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relays.js
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relays.js
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#!/usr/bin/env node
var argv = require("optimist")
.usage('Usage: $0 --relayPort [port] --servicePort [port]')
.demand(['relayPort', 'servicePort'])
.argv;
console.info(argv);
var net = require("net");
function uniqueKey(socket) {
var key = socket.remoteAddress + ':' + socket.remotePort;
return key;
}
var availableSockets = {};
function addAvailableSocket(socket) {
availableSockets[uniqueKey(socket)] = socket;
}
function nextAvailableSocket() {
var key = Object.keys(availableSockets)[0];
var socket = availableSockets[key];
delete availableSockets[key];
return socket;
}
function removeFromAvailableSockets(socket) {
var o = availableSockets[uniqueKey(socket)];
delete availableSockets[uniqueKey(socket)];
return o;
}
var socketPair = {};
function addSocketPair(socket1, socket2) {
socketPair[uniqueKey(socket1)] = socket2;
socketPair[uniqueKey(socket2)] = socket1;
}
function getSocketPair(socket) {
return socketPair[uniqueKey(socket)];
}
function deleteSocketPair(socket) {
delete socketPair[uniqueKey(socket)];
}
var pendingSockets = {};
function appendToPendingSocket(socket, data) {
var key = uniqueKey(socket);
var o = pendingSockets[key];
if (o == undefined) {
o = {};
o.socket = socket;
o.buffers = new Array();
pendingSockets[key] = o;
}
o.buffers[o.buffers.length] = data;
}
function deletePendingSocket(socket) {
var found = false;
var key = uniqueKey(socket);
var o = pendingSockets[key];
if (o != undefined) {
delete pendingSockets[key];
found = true;
}
return found;
}
function processPending(socket) {
var processed = false;
var key = Object.keys(pendingSockets)[0];
var o = pendingSockets[key];
if (o != undefined) {
addSocketPair(socket, o.socket);
console.info("processing pending client...")
if (o.buffers.length > 0) {
for (var i = 0; i < o.buffers.length; i++) {
socket.write(o.buffers[i]);
}
}
delete pendingSockets[key];
processed = true;
}
return processed;
}
function createRelayServer(port) {
var relay = net.createServer(function (socket) {
if (!processPending(socket)) {
console.info("adding to available relay sockets");
addAvailableSocket(socket);
}
socket.on("data", function (data) {
var clientSocket = getSocketPair(socket);
if (clientSocket == undefined) {
console.info("client socket not found, discarding data");
return;
}
try {
clientSocket.write(data);
} catch (ex) {
console.info(ex);
}
});
socket.on("close", function (had_error) {
console.info("relay socket closed");
if (removeFromAvailableSockets(socket)) {
console.info(" removing from available relay sockets");
return;
}
var clientSocket = getSocketPair(socket);
if (clientSocket == undefined) {
console.info(" client socket not found");
} else {
clientSocket.end();
deleteSocketPair(socket);
}
});
});
relay.listen(port);
}
function createInternetServer(port) {
var server = net.createServer(function (socket) {
console.info("client socket established");
var relaySocket = nextAvailableSocket();
if (relaySocket) {
addSocketPair(socket, relaySocket);
} else {
console.info(" no available relay socket, buffering...");
}
socket.on("data", function (data) {
var relaySocket = getSocketPair(socket);
if (relaySocket == undefined) {
appendToPendingSocket(socket, data);
return;
}
try {
relaySocket.write(data);
} catch (ex) {
console.info(ex);
}
});
socket.on("close", function (had_error) {
console.info("client socket closed");
var relaySocket = getSocketPair(socket);
if (relaySocket == undefined) {
if (!deletePendingSocket(socket)) {
console.info(" relay socket not found");
}
return;
}
relaySocket.end();
deleteSocketPair(socket);
});
});
server.listen(port);
}
createRelayServer(argv.relayPort);
createInternetServer(argv.servicePort);
process.on("uncaughtException", function (err) {
console.info(err);
});