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23 | "use strict";
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24 |
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25 | var clone = require('clone'),
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26 | consts = require('./consts'),
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27 | Question = require('./question'),
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28 | platform = require('./platform'),
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29 | Request = require('./request');
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30 |
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31 | var _queue = [];
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32 |
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33 | var sendQueued = function () {
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34 | _queue.forEach(function (request) {
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35 | request.start();
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36 | });
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37 | _queue = [];
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38 | };
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39 |
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40 | platform.on('ready', function () {
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41 | sendQueued();
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42 | });
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43 |
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44 | if (platform.ready) {
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45 | sendQueued();
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46 | }
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47 |
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48 | var Resolve = module.exports = function (opts, callback) {
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49 | this.domain = opts.domain;
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50 | this.rrtype = opts.rrtype;
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51 | this.check_hosts = opts.check_hosts;
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52 | this.callback = callback;
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53 |
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54 | this.buildQuestion(this.domain);
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55 |
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56 | this.started = false;
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57 | this.current_server = undefined;
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58 | this.server_list = [];
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59 |
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60 | this.request = undefined;
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61 |
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62 | if (!platform.ready) {
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63 | _queue.push(this);
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64 | } else {
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65 | this.start();
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66 | }
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67 | };
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68 |
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69 | Resolve.prototype.cancel = function () {
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70 | if (this.request) {
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71 | this.request.cancel();
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72 | }
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73 | };
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74 |
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75 | Resolve.prototype.buildQuestion = function (name) {
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76 | this.question = new Question();
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77 | this.question.type = this.rrtype;
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78 | this.question.class = consts.NAME_TO_QCLASS.IN;
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79 | this.question.name = name;
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80 | };
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81 |
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82 | Resolve.prototype.isInHosts = function () {
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83 | var results;
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84 | if (platform.hosts[this.question.name]) {
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85 | results = platform.hosts[this.question.name];
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86 | this.callback(null, results);
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87 | return true;
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88 | } else {
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89 | return false;
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90 | }
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91 | };
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92 |
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93 | Resolve.prototype.start = function () {
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94 | var tries = 0, s, slist,
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95 | self = this;
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96 |
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97 | if (!this.started) {
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98 | this.started = true;
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99 | this.try_edns = platform.edns;
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100 | this.search_path = platform.search_path.slice(0);
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101 |
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102 | slist = platform.name_servers;
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103 |
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104 | while (this.server_list.length < platform.attempts) {
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105 | s = clone(slist[tries % slist.length]);
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106 | s.type = 'udp';
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107 | this.server_list.push(s);
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108 | s = clone(s);
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109 | s.type = 'tcp';
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110 | this.server_list.push(s);
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111 | tries += 1;
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112 | }
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113 | this.server_list.reverse();
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114 | }
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115 |
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116 | if (this.check_hosts && this.isInHosts()) {
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117 | return;
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118 | }
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119 |
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120 | if (this.server_list.length === 0) {
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121 | this.handleTimeout();
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122 | } else {
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123 | this.current_server = this.server_list.pop();
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124 | this.request = Request({
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125 | question: this.question,
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126 | server: this.current_server,
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127 | timeout: platform.timeout,
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128 | try_edns: this.try_edns,
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129 | });
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130 |
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131 | this.request.on('timeout', function () {
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132 | self.handleTimeout();
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133 | });
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134 |
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135 | this.request.on('message', function (err, answer) {
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136 | self.handle(err, answer);
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137 | });
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138 |
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139 | this.request.send();
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140 | }
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141 | };
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142 |
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143 | Resolve.prototype.handle = function (err, answer) {
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144 | var rcode, errno;
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145 |
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146 | if (answer) {
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147 | rcode = answer.rcode;
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148 | }
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149 |
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150 | switch (rcode) {
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151 | case consts.NAME_TO_RCODE.NOERROR:
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152 | break;
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153 | case consts.NAME_TO_RCODE.NOTFOUND:
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154 | if (this.server_list.length > 0 && this.search_path.length > 0) {
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155 | this.buildQuestion([this.domain, this.search_path.pop()].join('.'));
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156 | } else {
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157 | errno = consts.NOTFOUND;
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158 | }
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159 | answer = undefined;
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160 | break;
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161 | case consts.NAME_TO_RCODE.FORMERR:
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162 | if (this.try_edns) {
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163 | this.try_edns = false;
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164 | this.server_list.splice(0, 1, this.current_server);
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165 | } else {
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166 | errno = consts.FORMERR;
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167 | }
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168 | answer = undefined;
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169 | break;
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170 | default:
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171 | errno = consts.RCODE_TO_NAME[rcode];
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172 | answer = undefined;
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173 | break;
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174 | }
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175 |
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176 | if (errno || answer) {
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177 | if (errno) {
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178 | err = new Error('getHostByName ' + errno);
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179 | err.errno = errno;
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180 | }
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181 | this.callback(err, answer);
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182 | } else {
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183 | this.start();
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184 | }
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185 | };
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186 |
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187 | Resolve.prototype.handleTimeout = function () {
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188 | var err;
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189 |
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190 | if (this.server_list.length === 0) {
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191 | err = new Error('getHostByName ' + consts.TIMEOUT);
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192 | err.errno = consts.TIMEOUT;
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193 | err.request = this;
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194 | this.callback(err, undefined);
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195 | } else {
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196 | this.start();
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197 | }
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198 | };
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