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.\"
.\" 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.
.\"
.TH "LWRES_CONTEXT" "3" "Jun 30, 2000" "BIND9" ""
.SH NAME
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
.SH SYNOPSIS
\fB#include <lwres/lwres.h>
.sp
.na
lwres_result_t
lwres_context_create(lwres_context_t **contextp, void *arg, lwres_malloc_t malloc_function, lwres_free_t free_function);
.ad
.sp
.na
lwres_result_t
lwres_context_destroy(lwres_context_t **contextp);
.ad
.sp
.na
void
lwres_context_initserial(lwres_context_t *ctx, lwres_uint32_t serial);
.ad
.sp
.na
lwres_uint32_t
lwres_context_nextserial(lwres_context_t *ctx);
.ad
.sp
.na
void
lwres_context_freemem(lwres_context_t *ctx, void *mem, size_t len);
.ad
.sp
.na
void
lwres_context_allocmem(lwres_context_t *ctx, size_t len);
.ad
.sp
.na
void *
lwres_context_sendrecv(lwres_context_t *ctx, void *sendbase, int sendlen, void *recvbase, int recvlen, int *recvd_len);
.ad
\fR
.SH "DESCRIPTION"
.PP
\fBlwres_context_create()\fR
creates a
\fBlwres_context_t\fR
structure for use in lightweight resolver operations.
It holds a socket and other data needed for communicating
with a resolver daemon.
The new
\fBlwres_context_t\fR
is returned throught
\fIcontextp\fR,
a pointer to a
\fBlwres_context_t\fR
pointer. This
\fBlwres_context_t\fR
pointer must initially be NULL, and is modified
to point to the newly created
\fBlwres_context_t\fR.
.PP
When the lightweight resolver needs to perform dynamic memory
allocation, it will call
\fImalloc_function\fR
to allocate memory and
\fIfree_function\fR
to free it. If
\fImalloc_function\fR
and
\fIfree_function\fR
are NULL, memory is allocated using
\&.Xr malloc 3
and
\fBfree\fR(3).
It is not permitted to have a NULL
\fImalloc_function\fR
and a non-NULL
\fIfree_function\fR
or vice versa.
\fIarg\fR
is passed as the first parameter to the memory
allocation functions.
If
\fImalloc_function\fR
and
\fIfree_function\fR
are NULL,
\fIarg\fR
is unused and should be passed as NULL.
.PP
Once memory for the structure has been allocated,
it is initialized using
\fBlwres_conf_init\fR(3)
and returned via
\fI*contextp\fR.
.PP
\fBlwres_context_destroy()\fR
destroys a
\fBlwres_context_t\fR,
closing its socket.
\fIcontextp\fR
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.
.PP
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
\fBlwres_context_initserial()\fR
and
\fBlwres_context_nextserial()\fR.
\fBlwres_context_initserial()\fR
sets the serial number for context
\fI*ctx\fR
to
\fIserial\fR.
\fBlwres_context_nextserial()\fR
increments the serial number and returns the previous value.
.PP
Memory for a lightweight resolver context is allocated and freed using
\fBlwres_context_allocmem()\fR
and
\fBlwres_context_freemem()\fR.
These use whatever allocations were defined when the context was
created with
\fBlwres_context_create()\fR.
\fBlwres_context_allocmem()\fR
allocates
\fIlen\fR
bytes of memory and if successful returns a pointer to the allocated
storage.
\fBlwres_context_freemem()\fR
frees
\fIlen\fR
bytes of space starting at location
\fImem\fR.
.PP
\fBlwres_context_sendrecv()\fR
performs I/O for the context
\fIctx\fR.
Data are read and written from the context's socket.
It writes data from
\fIsendbase\fR
\(em typically a lightweight resolver query packet \(em
and waits for a reply which is copied to the receive buffer at
\fIrecvbase\fR.
The number of bytes that were written to this receive buffer is
returned in
\fI*recvd_len\fR.
.SH "RETURN VALUES"
.PP
\fBlwres_context_create()\fR
returns
LWRES_R_NOMEMORY
if memory for the
\fBstruct lwres_context\fR
could not be allocated,
LWRES_R_SUCCESS
otherwise.
.PP
Successful calls to the memory allocator
\fBlwres_context_allocmem()\fR
return a pointer to the start of the allocated space.
It returns NULL if memory could not be allocated.
.PP
LWRES_R_SUCCESS
is returned when
\fBlwres_context_sendrecv()\fR
completes successfully.
LWRES_R_IOERROR
is returned if an I/O error occurs and
LWRES_R_TIMEOUT
is returned if
\fBlwres_context_sendrecv()\fR
times out waiting for a response.
.SH "SEE ALSO"
.PP
\fBlwres_conf_init\fR(3),
\fBmalloc\fR(3),
\fBfree\fR(3).
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