1 | 'use strict'
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2 |
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3 | var multicastdns = require('multicast-dns')
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4 | var dnsEqual = require('dns-equal')
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5 | var flatten = require('array-flatten')
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6 | var deepEqual = require('deep-equal')
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7 |
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8 | module.exports = Server
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9 |
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10 | function Server (opts) {
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11 | this.mdns = multicastdns(opts)
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12 | this.mdns.setMaxListeners(0)
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13 | this.registry = {}
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14 | this.mdns.on('query', this._respondToQuery.bind(this))
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15 | }
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16 |
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17 | Server.prototype.register = function (records) {
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18 | var self = this
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19 |
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20 | if (Array.isArray(records)) records.forEach(register)
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21 | else register(records)
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22 |
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23 | function register (record) {
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24 | var subRegistry = self.registry[record.type]
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25 | if (!subRegistry) subRegistry = self.registry[record.type] = []
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26 | else if (subRegistry.some(isDuplicateRecord(record))) return
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27 | subRegistry.push(record)
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28 | }
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29 | }
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30 |
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31 | Server.prototype.unregister = function (records) {
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32 | var self = this
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33 |
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34 | if (Array.isArray(records)) records.forEach(unregister)
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35 | else unregister(records)
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36 |
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37 | function unregister (record) {
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38 | var type = record.type
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39 | if (!(type in self.registry)) return
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40 | self.registry[type] = self.registry[type].filter(function (r) {
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41 | return r.name !== record.name
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42 | })
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43 | }
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44 | }
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45 |
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46 | Server.prototype._respondToQuery = function (query) {
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47 | var self = this
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48 | query.questions.forEach(function (question) {
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49 | var type = question.type
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50 | var name = question.name
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51 |
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52 |
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53 | var answers = type === 'ANY'
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54 | ? flatten.depth(Object.keys(self.registry).map(self._recordsFor.bind(self, name)), 1)
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55 | : self._recordsFor(name, type)
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56 |
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57 | if (answers.length === 0) return
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58 |
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59 |
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60 | var additionals = []
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61 | if (type !== 'ANY') {
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62 | answers.forEach(function (answer) {
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63 | if (answer.type !== 'PTR') return
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64 | additionals = additionals
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65 | .concat(self._recordsFor(answer.data, 'SRV'))
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66 | .concat(self._recordsFor(answer.data, 'TXT'))
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67 | })
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68 |
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69 |
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70 |
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71 | additionals
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72 | .filter(function (record) {
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73 | return record.type === 'SRV'
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74 | })
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75 | .map(function (record) {
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76 | return record.data.target
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77 | })
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78 | .filter(unique())
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79 | .forEach(function (target) {
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80 | additionals = additionals
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81 | .concat(self._recordsFor(target, 'A'))
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82 | .concat(self._recordsFor(target, 'AAAA'))
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83 | })
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84 | }
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85 |
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86 | self.mdns.respond({ answers: answers, additionals: additionals }, function (err) {
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87 | if (err) throw err
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88 | })
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89 | })
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90 | }
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91 |
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92 | Server.prototype._recordsFor = function (name, type) {
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93 | if (!(type in this.registry)) return []
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94 |
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95 | return this.registry[type].filter(function (record) {
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96 | var _name = ~name.indexOf('.') ? record.name : record.name.split('.')[0]
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97 | return dnsEqual(_name, name)
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98 | })
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99 | }
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100 |
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101 | function isDuplicateRecord (a) {
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102 | return function (b) {
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103 | return a.type === b.type &&
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104 | a.name === b.name &&
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105 | deepEqual(a.data, b.data)
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106 | }
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107 | }
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108 |
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109 | function unique () {
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110 | var set = []
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111 | return function (obj) {
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112 | if (~set.indexOf(obj)) return false
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113 | set.push(obj)
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114 | return true
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115 | }
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116 | }
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