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 for-
mat, 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 opera-
tion. 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 func-
tions return LWRES_R_UNEXPECTEDEND.
BIND9 Jun 30, 2000 LWRES_PACKET(3)
