LWRES_GABN(3)LWRES_GABN(3)NAME
lwres_gabnrequest_render, lwres_gabnresponse_render,
lwres_gabnrequest_parse, lwres_gabnresponse_parse,
lwres_gabnresponse_free, lwres_gabnrequest_free -
lightweight resolver getaddrbyname message handling
SYNOPSIS
#include <lwres/lwres.h>
lwres_result_t lwres_gabnrequest_render(lwres_context_t
*ctx, lwres_gabnrequest_t *req, lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t lwres_gabnresponse_render(lwres_context_t
*ctx, lwres_gabnresponse_t *req, lwres_lwpacket_t *pkt,
lwres_buffer_t *b);
lwres_result_t lwres_gabnrequest_parse(lwres_context_t
*ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gab-
nrequest_t **structp);
lwres_result_t lwres_gabnresponse_parse(lwres_context_t
*ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gab-
nresponse_t **structp);
void lwres_gabnresponse_free(lwres_context_t *ctx,
lwres_gabnresponse_t **structp);
void lwres_gabnrequest_free(lwres_context_t *ctx,
lwres_gabnrequest_t **structp);
DESCRIPTION
These are low-level routines for creating and parsing
lightweight resolver name-to-address lookup request and
response messages.
There are four main functions for the getaddrbyname
opcode. One render function converts a getaddrbyname
request structure -- lwres_gabnrequest_t -- to the ligh-
weight resolver's canonical format. It is complemented by
a parse function that converts a packet in this canonical
format to a getaddrbyname request structure. Another ren-
der function converts the getaddrbyname response structure
-- lwres_gabnresponse_t -- to the canonical format. This
is complemented by a parse function which converts a
packet in canonical format to a getaddrbyname response
structure.
These structures are defined in <lwres/lwres.h>. They are
shown below.
#define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint32_t addrtypes;
lwres_uint16_t namelen;
char *name;
} lwres_gabnrequest_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
lwres_uint16_t naddrs;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
lwres_addrlist_t addrs;
void *base;
size_t baselen;
} lwres_gabnresponse_t;
lwres_gabnrequest_render() uses resolver context ctx to
convert getaddrbyname 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_gabnresponse_render() performs the same task, except
it converts a getaddrbyname response structure lwres_gabn-
response_t to the lightweight resolver's canonical format.
lwres_gabnrequest_parse() uses context ctx to convert the
contents of packet pkt to a lwres_gabnrequest_t structure.
Buffer b provides space to be used for storing this struc-
ture. When the function succeeds, the resulting
lwres_gabnrequest_t is made available through *structp.
lwres_gabnresponse_parse() offers the same semantics as
lwres_gabnrequest_parse() except it yields a lwres_gabnre-
sponse_t structure.
lwres_gabnresponse_free() and lwres_gabnrequest_free()
release the memory in resolver context ctx that was allo-
cated to the lwres_gabnresponse_t or lwres_gabnrequest_t
structures referenced via structp. Any memory associated
with ancillary buffers and strings for those structures is
also discarded.
RETURN VALUES
The getaddrbyname opcode functions lwres_gabnrequest_ren-
der(), lwres_gabnresponse_render() lwres_gabnre-
quest_parse() and lwres_gabnresponse_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_gabn-
request_t and lwres_gabnresponse_t structures. lwres_gab-
nrequest_parse() and lwres_gabnresponse_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_GABN(3)
