[apple/xnu.git] / bsd / man / man4 / udp.4

.\"	$NetBSD: udp.4,v 1.3 1994/11/30 16:22:41 jtc Exp $
.\"
.\" Copyright (c) 1983, 1991, 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. 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.
.\"
.\"     @(#)udp.4	8.1 (Berkeley) 6/5/93
.\"
.Dd March 18, 2015 
.Dt UDP 4
.Os BSD 4.2
.Sh NAME
.Nm udp
.Nd Internet User Datagram Protocol
.Sh SYNOPSIS
.Fd #include <sys/socket.h>
.Fd #include <netinet/in.h>
.Ft int
.Fn socket AF_INET SOCK_DGRAM 0
.Sh DESCRIPTION
.Tn UDP
is a simple, unreliable datagram protocol which is used
to support the
.Dv SOCK_DGRAM
abstraction for the Internet
protocol family.
.Tn UDP
sockets are connectionless, and are
normally used with the
.Xr sendto
and
.Xr recvfrom
calls, though the
.Xr connect 2
or
.Xr connectx 2
call may also be used to fix the destination for future
packets (in which case the 
.Xr recv 2
or
.Xr read 2
and 
.Xr send 2
or
.Xr write 2
system calls may be used).
.Pp
.Tn UDP
address formats are identical to those used by
.Tn TCP .
In particular
.Tn UDP
provides a port identifier in addition
to the normal Internet address format.  Note that the
.Tn UDP
port
space is separate from the
.Tn TCP
port space (i.e. a
.Tn UDP
port
may not be
.Dq connected
to a
.Tn TCP
port).  In addition broadcast
packets may be sent (assuming the underlying network supports
this) by using a reserved
.Dq broadcast address ;
this address
is network interface dependent.
.Pp
Options at the
.Tn IP
transport level may be used with
.Tn UDP ;
see
.Xr ip 4 .
.Sh DIAGNOSTICS
A socket operation may fail with one of the following errors returned:
.Bl -tag -width [EADDRNOTAVAIL]
.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 hasn't 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 connect 2 ,
.Xr connectx 2 ,
.Xr getsockopt 2 ,
.Xr recv 2 ,
.Xr send 2 ,
.Xr socket 2 ,
.Xr inet 4 ,
.Xr intro 4 ,
.Xr ip 4
.Sh HISTORY
The
.Nm
protocol appeared in
.Bx 4.2 .
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: udp.4,v 1.3 1994/11/30 16:22:41 jtc Exp $
	2	.\"
	3	.\" Copyright (c) 1983, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)udp.4 8.1 (Berkeley) 6/5/93
	35	.\"
3e170ce0	36	.Dd March 18, 2015
9bccf70c A	37	.Dt UDP 4
	38	.Os BSD 4.2
	39	.Sh NAME
	40	.Nm udp
	41	.Nd Internet User Datagram Protocol
	42	.Sh SYNOPSIS
	43	.Fd #include <sys/socket.h>
	44	.Fd #include <netinet/in.h>
	45	.Ft int
	46	.Fn socket AF_INET SOCK_DGRAM 0
	47	.Sh DESCRIPTION
	48	.Tn UDP
	49	is a simple, unreliable datagram protocol which is used
	50	to support the
	51	.Dv SOCK_DGRAM
	52	abstraction for the Internet
	53	protocol family.
	54	.Tn UDP
	55	sockets are connectionless, and are
	56	normally used with the
	57	.Xr sendto
	58	and
	59	.Xr recvfrom
	60	calls, though the
	61	.Xr connect 2
3e170ce0 A	62	or
3e170ce0 A	63	.Xr connectx 2
9bccf70c A	64	call may also be used to fix the destination for future
	65	packets (in which case the
	66	.Xr recv 2
	67	or
	68	.Xr read 2
	69	and
	70	.Xr send 2
	71	or
	72	.Xr write 2
	73	system calls may be used).
	74	.Pp
	75	.Tn UDP
	76	address formats are identical to those used by
	77	.Tn TCP .
	78	In particular
	79	.Tn UDP
	80	provides a port identifier in addition
	81	to the normal Internet address format. Note that the
	82	.Tn UDP
	83	port
	84	space is separate from the
	85	.Tn TCP
	86	port space (i.e. a
	87	.Tn UDP
	88	port
	89	may not be
	90	.Dq connected
	91	to a
	92	.Tn TCP
	93	port). In addition broadcast
	94	packets may be sent (assuming the underlying network supports
	95	this) by using a reserved
	96	.Dq broadcast address ;
	97	this address
	98	is network interface dependent.
	99	.Pp
	100	Options at the
	101	.Tn IP
	102	transport level may be used with
	103	.Tn UDP ;
	104	see
	105	.Xr ip 4 .
	106	.Sh DIAGNOSTICS
	107	A socket operation may fail with one of the following errors returned:
	108	.Bl -tag -width [EADDRNOTAVAIL]
	109	.It Bq Er EISCONN
	110	when trying to establish a connection on a socket which
	111	already has one, or when trying to send a datagram with the destination
	112	address specified and the socket is already connected;
	113	.It Bq Er ENOTCONN
	114	when trying to send a datagram, but
	115	no destination address is specified, and the socket hasn't been
	116	connected;
	117	.It Bq Er ENOBUFS
	118	when the system runs out of memory for
	119	an internal data structure;
	120	.It Bq Er EADDRINUSE
	121	when an attempt
	122	is made to create a socket with a port which has already been
	123	allocated;
	124	.It Bq Er EADDRNOTAVAIL
	125	when an attempt is made to create a
	126	socket with a network address for which no network interface
	127	exists.
128	.El
129	.Sh SEE ALSO
3e170ce0 A	130	.Xr connect 2 ,
3e170ce0 A	131	.Xr connectx 2 ,
9bccf70c A	132	.Xr getsockopt 2 ,
	133	.Xr recv 2 ,
	134	.Xr send 2 ,
	135	.Xr socket 2 ,
9bccf70c	136	.Xr inet 4 ,
2d21ac55	137	.Xr intro 4 ,
9bccf70c A	138	.Xr ip 4
	139	.Sh HISTORY
	140	The
	141	.Nm
	142	protocol appeared in
	143	.Bx 4.2 .