lwres_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free — lightweight resolver getaddrbyname message handling
#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); |
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 lightweight 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 {
uint32_t flags;
uint32_t addrtypes;
uint16_t namelen;
char *name;
} lwres_gabnrequest_t;
typedef struct {
uint32_t flags;
uint16_t naliases;
uint16_t naddrs;
char *realname;
char **aliases;
uint16_t realnamelen;
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.
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.