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.\" Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000, 2001 Internet Software Consortium.
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
.\" AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
.\" LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
.\" OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
.\" PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $ISC: lwres_resutil.3,v 1.14.2.1.8.5 2005/10/13 02:33:54 marka Exp $
.\"
.hy 0
.ad l
.\" ** You probably do not want to edit this file directly **
.\" It was generated using the DocBook XSL Stylesheets (version 1.69.1).
.\" Instead of manually editing it, you probably should edit the DocBook XML
.\" source for it and then use the DocBook XSL Stylesheets to regenerate it.
.TH "LWRES_RESUTIL" "3" "Jun 30, 2000" "BIND9" "BIND9"
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
.SH "SYNOPSIS"
.nf
#include <lwres/lwres.h>
.fi
.HP 34
\fBlwres_result_t\ \fBlwres_string_parse\fR\fR\fB(\fR\fBlwres_buffer_t\ *b\fR\fB, \fR\fBchar\ **c\fR\fB, \fR\fBlwres_uint16_t\ *len\fR\fB);\fR
.HP 32
\fBlwres_result_t\ \fBlwres_addr_parse\fR\fR\fB(\fR\fBlwres_buffer_t\ *b\fR\fB, \fR\fBlwres_addr_t\ *addr\fR\fB);\fR
.HP 36
\fBlwres_result_t\ \fBlwres_getaddrsbyname\fR\fR\fB(\fR\fBlwres_context_t\ *ctx\fR\fB, \fR\fBconst\ char\ *name\fR\fB, \fR\fBlwres_uint32_t\ addrtypes\fR\fB, \fR\fBlwres_gabnresponse_t\ **structp\fR\fB);\fR
.HP 35
\fBlwres_result_t\ \fBlwres_getnamebyaddr\fR\fR\fB(\fR\fBlwres_context_t\ *ctx\fR\fB, \fR\fBlwres_uint32_t\ addrtype\fR\fB, \fR\fBlwres_uint16_t\ addrlen\fR\fB, \fR\fBconst\ unsigned\ char\ *addr\fR\fB, \fR\fBlwres_gnbaresponse_t\ **structp\fR\fB);\fR
.SH "DESCRIPTION"
.PP
\fBlwres_string_parse()\fR
retrieves a DNS\-encoded string starting the current pointer of lightweight resolver buffer
\fIb\fR: i.e.
\fBb\->current\fR. When the function returns, the address of the first byte of the encoded string is returned via
\fI*c\fR
and the length of that string is given by
\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
\fBNULL\fR
character.
.PP
\fBlwres_addr_parse()\fR
extracts an address from the buffer
\fIb\fR. The buffer's current pointer
\fBb\->current\fR
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
\fBaddr\->address\fR
and
\fBaddr\->length\fR
indicates the size in bytes of the address that was copied.
\fBb\->current\fR
is advanced to point at the next byte of available data in the buffer following the encoded address.
.PP
\fBlwres_getaddrsbyname()\fR
and
\fBlwres_getnamebyaddr()\fR
use the
\fBlwres_gnbaresponse_t\fR
structure defined below:
.sp
.nf
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
lwres_uint16_t naddrs;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
lwres_addrlist_t addrs;
void *base;
size_t baselen;
} lwres_gabnresponse_t;
.fi
.sp
The contents of this structure are not manipulated directly but they are controlled through the
\fBlwres_gabn\fR(3 )
functions.
.PP
The lightweight resolver uses
\fBlwres_getaddrsbyname()\fR
to perform foward lookups. Hostname
\fIname\fR
is looked up using the resolver context
\fIctx\fR
for memory allocation.
\fIaddrtypes\fR
is a bitmask indicating which type of addresses are to be looked up. Current values for this bitmask are
\fBLWRES_ADDRTYPE_V4\fR
for IPv4 addresses and
\fBLWRES_ADDRTYPE_V6\fR
for IPv6 addresses. Results of the lookup are returned in
\fI*structp\fR.
.PP
\fBlwres_getnamebyaddr()\fR
performs reverse lookups. Resolver context
\fIctx\fR
is used for memory allocation. The address type is indicated by
\fIaddrtype\fR:
\fBLWRES_ADDRTYPE_V4\fR
or
\fBLWRES_ADDRTYPE_V6\fR. The address to be looked up is given by
\fIaddr\fR
and its length is
\fIaddrlen\fR
bytes. The result of the function call is made available through
\fI*structp\fR.
.SH "RETURN VALUES"
.PP
Successful calls to
\fBlwres_string_parse()\fR
and
\fBlwres_addr_parse()\fR
return
\fBLWRES_R_SUCCESS.\fR
Both functions return
\fBLWRES_R_FAILURE\fR
if the buffer is corrupt or
\fBLWRES_R_UNEXPECTEDEND\fR
if the buffer has less space than expected for the components of the encoded string or address.
.PP
\fBlwres_getaddrsbyname()\fR
returns
\fBLWRES_R_SUCCESS\fR
on success and it returns
\fBLWRES_R_NOTFOUND\fR
if the hostname
\fIname\fR
could not be found.
.PP
\fBLWRES_R_SUCCESS\fR
is returned by a successful call to
\fBlwres_getnamebyaddr()\fR.
.PP
Both
\fBlwres_getaddrsbyname()\fR
and
\fBlwres_getnamebyaddr()\fR
return
\fBLWRES_R_NOMEMORY\fR
when memory allocation requests fail and
\fBLWRES_R_UNEXPECTEDEND\fR
if the buffers used for sending queries and receiving replies are too small.
.SH "SEE ALSO"
.PP
\fBlwres_buffer\fR(3),
\fBlwres_gabn\fR(3).
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