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
5.9 KiB
Groff
173 lines
5.9 KiB
Groff
.\" $NetBSD: lwres_context.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, 2003 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_context
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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_CONTEXT" "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_context_create, lwres_context_destroy, lwres_context_nextserial, lwres_context_initserial, lwres_context_freemem, lwres_context_allocmem, lwres_context_sendrecv \- lightweight resolver context management
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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 36
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.BI "lwres_result_t lwres_context_create(lwres_context_t\ **" "contextp" ", void\ *" "arg" ", lwres_malloc_t\ " "malloc_function" ", lwres_free_t\ " "free_function" ");"
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.HP 37
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.BI "lwres_result_t lwres_context_destroy(lwres_context_t\ **" "contextp" ");"
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.HP 30
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.BI "void lwres_context_initserial(lwres_context_t\ *" "ctx" ", lwres_uint32_t\ " "serial" ");"
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.HP 40
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.BI "lwres_uint32_t lwres_context_nextserial(lwres_context_t\ *" "ctx" ");"
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.HP 27
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.BI "void lwres_context_freemem(lwres_context_t\ *" "ctx" ", void\ *" "mem" ", size_t\ " "len" ");"
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.HP 28
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.BI "void lwres_context_allocmem(lwres_context_t\ *" "ctx" ", size_t\ " "len" ");"
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.HP 30
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.BI "void * lwres_context_sendrecv(lwres_context_t\ *" "ctx" ", void\ *" "sendbase" ", int\ " "sendlen" ", void\ *" "recvbase" ", int\ " "recvlen" ", int\ *" "recvd_len" ");"
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.SH "DESCRIPTION"
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.PP
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\fBlwres_context_create()\fR
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creates a
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\fBlwres_context_t\fR
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structure for use in lightweight resolver operations. It holds a socket and other data needed for communicating with a resolver daemon. The new
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\fBlwres_context_t\fR
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is returned through
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\fIcontextp\fR, a pointer to a
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\fBlwres_context_t\fR
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pointer. This
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\fBlwres_context_t\fR
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pointer must initially be NULL, and is modified to point to the newly created
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\fBlwres_context_t\fR.
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.PP
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When the lightweight resolver needs to perform dynamic memory allocation, it will call
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\fImalloc_function\fR
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to allocate memory and
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\fIfree_function\fR
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to free it. If
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\fImalloc_function\fR
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and
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\fIfree_function\fR
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are NULL, memory is allocated using
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\fBmalloc\fR(3). and
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\fBfree\fR(3). It is not permitted to have a NULL
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\fImalloc_function\fR
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and a non\-NULL
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\fIfree_function\fR
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or vice versa.
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\fIarg\fR
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is passed as the first parameter to the memory allocation functions. If
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\fImalloc_function\fR
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and
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\fIfree_function\fR
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are NULL,
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\fIarg\fR
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is unused and should be passed as NULL.
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.PP
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Once memory for the structure has been allocated, it is initialized using
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\fBlwres_conf_init\fR(3)
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and returned via
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\fI*contextp\fR.
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.PP
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\fBlwres_context_destroy()\fR
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destroys a
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\fBlwres_context_t\fR, closing its socket.
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\fIcontextp\fR
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is a pointer to a pointer to the context that is to be destroyed. The pointer will be set to NULL when the context has been destroyed.
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.PP
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The context holds a serial number that is used to identify resolver request packets and associate responses with the corresponding requests. This serial number is controlled using
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\fBlwres_context_initserial()\fR
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and
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\fBlwres_context_nextserial()\fR.
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\fBlwres_context_initserial()\fR
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sets the serial number for context
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\fI*ctx\fR
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to
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\fIserial\fR.
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\fBlwres_context_nextserial()\fR
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increments the serial number and returns the previous value.
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.PP
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Memory for a lightweight resolver context is allocated and freed using
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\fBlwres_context_allocmem()\fR
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and
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\fBlwres_context_freemem()\fR. These use whatever allocations were defined when the context was created with
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\fBlwres_context_create()\fR.
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\fBlwres_context_allocmem()\fR
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allocates
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\fIlen\fR
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bytes of memory and if successful returns a pointer to the allocated storage.
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\fBlwres_context_freemem()\fR
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frees
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\fIlen\fR
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bytes of space starting at location
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\fImem\fR.
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.PP
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\fBlwres_context_sendrecv()\fR
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performs I/O for the context
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\fIctx\fR. Data are read and written from the context's socket. It writes data from
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\fIsendbase\fR
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\(em typically a lightweight resolver query packet \(em and waits for a reply which is copied to the receive buffer at
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\fIrecvbase\fR. The number of bytes that were written to this receive buffer is returned in
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\fI*recvd_len\fR.
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.SH "RETURN VALUES"
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.PP
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\fBlwres_context_create()\fR
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returns
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\fBLWRES_R_NOMEMORY\fR
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if memory for the
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\fBstruct lwres_context\fR
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could not be allocated,
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\fBLWRES_R_SUCCESS\fR
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otherwise.
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.PP
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Successful calls to the memory allocator
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\fBlwres_context_allocmem()\fR
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return a pointer to the start of the allocated space. It returns NULL if memory could not be allocated.
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.PP
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\fBLWRES_R_SUCCESS\fR
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is returned when
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\fBlwres_context_sendrecv()\fR
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completes successfully.
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\fBLWRES_R_IOERROR\fR
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is returned if an I/O error occurs and
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\fBLWRES_R_TIMEOUT\fR
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is returned if
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\fBlwres_context_sendrecv()\fR
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times out waiting for a response.
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.SH "SEE ALSO"
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.PP
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\fBlwres_conf_init\fR(3),
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\fBmalloc\fR(3),
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\fBfree\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, 2003 Internet Software Consortium.
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.br
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