lwres_packet(3)

LWRES_PACKET(3)               BIND9               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 application wit the exception of the
         LWRES_LWPACKETFLAG_RESPONSE bit, which is set by the
         library in the lwres_gabn_*() and lwres_gnba_*() calls.

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LWRES_PACKET(3)               BIND9               LWRES_PACKET(3)

     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 application 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 supplied by the application.

     authtype
         defines the packet level authentication that is used.
         Authorisation 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

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LWRES_PACKET(3)               BIND9               LWRES_PACKET(3)

         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 transfers 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 insufficient space to copy data between the buffer
     *b and lightweight resolver packet *pkt both functions
     return LWRES_R_UNEXPECTEDEND.

AUTHOR

     Internet Systems Consortium, Inc.

COPYRIGHT

     Copyright 8c9 2004, 2005, 2007, 2014-2016 Internet Systems
     Consortium, Inc. ("ISC")
     Copyright 8c9 2000, 2001 Internet Software Consortium.

ISC                  Last change: 2007-06-18                    3