contrib/bind-9.3/lib/lwres/man/lwres_resutil.3

   1 .\" Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
   2 .\" Copyright (C) 2000, 2001 Internet Software Consortium.
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  16 .\" $Id: lwres_resutil.3,v 1.14.2.1.8.6 2006/06/29 13:02:31 marka Exp $
  17 .\"
  18 .hy 0
  19 .ad l
  20 .\"     Title: lwres_resutil
  21 .\"    Author:
  22 .\" Generator: DocBook XSL Stylesheets v1.70.1 <http://docbook.sf.net/>
  23 .\"      Date: Jun 30, 2000
  24 .\"    Manual: BIND9
  25 .\"    Source: BIND9
  26 .\"
  27 .TH "LWRES_RESUTIL" "3" "Jun 30, 2000" "BIND9" "BIND9"
  28 .\" disable hyphenation
  29 .nh
  30 .\" disable justification (adjust text to left margin only)
  31 .ad l
  32 .SH "NAME"
  33 lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
  34 .SH "SYNOPSIS"
  35 .nf
  36 #include <lwres/lwres.h>
  37 .fi
  38 .HP 34
  39 .BI "lwres_result_t lwres_string_parse(lwres_buffer_t\ *b, char\ **c, lwres_uint16_t\ *len);"
  40 .HP 32
  41 .BI "lwres_result_t lwres_addr_parse(lwres_buffer_t\ *b, lwres_addr_t\ *addr);"
  42 .HP 36
  43 .BI "lwres_result_t lwres_getaddrsbyname(lwres_context_t\ *ctx, const\ char\ *name, lwres_uint32_t\ addrtypes, lwres_gabnresponse_t\ **structp);"
  44 .HP 35
  45 .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);"
  46 .SH "DESCRIPTION"
  47 .PP
  48 \fBlwres_string_parse()\fR
  49 retrieves a DNS\-encoded string starting the current pointer of lightweight resolver buffer
  50 \fIb\fR: i.e.
  51 \fBb\->current\fR. When the function returns, the address of the first byte of the encoded string is returned via
  52 \fI*c\fR
  53 and the length of that string is given by
  54 \fI*len\fR. The buffer's current pointer is advanced to point at the character following the string length, the encoded string, and the trailing
  55 \fBNULL\fR
  56 character.
  57 .PP
  58 \fBlwres_addr_parse()\fR
  59 extracts an address from the buffer
  60 \fIb\fR. The buffer's current pointer
  61 \fBb\->current\fR
  62 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
  63 \fBaddr\->address\fR
  64 and
  65 \fBaddr\->length\fR
  66 indicates the size in bytes of the address that was copied.
  67 \fBb\->current\fR
  68 is advanced to point at the next byte of available data in the buffer following the encoded address.
  69 .PP
  70 \fBlwres_getaddrsbyname()\fR
  71 and
  72 \fBlwres_getnamebyaddr()\fR
  73 use the
  74 \fBlwres_gnbaresponse_t\fR
  75 structure defined below:
  76 .sp
  77 .RS 3n
  78 .nf
  79 typedef struct {
  80         lwres_uint32_t          flags;
  81         lwres_uint16_t          naliases;
  82         lwres_uint16_t          naddrs;
  83         char                   *realname;
  84         char                  **aliases;
  85         lwres_uint16_t          realnamelen;
  86         lwres_uint16_t         *aliaslen;
  87         lwres_addrlist_t        addrs;
  88         void                   *base;
  89         size_t                  baselen;
  90 } lwres_gabnresponse_t;
  91 .fi
  92 .RE
  93 .sp
  94 The contents of this structure are not manipulated directly but they are controlled through the
  95 \fBlwres_gabn\fR(3 )
  96 functions.
  97 .PP
  98 The lightweight resolver uses
  99 \fBlwres_getaddrsbyname()\fR
 100 to perform foward lookups. Hostname
 101 \fIname\fR
 102 is looked up using the resolver context
 103 \fIctx\fR
 104 for memory allocation.
 105 \fIaddrtypes\fR
 106 is a bitmask indicating which type of addresses are to be looked up. Current values for this bitmask are
 107 \fBLWRES_ADDRTYPE_V4\fR
 108 for IPv4 addresses and
 109 \fBLWRES_ADDRTYPE_V6\fR
 110 for IPv6 addresses. Results of the lookup are returned in
 111 \fI*structp\fR.
 112 .PP
 113 \fBlwres_getnamebyaddr()\fR
 114 performs reverse lookups. Resolver context
 115 \fIctx\fR
 116 is used for memory allocation. The address type is indicated by
 117 \fIaddrtype\fR:
 118 \fBLWRES_ADDRTYPE_V4\fR
 119 or
 120 \fBLWRES_ADDRTYPE_V6\fR. The address to be looked up is given by
 121 \fIaddr\fR
 122 and its length is
 123 \fIaddrlen\fR
 124 bytes. The result of the function call is made available through
 125 \fI*structp\fR.
 126 .SH "RETURN VALUES"
 127 .PP
 128 Successful calls to
 129 \fBlwres_string_parse()\fR
 130 and
 131 \fBlwres_addr_parse()\fR
 132 return
 133 \fBLWRES_R_SUCCESS.\fR
 134 Both functions return
 135 \fBLWRES_R_FAILURE\fR
 136 if the buffer is corrupt or
 137 \fBLWRES_R_UNEXPECTEDEND\fR
 138 if the buffer has less space than expected for the components of the encoded string or address.
 139 .PP
 140 \fBlwres_getaddrsbyname()\fR
 141 returns
 142 \fBLWRES_R_SUCCESS\fR
 143 on success and it returns
 144 \fBLWRES_R_NOTFOUND\fR
 145 if the hostname
 146 \fIname\fR
 147 could not be found.
 148 .PP
 149 \fBLWRES_R_SUCCESS\fR
 150 is returned by a successful call to
 151 \fBlwres_getnamebyaddr()\fR.
 152 .PP
 153 Both
 154 \fBlwres_getaddrsbyname()\fR
 155 and
 156 \fBlwres_getnamebyaddr()\fR
 157 return
 158 \fBLWRES_R_NOMEMORY\fR
 159 when memory allocation requests fail and
 160 \fBLWRES_R_UNEXPECTEDEND\fR
 161 if the buffers used for sending queries and receiving replies are too small.
 162 .SH "SEE ALSO"
 163 .PP
 164 \fBlwres_buffer\fR(3),
 165 \fBlwres_gabn\fR(3).
 166 .SH "COPYRIGHT"
 167 Copyright \(co 2004, 2005 Internet Systems Consortium, Inc. ("ISC")