00b67f09dd
Also known as ISC bind. This import adds utilities such as host(1), dig(1), and nslookup(1), as well as many other tools and libraries. Change-Id: I035ca46e64f1965d57019e773f4ff0ef035e4aa3
173 lines
5.6 KiB
Groff
173 lines
5.6 KiB
Groff
.\" $NetBSD: lwres_resutil.3,v 1.5 2014/12/10 04:38:02 christos Exp $
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.\"
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.\" Copyright (C) 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc. ("ISC")
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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/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
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.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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.\" AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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.\" LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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.\" OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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.\" PERFORMANCE OF THIS SOFTWARE.
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.\"
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.\" Id
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.\"
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.hy 0
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.ad l
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.\" Title: lwres_resutil
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.\" Author:
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.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
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.\" Date: June 18, 2007
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.\" Manual: BIND9
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.\" Source: BIND9
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.\"
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.TH "LWRES_RESUTIL" "3" "June 18, 2007" "BIND9" "BIND9"
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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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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.nf
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#include <lwres/lwres.h>
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.fi
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.HP 34
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.BI "lwres_result_t lwres_string_parse(lwres_buffer_t\ *" "b" ", char\ **" "c" ", lwres_uint16_t\ *" "len" ");"
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.HP 32
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.BI "lwres_result_t lwres_addr_parse(lwres_buffer_t\ *" "b" ", lwres_addr_t\ *" "addr" ");"
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.HP 36
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.BI "lwres_result_t lwres_getaddrsbyname(lwres_context_t\ *" "ctx" ", const\ char\ *" "name" ", lwres_uint32_t\ " "addrtypes" ", lwres_gabnresponse_t\ **" "structp" ");"
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.HP 35
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.BI "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" ");"
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.SH "DESCRIPTION"
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.PP
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\fBlwres_string_parse()\fR
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retrieves a DNS\-encoded string starting the current pointer of lightweight resolver buffer
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\fIb\fR: i.e.
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\fBb\->current\fR. When the function returns, the address of the first byte of the encoded string is returned via
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\fI*c\fR
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and the length of that string is given by
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\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
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\fBNULL\fR
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character.
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.PP
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\fBlwres_addr_parse()\fR
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extracts an address from the buffer
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\fIb\fR. The buffer's current pointer
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\fBb\->current\fR
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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
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\fBaddr\->address\fR
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and
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\fBaddr\->length\fR
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indicates the size in bytes of the address that was copied.
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\fBb\->current\fR
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is advanced to point at the next byte of available data in the buffer 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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.PP
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.RS 4
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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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.fi
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.RE
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.PP
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The contents of this structure are not manipulated directly but 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
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to perform forward lookups. Hostname
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\fIname\fR
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is looked up using the resolver context
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\fIctx\fR
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for memory allocation.
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\fIaddrtypes\fR
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is a bitmask indicating which type of addresses are to be looked up. Current values for this bitmask are
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\fBLWRES_ADDRTYPE_V4\fR
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for IPv4 addresses and
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\fBLWRES_ADDRTYPE_V6\fR
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for IPv6 addresses. Results of the lookup are returned in
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\fI*structp\fR.
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.PP
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\fBlwres_getnamebyaddr()\fR
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performs reverse lookups. Resolver context
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\fIctx\fR
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is used for memory allocation. The address type is indicated by
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\fIaddrtype\fR:
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\fBLWRES_ADDRTYPE_V4\fR
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or
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\fBLWRES_ADDRTYPE_V6\fR. The address to be looked up is given by
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\fIaddr\fR
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and its length is
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\fIaddrlen\fR
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bytes. The result of the function call is made available through
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\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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\fBLWRES_R_SUCCESS.\fR
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Both functions return
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\fBLWRES_R_FAILURE\fR
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if the buffer is corrupt or
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\fBLWRES_R_UNEXPECTEDEND\fR
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if the buffer has less space than expected for the components of the 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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\fBLWRES_R_SUCCESS\fR
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on success and it returns
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\fBLWRES_R_NOTFOUND\fR
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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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\fBLWRES_R_SUCCESS\fR
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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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\fBLWRES_R_NOMEMORY\fR
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when memory allocation requests fail and
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\fBLWRES_R_UNEXPECTEDEND\fR
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if the buffers used for sending queries and receiving replies are too 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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.SH "COPYRIGHT"
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Copyright \(co 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc. ("ISC")
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.br
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Copyright \(co 2000, 2001 Internet Software Consortium.
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.br
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