LWRES_GNBA(3)                 BIND9                 LWRES_GNBA(3)



NAME
       lwres_gnbarequest_render, lwres_gnbaresponse_render,
       lwres_gnbarequest_parse, lwres_gnbaresponse_parse,
       lwres_gnbaresponse_free, lwres_gnbarequest_free -
       lightweight resolver getnamebyaddress message handling

SYNOPSIS
       #include 

       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);

DESCRIPTION
       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.

RETURN VALUES
       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.

SEE ALSO
       lwres_packet(3).



BIND9                      Jun 30, 2000             LWRES_GNBA(3)