'use strict'
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var multicastdns = require('multicast-dns')
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var dnsEqual = require('dns-equal')
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var flatten = require('array-flatten')
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var deepEqual = require('deep-equal')
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module.exports = Server
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function Server (opts) {
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this.mdns = multicastdns(opts)
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this.mdns.setMaxListeners(0)
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this.registry = {}
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this.mdns.on('query', this._respondToQuery.bind(this))
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}
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Server.prototype.register = function (records) {
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var self = this
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if (Array.isArray(records)) records.forEach(register)
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else register(records)
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function register (record) {
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var subRegistry = self.registry[record.type]
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if (!subRegistry) subRegistry = self.registry[record.type] = []
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else if (subRegistry.some(isDuplicateRecord(record))) return
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subRegistry.push(record)
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}
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}
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Server.prototype.unregister = function (records) {
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var self = this
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if (Array.isArray(records)) records.forEach(unregister)
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else unregister(records)
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function unregister (record) {
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var type = record.type
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if (!(type in self.registry)) return
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self.registry[type] = self.registry[type].filter(function (r) {
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return r.name !== record.name
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})
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}
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}
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Server.prototype._respondToQuery = function (query) {
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var self = this
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query.questions.forEach(function (question) {
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var type = question.type
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var name = question.name
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// generate the answers section
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var answers = type === 'ANY'
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? flatten.depth(Object.keys(self.registry).map(self._recordsFor.bind(self, name)), 1)
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: self._recordsFor(name, type)
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if (answers.length === 0) return
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// generate the additionals section
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var additionals = []
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if (type !== 'ANY') {
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answers.forEach(function (answer) {
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if (answer.type !== 'PTR') return
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additionals = additionals
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.concat(self._recordsFor(answer.data, 'SRV'))
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.concat(self._recordsFor(answer.data, 'TXT'))
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})
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// to populate the A and AAAA records, we need to get a set of unique
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// targets from the SRV record
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additionals
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.filter(function (record) {
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return record.type === 'SRV'
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})
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.map(function (record) {
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return record.data.target
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})
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.filter(unique())
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.forEach(function (target) {
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additionals = additionals
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.concat(self._recordsFor(target, 'A'))
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.concat(self._recordsFor(target, 'AAAA'))
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})
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}
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self.mdns.respond({ answers: answers, additionals: additionals }, function (err) {
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if (err) throw err // TODO: Handle this (if no callback is given, the error will be ignored)
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})
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})
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}
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Server.prototype._recordsFor = function (name, type) {
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if (!(type in this.registry)) return []
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return this.registry[type].filter(function (record) {
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var _name = ~name.indexOf('.') ? record.name : record.name.split('.')[0]
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return dnsEqual(_name, name)
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})
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}
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function isDuplicateRecord (a) {
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return function (b) {
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return a.type === b.type &&
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a.name === b.name &&
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deepEqual(a.data, b.data)
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}
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}
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function unique () {
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var set = []
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return function (obj) {
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if (~set.indexOf(obj)) return false
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set.push(obj)
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return true
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}
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}
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