lwres_gnbarequest_render, lwres_gnbaresponse_render, lwres_gnbarequest_parse, lwres_gnbaresponse_parse, lwres_gnbaresponse_free, lwres_gnbarequest_free — lightweight resolver getnamebyaddress message handling
#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); |
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.
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.