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)

AUTHOR

       Internet Systems Consortium, Inc.

COPYRIGHT

       Copyright © 2000, 2001, 2004, 2005, 2007, 2014-2016 Internet Systems Consortium, Inc.
       ("ISC")