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Annotation of 43BSDReno/share/man/man4/udp.4, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1983 The Regents of the University of California.
                      2: .\" All rights reserved.
                      3: .\"
                      4: .\" Redistribution and use in source and binary forms are permitted provided
                      5: .\" that: (1) source distributions retain this entire copyright notice and
                      6: .\" comment, and (2) distributions including binaries display the following
                      7: .\" acknowledgement:  ``This product includes software developed by the
                      8: .\" University of California, Berkeley and its contributors'' in the
                      9: .\" documentation or other materials provided with the distribution and in
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                     11: .\" Neither the name of the University nor the names of its contributors may
                     12: .\" be used to endorse or promote products derived from this software without
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                     14: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
                     15: .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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                     17: .\"
                     18: .\"    @(#)udp.4       6.4 (Berkeley) 6/23/90
                     19: .\"
                     20: .TH UDP 4 "June 23, 1990"
                     21: .UC 5
                     22: .SH NAME
                     23: udp \- Internet User Datagram Protocol
                     24: .SH SYNOPSIS
                     25: .B #include <sys/socket.h>
                     26: .br
                     27: .B #include <netinet/in.h>
                     28: .PP
                     29: .B s = socket(AF_INET, SOCK_DGRAM, 0);
                     30: .SH DESCRIPTION
                     31: UDP is a simple, unreliable datagram protocol which is used
                     32: to support the SOCK_DGRAM abstraction for the Internet
                     33: protocol family.  UDP sockets are connectionless, and are
                     34: normally used with the
                     35: .I sendto 
                     36: and
                     37: .IR recvfrom 
                     38: calls, though the
                     39: .IR connect (2)
                     40: call may also be used to fix the destination for future
                     41: packets (in which case the 
                     42: .IR recv (2)
                     43: or
                     44: .IR read (2)
                     45: and 
                     46: .IR send (2)
                     47: or
                     48: .IR write(2)
                     49: system calls may be used).
                     50: .PP
                     51: UDP address formats are identical to those used by
                     52: TCP. In particular UDP provides a port identifier in addition
                     53: to the normal Internet address format.  Note that the UDP port
                     54: space is separate from the TCP port space (i.e. a UDP port
                     55: may not be \*(lqconnected\*(rq to a TCP port).  In addition broadcast
                     56: packets may be sent (assuming the underlying network supports
                     57: this) by using a reserved \*(lqbroadcast address\*(rq; this address
                     58: is network interface dependent.
                     59: .PP
                     60: Options at the IP transport level may be used with UDP; see
                     61: .IR ip (4).
                     62: .SH DIAGNOSTICS
                     63: A socket operation may fail with one of the following errors returned:
                     64: .TP 15
                     65: [EISCONN]
                     66: when trying to establish a connection on a socket which
                     67: already has one, or when trying to send a datagram with the destination
                     68: address specified and the socket is already connected;
                     69: .TP 15
                     70: [ENOTCONN]
                     71: when trying to send a datagram, but
                     72: no destination address is specified, and the socket hasn't been
                     73: connected;
                     74: .TP 15
                     75: [ENOBUFS]
                     76: when the system runs out of memory for
                     77: an internal data structure;
                     78: .TP 15
                     79: [EADDRINUSE]
                     80: when an attempt
                     81: is made to create a socket with a port which has already been
                     82: allocated;
                     83: .TP 15
                     84: [EADDRNOTAVAIL]
                     85: when an attempt is made to create a 
                     86: socket with a network address for which no network interface
                     87: exists.
                     88: .SH SEE ALSO
                     89: getsockopt(2), recv(2), send(2), socket(2), intro(4), inet(4), ip(4)

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