freebsd-nq/share/man/man4/udplite.4

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.Dd October 1, 2014
.Dt UDPLITE 4
.Os
.Sh NAME
.Nm udplite
.Nd Lightweight User Datagram Protocol
.Sh SYNOPSIS
.In sys/types.h
.In sys/socket.h
.In netinet/udplite.h
.Ft int
.Fn socket AF_INET SOCK_DGRAM IPPROTO_UDPLITE
.Sh DESCRIPTION
The
.Tn UDP-Lite
protocol provides a partial checksum which allows
corrupted packets to be transmitted to the receiving
application.
This has advantages for some types of multimedia
transport that may be able to make use of slightly
damaged datagrams, rather than having them discarded
by lower-layer protocols.
.Pp
.Tn UDP-Lite
supports a number of socket options which can be set with
.Xr setsockopt 2
and tested with
.Xr getsockopt 2 :
.Bl -tag -width ".Dv UDPLITE_SEND_CSCOV"
.It Dv UDPLITE_SEND_CSCOV
This option sets the sender checksum coverage.
A value of zero indicates that all sent packets will have
full checksum coverage.
A value of 8 to 65535 limits the checksum coverage of all sent packets
to the value given.
.It Dv UDPLITE_RECV_CSCOV
This option is the receiver-side analogue.
A value of zero instructs the kernel to drop all received packets
not having full checksum coverage.
A value of 8 to 65535 instructs the kernel to drop all received
packets with a partial checksum coverage smaller than the value specified.
.El
.Sh ERRORS
A socket operation may fail with one of the following errors returned:
.Bl -tag -width Er
.It Bq Er EISCONN
when trying to establish a connection on a socket which
already has one, or when trying to send a datagram with the destination
address specified and the socket is already connected;
.It Bq Er ENOTCONN
when trying to send a datagram, but
no destination address is specified, and the socket has not been
connected;
.It Bq Er ENOBUFS
when the system runs out of memory for
an internal data structure;
.It Bq Er EADDRINUSE
when an attempt
is made to create a socket with a port which has already been
allocated;
.It Bq Er EADDRNOTAVAIL
when an attempt is made to create a
socket with a network address for which no network interface
exists.
.El
.Sh SEE ALSO
.Xr getsockopt 2 ,
.Xr recv 2 ,
.Xr send 2 ,
.Xr socket 2