lwres_gabn.3

bind 9.3结合mysql数据库

.\" Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000, 2001  Internet Software Consortium.
.\"
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.\" $Id: lwres_gabn.3,v 1.13.2.1.8.1 2004/03/06 07:41:42 marka Exp $
.\"
.TH "LWRES_GABN" "3" "Jun 30, 2000" "BIND9" ""
.SH NAME
lwres_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free \- lightweight resolver getaddrbyname message handling
.SH SYNOPSIS
\fB#include <lwres/lwres.h>
.sp
.na
lwres_result_t
lwres_gabnrequest_render(lwres_context_t *ctx, lwres_gabnrequest_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);
.ad
.sp
.na
lwres_result_t
lwres_gabnresponse_render(lwres_context_t *ctx, lwres_gabnresponse_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);
.ad
.sp
.na
lwres_result_t
lwres_gabnrequest_parse(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gabnrequest_t **structp);
.ad
.sp
.na
lwres_result_t
lwres_gabnresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gabnresponse_t **structp);
.ad
.sp
.na
void
lwres_gabnresponse_free(lwres_context_t *ctx, lwres_gabnresponse_t **structp);
.ad
.sp
.na
void
lwres_gabnrequest_free(lwres_context_t *ctx, lwres_gabnrequest_t **structp);
.ad
\fR
.SH "DESCRIPTION"
.PP
These are low-level routines for creating and parsing
lightweight resolver name-to-address lookup request and 
response messages.
.PP
There are four main functions for the getaddrbyname opcode.
One render function converts a getaddrbyname request structure \(em
\fBlwres_gabnrequest_t\fR \(em
to the lighweight resolver's canonical format.
It is complemented by a parse function that converts a packet in this
canonical format to a getaddrbyname request structure.
Another render function converts the getaddrbyname response structure \(em
\fBlwres_gabnresponse_t\fR \(em
to the canonical format.
This is complemented by a parse function which converts a packet in
canonical format to a getaddrbyname response structure.
.PP
These structures are defined in
\fI<lwres/lwres.h>\fR.
They are shown below.
.sp
.nf
#define LWRES_OPCODE_GETADDRSBYNAME     0x00010001U

typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;

typedef struct {
        lwres_uint32_t  flags;
        lwres_uint32_t  addrtypes;
        lwres_uint16_t  namelen;
        char           *name;
} lwres_gabnrequest_t;

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;
.sp
.fi
.PP
\fBlwres_gabnrequest_render()\fR
uses resolver context
\fIctx\fR
to convert getaddrbyname request structure
\fIreq\fR
to canonical format.
The packet header structure
\fIpkt\fR
is initialised and transferred to
buffer
\fIb\fR.
The contents of
\fI*req\fR
are then appended to the buffer in canonical format.
\fBlwres_gabnresponse_render()\fR
performs the same task, except it converts a getaddrbyname response structure
\fBlwres_gabnresponse_t\fR
to the lightweight resolver's canonical format.
.PP
\fBlwres_gabnrequest_parse()\fR
uses context
\fIctx\fR
to convert the contents of packet
\fIpkt\fR
to a
\fBlwres_gabnrequest_t\fR
structure.
Buffer
\fIb\fR
provides space to be used for storing this structure.
When the function succeeds, the resulting
\fBlwres_gabnrequest_t\fR
is made available through
\fI*structp\fR.
\fBlwres_gabnresponse_parse()\fR
offers the same semantics as
\fBlwres_gabnrequest_parse()\fR
except it yields a
\fBlwres_gabnresponse_t\fR
structure.
.PP
\fBlwres_gabnresponse_free()\fR
and
\fBlwres_gabnrequest_free()\fR
release the memory in resolver context
\fIctx\fR
that was allocated to the
\fBlwres_gabnresponse_t\fR
or
\fBlwres_gabnrequest_t\fR
structures referenced via
\fIstructp\fR.
Any memory associated with ancillary buffers and strings for those
structures is also discarded.
.SH "RETURN VALUES"
.PP
The getaddrbyname opcode functions
\fBlwres_gabnrequest_render()\fR, 
\fBlwres_gabnresponse_render()\fR
\fBlwres_gabnrequest_parse()\fR
and
\fBlwres_gabnresponse_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
\fIb\fR
is too small to accommodate the packet header or the
\fBlwres_gabnrequest_t\fR
and
\fBlwres_gabnresponse_t\fR
structures.
\fBlwres_gabnrequest_parse()\fR
and
\fBlwres_gabnresponse_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)