2a09d1a4
 liuqimichale
添加宜春 天水 宣化
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var packet = require('dns-packet')
var dgram = require('dgram')
var thunky = require('thunky')
var events = require('events')
var os = require('os')
var noop = function () {}
module.exports = function (opts) {
if (!opts) opts = {}
var that = new events.EventEmitter()
var port = typeof opts.port === 'number' ? opts.port : 5353
var type = opts.type || 'udp4'
var ip = opts.ip || opts.host || (type === 'udp4' ? '224.0.0.251' : null)
var me = {address: ip, port: port}
var memberships = {}
var destroyed = false
var interval = null
if (type === 'udp6' && (!ip || !opts.interface)) {
throw new Error('For IPv6 multicast you must specify `ip` and `interface`')
}
var socket = opts.socket || dgram.createSocket({
type: type,
reuseAddr: opts.reuseAddr !== false,
toString: function () {
return type
}
})
socket.on('error', function (err) {
if (err.code === 'EACCES' || err.code === 'EADDRINUSE') that.emit('error', err)
else that.emit('warning', err)
})
socket.on('message', function (message, rinfo) {
try {
message = packet.decode(message)
} catch (err) {
that.emit('warning', err)
return
}
that.emit('packet', message, rinfo)
if (message.type === 'query') that.emit('query', message, rinfo)
if (message.type === 'response') that.emit('response', message, rinfo)
})
socket.on('listening', function () {
if (!port) port = me.port = socket.address().port
if (opts.multicast !== false) {
that.update()
interval = setInterval(that.update, 5000)
socket.setMulticastTTL(opts.ttl || 255)
socket.setMulticastLoopback(opts.loopback !== false)
}
})
var bind = thunky(function (cb) {
if (!port) return cb(null)
socket.once('error', cb)
socket.bind(port, opts.interface, function () {
socket.removeListener('error', cb)
cb(null)
})
})
bind(function (err) {
if (err) return that.emit('error', err)
that.emit('ready')
})
that.send = function (value, rinfo, cb) {
if (typeof rinfo === 'function') return that.send(value, null, rinfo)
if (!cb) cb = noop
if (!rinfo) rinfo = me
bind(onbind)
function onbind (err) {
if (destroyed) return cb()
if (err) return cb(err)
var message = packet.encode(value)
socket.send(message, 0, message.length, rinfo.port, rinfo.address || rinfo.host, cb)
}
}
that.response =
that.respond = function (res, rinfo, cb) {
if (Array.isArray(res)) res = {answers: res}
res.type = 'response'
res.flags = (res.flags || 0) | packet.AUTHORITATIVE_ANSWER
that.send(res, rinfo, cb)
}
that.query = function (q, type, rinfo, cb) {
if (typeof type === 'function') return that.query(q, null, null, type)
if (typeof type === 'object' && type && type.port) return that.query(q, null, type, rinfo)
if (typeof rinfo === 'function') return that.query(q, type, null, rinfo)
if (!cb) cb = noop
if (typeof q === 'string') q = [{name: q, type: type || 'ANY'}]
if (Array.isArray(q)) q = {type: 'query', questions: q}
q.type = 'query'
that.send(q, rinfo, cb)
}
that.destroy = function (cb) {
if (!cb) cb = noop
if (destroyed) return process.nextTick(cb)
destroyed = true
clearInterval(interval)
socket.once('close', cb)
socket.close()
}
that.update = function () {
var ifaces = opts.interface ? [].concat(opts.interface) : allInterfaces()
var updated = false
for (var i = 0; i < ifaces.length; i++) {
var addr = ifaces[i]
if (memberships[addr]) continue
memberships[addr] = true
updated = true
try {
socket.addMembership(ip, addr)
} catch (err) {
that.emit('warning', err)
}
}
if (!updated || !socket.setMulticastInterface) return
socket.setMulticastInterface(opts.interface || defaultInterface())
}
return that
}
function defaultInterface () {
var networks = os.networkInterfaces()
var names = Object.keys(networks)
for (var i = 0; i < names.length; i++) {
var net = networks[names[i]]
for (var j = 0; j < net.length; j++) {
var iface = net[j]
if (iface.family === 'IPv4' && !iface.internal) return iface.address
}
}
return '127.0.0.1'
}
function allInterfaces () {
var networks = os.networkInterfaces()
var names = Object.keys(networks)
var res = []
for (var i = 0; i < names.length; i++) {
var net = networks[names[i]]
for (var j = 0; j < net.length; j++) {
var iface = net[j]
if (iface.family === 'IPv4') {
res.push(iface.address)
// could only addMembership once per interface (https://nodejs.org/api/dgram.html#dgram_socket_addmembership_multicastaddress_multicastinterface)
break
}
}
}
return res
}
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