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 complemented 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 canonical format. This is complemented by a parse function which converts a packet in canonical format to a
getnamebyaddr 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 canonical 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 structure. 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_gnbaresponse_t structure.

lwres_gnbaresponse_free() and lwres_gnbarequest_free() release the memory in resolver context ctx that was allocated 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_render(), lwres_gnbaresponse_render() lwres_gnbarequest_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 ALSO

lwres_packet(3).

COPYRIGHT

Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc.
("ISC")
Copyright (C) 2000, 2001 Internet Software Consortium.

BIND9 Jun 30, 2000 LWRES_GNBA(3)