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.

       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.

COPYRIGHT

       Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC")
       Copyright (C) 2000, 2001 Internet Software Consortium.

BIND9								   Jun 30, 2000 						   LWRES_PACKET(3)