const server = dgram.createSocket("udp4"); | |
| server.on("error", (e) => { | |
| throw e; | |
| }); | |
| server.on("listening", () => `listening on ${listenport}`); | |
| server.bind(listenport); | |
| const fwds = {}; | |
| server.on("message", (msg, info) => { | |
| const { address, port } = info; | |
| const key = `${address}:${port}`; | |
| let sock = fwds[key]; | |
| if (!sock) { | |
| fwds[key] = sock = dgram.createSocket("udp4"); | |
| sock.on("error", (e) => { | |
| throw e; | |
| }); | |
| server.on("listening", () => | |
| console.log( | |
| `new connection from ${address}:${port} relaying via port ${ | |
| sock.address().port | |
| }` | |
| ) | |
| ); | |
| sock.on("message", (m) => | |
| delaysend(server, m, port, address, fwdport, fwdaddr) | |
| ); | |
| } | |
| delaysend(sock, msg, fwdport, fwdaddr, port, address); | |
| }); |
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