LWRES_GABN(3)                 BIND9                 LWRES_GABN(3)



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_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 . 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 )



BIND9                      Jun 30, 2000             LWRES_GABN(3)