1.\" Copyright (c) 2014, Kevin Lo. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd April 7, 2014 28.Dt UDPLITE 4 29.Os 30.Sh NAME 31.Nm udplite 32.Nd Lightweight User Datagram Protocol 33.Sh SYNOPSIS 34.In sys/types.h 35.In sys/socket.h 36.In netinet/udplite.h 37.Ft int 38.Fn socket AF_INET SOCK_DGRAM IPPROTO_UDPLITE 39.Sh DESCRIPTION 40The 41.Tn UDP-Lite 42protocol provides a partial checksum which allows 43corrupted packets to be transmitted to the receiving 44application. 45This has advantages for some types of multimedia 46transport that may be able to make use of slightly 47damaged datagrams, rather than having them discarded 48by lower-layer protocols. 49.Pp 50.Tn UDP-Lite 51supports a number of socket options which can be set with 52.Xr setsockopt 2 53and tested with 54.Xr getsockopt 2 : 55.Bl -tag -width ".Dv UDPLITE_SEND_CSCOV" 56.It Dv UDPLITE_SEND_CSCOV 57This option sets the sender checksum coverage. 58A value of zero indicates that the entire packet 59is covered by the checksum. 60A value of 1 to 7 must be discarded by the receiver. 61.It Dv UDPLITE_RECV_CSCOV 62This option is the receiver-side analogue. 63It is truly optional, i.e. not required to enable traffic 64with partial checksum coverage. 65Its function is that of a traffic filter: 66when enabled, it instructs the kernel to drop 67all packets which have a coverage less than this value. 68.El 69.Sh ERRORS 70A socket operation may fail with one of the following errors returned: 71.Bl -tag -width Er 72.It Bq Er EISCONN 73when trying to establish a connection on a socket which 74already has one, or when trying to send a datagram with the destination 75address specified and the socket is already connected; 76.It Bq Er ENOTCONN 77when trying to send a datagram, but 78no destination address is specified, and the socket has not been 79connected; 80.It Bq Er ENOBUFS 81when the system runs out of memory for 82an internal data structure; 83.It Bq Er EADDRINUSE 84when an attempt 85is made to create a socket with a port which has already been 86allocated; 87.It Bq Er EADDRNOTAVAIL 88when an attempt is made to create a 89socket with a network address for which no network interface 90exists. 91.El 92.Sh SEE ALSO 93.Xr getsockopt 2 , 94.Xr recv 2 , 95.Xr send 2 , 96.Xr socket 2 97