118094e60b
regents and renumber. This patch skips files in contrib/ and crypto/ Acked by: imp Discussed with: emaste
70 lines
3.3 KiB
Perl
70 lines
3.3 KiB
Perl
.\" Copyright (c) 1983, 1986, 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. 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.
|
|
.\"
|
|
.\" @(#)d.t 8.1 (Berkeley) 6/8/93
|
|
.\"
|
|
.nr H2 1
|
|
.\".ds RH "Out of band data
|
|
.br
|
|
.ne 2i
|
|
.NH
|
|
\s+2Out of band data\s0
|
|
.PP
|
|
Out of band data is a facility peculiar to the stream socket
|
|
abstraction defined. Little agreement appears to exist as
|
|
to what its semantics should be. TCP defines the notion of
|
|
``urgent data'' as in-line, while the NBS protocols [Burruss81]
|
|
and numerous others provide a fully independent logical
|
|
transmission channel along which out of band data is to be
|
|
sent.
|
|
In addition, the amount of the data which may be sent as an out
|
|
of band message varies from protocol to protocol; everything
|
|
from 1 bit to 16 bytes or more.
|
|
.PP
|
|
A stream socket's notion of out of band data has been defined
|
|
as the lowest reasonable common denominator (at least reasonable
|
|
in our minds);
|
|
clearly this is subject to debate. Out of band data is expected
|
|
to be transmitted out of the normal sequencing and flow control
|
|
constraints of the data stream. A minimum of 1 byte of out of
|
|
band data and one outstanding out of band message are expected to
|
|
be supported by the protocol supporting a stream socket.
|
|
It is a protocol's prerogative to support larger-sized messages, or
|
|
more than one outstanding out of band message at a time.
|
|
.PP
|
|
Out of band data is maintained by the protocol and is usually not
|
|
stored in the socket's receive queue.
|
|
A socket-level option, SO_OOBINLINE,
|
|
is provided to force out-of-band data to be placed in the normal
|
|
receive queue when urgent data is received;
|
|
this sometimes amelioriates problems due to loss of data
|
|
when multiple out-of-band
|
|
segments are received before the first has been passed to the user.
|
|
The PRU_SENDOOB and PRU_RCVOOB
|
|
requests to the \fIpr_usrreq\fP routine are used in sending and
|
|
receiving data.
|