1 | .\" $Id: ares_search.3,v 1.1 1998-08-13 18:07:35 ghudson Exp $ |
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2 | .\" |
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3 | .\" Copyright 1998 by the Massachusetts Institute of Technology. |
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4 | .\" |
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5 | .\" Permission to use, copy, modify, and distribute this |
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6 | .\" software and its documentation for any purpose and without |
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7 | .\" fee is hereby granted, provided that the above copyright |
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8 | .\" notice appear in all copies and that both that copyright |
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9 | .\" notice and this permission notice appear in supporting |
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10 | .\" documentation, and that the name of M.I.T. not be used in |
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11 | .\" advertising or publicity pertaining to distribution of the |
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12 | .\" software without specific, written prior permission. |
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13 | .\" M.I.T. makes no representations about the suitability of |
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14 | .\" this software for any purpose. It is provided "as is" |
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15 | .\" without express or implied warranty. |
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16 | .\" |
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17 | .TH ARES_SEARCH 3 "24 July 1998" |
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18 | .SH NAME |
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19 | ares_search \- Initiate a DNS query with domain search |
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20 | .SH SYNOPSIS |
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21 | .nf |
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22 | .B #include <ares.h> |
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23 | .PP |
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24 | .B typedef void (*ares_callback)(void *\fIarg\fP, int \fIstatus\fP, |
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25 | .B unsigned char *\fIabuf\fP, int \fIalen\fP) |
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26 | .PP |
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27 | .B void ares_search(ares_channel \fIchannel\fP, const char *\fIname\fP, |
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28 | .B int \fIclass\fP, int \fItype\fP, ares_callback \fIcallback\fP, |
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29 | .B void *\fIarg\fP) |
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30 | .fi |
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31 | .SH DESCRIPTION |
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32 | The |
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33 | .B ares_search |
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34 | function initiates a series of single-question DNS queries on the name |
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35 | service channel identified by |
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36 | .IR channel , |
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37 | using the channel's search domains as well as a host alias file given |
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38 | by the HOSTALIAS environment variable. The parameter |
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39 | .I name |
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40 | gives the alias name or the base of the query name as a NUL-terminated |
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41 | C string of period-separated labels; if it ends with a period, the |
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42 | channel's search domains will not be used. Periods and backslashes |
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43 | within a label must be escaped with a backslash. The parameters |
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44 | .I class |
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45 | and |
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46 | .I type |
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47 | give the class and type of the query using the values defined in |
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48 | .BR <arpa/nameser.h> . |
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49 | When the query sequence is complete or has failed, the ares library |
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50 | will invoke |
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51 | .IR callback . |
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52 | Completion or failure of the query sequence may happen immediately, or |
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53 | may happen during a later call to |
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54 | .BR ares_process (3) |
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55 | or |
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56 | .BR ares_destroy (3). |
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57 | .PP |
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58 | The callback argument |
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59 | .I arg |
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60 | is copied from the |
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61 | .B ares_search |
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62 | argument |
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63 | .IR arg . |
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64 | The callback argument |
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65 | .I status |
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66 | indicates whether the query sequence ended with a successful query |
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67 | and, if not, how the query sequence failed. It may have any of the |
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68 | following values: |
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69 | .TP 19 |
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70 | .B ARES_SUCCESS |
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71 | A query completed successfully. |
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72 | .TP 19 |
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73 | .B ARES_ENODATA |
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74 | No query completed successfully; when the query was tried without a |
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75 | search domain appended, a response was returned with no answers. |
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76 | .TP 19 |
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77 | .B ARES_EFORMERR |
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78 | A query completed but the server claimed that the query was |
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79 | malformatted. |
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80 | .TP 19 |
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81 | .B ARES_ESERVFAIL |
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82 | No query completed successfully; when the query was tried without a |
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83 | search domain appended, the server claimed to have experienced a |
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84 | failure. (This code can only occur if the |
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85 | .B ARES_FLAG_NOCHECKRESP |
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86 | flag was specified at channel initialization time; otherwise, such |
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87 | responses are ignored at the |
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88 | .BR ares_send (3) |
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89 | level.) |
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90 | .TP 19 |
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91 | .B ARES_ENOTFOUND |
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92 | No query completed successfully; when the query was tried without a |
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93 | search domain appended, the server reported that the queried-for |
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94 | domain name was not found. |
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95 | .TP 19 |
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96 | .B ARES_ENOTIMP |
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97 | A query completed but the server does not implement the operation |
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98 | requested by the query. (This code can only occur if the |
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99 | .B ARES_FLAG_NOCHECKRESP |
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100 | flag was specified at channel initialization time; otherwise, such |
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101 | responses are ignored at the |
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102 | .BR ares_send (3) |
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103 | level.) |
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104 | .TP 19 |
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105 | .B ARES_EREFUSED |
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106 | A query completed but the server refused the query. (This code can |
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107 | only occur returned if the |
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108 | .B ARES_FLAG_NOCHECKRESP |
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109 | flag was specified at channel initialization time; otherwise, such |
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110 | responses are ignored at the |
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111 | .BR ares_send (3) |
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112 | level.) |
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113 | .TP 19 |
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114 | .B ARES_TIMEOUT |
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115 | No name servers responded to a query within the timeout period. |
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116 | .TP 19 |
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117 | .B ARES_ECONNREFUSED |
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118 | No name servers could be contacted. |
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119 | .TP 19 |
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120 | .B ARES_ENOMEM |
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121 | Memory was exhausted. |
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122 | .TP 19 |
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123 | .B ARES_EDESTRUCTION |
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124 | The name service channel |
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125 | .I channel |
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126 | is being destroyed; the query will not be completed. |
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127 | .PP |
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128 | If a query completed successfully, the callback argument |
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129 | .I abuf |
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130 | points to a result buffer of length |
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131 | .IR alen . |
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132 | If the query did not complete successfully, |
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133 | .I abuf |
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134 | will usually be NULL and |
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135 | .I alen |
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136 | will usually be 0, but in some cases an unsuccessful query result may |
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137 | be placed in |
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138 | .IR abuf . |
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139 | .SH SEE ALSO |
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140 | .BR ares_process (3) |
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141 | .SH AUTHOR |
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142 | Greg Hudson, MIT Information Systems |
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143 | .br |
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144 | Copyright 1998 by the Massachusetts Institute of Technology. |
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