207 lines
5.3 KiB
Groff
207 lines
5.3 KiB
Groff
.\" 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 INTERNET SOFTWARE CONSORTIUM
|
|
.\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
|
|
.\" INTERNET SOFTWARE CONSORTIUM 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 1.11 2001/06/08 19:33:00 gson 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.
|
|
\fBlwres_string_parse()\fR
|
|
has an assertion check that
|
|
\fIb\fR
|
|
is not
|
|
\fBNULL\fR.
|
|
.PP
|
|
\fBlwres_addr_parse()\fR
|
|
extracts an address from the buffer
|
|
\fIb\fR.
|
|
It checks that
|
|
\fIaddr\fR
|
|
is not null.
|
|
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.
|
|
\fBlwres_getaddrsbyname()\fR
|
|
checks that its pointer arguments are not
|
|
\fBNULL\fR
|
|
and that
|
|
\fIaddrtypes\fR
|
|
is non-zero.
|
|
.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.
|
|
Like
|
|
\fBlwres_getaddrsbyname()\fR,
|
|
\fBlwres_getnamebyaddr()\fR
|
|
uses assertion checking to ensure its pointer arguments are not
|
|
\fBNULL\fR
|
|
and
|
|
\fIaddrtype\fR
|
|
is not zero.
|
|
\fBlwres_getaddrsbyname()\fR
|
|
also checks that
|
|
\fIaddrlen\fR
|
|
is non-zero.
|
|
.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).
|