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.\" Copyright (C) 2000, 2001 Internet Software Consortium.
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.TH "LWRES_GNBA" "3" "Jun 30, 2000" "BIND9" ""
.SH NAME
lwres_gnbarequest_render, lwres_gnbaresponse_render, lwres_gnbarequest_parse, lwres_gnbaresponse_parse, lwres_gnbaresponse_free, lwres_gnbarequest_free \- lightweight resolver getnamebyaddress message handling
.SH SYNOPSIS
\fB#include <lwres/lwres.h>
.sp
.na
lwres_result_t
lwres_gnbarequest_render(lwres_context_t *\fIctx\fB, lwres_gnbarequest_t *\fIreq\fB, lwres_lwpacket_t *\fIpkt\fB, lwres_buffer_t *\fIb\fB);
.ad
.sp
.na
lwres_result_t
lwres_gnbaresponse_render(lwres_context_t *ctx, lwres_gnbaresponse_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);
.ad
.sp
.na
lwres_result_t
lwres_gnbarequest_parse(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbarequest_t **structp);
.ad
.sp
.na
lwres_result_t
lwres_gnbaresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbaresponse_t **structp);
.ad
.sp
.na
void
lwres_gnbaresponse_free(lwres_context_t *ctx, lwres_gnbaresponse_t **structp);
.ad
.sp
.na
void
lwres_gnbarequest_free(lwres_context_t *ctx, lwres_gnbarequest_t **structp);
.ad
\fR
.SH "DESCRIPTION"
.PP
These are low-level routines for creating and parsing
lightweight resolver address-to-name lookup request and
response messages.
.PP
There are four main functions for the getnamebyaddr opcode.
One render function converts a getnamebyaddr request structure \(em
\fBlwres_gnbarequest_t\fR \(em
to the lightweight resolver's canonical format.
It is complemented by a parse function that converts a packet in this
canonical format to a getnamebyaddr request structure.
Another render function converts the getnamebyaddr response structure \(em
\fBlwres_gnbaresponse_t\fR
to the canonical format.
This is complemented by a parse function which converts a packet in
canonical format to a getnamebyaddr response structure.
.PP
These structures are defined in
\fIlwres/lwres.h\fR.
They are shown below.
.sp
.nf
#define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U
typedef struct {
lwres_uint32_t flags;
lwres_addr_t addr;
} lwres_gnbarequest_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
void *base;
size_t baselen;
} lwres_gnbaresponse_t;
.sp
.fi
.PP
\fBlwres_gnbarequest_render()\fR
uses resolver context
ctx
to convert getnamebyaddr request structure
req
to canonical format.
The packet header structure
pkt
is initialised and transferred to
buffer
b.
The contents of
*req
are then appended to the buffer in canonical format.
\fBlwres_gnbaresponse_render()\fR
performs the same task, except it converts a getnamebyaddr response structure
\fBlwres_gnbaresponse_t\fR
to the lightweight resolver's canonical format.
.PP
\fBlwres_gnbarequest_parse()\fR
uses context
ctx
to convert the contents of packet
pkt
to a
\fBlwres_gnbarequest_t\fR
structure.
Buffer
b
provides space to be used for storing this structure.
When the function succeeds, the resulting
\fBlwres_gnbarequest_t\fR
is made available through
*structp.
\fBlwres_gnbaresponse_parse()\fR
offers the same semantics as
\fBlwres_gnbarequest_parse()\fR
except it yields a
\fBlwres_gnbaresponse_t\fR
structure.
.PP
\fBlwres_gnbaresponse_free()\fR
and
\fBlwres_gnbarequest_free()\fR
release the memory in resolver context
ctx
that was allocated to the
\fBlwres_gnbaresponse_t\fR
or
\fBlwres_gnbarequest_t\fR
structures referenced via
structp.
Any memory associated with ancillary buffers and strings for those
structures is also discarded.
.SH "RETURN VALUES"
.PP
The getnamebyaddr opcode functions
\fBlwres_gnbarequest_render()\fR,
\fBlwres_gnbaresponse_render()\fR
\fBlwres_gnbarequest_parse()\fR
and
\fBlwres_gnbaresponse_parse()\fR
all return
LWRES_R_SUCCESS
on success.
They return
LWRES_R_NOMEMORY
if memory allocation fails.
LWRES_R_UNEXPECTEDEND
is returned if the available space in the buffer
b
is too small to accommodate the packet header or the
\fBlwres_gnbarequest_t\fR
and
\fBlwres_gnbaresponse_t\fR
structures.
\fBlwres_gnbarequest_parse()\fR
and
\fBlwres_gnbaresponse_parse()\fR
will return
LWRES_R_UNEXPECTEDEND
if the buffer is not empty after decoding the received packet.
These functions will return
LWRES_R_FAILURE
if
\fBpktflags\fR
in the packet header structure
\fBlwres_lwpacket_t\fR
indicate that the packet is not a response to an earlier query.
.SH "SEE ALSO"
.PP
\fBlwres_packet\fR(3).