1 | /* |
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2 | * Copyright (c) 1988, 1993 |
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3 | * The Regents of the University of California. All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * 3. All advertising materials mentioning features or use of this software |
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14 | * must display the following acknowledgement: |
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15 | * This product includes software developed by the University of |
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16 | * California, Berkeley and its contributors. |
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17 | * 4. Neither the name of the University nor the names of its contributors |
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18 | * may be used to endorse or promote products derived from this software |
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19 | * without specific prior written permission. |
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20 | * |
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21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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31 | * SUCH DAMAGE. |
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32 | */ |
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33 | |
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34 | /* |
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35 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
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36 | * |
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37 | * Permission to use, copy, modify, and distribute this software for any |
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38 | * purpose with or without fee is hereby granted, provided that the above |
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39 | * copyright notice and this permission notice appear in all copies, and that |
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40 | * the name of Digital Equipment Corporation not be used in advertising or |
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41 | * publicity pertaining to distribution of the document or software without |
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42 | * specific, written prior permission. |
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43 | * |
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44 | * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
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45 | * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
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46 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
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47 | * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
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48 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
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49 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
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50 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
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51 | * SOFTWARE. |
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52 | */ |
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53 | |
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54 | /* |
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55 | * Portions Copyright (c) 1996 by Internet Software Consortium. |
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56 | * |
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57 | * Permission to use, copy, modify, and distribute this software for any |
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58 | * purpose with or without fee is hereby granted, provided that the above |
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59 | * copyright notice and this permission notice appear in all copies. |
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60 | * |
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61 | * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS |
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62 | * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES |
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63 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE |
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64 | * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
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65 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
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66 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
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67 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
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68 | * SOFTWARE. |
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69 | */ |
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70 | |
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71 | #if HAVE_CONFIG_H |
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72 | #include "config.h" |
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73 | #endif |
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74 | |
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75 | #include <sys/types.h> |
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76 | #include <sys/param.h> |
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77 | #include <netinet/in.h> |
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78 | #include <arpa/inet.h> |
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79 | #include <arpa/nameser.h> |
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80 | #include <ctype.h> |
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81 | #include <errno.h> |
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82 | #include <netdb.h> |
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83 | #include <resolv.h> |
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84 | #include <stdio.h> |
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85 | #include <stdlib.h> |
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86 | #include <string.h> |
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87 | |
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88 | #include "res_config.h" |
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89 | |
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90 | #if PACKETSZ > 1024 |
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91 | #define MAXPACKET PACKETSZ |
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92 | #else |
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93 | #define MAXPACKET 1024 |
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94 | #endif |
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95 | |
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96 | /* |
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97 | * Formulate a normal query, send, and await answer. |
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98 | * Returned answer is placed in supplied buffer "answer". |
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99 | * Perform preliminary check of answer, returning success only |
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100 | * if no error is indicated and the answer count is nonzero. |
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101 | * Return the size of the response on success, -1 on error. |
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102 | * Error number is left in h_errno. |
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103 | * |
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104 | * Caller must parse answer and determine whether it answers the question. |
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105 | */ |
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106 | int |
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107 | res_query( |
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108 | const char *name, /* domain name */ |
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109 | int class, int type, /* class and type of query */ |
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110 | u_char *answer, /* buffer to put answer */ |
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111 | int anslen) /* size of answer buffer */ |
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112 | { |
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113 | u_char buf[MAXPACKET]; |
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114 | HEADER *hp = (HEADER *) answer; |
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115 | int n; |
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116 | |
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117 | hp->rcode = NOERROR; /* default */ |
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118 | |
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119 | if ((_res.options & RES_INIT) == 0 && res_init() == -1) { |
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120 | h_errno = NETDB_INTERNAL; |
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121 | return (-1); |
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122 | } |
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123 | #ifdef DEBUG |
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124 | if (_res.options & RES_DEBUG) |
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125 | printf(";; res_query(%s, %d, %d)\n", name, class, type); |
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126 | #endif |
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127 | |
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128 | n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL, |
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129 | buf, sizeof(buf)); |
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130 | if (n <= 0) { |
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131 | #ifdef DEBUG |
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132 | if (_res.options & RES_DEBUG) |
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133 | printf(";; res_query: mkquery failed\n"); |
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134 | #endif |
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135 | h_errno = NO_RECOVERY; |
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136 | return (n); |
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137 | } |
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138 | n = res_send(buf, n, answer, anslen); |
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139 | if (n < 0) { |
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140 | #ifdef DEBUG |
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141 | if (_res.options & RES_DEBUG) |
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142 | printf(";; res_query: send error\n"); |
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143 | #endif |
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144 | h_errno = TRY_AGAIN; |
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145 | return (n); |
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146 | } |
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147 | |
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148 | if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { |
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149 | #ifdef DEBUG |
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150 | if (_res.options & RES_DEBUG) |
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151 | printf(";; rcode = %d, ancount=%d\n", hp->rcode, |
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152 | ntohs(hp->ancount)); |
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153 | #endif |
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154 | switch (hp->rcode) { |
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155 | case NXDOMAIN: |
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156 | h_errno = HOST_NOT_FOUND; |
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157 | break; |
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158 | case SERVFAIL: |
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159 | h_errno = TRY_AGAIN; |
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160 | break; |
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161 | case NOERROR: |
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162 | h_errno = NO_DATA; |
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163 | break; |
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164 | case FORMERR: |
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165 | case NOTIMP: |
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166 | case REFUSED: |
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167 | default: |
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168 | h_errno = NO_RECOVERY; |
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169 | break; |
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170 | } |
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171 | return (-1); |
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172 | } |
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173 | return (n); |
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174 | } |
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175 | |
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176 | /* |
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177 | * Formulate a normal query, send, and retrieve answer in supplied buffer. |
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178 | * Return the size of the response on success, -1 on error. |
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179 | * If enabled, implement search rules until answer or unrecoverable failure |
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180 | * is detected. Error code, if any, is left in h_errno. |
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181 | */ |
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182 | int |
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183 | res_search( |
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184 | const char *name, /* domain name */ |
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185 | int class, int type, /* class and type of query */ |
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186 | u_char *answer, /* buffer to put answer */ |
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187 | int anslen) /* size of answer */ |
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188 | { |
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189 | const char *cp, * const *domain; |
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190 | HEADER *hp = (HEADER *) answer; |
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191 | u_int dots; |
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192 | int trailing_dot, ret, saved_herrno; |
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193 | int got_nodata = 0, got_servfail = 0, tried_as_is = 0; |
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194 | |
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195 | if ((_res.options & RES_INIT) == 0 && res_init() == -1) { |
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196 | h_errno = NETDB_INTERNAL; |
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197 | return (-1); |
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198 | } |
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199 | errno = 0; |
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200 | h_errno = HOST_NOT_FOUND; /* default, if we never query */ |
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201 | dots = 0; |
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202 | for (cp = name; *cp; cp++) |
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203 | dots += (*cp == '.'); |
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204 | trailing_dot = 0; |
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205 | if (cp > name && *--cp == '.') |
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206 | trailing_dot++; |
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207 | |
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208 | /* If there aren't any dots, it could be a user-level alias */ |
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209 | if (!dots && (cp = hostalias(name)) != NULL) |
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210 | return (res_query(cp, class, type, answer, anslen)); |
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211 | |
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212 | /* |
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213 | * If there are dots in the name already, let's just give it a try |
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214 | * 'as is'. The threshold can be set with the "ndots" option. |
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215 | */ |
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216 | saved_herrno = -1; |
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217 | if (dots >= _res.ndots) { |
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218 | ret = res_querydomain(name, NULL, class, type, answer, anslen); |
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219 | if (ret > 0) |
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220 | return (ret); |
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221 | saved_herrno = h_errno; |
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222 | tried_as_is++; |
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223 | } |
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224 | |
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225 | /* |
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226 | * We do at least one level of search if |
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227 | * - there is no dot and RES_DEFNAME is set, or |
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228 | * - there is at least one dot, there is no trailing dot, |
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229 | * and RES_DNSRCH is set. |
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230 | */ |
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231 | if ((!dots && (_res.options & RES_DEFNAMES)) || |
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232 | (dots && !trailing_dot && (_res.options & RES_DNSRCH))) { |
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233 | int done = 0; |
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234 | |
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235 | for (domain = (const char * const *)_res.dnsrch; |
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236 | *domain && !done; |
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237 | domain++) { |
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238 | |
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239 | ret = res_querydomain(name, *domain, class, type, |
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240 | answer, anslen); |
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241 | if (ret > 0) |
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242 | return (ret); |
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243 | |
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244 | /* |
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245 | * If no server present, give up. |
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246 | * If name isn't found in this domain, |
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247 | * keep trying higher domains in the search list |
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248 | * (if that's enabled). |
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249 | * On a NO_DATA error, keep trying, otherwise |
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250 | * a wildcard entry of another type could keep us |
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251 | * from finding this entry higher in the domain. |
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252 | * If we get some other error (negative answer or |
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253 | * server failure), then stop searching up, |
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254 | * but try the input name below in case it's |
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255 | * fully-qualified. |
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256 | */ |
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257 | if (errno == ECONNREFUSED) { |
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258 | h_errno = TRY_AGAIN; |
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259 | return (-1); |
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260 | } |
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261 | |
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262 | switch (h_errno) { |
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263 | case NO_DATA: |
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264 | got_nodata++; |
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265 | /* FALLTHROUGH */ |
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266 | case HOST_NOT_FOUND: |
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267 | /* keep trying */ |
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268 | break; |
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269 | case TRY_AGAIN: |
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270 | if (hp->rcode == SERVFAIL) { |
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271 | /* try next search element, if any */ |
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272 | got_servfail++; |
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273 | break; |
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274 | } |
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275 | /* FALLTHROUGH */ |
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276 | default: |
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277 | /* anything else implies that we're done */ |
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278 | done++; |
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279 | } |
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280 | |
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281 | /* if we got here for some reason other than DNSRCH, |
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282 | * we only wanted one iteration of the loop, so stop. |
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283 | */ |
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284 | if (!(_res.options & RES_DNSRCH)) |
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285 | done++; |
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286 | } |
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287 | } |
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288 | |
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289 | /* |
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290 | * If we have not already tried the name "as is", do that now. |
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291 | * note that we do this regardless of how many dots were in the |
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292 | * name or whether it ends with a dot unless NOTLDQUERY is set. |
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293 | */ |
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294 | if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) { |
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295 | ret = res_querydomain(name, NULL, class, type, answer, anslen); |
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296 | if (ret > 0) |
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297 | return (ret); |
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298 | } |
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299 | |
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300 | /* if we got here, we didn't satisfy the search. |
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301 | * if we did an initial full query, return that query's h_errno |
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302 | * (note that we wouldn't be here if that query had succeeded). |
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303 | * else if we ever got a nodata, send that back as the reason. |
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304 | * else send back meaningless h_errno, that being the one from |
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305 | * the last DNSRCH we did. |
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306 | */ |
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307 | if (saved_herrno != -1) |
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308 | h_errno = saved_herrno; |
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309 | else if (got_nodata) |
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310 | h_errno = NO_DATA; |
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311 | else if (got_servfail) |
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312 | h_errno = TRY_AGAIN; |
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313 | return (-1); |
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314 | } |
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315 | |
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316 | /* |
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317 | * Perform a call on res_query on the concatenation of name and domain, |
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318 | * removing a trailing dot from name if domain is NULL. |
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319 | */ |
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320 | int |
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321 | res_querydomain( |
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322 | const char *name, const char *domain, |
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323 | int class, int type, /* class and type of query */ |
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324 | u_char *answer, /* buffer to put answer */ |
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325 | int anslen) /* size of answer */ |
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326 | { |
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327 | char nbuf[MAXDNAME]; |
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328 | const char *longname = nbuf; |
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329 | int n, d; |
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330 | |
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331 | if ((_res.options & RES_INIT) == 0 && res_init() == -1) { |
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332 | h_errno = NETDB_INTERNAL; |
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333 | return (-1); |
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334 | } |
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335 | #ifdef DEBUG |
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336 | if (_res.options & RES_DEBUG) |
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337 | printf(";; res_querydomain(%s, %s, %d, %d)\n", |
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338 | name, domain?domain:"<Nil>", class, type); |
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339 | #endif |
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340 | if (domain == NULL) { |
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341 | /* |
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342 | * Check for trailing '.'; |
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343 | * copy without '.' if present. |
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344 | */ |
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345 | n = strlen(name); |
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346 | if (n >= MAXDNAME) { |
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347 | h_errno = NO_RECOVERY; |
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348 | return (-1); |
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349 | } |
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350 | n--; |
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351 | if (n >= 0 && name[n] == '.') { |
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352 | strncpy(nbuf, name, n); |
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353 | nbuf[n] = '\0'; |
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354 | } else |
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355 | longname = name; |
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356 | } else { |
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357 | n = strlen(name); |
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358 | d = strlen(domain); |
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359 | if (n + d + 1 >= MAXDNAME) { |
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360 | h_errno = NO_RECOVERY; |
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361 | return (-1); |
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362 | } |
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363 | sprintf(nbuf, "%s.%s", name, domain); |
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364 | } |
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365 | return (res_query(longname, class, type, answer, anslen)); |
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366 | } |
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367 | |
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368 | const char * |
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369 | hostalias(const char *name) |
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370 | { |
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371 | register char *cp1, *cp2; |
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372 | FILE *fp; |
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373 | char *file; |
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374 | char buf[BUFSIZ]; |
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375 | static char abuf[MAXDNAME]; |
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376 | |
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377 | if (_res.options & RES_NOALIASES) |
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378 | return (NULL); |
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379 | if (issetugid()) |
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380 | return (NULL); |
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381 | file = getenv("HOSTALIASES"); |
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382 | if (file == NULL || (fp = fopen(file, "r")) == NULL) |
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383 | return (NULL); |
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384 | setbuf(fp, NULL); |
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385 | buf[sizeof(buf) - 1] = '\0'; |
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386 | while (fgets(buf, sizeof(buf), fp)) { |
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387 | for (cp1 = buf; *cp1 && !isspace((int)*cp1); ++cp1) |
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388 | ; |
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389 | if (!*cp1) |
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390 | break; |
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391 | *cp1 = '\0'; |
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392 | if (!strcasecmp(buf, name)) { |
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393 | while (isspace((int)*++cp1)) |
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394 | ; |
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395 | if (!*cp1) |
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396 | break; |
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397 | for (cp2 = cp1 + 1; *cp2 && !isspace((int)*cp2); ++cp2) |
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398 | ; |
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399 | abuf[sizeof(abuf) - 1] = *cp2 = '\0'; |
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400 | strncpy(abuf, cp1, sizeof(abuf) - 1); |
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401 | fclose(fp); |
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402 | return (abuf); |
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403 | } |
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404 | } |
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405 | fclose(fp); |
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406 | return (NULL); |
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407 | } |
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