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
I lwres_result_t lwres_gnbarequest_render(lwres_context_t * ctx , lwres_gnbarequest_t * req , lwres_lwpacket_t * pkt , lwres_buffer_t * b );
I lwres_result_t lwres_gnbaresponse_render(lwres_context_t * ctx , lwres_gnbaresponse_t * req , lwres_lwpacket_t * pkt , lwres_buffer_t * b );
I lwres_result_t lwres_gnbarequest_parse(lwres_context_t * ctx , lwres_buffer_t * b , lwres_lwpacket_t * pkt , lwres_gnbarequest_t ** structp );
I lwres_result_t lwres_gnbaresponse_parse(lwres_context_t * ctx , lwres_buffer_t * b , lwres_lwpacket_t * pkt , lwres_gnbaresponse_t ** structp );
I void lwres_gnbaresponse_free(lwres_context_t * ctx , lwres_gnbaresponse_t ** structp );
I 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 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
Copyright 2000, 2001 Internet Software Consortium.
