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); .SH "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.


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

     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