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)
