lwres_resutil.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.
.\"
.\" 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.
.\"
.\" $Id: lwres_resutil.3,v 1.14.2.1.8.1 2004/03/06 07:41:44 marka Exp $
.\"
.TH "LWRES_RESUTIL" "3" "Jun 30, 2000" "BIND9" ""
.SH NAME
lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
.SH SYNOPSIS
\fB#include <lwres/lwres.h>
.sp
.na
lwres_result_t
lwres_string_parse(lwres_buffer_t *b, char **c, lwres_uint16_t *len);
.ad
.sp
.na
lwres_result_t
lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr);
.ad
.sp
.na
lwres_result_t
lwres_getaddrsbyname(lwres_context_t *ctx, const char *name, lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);
.ad
.sp
.na
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);
.ad
\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. b->current.
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
b->current 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
addr->address and
addr->length indicates the size in bytes of
the address that was copied. b->current 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;
.sp
.fi
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
LWRES_R_SUCCESS.
Both functions return
LWRES_R_FAILURE
if the buffer is corrupt or
LWRES_R_UNEXPECTEDEND
if the buffer has less space than expected for the components of the
encoded string or address.
.PP
\fBlwres_getaddrsbyname()\fR
returns
LWRES_R_SUCCESS
on success and it returns
LWRES_R_NOTFOUND
if the hostname
\fIname\fR
could not be found.
.PP
LWRES_R_SUCCESS
is returned by a successful call to
\fBlwres_getnamebyaddr()\fR.
.PP
Both
\fBlwres_getaddrsbyname()\fR
and
\fBlwres_getnamebyaddr()\fR
return
LWRES_R_NOMEMORY
when memory allocation requests fail and
LWRES_R_UNEXPECTEDEND
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).