97 lines
3.4 KiB
Groff
97 lines
3.4 KiB
Groff
.\" Copyright (c) 2014, Kevin Lo.
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.\" 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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.\"
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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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.\" $FreeBSD$
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.\"
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.Dd April 7, 2014
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.Dt UDPLITE 4
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.Os
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.Sh NAME
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.Nm udplite
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.Nd Lightweight User Datagram Protocol
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/socket.h
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.In netinet/udplite.h
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.Ft int
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.Fn socket AF_INET SOCK_DGRAM IPPROTO_UDPLITE
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.Sh DESCRIPTION
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The
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.Tn UDP-Lite
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protocol provides a partial checksum which allows
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corrupted packets to be transmitted to the receiving
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application.
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This has advantages for some types of multimedia
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transport that may be able to make use of slightly
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damaged datagrams, rather than having them discarded
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by lower-layer protocols.
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.Pp
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.Tn UDP-Lite
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supports a number of socket options which can be set with
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.Xr setsockopt 2
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and tested with
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.Xr getsockopt 2 :
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.Bl -tag -width ".Dv UDPLITE_SEND_CSCOV"
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.It Dv UDPLITE_SEND_CSCOV
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This option sets the sender checksum coverage.
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A value of zero indicates that the entire packet
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is covered by the checksum.
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A value of 1 to 7 must be discarded by the receiver.
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.It Dv UDPLITE_RECV_CSCOV
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This option is the receiver-side analogue.
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It is truly optional, i.e. not required to enable traffic
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with partial checksum coverage.
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Its function is that of a traffic filter:
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when enabled, it instructs the kernel to drop
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all packets which have a coverage less than this value.
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.El
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.Sh ERRORS
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A socket operation may fail with one of the following errors returned:
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.Bl -tag -width Er
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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, or when trying to send a datagram with the destination
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address specified and the socket is already connected;
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.It Bq Er ENOTCONN
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when trying to send a datagram, but
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no destination address is specified, and the socket has not been
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connected;
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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 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 SEE ALSO
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.Xr getsockopt 2 ,
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.Xr recv 2 ,
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.Xr send 2 ,
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.Xr socket 2
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