#include <lwres/lwres.h>
lwres_result_t
lwres_context_create(lwres_context_t **contextp, void *arg, lwres_malloc_t malloc_function, lwres_free_t free_function);
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, int *recvd_len);
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.