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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/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);

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 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 {
                   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)

COPYRIGHT
       Copyright (C) 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc.
       ("ISC")
       Copyright (C) 2000, 2001 Internet Software Consortium.

BIND9                            June 18, 2007                   LWRES_GABN(3)