LWRES_GNBA(3)LWRES_GNBA(3)NAME
lwres_gnbarequest_render, lwres_gnbaresponse_render,
lwres_gnbarequest_parse, lwres_gnbaresponse_parse,
lwres_gnbaresponse_free, lwres_gnbarequest_free -
lightweight resolver getnamebyaddress message handling
SYNOPSIS
#include <lwres/lwres.h>
lwres_result_t lwres_gnbarequest_render(lwres_context_t
*ctx, lwres_gnbarequest_t *req, lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t lwres_gnbaresponse_render(lwres_context_t
*ctx, lwres_gnbaresponse_t *req, lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t lwres_gnbarequest_parse(lwres_context_t
*ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt,
lwres_gnbarequest_t **structp);
lwres_result_t lwres_gnbaresponse_parse(lwres_context_t
*ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt,
lwres_gnbaresponse_t **structp);
void lwres_gnbaresponse_free(lwres_context_t *ctx,
lwres_gnbaresponse_t **structp);
void lwres_gnbarequest_free(lwres_context_t *ctx,
lwres_gnbarequest_t **structp);
DESCRIPTION
These are low-level routines for creating and parsing
lightweight resolver address-to-name lookup request and
response messages.
There are four main functions for the getnamebyaddr
opcode. One render function converts a getnamebyaddr
request structure -- lwres_gnbarequest_t -- to the
lightweight resolver's canonical format. It is comple-
mented by a parse function that converts a packet in this
canonical format to a getnamebyaddr request structure.
Another render function converts the getnamebyaddr
response structure -- lwres_gnbaresponse_t to the canoni-
cal format. This is complemented by a parse function
which converts a packet in canonical format to a getname-
byaddr response structure.
These structures are defined in lwres/lwres.h. They are
shown below.
#define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U
typedef struct {
lwres_uint32_t flags;
lwres_addr_t addr;
} lwres_gnbarequest_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
void *base;
size_t baselen;
} lwres_gnbaresponse_t;
lwres_gnbarequest_render() uses resolver context ctx to
convert getnamebyaddr request structure req to canonical
format. The packet header structure pkt is initialised
and transferred to buffer b. The contents of *req are
then appended to the buffer in canonical format.
lwres_gnbaresponse_render() performs the same task, except
it converts a getnamebyaddr response structure
lwres_gnbaresponse_t to the lightweight resolver's canoni-
cal format.
lwres_gnbarequest_parse() uses context ctx to convert the
contents of packet pkt to a lwres_gnbarequest_t structure.
Buffer b provides space to be used for storing this struc-
ture. When the function succeeds, the resulting
lwres_gnbarequest_t is made available through *structp.
lwres_gnbaresponse_parse() offers the same semantics as
lwres_gnbarequest_parse() except it yields a lwres_gnbare-
sponse_t structure.
lwres_gnbaresponse_free() and lwres_gnbarequest_free()
release the memory in resolver context ctx that was allo-
cated to the lwres_gnbaresponse_t or lwres_gnbarequest_t
structures referenced via structp. Any memory associated
with ancillary buffers and strings for those structures is
also discarded.
RETURN VALUES
The getnamebyaddr opcode functions lwres_gnbarequest_ren-
der(), lwres_gnbaresponse_render() lwres_gnbare-
quest_parse() and lwres_gnbaresponse_parse() all return
LWRES_R_SUCCESS on success. They return LWRES_R_NOMEMORY
if memory allocation fails. LWRES_R_UNEXPECTEDEND is
returned if the available space in the buffer b is too
small to accommodate the packet header or the
lwres_gnbarequest_t and lwres_gnbaresponse_t structures.
lwres_gnbarequest_parse() and lwres_gnbaresponse_parse()
will return LWRES_R_UNEXPECTEDEND if the buffer is not
empty after decoding the received packet. These functions
will return LWRES_R_FAILURE if pktflags in the packet
header structure lwres_lwpacket_t indicate that the packet
is not a response to an earlier query.
SEE ALSOlwres_packet(3).
BIND9 Jun 30, 2000 LWRES_GNBA(3)
