153 lines
4.8 KiB
Groff
153 lines
4.8 KiB
Groff
.\"
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.\" Copyright (C) 2000, 2001 Internet Software Consortium.
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
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.\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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.\" INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
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.\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.TH "LWRES_RESUTIL" "3" "Jun 30, 2000" "BIND9" ""
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.SH NAME
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lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr \- lightweight resolver utility functions
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.SH SYNOPSIS
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\fB#include <lwres/lwres.h>
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.sp
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.na
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lwres_result_t
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lwres_string_parse(lwres_buffer_t *b, char **c, lwres_uint16_t *len);
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.ad
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.sp
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.na
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lwres_result_t
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lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr);
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.ad
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.sp
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.na
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lwres_result_t
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lwres_getaddrsbyname(lwres_context_t *ctx, const char *name, lwres_uint32_t addrtypes, lwres_gabnresponse_t **structp);
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.ad
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.sp
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.na
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lwres_result_t
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lwres_getnamebyaddr(lwres_context_t *ctx, lwres_uint32_t addrtype, lwres_uint16_t addrlen, const unsigned char *addr, lwres_gnbaresponse_t **structp);
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.ad
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\fR
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.SH "DESCRIPTION"
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.PP
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\fBlwres_string_parse()\fR retrieves a DNS-encoded
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string starting the current pointer of lightweight resolver buffer
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\fIb\fR: i.e. b->current.
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When the function returns, the address of the first byte of the
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encoded string is returned via \fI*c\fR and the
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length of that string is given by \fI*len\fR. The
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buffer's current pointer is advanced to point at the character
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following the string length, the encoded string, and the trailing
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\fBNULL\fR character.
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.PP
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\fBlwres_addr_parse()\fR extracts an address from the
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buffer \fIb\fR. The buffer's current pointer
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b->current is presumed to point at an encoded
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address: the address preceded by a 32-bit protocol family identifier
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and a 16-bit length field. The encoded address is copied to
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addr->address and
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addr->length indicates the size in bytes of
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the address that was copied. b->current is
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advanced to point at the next byte of available data in the buffer
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following the encoded address.
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.PP
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\fBlwres_getaddrsbyname()\fR
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and
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\fBlwres_getnamebyaddr()\fR
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use the
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\fBlwres_gnbaresponse_t\fR
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structure defined below:
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.sp
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.nf
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typedef struct {
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lwres_uint32_t flags;
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lwres_uint16_t naliases;
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lwres_uint16_t naddrs;
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char *realname;
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char **aliases;
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lwres_uint16_t realnamelen;
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lwres_uint16_t *aliaslen;
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lwres_addrlist_t addrs;
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void *base;
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size_t baselen;
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} lwres_gabnresponse_t;
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.sp
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.fi
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The contents of this structure are not manipulated directly but
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they are controlled through the
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\fBlwres_gabn\fR(3)
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functions.
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.PP
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The lightweight resolver uses
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\fBlwres_getaddrsbyname()\fR to perform foward lookups.
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Hostname \fIname\fR is looked up using the resolver
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context \fIctx\fR for memory allocation.
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\fIaddrtypes\fR is a bitmask indicating which type of
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addresses are to be looked up. Current values for this bitmask are
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\fBLWRES_ADDRTYPE_V4\fR for IPv4 addresses and
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\fBLWRES_ADDRTYPE_V6\fR for IPv6 addresses. Results of the
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lookup are returned in \fI*structp\fR.
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.PP
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\fBlwres_getnamebyaddr()\fR performs reverse lookups.
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Resolver context \fIctx\fR is used for memory
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allocation. The address type is indicated by
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\fIaddrtype\fR: \fBLWRES_ADDRTYPE_V4\fR or
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\fBLWRES_ADDRTYPE_V6\fR. The address to be looked up is given
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by \fIaddr\fR and its length is
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\fIaddrlen\fR bytes. The result of the function call
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is made available through \fI*structp\fR.
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.SH "RETURN VALUES"
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.PP
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Successful calls to
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\fBlwres_string_parse()\fR
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and
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\fBlwres_addr_parse()\fR
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return
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LWRES_R_SUCCESS.
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Both functions return
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LWRES_R_FAILURE
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if the buffer is corrupt or
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LWRES_R_UNEXPECTEDEND
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if the buffer has less space than expected for the components of the
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encoded string or address.
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.PP
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\fBlwres_getaddrsbyname()\fR
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returns
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LWRES_R_SUCCESS
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on success and it returns
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LWRES_R_NOTFOUND
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if the hostname
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\fIname\fR
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could not be found.
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.PP
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LWRES_R_SUCCESS
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is returned by a successful call to
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\fBlwres_getnamebyaddr()\fR.
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.PP
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Both
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\fBlwres_getaddrsbyname()\fR
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and
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\fBlwres_getnamebyaddr()\fR
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return
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LWRES_R_NOMEMORY
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when memory allocation requests fail and
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LWRES_R_UNEXPECTEDEND
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if the buffers used for sending queries and receiving replies are too
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small.
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.SH "SEE ALSO"
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.PP
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\fBlwres_buffer\fR(3),
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\fBlwres_gabn\fR(3).
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