pup.4f

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)pup.4f	8.1	9/11/90
.\" SCCSID: @(#)pup.4f	8.1	9/11/90
.TH pup 4f VAX "" Unsupported
.SH Name
pup \- Xerox PUP-I protocol family
.SH Syntax
.B #include <sys/types.h>
.br
.B #include <netpup/pup.h>
.SH Description
.de _d
.if t .ta .6i 2.1i 2.6i
.\" 2.94 went to 2.6, 3.64 to 3.30
.if n .ta .84i 2.6i 3.30i
..
.de _f
.if t .ta .5i 1.25i 2.5i
.\" 3.5i went to 3.8i
.if n .ta .7i 1.75i 3.8i
..
The PUP-I protocol family is a collection of protocols
layered atop the PUP Level-0 packet format, and
utilizing the PUP Internet address format.
The PUP family is currently supported only by a raw interface.
.SS Addressing
PUP addresses are composed of network, host, and port
portions.
The include file
.RI < netpup/pup.h >
defines this address as,
.PP
.nf
._f
\f(CWstruct	pupport {
	u_char	pup_net;
	u_char	pup_host;
	u_char	pup_socket[4];
};\fP
.fi
.PP
Sockets bound to the PUP protocol family utilize
the following addressing structure,
.PP
.nf
._f
\f(CWstruct sockaddr_pup {
	short	spup_family;
	short	spup_zero1;
	u_char	spup_net;
	u_char	spup_host;
	u_char	spup_sock[4];
	char	spup_zero2[4];
};\fP
.fi
.SS Headers
The current PUP support provides only raw access to the
3Mb/s Ethernet.  Packets sent through this interface
must have space for the following packet header present at the
front of the message,
.sp 1
.nf
._f
\f(CWstruct pup_header {
	u_short	pup_length;
	u_char	pup_tcontrol;		/* transport control */
	u_char	pup_type;		/* protocol type */
	u_long	pup_id;			/* used by protocols */
	u_char	pup_dnet;		/* destination */
	u_char	pup_dhost;
	u_char	pup_dsock[4];
	u_char	pup_snet;		/* source */
	u_char	pup_shost;
	u_char	pup_ssock[4];
};\fP
.fi
.PP
The sender should fill in the 
.IR pup_tcontrol ,
.IR pup_type ,
and
.IR pup_id
fields.  The remaining fields are filled in by the system.
The system checks the message to insure its size is valid
and, calulates a checksum for the message.  If no checksum
should be calculated, the checksum field (the last 16-bit
word in the message) should be set to PUP_NOCKSUM.
.PP
The
.I pup_tcontrol
field is restricted to be 0 or PUP_TRACE; PUP_TRACE
indicates packet tracing should be performed.  The
.I pup_type
field may not be 0.
.PP
On input, the entire packet, including header, is provided the user.
No checksum validation is performed.
.SH See Also
intro(4n), pup(4p), en(4)