listing for L
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
lwres_result_t lwres_context_create(lwres_context_t **contextp, void *arg,
lwres_result_t lwres_context_destroy(lwres_context_t **contextp);
void lwres_context_initserial(lwres_context_t *ctx, lwres_uint32_t serial);
lwres_uint32_t lwres_context_nextserial(lwres_context_t *ctx);
void lwres_context_freemem(lwres_context_t *ctx, void *mem, size_t len);
void lwres_context_allocmem(lwres_context_t *ctx, size_t len);
void * lwres_context_sendrecv(lwres_context_t *ctx, void *sendbase,
int sendlen, void *recvbase, int recvlen,
lwres_context_create() creates a lwres_context_t structure for use in
lightweight resolver operations. It holds a socket and other data needed
for communicating with a resolver daemon. The new lwres_context_t is
returned through contextp, a pointer to a lwres_context_t pointer. This
lwres_context_t pointer must initially be NULL, and is modified to point to
the newly created lwres_context_t.
When the lightweight resolver needs to perform dynamic memory allocation,
it will call malloc_function to allocate memory and free_function to free
it. If malloc_function and free_function are NULL, memory is allocated
using .Xr malloc 3 and free(3). It is not permitted to have a NULL
malloc_function and a non-NULL free_function or vice versa. arg is passed
as the first parameter to the memory allocation functions. If
malloc_function and free_function are NULL, arg is unused and should be
passed as NULL.
Once memory for the structure has been allocated, it is initialized using
lwres_conf_init(3) and returned via *contextp.
lwres_context_destroy() destroys a lwres_context_t, closing its socket.
contextp 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.
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 lwres_context_initserial() and
lwres_context_nextserial(). lwres_context_initserial() sets the serial
number for context *ctx to serial. lwres_context_nextserial() increments
the serial number and returns the previous value.
Memory for a lightweight resolver context is allocated and freed using
lwres_context_allocmem() and lwres_context_freemem(). These use whatever
allocations were defined when the context was created with
lwres_context_create(). lwres_context_allocmem() allocates len bytes of
memory and if successful returns a pointer to the allocated storage.
lwres_context_freemem() frees len bytes of space starting at location mem.
lwres_context_sendrecv() performs I/O for the context ctx. Data are read
and written from the context's socket. It writes data from sendbase -
typically a lightweight resolver query packet - and waits for a reply which
is copied to the receive buffer at recvbase. The number of bytes that were
written to this receive buffer is returned in *recvd_len.
lwres_context_create() returns LWRES_R_NOMEMORY if memory for the struct
lwres_context could not be allocated, LWRES_R_SUCCESS otherwise.
Successful calls to the memory allocator lwres_context_allocmem() return a
pointer to the start of the allocated space. It returns NULL if memory
could not be allocated.
LWRES_R_SUCCESS is returned when lwres_context_sendrecv() completes
successfully. LWRES_R_IOERROR is returned if an I/O error occurs and
LWRES_R_TIMEOUT is returned if lwres_context_sendrecv() times out waiting
for a response.
lwres_conf_init(3), malloc(3), free(3 ).
Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
listing for L