1 | 'use strict'
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2 |
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3 | var dnsEqual = require('dns-equal')
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4 | var flatten = require('array-flatten')
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5 | var Service = require('./service')
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6 |
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7 | var REANNOUNCE_MAX_MS = 60 * 60 * 1000
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8 | var REANNOUNCE_FACTOR = 3
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9 |
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10 | module.exports = Registry
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11 |
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12 | function Registry (server) {
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13 | this._server = server
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14 | this._services = []
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15 | }
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16 |
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17 | Registry.prototype.publish = function (opts) {
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18 | var service = new Service(opts)
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19 | service.start = start.bind(service, this)
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20 | service.stop = stop.bind(service, this)
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21 | service.start({ probe: opts.probe !== false })
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22 | return service
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23 | }
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24 |
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25 | Registry.prototype.unpublishAll = function (cb) {
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26 | teardown(this._server, this._services, cb)
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27 | this._services = []
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28 | }
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29 |
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30 | Registry.prototype.destroy = function () {
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31 | this._services.forEach(function (service) {
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32 | service._destroyed = true
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33 | })
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34 | }
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35 |
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36 | function start (registry, opts) {
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37 | if (this._activated) return
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38 | this._activated = true
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39 |
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40 | registry._services.push(this)
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41 |
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42 | if (opts.probe) {
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43 | var service = this
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44 | probe(registry._server.mdns, this, function (exists) {
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45 | if (exists) {
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46 | service.stop()
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47 | service.emit('error', new Error('Service name is already in use on the network'))
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48 | return
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49 | }
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50 | announce(registry._server, service)
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51 | })
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52 | } else {
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53 | announce(registry._server, this)
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54 | }
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55 | }
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56 |
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57 | function stop (registry, cb) {
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58 | if (!this._activated) return
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59 |
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60 | teardown(registry._server, this, cb)
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61 |
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62 | var index = registry._services.indexOf(this)
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63 | if (index !== -1) registry._services.splice(index, 1)
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64 | }
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65 |
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66 |
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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 |
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72 |
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73 |
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74 |
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75 |
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76 |
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77 |
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78 | function probe (mdns, service, cb) {
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79 | var sent = false
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80 | var retries = 0
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81 | var timer
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82 |
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83 | mdns.on('response', onresponse)
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84 | setTimeout(send, Math.random() * 250)
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85 |
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86 | function send () {
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87 |
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88 | if (!service._activated || service._destroyed) return
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89 |
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90 | mdns.query(service.fqdn, 'ANY', function () {
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91 |
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92 |
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93 | sent = true
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94 | timer = setTimeout(++retries < 3 ? send : done, 250)
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95 | timer.unref()
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96 | })
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97 | }
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98 |
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99 | function onresponse (packet) {
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100 |
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101 |
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102 |
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103 |
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104 |
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105 | if (!sent) return
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106 |
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107 | if (packet.answers.some(matchRR) || packet.additionals.some(matchRR)) done(true)
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108 | }
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109 |
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110 | function matchRR (rr) {
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111 | return dnsEqual(rr.name, service.fqdn)
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112 | }
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113 |
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114 | function done (exists) {
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115 | mdns.removeListener('response', onresponse)
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116 | clearTimeout(timer)
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117 | cb(!!exists)
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118 | }
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119 | }
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120 |
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121 |
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122 |
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123 |
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124 |
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125 |
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126 |
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127 |
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128 |
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129 | function announce (server, service) {
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130 | var delay = 1000
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131 | var packet = service._records()
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132 |
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133 | server.register(packet)
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134 |
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135 | ;(function broadcast () {
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136 |
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137 | if (!service._activated || service._destroyed) return
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138 |
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139 | server.mdns.respond(packet, function () {
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140 |
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141 |
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142 | if (!service.published) {
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143 | service._activated = true
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144 | service.published = true
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145 | service.emit('up')
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146 | }
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147 | delay = delay * REANNOUNCE_FACTOR
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148 | if (delay < REANNOUNCE_MAX_MS && !service._destroyed) {
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149 | setTimeout(broadcast, delay).unref()
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150 | }
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151 | })
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152 | })()
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153 | }
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154 |
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155 |
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156 |
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157 |
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158 |
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159 |
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160 |
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161 |
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162 | function teardown (server, services, cb) {
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163 | if (!Array.isArray(services)) services = [services]
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164 |
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165 | services = services.filter(function (service) {
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166 | return service._activated
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167 | })
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168 |
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169 | var records = flatten.depth(services.map(function (service) {
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170 | service._activated = false
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171 | var records = service._records()
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172 | records.forEach(function (record) {
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173 | record.ttl = 0
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174 | })
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175 | return records
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176 | }), 1)
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177 |
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178 | if (records.length === 0) return cb && cb()
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179 |
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180 | server.unregister(records)
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181 |
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182 |
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183 | server.mdns.respond(records, function () {
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184 | services.forEach(function (service) {
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185 | service.published = false
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186 | })
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187 | if (cb) cb.apply(null, arguments)
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188 | })
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189 | }
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