1 | /* Copyright (C) 1993, 1995-2003, 2004 Free Software Foundation, Inc. |
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2 | This file is part of the GNU C Library. |
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3 | Contributed by David Mosberger (davidm@azstarnet.com). |
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4 | |
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5 | The GNU C Library is free software; you can redistribute it and/or |
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6 | modify it under the terms of the GNU Lesser General Public |
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7 | License as published by the Free Software Foundation; either |
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8 | version 2.1 of the License, or (at your option) any later version. |
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9 | |
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10 | The GNU C Library is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 | Lesser General Public License for more details. |
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14 | |
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15 | You should have received a copy of the GNU Lesser General Public |
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16 | License along with the GNU C Library; if not, write to the Free |
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17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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18 | 02111-1307 USA. */ |
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19 | |
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20 | /* This file provides a Linux /etc/host.conf compatible front end to |
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21 | the various name resolvers (/etc/hosts, named, NIS server, etc.). |
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22 | Though mostly compatibly, the following differences exist compared |
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23 | to the original implementation: |
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24 | |
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25 | - new command "spoof" takes an arguments like RESOLV_SPOOF_CHECK |
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26 | environment variable (i.e., `off', `nowarn', or `warn'). |
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27 | |
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28 | - line comments can appear anywhere (not just at the beginning of |
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29 | a line) |
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30 | */ |
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31 | |
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32 | #include <assert.h> |
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33 | #include <errno.h> |
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34 | #include <ctype.h> |
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35 | #include <libintl.h> |
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36 | #include <memory.h> |
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37 | #include <stdio.h> |
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38 | #include <stdio_ext.h> |
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39 | #include <stdlib.h> |
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40 | #include <string.h> |
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41 | #include <net/if.h> |
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42 | #include <sys/ioctl.h> |
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43 | #include <unistd.h> |
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44 | #include <netinet/in.h> |
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45 | #define _IO_MTSAFE_IO |
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46 | #include <bits/libc-lock.h> |
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47 | #include "ifreq.h" |
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48 | #include "res_hconf.h" |
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49 | #include "local.h" |
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50 | #ifdef USE_IN_LIBIO |
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51 | # include <wchar.h> |
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52 | #endif |
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53 | |
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54 | #define _PATH_HOSTCONF "/etc/host.conf" |
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55 | |
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56 | /* Environment vars that all user to override default behavior: */ |
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57 | #define ENV_HOSTCONF "RESOLV_HOST_CONF" |
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58 | #define ENV_SERVORDER "RESOLV_SERV_ORDER" |
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59 | #define ENV_SPOOF "RESOLV_SPOOF_CHECK" |
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60 | #define ENV_TRIM_OVERR "RESOLV_OVERRIDE_TRIM_DOMAINS" |
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61 | #define ENV_TRIM_ADD "RESOLV_ADD_TRIM_DOMAINS" |
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62 | #define ENV_MULTI "RESOLV_MULTI" |
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63 | #define ENV_REORDER "RESOLV_REORDER" |
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64 | |
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65 | static const char *arg_service_list (const char *, int, const char *, |
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66 | unsigned int); |
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67 | static const char *arg_trimdomain_list (const char *, int, const char *, |
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68 | unsigned int); |
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69 | static const char *arg_spoof (const char *, int, const char *, unsigned int); |
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70 | static const char *arg_bool (const char *, int, const char *, unsigned int); |
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71 | |
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72 | static struct cmd |
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73 | { |
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74 | const char *name; |
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75 | const char *(*parse_args) (const char * filename, int line_num, |
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76 | const char * args, unsigned int arg); |
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77 | unsigned int arg; |
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78 | } cmd[] = |
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79 | { |
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80 | {"order", arg_service_list, 0}, |
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81 | {"trim", arg_trimdomain_list, 0}, |
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82 | {"spoof", arg_spoof, 0}, |
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83 | {"multi", arg_bool, HCONF_FLAG_MULTI}, |
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84 | {"nospoof", arg_bool, HCONF_FLAG_SPOOF}, |
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85 | {"spoofalert", arg_bool, HCONF_FLAG_SPOOFALERT}, |
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86 | {"reorder", arg_bool, HCONF_FLAG_REORDER} |
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87 | }; |
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88 | |
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89 | /* Structure containing the state. */ |
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90 | struct hconf _res_hconf; |
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91 | |
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92 | /* Skip white space. */ |
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93 | static const char * |
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94 | skip_ws (const char *str) |
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95 | { |
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96 | while (isspace (*str)) ++str; |
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97 | return str; |
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98 | } |
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99 | |
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100 | |
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101 | /* Skip until whitespace, comma, end of line, or comment character. */ |
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102 | static const char * |
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103 | skip_string (const char *str) |
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104 | { |
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105 | while (*str && !isspace (*str) && *str != '#' && *str != ',') |
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106 | ++str; |
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107 | return str; |
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108 | } |
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109 | |
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110 | |
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111 | static const char * |
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112 | arg_service_list (const char *fname, int line_num, const char *args, |
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113 | unsigned int arg) |
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114 | { |
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115 | enum Name_Service service; |
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116 | const char *start; |
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117 | size_t len; |
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118 | size_t i; |
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119 | static struct |
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120 | { |
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121 | const char * name; |
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122 | enum Name_Service service; |
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123 | } svcs[] = |
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124 | { |
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125 | {"bind", SERVICE_BIND}, |
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126 | {"hosts", SERVICE_HOSTS}, |
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127 | {"nis", SERVICE_NIS}, |
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128 | }; |
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129 | |
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130 | do |
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131 | { |
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132 | start = args; |
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133 | args = skip_string (args); |
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134 | len = args - start; |
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135 | |
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136 | service = SERVICE_NONE; |
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137 | for (i = 0; i < sizeof (svcs) / sizeof (svcs[0]); ++i) |
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138 | { |
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139 | if (strncasecmp (start, svcs[i].name, len) == 0 |
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140 | && len == strlen (svcs[i].name)) |
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141 | { |
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142 | service = svcs[i].service; |
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143 | break; |
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144 | } |
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145 | } |
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146 | if (service == SERVICE_NONE) |
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147 | { |
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148 | char *buf; |
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149 | |
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150 | if (asprintf (&buf, |
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151 | _("%s: line %d: expected service, found `%s'\n"), |
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152 | fname, line_num, start) < 0) |
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153 | return 0; |
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154 | |
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155 | #ifdef USE_IN_LIBIO |
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156 | if (_IO_fwide (stderr, 0) > 0) |
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157 | __fwprintf (stderr, L"%s", buf); |
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158 | else |
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159 | #endif |
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160 | fputs (buf, stderr); |
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161 | |
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162 | free (buf); |
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163 | return 0; |
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164 | } |
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165 | if (_res_hconf.num_services >= SERVICE_MAX) |
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166 | { |
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167 | char *buf; |
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168 | |
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169 | if (asprintf (&buf, _("\ |
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170 | %s: line %d: cannot specify more than %d services"), |
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171 | fname, line_num, SERVICE_MAX) < 0) |
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172 | return 0; |
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173 | |
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174 | #ifdef USE_IN_LIBIO |
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175 | if (_IO_fwide (stderr, 0) > 0) |
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176 | __fwprintf (stderr, L"%s", buf); |
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177 | else |
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178 | #endif |
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179 | fputs (buf, stderr); |
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180 | |
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181 | free (buf); |
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182 | return 0; |
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183 | } |
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184 | _res_hconf.service[_res_hconf.num_services++] = service; |
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185 | |
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186 | args = skip_ws (args); |
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187 | switch (*args) |
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188 | { |
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189 | case ',': |
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190 | case ';': |
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191 | case ':': |
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192 | args = skip_ws (++args); |
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193 | if (!*args || *args == '#') |
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194 | { |
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195 | char *buf; |
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196 | |
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197 | if (asprintf (&buf, _("\ |
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198 | %s: line %d: list delimiter not followed by keyword"), |
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199 | fname, line_num) < 0) |
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200 | return 0; |
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201 | |
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202 | #ifdef USE_IN_LIBIO |
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203 | if (_IO_fwide (stderr, 0) > 0) |
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204 | __fwprintf (stderr, L"%s", buf); |
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205 | else |
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206 | #endif |
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207 | fputs (buf, stderr); |
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208 | |
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209 | free (buf); |
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210 | return 0; |
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211 | } |
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212 | default: |
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213 | break; |
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214 | } |
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215 | } |
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216 | while (*args && *args != '#'); |
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217 | return args; |
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218 | } |
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219 | |
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220 | |
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221 | static const char * |
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222 | arg_trimdomain_list (const char *fname, int line_num, const char *args, |
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223 | unsigned int flag) |
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224 | { |
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225 | const char * start; |
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226 | size_t len; |
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227 | |
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228 | do |
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229 | { |
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230 | start = args; |
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231 | args = skip_string (args); |
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232 | len = args - start; |
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233 | |
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234 | if (_res_hconf.num_trimdomains >= TRIMDOMAINS_MAX) |
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235 | { |
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236 | char *buf; |
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237 | |
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238 | if (asprintf (&buf, _("\ |
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239 | %s: line %d: cannot specify more than %d trim domains"), |
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240 | fname, line_num, TRIMDOMAINS_MAX) < 0) |
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241 | return 0; |
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242 | |
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243 | #ifdef USE_IN_LIBIO |
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244 | if (_IO_fwide (stderr, 0) > 0) |
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245 | __fwprintf (stderr, L"%s", buf); |
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246 | else |
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247 | #endif |
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248 | fputs (buf, stderr); |
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249 | |
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250 | free (buf); |
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251 | return 0; |
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252 | } |
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253 | _res_hconf.trimdomain[_res_hconf.num_trimdomains++] = |
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254 | strndup (start, len); |
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255 | args = skip_ws (args); |
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256 | switch (*args) |
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257 | { |
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258 | case ',': case ';': case ':': |
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259 | args = skip_ws (++args); |
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260 | if (!*args || *args == '#') |
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261 | { |
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262 | char *buf; |
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263 | |
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264 | if (asprintf (&buf, _("\ |
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265 | %s: line %d: list delimiter not followed by domain"), |
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266 | fname, line_num) < 0) |
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267 | return 0; |
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268 | |
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269 | #ifdef USE_IN_LIBIO |
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270 | if (_IO_fwide (stderr, 0) > 0) |
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271 | __fwprintf (stderr, L"%s", buf); |
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272 | else |
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273 | #endif |
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274 | fputs (buf, stderr); |
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275 | |
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276 | free (buf); |
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277 | return 0; |
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278 | } |
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279 | default: |
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280 | break; |
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281 | } |
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282 | } |
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283 | while (*args && *args != '#'); |
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284 | return args; |
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285 | } |
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286 | |
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287 | |
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288 | static const char * |
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289 | arg_spoof (const char *fname, int line_num, const char *args, unsigned flag) |
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290 | { |
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291 | const char *start = args; |
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292 | size_t len; |
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293 | |
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294 | args = skip_string (args); |
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295 | len = args - start; |
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296 | |
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297 | if (len == 3 && strncasecmp (start, "off", len) == 0) |
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298 | _res_hconf.flags &= ~(HCONF_FLAG_SPOOF | HCONF_FLAG_SPOOFALERT); |
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299 | else |
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300 | { |
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301 | _res_hconf.flags |= (HCONF_FLAG_SPOOF | HCONF_FLAG_SPOOFALERT); |
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302 | if ((len == 6 && strncasecmp (start, "nowarn", len) == 0) |
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303 | || !(len == 4 && strncasecmp (start, "warn", len) == 0)) |
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304 | _res_hconf.flags &= ~HCONF_FLAG_SPOOFALERT; |
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305 | } |
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306 | return args; |
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307 | } |
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308 | |
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309 | |
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310 | static const char * |
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311 | arg_bool (const char *fname, int line_num, const char *args, unsigned flag) |
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312 | { |
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313 | if (strncasecmp (args, "on", 2) == 0) |
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314 | { |
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315 | args += 2; |
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316 | _res_hconf.flags |= flag; |
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317 | } |
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318 | else if (strncasecmp (args, "off", 3) == 0) |
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319 | { |
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320 | args += 3; |
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321 | _res_hconf.flags &= ~flag; |
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322 | } |
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323 | else |
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324 | { |
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325 | char *buf; |
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326 | |
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327 | if (asprintf (&buf, |
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328 | _("%s: line %d: expected `on' or `off', found `%s'\n"), |
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329 | fname, line_num, args) < 0) |
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330 | return 0; |
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331 | |
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332 | #ifdef USE_IN_LIBIO |
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333 | if (_IO_fwide (stderr, 0) > 0) |
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334 | __fwprintf (stderr, L"%s", buf); |
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335 | else |
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336 | #endif |
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337 | fputs (buf, stderr); |
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338 | |
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339 | free (buf); |
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340 | return 0; |
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341 | } |
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342 | return args; |
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343 | } |
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344 | |
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345 | |
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346 | static void |
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347 | parse_line (const char *fname, int line_num, const char *str) |
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348 | { |
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349 | const char *start; |
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350 | struct cmd *c = 0; |
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351 | size_t len; |
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352 | size_t i; |
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353 | |
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354 | str = skip_ws (str); |
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355 | |
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356 | /* skip line comment and empty lines: */ |
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357 | if (*str == '\0' || *str == '#') return; |
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358 | |
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359 | start = str; |
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360 | str = skip_string (str); |
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361 | len = str - start; |
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362 | |
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363 | for (i = 0; i < sizeof (cmd) / sizeof (cmd[0]); ++i) |
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364 | { |
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365 | if (strncasecmp (start, cmd[i].name, len) == 0 |
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366 | && strlen (cmd[i].name) == len) |
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367 | { |
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368 | c = &cmd[i]; |
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369 | break; |
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370 | } |
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371 | } |
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372 | if (c == NULL) |
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373 | { |
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374 | char *buf; |
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375 | |
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376 | if (asprintf (&buf, _("%s: line %d: bad command `%s'\n"), |
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377 | fname, line_num, start) < 0) |
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378 | return; |
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379 | |
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380 | #ifdef USE_IN_LIBIO |
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381 | if (_IO_fwide (stderr, 0) > 0) |
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382 | __fwprintf (stderr, L"%s", buf); |
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383 | else |
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384 | #endif |
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385 | fputs (buf, stderr); |
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386 | |
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387 | free (buf); |
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388 | return; |
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389 | } |
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390 | |
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391 | /* process args: */ |
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392 | str = skip_ws (str); |
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393 | str = (*c->parse_args) (fname, line_num, str, c->arg); |
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394 | if (!str) |
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395 | return; |
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396 | |
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397 | /* rest of line must contain white space or comment only: */ |
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398 | while (*str) |
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399 | { |
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400 | if (!isspace (*str)) { |
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401 | if (*str != '#') |
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402 | { |
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403 | char *buf; |
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404 | |
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405 | if (asprintf (&buf, |
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406 | _("%s: line %d: ignoring trailing garbage `%s'\n"), |
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407 | fname, line_num, str) < 0) |
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408 | break; |
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409 | |
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410 | #ifdef USE_IN_LIBIO |
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411 | if (_IO_fwide (stderr, 0) > 0) |
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412 | __fwprintf (stderr, L"%s", buf); |
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413 | else |
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414 | #endif |
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415 | fputs (buf, stderr); |
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416 | |
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417 | free (buf); |
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418 | } |
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419 | break; |
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420 | } |
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421 | ++str; |
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422 | } |
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423 | } |
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424 | |
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425 | |
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426 | static void |
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427 | do_init (void) |
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428 | { |
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429 | const char *hconf_name; |
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430 | int line_num = 0; |
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431 | char buf[256], *envval; |
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432 | FILE *fp; |
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433 | |
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434 | memset (&_res_hconf, '\0', sizeof (_res_hconf)); |
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435 | |
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436 | hconf_name = getenv (ENV_HOSTCONF); |
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437 | if (hconf_name == NULL) |
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438 | hconf_name = _PATH_HOSTCONF; |
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439 | |
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440 | fp = fopen (hconf_name, "rc"); |
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441 | if (!fp) |
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442 | /* make up something reasonable: */ |
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443 | _res_hconf.service[_res_hconf.num_services++] = SERVICE_BIND; |
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444 | else |
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445 | { |
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446 | /* No threads using this stream. */ |
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447 | __fsetlocking (fp, FSETLOCKING_BYCALLER); |
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448 | |
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449 | while (fgets (buf, sizeof (buf), fp)) |
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450 | { |
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451 | char *tmp; |
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452 | ++line_num; |
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453 | tmp = strchr (buf, '\n'); |
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454 | if (tmp != NULL) |
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455 | *tmp = '\0'; |
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456 | parse_line (hconf_name, line_num, buf); |
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457 | } |
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458 | fclose (fp); |
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459 | } |
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460 | |
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461 | envval = getenv (ENV_SERVORDER); |
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462 | if (envval) |
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463 | { |
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464 | _res_hconf.num_services = 0; |
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465 | arg_service_list (ENV_SERVORDER, 1, envval, 0); |
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466 | } |
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467 | |
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468 | envval = getenv (ENV_SPOOF); |
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469 | if (envval) |
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470 | arg_spoof (ENV_SPOOF, 1, envval, 0); |
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471 | |
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472 | envval = getenv (ENV_MULTI); |
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473 | if (envval) |
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474 | arg_bool (ENV_MULTI, 1, envval, HCONF_FLAG_MULTI); |
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475 | |
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476 | envval = getenv (ENV_REORDER); |
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477 | if (envval) |
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478 | arg_bool (ENV_REORDER, 1, envval, HCONF_FLAG_REORDER); |
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479 | |
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480 | envval = getenv (ENV_TRIM_ADD); |
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481 | if (envval) |
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482 | arg_trimdomain_list (ENV_TRIM_ADD, 1, envval, 0); |
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483 | |
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484 | envval = getenv (ENV_TRIM_OVERR); |
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485 | if (envval) |
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486 | { |
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487 | _res_hconf.num_trimdomains = 0; |
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488 | arg_trimdomain_list (ENV_TRIM_OVERR, 1, envval, 0); |
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489 | } |
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490 | |
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491 | _res_hconf.initialized = 1; |
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492 | } |
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493 | |
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494 | |
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495 | /* Initialize hconf datastructure by reading host.conf file and |
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496 | environment variables. */ |
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497 | void |
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498 | _res_hconf_init (void) |
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499 | { |
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500 | __libc_once_define (static, once); |
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501 | |
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502 | __libc_once (once, do_init); |
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503 | } |
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504 | |
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505 | |
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506 | /* List of known interfaces. */ |
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507 | libc_freeres_ptr ( |
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508 | static struct netaddr |
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509 | { |
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510 | int addrtype; |
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511 | union |
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512 | { |
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513 | struct |
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514 | { |
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515 | u_int32_t addr; |
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516 | u_int32_t mask; |
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517 | } ipv4; |
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518 | } u; |
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519 | } *ifaddrs); |
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520 | |
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521 | /* We need to protect the dynamic buffer handling. */ |
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522 | __libc_lock_define_initialized (static, lock); |
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523 | |
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524 | /* Reorder addresses returned in a hostent such that the first address |
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525 | is an address on the local subnet, if there is such an address. |
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526 | Otherwise, nothing is changed. |
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527 | |
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528 | Note that this function currently only handles IPv4 addresses. */ |
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529 | |
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530 | void |
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531 | _res_hconf_reorder_addrs (struct hostent *hp) |
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532 | { |
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533 | #if defined SIOCGIFCONF && defined SIOCGIFNETMASK |
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534 | int i, j; |
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535 | /* Number of interfaces. */ |
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536 | static int num_ifs = -1; |
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537 | |
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538 | /* Only reorder if we're supposed to. */ |
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539 | if ((_res_hconf.flags & HCONF_FLAG_REORDER) == 0) |
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540 | return; |
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541 | |
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542 | /* Can't deal with anything but IPv4 for now... */ |
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543 | if (hp->h_addrtype != AF_INET) |
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544 | return; |
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545 | |
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546 | if (num_ifs <= 0) |
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547 | { |
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548 | struct ifreq *ifr, *cur_ifr; |
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549 | int sd, num, i; |
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550 | /* Save errno. */ |
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551 | int save = errno; |
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552 | |
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553 | /* Initialize interface table. */ |
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554 | |
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555 | num_ifs = 0; |
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556 | |
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557 | /* The SIOCGIFNETMASK ioctl will only work on an AF_INET socket. */ |
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558 | sd = socket (AF_INET, SOCK_DGRAM, 0); |
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559 | if (sd < 0) |
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560 | return; |
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561 | |
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562 | /* Get lock. */ |
---|
563 | __libc_lock_lock (lock); |
---|
564 | |
---|
565 | /* Get a list of interfaces. */ |
---|
566 | __ifreq (&ifr, &num, sd); |
---|
567 | if (!ifr) |
---|
568 | goto cleanup; |
---|
569 | |
---|
570 | ifaddrs = malloc (num * sizeof (ifaddrs[0])); |
---|
571 | if (!ifaddrs) |
---|
572 | goto cleanup1; |
---|
573 | |
---|
574 | /* Copy usable interfaces in ifaddrs structure. */ |
---|
575 | for (cur_ifr = ifr, i = 0; i < num; cur_ifr = __if_nextreq (cur_ifr), ++i) |
---|
576 | { |
---|
577 | if (cur_ifr->ifr_addr.sa_family != AF_INET) |
---|
578 | continue; |
---|
579 | |
---|
580 | ifaddrs[num_ifs].addrtype = AF_INET; |
---|
581 | ifaddrs[num_ifs].u.ipv4.addr = |
---|
582 | ((struct sockaddr_in *) &cur_ifr->ifr_addr)->sin_addr.s_addr; |
---|
583 | |
---|
584 | if (ioctl (sd, SIOCGIFNETMASK, cur_ifr) < 0) |
---|
585 | continue; |
---|
586 | |
---|
587 | ifaddrs[num_ifs].u.ipv4.mask = |
---|
588 | ((struct sockaddr_in *) &cur_ifr->ifr_netmask)->sin_addr.s_addr; |
---|
589 | |
---|
590 | /* Now we're committed to this entry. */ |
---|
591 | ++num_ifs; |
---|
592 | } |
---|
593 | /* Just keep enough memory to hold all the interfaces we want. */ |
---|
594 | ifaddrs = realloc (ifaddrs, num_ifs * sizeof (ifaddrs[0])); |
---|
595 | assert (ifaddrs != NULL); |
---|
596 | |
---|
597 | cleanup1: |
---|
598 | __if_freereq (ifr, num); |
---|
599 | |
---|
600 | cleanup: |
---|
601 | /* Release lock, preserve error value, and close socket. */ |
---|
602 | save = errno; |
---|
603 | __libc_lock_unlock (lock); |
---|
604 | close (sd); |
---|
605 | } |
---|
606 | |
---|
607 | if (num_ifs == 0) |
---|
608 | return; |
---|
609 | |
---|
610 | /* Find an address for which we have a direct connection. */ |
---|
611 | for (i = 0; hp->h_addr_list[i]; ++i) |
---|
612 | { |
---|
613 | struct in_addr *haddr = (struct in_addr *) hp->h_addr_list[i]; |
---|
614 | |
---|
615 | for (j = 0; j < num_ifs; ++j) |
---|
616 | { |
---|
617 | u_int32_t if_addr = ifaddrs[j].u.ipv4.addr; |
---|
618 | u_int32_t if_netmask = ifaddrs[j].u.ipv4.mask; |
---|
619 | |
---|
620 | if (((haddr->s_addr ^ if_addr) & if_netmask) == 0) |
---|
621 | { |
---|
622 | void *tmp; |
---|
623 | |
---|
624 | tmp = hp->h_addr_list[i]; |
---|
625 | hp->h_addr_list[i] = hp->h_addr_list[0]; |
---|
626 | hp->h_addr_list[0] = tmp; |
---|
627 | return; |
---|
628 | } |
---|
629 | } |
---|
630 | } |
---|
631 | #endif /* defined(SIOCGIFCONF) && ... */ |
---|
632 | } |
---|
633 | |
---|
634 | |
---|
635 | /* If HOSTNAME has a postfix matching any of the trimdomains, trim away |
---|
636 | that postfix. Notice that HOSTNAME is modified inplace. Also, the |
---|
637 | original code applied all trimdomains in order, meaning that the |
---|
638 | same domainname could be trimmed multiple times. I believe this |
---|
639 | was unintentional. */ |
---|
640 | void |
---|
641 | _res_hconf_trim_domain (char *hostname) |
---|
642 | { |
---|
643 | size_t hostname_len, trim_len; |
---|
644 | int i; |
---|
645 | |
---|
646 | hostname_len = strlen (hostname); |
---|
647 | |
---|
648 | for (i = 0; i < _res_hconf.num_trimdomains; ++i) |
---|
649 | { |
---|
650 | const char *trim = _res_hconf.trimdomain[i]; |
---|
651 | |
---|
652 | trim_len = strlen (trim); |
---|
653 | if (hostname_len > trim_len |
---|
654 | && strcasecmp (&hostname[hostname_len - trim_len], trim) == 0) |
---|
655 | { |
---|
656 | hostname[hostname_len - trim_len] = '\0'; |
---|
657 | break; |
---|
658 | } |
---|
659 | } |
---|
660 | } |
---|
661 | |
---|
662 | |
---|
663 | /* Trim all hostnames/aliases in HP according to the trimdomain list. |
---|
664 | Notice that HP is modified inplace! */ |
---|
665 | void |
---|
666 | _res_hconf_trim_domains (struct hostent *hp) |
---|
667 | { |
---|
668 | int i; |
---|
669 | |
---|
670 | if (_res_hconf.num_trimdomains == 0) |
---|
671 | return; |
---|
672 | |
---|
673 | _res_hconf_trim_domain (hp->h_name); |
---|
674 | for (i = 0; hp->h_aliases[i]; ++i) |
---|
675 | _res_hconf_trim_domain (hp->h_aliases[i]); |
---|
676 | } |
---|