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1 /* |
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2 * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package sun.net.dns; |
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27 |
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28 import java.util.List; |
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29 import java.util.LinkedList; |
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30 import java.util.StringTokenizer; |
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31 import java.io.BufferedReader; |
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32 import java.io.FileReader; |
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33 import java.io.IOException; |
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34 |
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35 /* |
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36 * An implementation of ResolverConfiguration for Solaris |
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37 * and Linux. |
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38 */ |
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39 |
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40 public class ResolverConfigurationImpl |
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41 extends ResolverConfiguration |
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42 { |
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43 // Lock helds whilst loading configuration or checking |
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44 private static Object lock = new Object(); |
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45 |
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46 // Time of last refresh. |
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47 private static long lastRefresh = -1; |
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48 |
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49 // Cache timeout (300 seconds) - should be converted into property |
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50 // or configured as preference in the future. |
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51 private static final int TIMEOUT = 300000; |
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52 |
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53 // Resolver options |
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54 private final Options opts; |
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55 |
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56 // Parse /etc/resolv.conf to get the values for a particular |
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57 // keyword. |
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58 // |
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59 private LinkedList<String> resolvconf(String keyword, |
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60 int maxperkeyword, |
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61 int maxkeywords) |
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62 { |
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63 LinkedList<String> ll = new LinkedList<>(); |
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64 |
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65 try { |
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66 BufferedReader in = |
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67 new BufferedReader(new FileReader("/etc/resolv.conf")); |
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68 String line; |
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69 while ((line = in.readLine()) != null) { |
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70 int maxvalues = maxperkeyword; |
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71 if (line.length() == 0) |
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72 continue; |
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73 if (line.charAt(0) == '#' || line.charAt(0) == ';') |
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74 continue; |
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75 if (!line.startsWith(keyword)) |
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76 continue; |
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77 String value = line.substring(keyword.length()); |
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78 if (value.length() == 0) |
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79 continue; |
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80 if (value.charAt(0) != ' ' && value.charAt(0) != '\t') |
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81 continue; |
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82 StringTokenizer st = new StringTokenizer(value, " \t"); |
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83 while (st.hasMoreTokens()) { |
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84 String val = st.nextToken(); |
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85 if (val.charAt(0) == '#' || val.charAt(0) == ';') { |
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86 break; |
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87 } |
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88 ll.add(val); |
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89 if (--maxvalues == 0) { |
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90 break; |
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91 } |
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92 } |
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93 if (--maxkeywords == 0) { |
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94 break; |
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95 } |
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96 } |
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97 in.close(); |
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98 } catch (IOException ioe) { |
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99 // problem reading value |
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100 } |
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101 |
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102 return ll; |
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103 } |
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104 |
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105 private LinkedList<String> searchlist; |
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106 private LinkedList<String> nameservers; |
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107 |
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108 |
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109 // Load DNS configuration from OS |
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110 |
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111 private void loadConfig() { |
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112 assert Thread.holdsLock(lock); |
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113 |
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114 // check if cached settings have expired. |
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115 if (lastRefresh >= 0) { |
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116 long currTime = System.currentTimeMillis(); |
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117 if ((currTime - lastRefresh) < TIMEOUT) { |
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118 return; |
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119 } |
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120 } |
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121 |
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122 // get the name servers from /etc/resolv.conf |
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123 nameservers = |
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124 java.security.AccessController.doPrivileged( |
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125 new java.security.PrivilegedAction<LinkedList<String>>() { |
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126 public LinkedList<String> run() { |
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127 // typically MAXNS is 3 but we've picked 5 here |
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128 // to allow for additional servers if required. |
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129 return resolvconf("nameserver", 1, 5); |
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130 } /* run */ |
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131 }); |
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132 |
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133 // get the search list (or domain) |
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134 searchlist = getSearchList(); |
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135 |
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136 // update the timestamp on the configuration |
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137 lastRefresh = System.currentTimeMillis(); |
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138 } |
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139 |
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140 |
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141 // obtain search list or local domain |
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142 |
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143 private LinkedList<String> getSearchList() { |
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144 |
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145 LinkedList<String> sl; |
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146 |
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147 // first try the search keyword in /etc/resolv.conf |
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148 |
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149 sl = java.security.AccessController.doPrivileged( |
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150 new java.security.PrivilegedAction<LinkedList<String>>() { |
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151 public LinkedList<String> run() { |
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152 LinkedList<String> ll; |
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153 |
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154 // first try search keyword (max 6 domains) |
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155 ll = resolvconf("search", 6, 1); |
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156 if (ll.size() > 0) { |
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157 return ll; |
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158 } |
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159 |
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160 return null; |
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161 |
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162 } /* run */ |
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163 |
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164 }); |
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165 if (sl != null) { |
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166 return sl; |
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167 } |
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168 |
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169 // No search keyword so use local domain |
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170 |
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171 |
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172 // LOCALDOMAIN has absolute priority on Solaris |
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173 |
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174 String localDomain = localDomain0(); |
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175 if (localDomain != null && localDomain.length() > 0) { |
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176 sl = new LinkedList<String>(); |
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177 sl.add(localDomain); |
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178 return sl; |
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179 } |
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180 |
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181 // try domain keyword in /etc/resolv.conf |
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182 |
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183 sl = java.security.AccessController.doPrivileged( |
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184 new java.security.PrivilegedAction<LinkedList<String>>() { |
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185 public LinkedList<String> run() { |
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186 LinkedList<String> ll; |
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187 |
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188 ll = resolvconf("domain", 1, 1); |
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189 if (ll.size() > 0) { |
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190 return ll; |
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191 } |
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192 return null; |
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193 |
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194 } /* run */ |
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195 }); |
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196 if (sl != null) { |
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197 return sl; |
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198 } |
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199 |
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200 // no local domain so try fallback (RPC) domain or |
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201 // hostName |
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202 |
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203 sl = new LinkedList<>(); |
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204 String domain = fallbackDomain0(); |
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205 if (domain != null && domain.length() > 0) { |
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206 sl.add(domain); |
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207 } |
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208 |
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209 return sl; |
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210 } |
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211 |
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212 |
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213 // ---- |
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214 |
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215 ResolverConfigurationImpl() { |
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216 opts = new OptionsImpl(); |
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217 } |
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218 |
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219 @SuppressWarnings("unchecked") |
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220 public List<String> searchlist() { |
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221 synchronized (lock) { |
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222 loadConfig(); |
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223 |
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224 // List is mutable so return a shallow copy |
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225 return (List<String>)searchlist.clone(); |
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226 } |
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227 } |
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228 |
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229 @SuppressWarnings("unchecked") |
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230 public List<String> nameservers() { |
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231 synchronized (lock) { |
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232 loadConfig(); |
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233 |
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234 // List is mutable so return a shallow copy |
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235 |
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236 return (List<String>)nameservers.clone(); |
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237 |
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238 } |
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239 } |
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240 |
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241 public Options options() { |
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242 return opts; |
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243 } |
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244 |
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245 |
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246 // --- Native methods -- |
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247 |
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248 static native String localDomain0(); |
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249 |
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250 static native String fallbackDomain0(); |
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251 |
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252 static { |
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253 java.security.AccessController.doPrivileged( |
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254 new java.security.PrivilegedAction<Void>() { |
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255 public Void run() { |
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256 System.loadLibrary("net"); |
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257 return null; |
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258 } |
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259 }); |
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260 } |
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261 |
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262 } |
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263 |
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264 /** |
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265 * Implementation of {@link ResolverConfiguration.Options} |
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266 */ |
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267 class OptionsImpl extends ResolverConfiguration.Options { |
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268 } |