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lwres_gabn(3)

NAME

       lwres_gabnrequest_render,    lwres_gabnresponse_render,	 lwres_gabnre-
       quest_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_gabnre-
       quest_t	--  to the lighweight resolver's canonical format.  It is com-
       plemented 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		     **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	getad-
       drbyname  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 light-
       weight 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_gabnre-
       quest_parse() except it yields a lwres_gabnresponse_t structure.

       lwres_gabnresponse_free() and lwres_gabnrequest_free() release the mem-
       ory in resolver context ctx that was  allocated	to  the  lwres_gabnre-
       sponse_t or lwres_gabnrequest_t structures referenced via structp.  Any
       memory associated with ancillary buffers and strings for  those	struc-
       tures is also discarded.

RETURN VALUES

       The    getaddrbyname   opcode   functions   lwres_gabnrequest_render(),
       lwres_gabnresponse_render() lwres_gabnrequest_parse() and lwres_gabnre-
       sponse_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 accom-
       modate the packet header or the lwres_gabnrequest_t  and  lwres_gabnre-
       sponse_t   structures.	 lwres_gabnrequest_parse()  and  lwres_gabnre-
       sponse_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 ear-
       lier query.

SEE ALSO

       lwres_packet(3)

BIND9				 Jun 30, 2000			 LWRES_GABN(3)

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