lwres_gnba(3) BIND9 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).
AUTHOR
Internet Systems Consortium, Inc.
COPYRIGHT
Copyright (C) 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium,
Inc. ("ISC")
Copyright (C) 2000, 2001 Internet Software Consortium.
ISC 2007-06-18 lwres_gnba(3)
bind 9.10.4 - Generated Fri Apr 29 20:44:00 CDT 2016