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.

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

ISC                               2007-06-18                   LWRES_PACKET(3)