.\" .\" 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).