ns.4

早期freebsd实现

.\" Copyright (c) 1985, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)ns.4	8.2 (Berkeley) 11/30/93
.\"
.Dd November 30, 1993
.Dt NS 4
.Os BSD 4.3
.Sh NAME
.Nm ns
.Nd Xerox Network Systems(tm) protocol family
.Sh SYNOPSIS
.Nm options NS
.Nm options NSIP
.Nm pseudo-device ns
.Sh DESCRIPTION
The
.Tn NS
protocol family is a collection of protocols
layered atop the
.Em Internet  Datagram  Protocol
.Pq Tn IDP
transport layer, and using the Xerox 
.Tn NS
address formats.
The
.Tn NS
family provides protocol support for the
.Dv SOCK_STREAM , SOCK_DGRAM , SOCK_SEQPACKET ,
and
.Dv SOCK_RAW
socket types; the
.Dv SOCK_RAW
interface is a debugging tool, allowing you to trace all packets
entering, (or with toggling kernel variable, additionally leaving) the local
host.
.Sh ADDRESSING
.Tn NS
addresses are 12 byte quantities, consisting of a 
4 byte Network number, a 6 byte Host number and a 2 byte port number,
all stored in network standard format.
(on the
.Tn VAX
these are word and byte reversed; on the
.Tn SUN 
they are not
reversed).  The include file
.Aq Pa netns/ns.h
defines the
.Tn NS
address as a structure containing unions (for quicker
comparisons).
.Pp
Sockets in the Internet protocol family use the following
addressing structure:
.Bd -literal -offset indent
struct sockaddr_ns {
	short		sns_family;
	struct ns_addr	sns_addr;
	char		sns_zero[2];
};
.Ed
.Pp
where an
.Ar ns_addr
is composed as follows:
.Bd -literal -offset indent
union ns_host {
	u_char		c_host[6];
	u_short		s_host[3];
};

union ns_net {
	u_char		c_net[4];
	u_short		s_net[2];
};

struct ns_addr {
	union ns_net	x_net;
	union ns_host	x_host;
	u_short	x_port;
};
.Ed
.Pp
Sockets may be created with an address of all zeroes to effect
.Dq wildcard
matching on incoming messages.
The local port address specified in a
.Xr bind 2
call is restricted to be greater than
.Dv NSPORT_RESERVED
(=3000, in
.Aq Pa netns/ns.h )
unless the creating process is running
as the super-user, providing a space of protected port numbers.
.Sh PROTOCOLS
The
.Tn NS
protocol family supported by the operating system
is comprised of
the Internet Datagram Protocol
.Pq Tn IDP
.Xr idp 4 ,
Error Protocol (available through
.Tn IDP ) ,
and
Sequenced Packet Protocol
.Pq Tn SPP
.Xr spp 4 .
.Pp
.Tn SPP
is used to support the
.Dv SOCK_STREAM
and
.Dv SOCK_SEQPACKET
abstraction,
while
.Tn IDP
is used to support the
.Dv SOCK_DGRAM
abstraction.
The Error protocol is responded to by the kernel
to handle and report errors in protocol processing;
it is, however,
only accessible to user programs through heroic actions.
.Sh SEE ALSO
.Xr intro 3 ,
.Xr byteorder 3 ,
.Xr gethostbyname 3 ,
.Xr getnetent 3 ,
.Xr getprotoent 3 ,
.Xr getservent 3 ,
.Xr ns 3 ,
.Xr intro 4 ,
.Xr spp 4 ,
.Xr idp 4 ,
.Xr nsip 4
.Rs
.%T "Internet Transport Protocols"
.%R Xerox Corporation document XSIS
.%N 028112
.Re
.Rs
.%T "An Advanced 4.3 BSD Interprocess Communication Tutorial"
.Re
.Sh HISTORY
The
.Nm
protocol family
appeared in
.Bx 4.3 .