194 lines
6.3 KiB
Groff
194 lines
6.3 KiB
Groff
.\" $NetBSD: spp.4,v 1.3 1994/11/30 16:22:33 jtc Exp $
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.\"
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.\" Copyright (c) 1985, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)spp.4 8.2 (Berkeley) 4/19/94
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.\"
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.Dd April 19, 1994
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.Dt SPP 4
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.Os BSD 4.3
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.Sh NAME
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.Nm spp
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.Nd Xerox Sequenced Packet Protocol
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.Sh SYNOPSIS
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.Fd #include <sys/socket.h>
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.Fd #include <netns/ns.h>
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.Fd #include <netns/sp.h>
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.Ft int
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.Fn socket AF_NS SOCK_STREAM 0
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.Ft int
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.Fn socket AF_NS SOCK_SEQPACKET 0
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.Sh DESCRIPTION
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The
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.Tn SPP
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protocol provides reliable, flow-controlled, two-way
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transmission of data. It is a byte-stream protocol used to
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support the
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.Dv SOCK_STREAM
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abstraction.
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.Tn SPP
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uses the standard
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.Tn NS Ns (tm)
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address formats.
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.Pp
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Sockets utilizing the
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.Tn SPP
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protocol are either
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.Dq active
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or
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.Dq passive .
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Active sockets initiate connections to passive
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sockets. By default
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.Tn SPP
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sockets are created active; to create a
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passive socket the
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.Xr listen 2
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system call must be used
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after binding the socket with the
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.Xr bind 2
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system call. Only
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passive sockets may use the
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.Xr accept 2
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call to accept incoming connections. Only active sockets may
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use the
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.Xr connect 2
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call to initiate connections.
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.Pp
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Passive sockets may
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.Dq underspecify
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their location to match
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incoming connection requests from multiple networks. This
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technique, termed
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.Dq wildcard addressing ,
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allows a single
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server to provide service to clients on multiple networks.
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To create a socket which listens on all networks, the
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.Tn NS
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address of all zeroes must be bound.
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The
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.Tn SPP
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port may still be specified
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at this time; if the port is not specified the system will assign one.
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Once a connection has been established the socket's address is
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fixed by the peer entity's location. The address assigned the
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socket is the address associated with the network interface
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through which packets are being transmitted and received. Normally
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this address corresponds to the peer entity's network.
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.Pp
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If the
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.Dv SOCK_SEQPACKET
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socket type is specified,
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each packet received has the actual 12 byte sequenced packet header
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left for the user to inspect:
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.Bd -literal -offset indent
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struct sphdr {
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u_char sp_cc; /* connection control */
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#define SP_EM 0x10 /* end of message */
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u_char sp_dt; /* datastream type */
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u_short sp_sid;
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u_short sp_did;
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u_short sp_seq;
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u_short sp_ack;
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u_short sp_alo;
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};
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.Ed
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.Pp
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This facilitates the implementation of higher level Xerox protocols
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which make use of the data stream type field and the end of message bit.
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Conversely, the user is required to supply a 12 byte header,
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the only part of which inspected is the data stream type and end of message
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fields.
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.Pp
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For either socket type,
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packets received with the Attention bit sent are interpreted as
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out of band data. Data sent with
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.Dq send(..., ..., ..., Dv MSG_OOB )
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cause the attention bit to be set.
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.Sh DIAGNOSTICS
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A socket operation may fail with one of the following errors returned:
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.Bl -tag -width [EADDRNOTAVAIL]
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.It Bq Er EISCONN
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when trying to establish a connection on a socket which
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already has one;
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.It Bq Er ENOBUFS
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when the system runs out of memory for
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an internal data structure;
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.It Bq Er ETIMEDOUT
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when a connection was dropped
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due to excessive retransmissions;
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.It Bq Er ECONNRESET
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when the remote peer
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forces the connection to be closed;
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.It Bq Er ECONNREFUSED
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when the remote
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peer actively refuses connection establishment (usually because
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no process is listening to the port);
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.It Bq Er EADDRINUSE
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when an attempt
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is made to create a socket with a port which has already been
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allocated;
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.It Bq Er EADDRNOTAVAIL
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when an attempt is made to create a
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socket with a network address for which no network interface
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exists.
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.El
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.Sh SOCKET OPTIONS
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.Bl -tag -width SO_DEFAULT_HEADERS
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.It Dv SO_DEFAULT_HEADERS
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when set, this determines the data stream type and whether
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the end of message bit is to be set on every ensuing packet.
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.It Dv SO_MTU
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This specifies the maximum amount of user data in a single packet.
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The default is 576 bytes - sizeof(struct spidp). This quantity
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affects windowing \- increasing it without increasing the amount
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of buffering in the socket will lower the number of unread packets
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accepted. Anything larger than the default will not be forwarded
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by a bona fide
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.Tn XEROX
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product internetwork router.
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The data argument for the setsockopt call must be
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an unsigned short.
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.El
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.Sh SEE ALSO
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.Xr intro 4 ,
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.Xr ns 4
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.Sh HISTORY
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The
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.Nm
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protocol appeared in
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.Bx 4.3 .
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.Sh BUGS
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There should be some way to reflect record boundaries in
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a stream.
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For stream mode, there should be an option to get the data stream type of
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the record the user process is about to receive.
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