LWRES_GABN
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
I lwres_result_t lwres_gabnrequest_render(lwres_context_t * ctx , lwres_gabnrequest_t * req , lwres_lwpacket_t * pkt , lwres_buffer_t * b );
I lwres_result_t lwres_gabnresponse_render(lwres_context_t * ctx , lwres_gabnresponse_t * req , lwres_lwpacket_t * pkt , lwres_buffer_t * b );
I lwres_result_t lwres_gabnrequest_parse(lwres_context_t * ctx , lwres_buffer_t * b , lwres_lwpacket_t * pkt , lwres_gabnrequest_t ** structp );
I lwres_result_t lwres_gabnresponse_parse(lwres_context_t * ctx , lwres_buffer_t * b , lwres_lwpacket_t * pkt , lwres_gabnresponse_t ** structp );
I void lwres_gabnresponse_free(lwres_context_t * ctx , lwres_gabnresponse_t ** structp );
I 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 lighweight 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 render 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_gabnresponse_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 structure. 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_gabnresponse_t
structure.
lwres_gabnresponse_free()
and
lwres_gabnrequest_free()
release the memory in resolver context
ctx
that was allocated 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_render(),
lwres_gabnresponse_render()
lwres_gabnrequest_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_gabnrequest_t
and
lwres_gabnresponse_t
structures.
lwres_gabnrequest_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 ALSO
lwres_packet(3)
COPYRIGHT
Copyright 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
Copyright 2000, 2001 Internet Software Consortium.
