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_gabnrequest_t **structp);
lwres_result_t lwres_gabnresponse_parse(lwres_context_t *ctx,
lwres_buffer_t *b,
lwres_lwpacket_t *pkt,
lwres_gabnresponse_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 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 (C) 2004, 2005, 2007 Internet Systems Consortium, Inc.
("ISC")
Copyright (C) 2000, 2001 Internet Software Consortium.