contrib/bind9/lib/lwres/man/lwres_resutil.3

   1 .\" Copyright (C) 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
   2 .\" Copyright (C) 2000, 2001 Internet Software Consortium.
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  15 .\"
  16 .hy 0
  17 .ad l
  18 '\" t
  19 .\"     Title: lwres_resutil
  20 .\"    Author:
  21 .\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
  22 .\"      Date: 2007-06-18
  23 .\"    Manual: BIND9
  24 .\"    Source: ISC
  25 .\"  Language: English
  26 .\"
  27 .TH "LWRES_RESUTIL" "3" "2007\-06\-18" "ISC" "BIND9"
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  29 .\" * Define some portability stuff
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  32 .\" http://bugs.debian.org/507673
  33 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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  45 .\" * MAIN CONTENT STARTS HERE *
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  47 .SH "NAME"
  48 lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
  49 .SH "SYNOPSIS"
  50 .sp
  51 .ft B
  52 .nf
  53 #include <lwres/lwres\&.h>
  54 .fi
  55 .ft
  56 .HP \w'lwres_result_t\ lwres_string_parse('u
  57 .BI "lwres_result_t lwres_string_parse(lwres_buffer_t\ *" "b" ", char\ **" "c" ", lwres_uint16_t\ *" "len" ");"
  58 .HP \w'lwres_result_t\ lwres_addr_parse('u
  59 .BI "lwres_result_t lwres_addr_parse(lwres_buffer_t\ *" "b" ", lwres_addr_t\ *" "addr" ");"
  60 .HP \w'lwres_result_t\ lwres_getaddrsbyname('u
  61 .BI "lwres_result_t lwres_getaddrsbyname(lwres_context_t\ *" "ctx" ", const\ char\ *" "name" ", lwres_uint32_t\ " "addrtypes" ", lwres_gabnresponse_t\ **" "structp" ");"
  62 .HP \w'lwres_result_t\ lwres_getnamebyaddr('u
  63 .BI "lwres_result_t lwres_getnamebyaddr(lwres_context_t\ *" "ctx" ", lwres_uint32_t\ " "addrtype" ", lwres_uint16_t\ " "addrlen" ", const\ unsigned\ char\ *" "addr" ", lwres_gnbaresponse_t\ **" "structp" ");"
  64 .SH "DESCRIPTION"
  65 .PP
  66 \fBlwres_string_parse()\fR
  67 retrieves a DNS\-encoded string starting the current pointer of lightweight resolver buffer
  68 \fIb\fR: i\&.e\&.
  69 \fBb\->current\fR\&. When the function returns, the address of the first byte of the encoded string is returned via
  70 \fI*c\fR
  71 and the length of that string is given by
  72 \fI*len\fR\&. The buffer\*(Aqs current pointer is advanced to point at the character following the string length, the encoded string, and the trailing
  73 \fBNULL\fR
  74 character\&.
  75 .PP
  76 \fBlwres_addr_parse()\fR
  77 extracts an address from the buffer
  78 \fIb\fR\&. The buffer\*(Aqs current pointer
  79 \fBb\->current\fR
  80 is presumed to point at an encoded address: the address preceded by a 32\-bit protocol family identifier and a 16\-bit length field\&. The encoded address is copied to
  81 \fBaddr\->address\fR
  82 and
  83 \fBaddr\->length\fR
  84 indicates the size in bytes of the address that was copied\&.
  85 \fBb\->current\fR
  86 is advanced to point at the next byte of available data in the buffer following the encoded address\&.
  87 .PP
  88 \fBlwres_getaddrsbyname()\fR
  89 and
  90 \fBlwres_getnamebyaddr()\fR
  91 use the
  92 \fBlwres_gnbaresponse_t\fR
  93 structure defined below:
  94 .PP
  95 .if n \{\
  96 .RS 4
  97 .\}
  98 .nf
  99 typedef struct {
 100         lwres_uint32_t          flags;
 101         lwres_uint16_t          naliases;
 102         lwres_uint16_t          naddrs;
 103         char                   *realname;
 104         char                  **aliases;
 105         lwres_uint16_t          realnamelen;
 106         lwres_uint16_t         *aliaslen;
 107         lwres_addrlist_t        addrs;
 108         void                   *base;
 109         size_t                  baselen;
 110 } lwres_gabnresponse_t;
 111 .fi
 112 .if n \{\
 113 .RE
 114 .\}
 115 .PP
 116 The contents of this structure are not manipulated directly but they are controlled through the
 117 \fBlwres_gabn\fR(3)
 118 functions\&.
 119 .PP
 120 The lightweight resolver uses
 121 \fBlwres_getaddrsbyname()\fR
 122 to perform forward lookups\&. Hostname
 123 \fIname\fR
 124 is looked up using the resolver context
 125 \fIctx\fR
 126 for memory allocation\&.
 127 \fIaddrtypes\fR
 128 is a bitmask indicating which type of addresses are to be looked up\&. Current values for this bitmask are
 129 \fBLWRES_ADDRTYPE_V4\fR
 130 for IPv4 addresses and
 131 \fBLWRES_ADDRTYPE_V6\fR
 132 for IPv6 addresses\&. Results of the lookup are returned in
 133 \fI*structp\fR\&.
 134 .PP
 135 \fBlwres_getnamebyaddr()\fR
 136 performs reverse lookups\&. Resolver context
 137 \fIctx\fR
 138 is used for memory allocation\&. The address type is indicated by
 139 \fIaddrtype\fR:
 140 \fBLWRES_ADDRTYPE_V4\fR
 141 or
 142 \fBLWRES_ADDRTYPE_V6\fR\&. The address to be looked up is given by
 143 \fIaddr\fR
 144 and its length is
 145 \fIaddrlen\fR
 146 bytes\&. The result of the function call is made available through
 147 \fI*structp\fR\&.
 148 .SH "RETURN VALUES"
 149 .PP
 150 Successful calls to
 151 \fBlwres_string_parse()\fR
 152 and
 153 \fBlwres_addr_parse()\fR
 154 return
 155 \fBLWRES_R_SUCCESS\&.\fR
 156 Both functions return
 157 \fBLWRES_R_FAILURE\fR
 158 if the buffer is corrupt or
 159 \fBLWRES_R_UNEXPECTEDEND\fR
 160 if the buffer has less space than expected for the components of the encoded string or address\&.
 161 .PP
 162 \fBlwres_getaddrsbyname()\fR
 163 returns
 164 \fBLWRES_R_SUCCESS\fR
 165 on success and it returns
 166 \fBLWRES_R_NOTFOUND\fR
 167 if the hostname
 168 \fIname\fR
 169 could not be found\&.
 170 .PP
 171 \fBLWRES_R_SUCCESS\fR
 172 is returned by a successful call to
 173 \fBlwres_getnamebyaddr()\fR\&.
 174 .PP
 175 Both
 176 \fBlwres_getaddrsbyname()\fR
 177 and
 178 \fBlwres_getnamebyaddr()\fR
 179 return
 180 \fBLWRES_R_NOMEMORY\fR
 181 when memory allocation requests fail and
 182 \fBLWRES_R_UNEXPECTEDEND\fR
 183 if the buffers used for sending queries and receiving replies are too small\&.
 184 .SH "SEE ALSO"
 185 .PP
 186 \fBlwres_buffer\fR(3),
 187 \fBlwres_gabn\fR(3)\&.
 188 .SH "AUTHOR"
 189 .PP
 190 \fBInternet Systems Consortium, Inc\&.\fR
 191 .SH "COPYRIGHT"
 192 .br
 193 Copyright \(co 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
 194 .br
 195 Copyright \(co 2000, 2001 Internet Software Consortium.
 196 .br