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udpserver.js
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Neil Gershenfeld authoredNeil Gershenfeld authored
udpserver.js 3.21 KiB
//
// udpserver.js
// WebSocket UDP server
//
// Neil Gershenfeld
// (c) Massachusetts Institute of Technology 2016
//
// This work may be reproduced, modified, distributed, performed, and
// displayed for any purpose, but must acknowledge the mods
// project. Copyright is retained and must be preserved. The work is
// provided as is; no warranty is provided, and users accept all
// liability.
//
// check command line
//
if (process.argv.length < 4) {
console.log("command line: node udpserver.js client_address server_port")
process.exit(-1)
}
//
// get address(es)
//
var os = require('os')
var interfaces = os.networkInterfaces()
var addresses = []
for (var i in interfaces) {
for (var j in interfaces[i]) {
var address = interfaces[i][j]
if (address.family === 'IPv4')
addresses.push(address.address)
}
}
//
// start server
//
var dgram = require("dgram")
var client_address = process.argv[2]
var server_port = process.argv[3]
console.log("listening for connection from client address "+client_address+" on server port "+server_port)
var WebSocketServer = require('ws').Server
wss = new WebSocketServer({port:server_port})
//
// handle connection
//
wss.on('connection',function(ws) {
//
// check address
//
if (ws._socket.remoteAddress != client_address) {
console.log("connection rejected from "+ws._socket.remoteAddress)
ws.send('socket closed')
ws.close()
}
else {
console.log("connection accepted from "+ws._socket.remoteAddress)
}
//
// handle messages
//
var server = null
ws.on("message",function(message) {
var msg = JSON.parse(message)
//
// open local server
//
if (msg.type == 'open local') {
var port = parseInt(msg.port)
server = dgram.createSocket("udp4")
server.bind(port)
server.on('listening',function() {
console.log("server listening on port "+port)
msg = {}
msg.type = 'listening'
msg.addresses = addresses
msg.status = 'listening on '+port
ws.send(JSON.stringify(msg))
})
server.on("message",function(message,info) {
var msg = {}
msg.type = 'message'
msg.message = message.toString('utf8')
msg.info = info
ws.send(JSON.stringify(msg))
})
server.on("error",function(err) {
msg = {}
msg.type = 'status'
msg.status = 'error: '+JSON.stringify(err)
ws.send(JSON.stringify(msg))
})
}
//
// send string
//
else if (msg.type = 'send string') {
var client = dgram.createSocket("udp4")
client.send(msg.string,0,msg.string.length,msg.port,msg.host,
function(err) {
client.close()
msg = {}
msg.type = 'status'
msg.status = 'transmit ('+JSON.stringify(err)+')'
ws.send(JSON.stringify(msg))
}
)
}
})
//
// close
//
ws.on("close",function() {
console.log("connection closed")
if (server != null)
server.close()
server = null
})
})