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lwres_packet

LWRES_PACKET(3)                                                LWRES_PACKET(3)



NAME
       lwres_lwpacket_renderheader,  lwres_lwpacket_parseheader  - lightweight
       resolver packet handling functions

SYNOPSIS
       #include <lwres/lwpacket.h>

       lwres_result_t lwres_lwpacket_renderheader(lwres_buffer_t *b,
       lwres_lwpacket_t *pkt);

       lwres_result_t lwres_lwpacket_parseheader(lwres_buffer_t *b,
       lwres_lwpacket_t *pkt);

DESCRIPTION
       These functions rely on a struct lwres_lwpacket  which  is  defined  in
       lwres/lwpacket.h.

       typedef struct lwres_lwpacket lwres_lwpacket_t;

       struct lwres_lwpacket {
               lwres_uint32_t          length;
               lwres_uint16_t          version;
               lwres_uint16_t          pktflags;
               lwres_uint32_t          serial;
               lwres_uint32_t          opcode;
               lwres_uint32_t          result;
               lwres_uint32_t          recvlength;
               lwres_uint16_t          authtype;
               lwres_uint16_t          authlength;
       };


       The elements of this structure are:

       length the  overall  packet length, including the entire packet header.
              This field is filled in by the lwres_gabn_*() and lwres_gnba_*()
              calls.

       version
              the   header   format.  There  is  currently  only  one  format,
              LWRES_LWPACKETVERSION_0.   This  field  is  filled  in  by   the
              lwres_gabn_*() and lwres_gnba_*() calls.

       pktflags
              library-defined  flags for this packet: for instance whether the
              packet is a request or a reply. Flag values can be set, but  not
              defined  by the caller.  This field is filled in by the applica-
              tion wit the exception of the  LWRES_LWPACKETFLAG_RESPONSE  bit,
              which   is   set  by  the  library  in  the  lwres_gabn_*()  and
              lwres_gnba_*() calls.

       serial is set by the requestor and is returned in all replies.  If  two
              or more packets from the same source have the same serial number
              and are from the same source, they are assumed to be  duplicates
              and  the  latter ones may be dropped.  This field must be set by
              the application.

       opcode indicates  the  operation.   Opcodes  between   0x00000000   and
              0x03ffffff  are  reserved  for  use  by the lightweight resolver
              library. Opcodes between 0x04000000 and 0xffffffff are  applica-
              tion defined.  This field is filled in by the lwres_gabn_*() and
              lwres_gnba_*() calls.

       result is only valid  for  replies.   Results  between  0x04000000  and
              0xffffffff  are application defined.  Results between 0x00000000
              and 0x03ffffff are reserved for  library  use.   This  field  is
              filled in by the lwres_gabn_*() and lwres_gnba_*() calls.

       recvlength
              is  the  maximum  buffer  size  that  the receiver can handle on
              requests and the size of the buffer needed to satisfy a  request
              when  the  buffer  is too large for replies.  This field is sup-
              plied by the application.

       authtype
              defines the packet level authentication that is used.   Authori-
              sation  types  between 0x1000 and 0xffff are application defined
              and types between 0x0000 and 0x0fff  are  reserved  for  library
              use.  Currently these are not used and must be zero.

       authlen
              gives  the  length  of  the  authentication  data.  Since packet
              authentication is currently not used, this must be zero.

       The following opcodes are currently defined:

       NOOP   Success is always returned and the packet contents  are  echoed.
              The lwres_noop_*() functions should be used for this type.

       GETADDRSBYNAME
              returns   all   known   addresses   for   a   given  name.   The
              lwres_gabn_*() functions should be used for this type.

       GETNAMEBYADDR
              return the hostname for the given address.   The  lwres_gnba_*()
              functions should be used for this type.

       lwres_lwpacket_renderheader()  transfers  the  contents  of lightweight
       resolver packet structure lwres_lwpacket_t *pkt in network  byte  order
       to the lightweight resolver buffer, *b.

       lwres_lwpacket_parseheader() performs the converse operation. It trans-
       fers data in network byte order from buffer *b to resolver packet *pkt.
       The contents of the buffer b should correspond to a lwres_lwpacket_t.

RETURN VALUES
       Successful      calls      to     lwres_lwpacket_renderheader()     and
       lwres_lwpacket_parseheader() return LWRES_R_SUCCESS. If there is insuf-
       ficient  space  to  copy  data  between  the  buffer *b and lightweight
       resolver packet *pkt both functions return LWRES_R_UNEXPECTEDEND.



BIND9                            Jun 30, 2000                  LWRES_PACKET(3)