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

1.1       root        1: .\" Copyright (c) 1983 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)udp.4p      6.2 (Berkeley) 5/16/86
                      6: .\"
                      7: .TH UDP 4P "May 16, 1986"
                      8: .UC 5
                      9: .SH NAME
                     10: udp \- Internet User Datagram Protocol
                     11: .SH SYNOPSIS
                     12: .B #include <sys/socket.h>
                     13: .br
                     14: .B #include <netinet/in.h>
                     15: .PP
                     16: .B s = socket(AF_INET, SOCK_DGRAM, 0);
                     17: .SH DESCRIPTION
                     18: UDP is a simple, unreliable datagram protocol which is used
                     19: to support the SOCK_DGRAM abstraction for the Internet
                     20: protocol family.  UDP sockets are connectionless, and are
                     21: normally used with the
                     22: .I sendto 
                     23: and
                     24: .IR recvfrom 
                     25: calls, though the
                     26: .IR connect (2)
                     27: call may also be used to fix the destination for future
                     28: packets (in which case the 
                     29: .IR recv (2)
                     30: or
                     31: .IR read (2)
                     32: and 
                     33: .IR send (2)
                     34: or
                     35: .IR write(2)
                     36: system calls may be used).
                     37: .PP
                     38: UDP address formats are identical to those used by
                     39: TCP. In particular UDP provides a port identifier in addition
                     40: to the normal Internet address format.  Note that the UDP port
                     41: space is separate from the TCP port space (i.e. a UDP port
                     42: may not be \*(lqconnected\*(rq to a TCP port).  In addition broadcast
                     43: packets may be sent (assuming the underlying network supports
                     44: this) by using a reserved \*(lqbroadcast address\*(rq; this address
                     45: is network interface dependent.
                     46: .PP
                     47: Options at the IP transport level may be used with UDP; see
                     48: .IR ip (4P).
                     49: .SH DIAGNOSTICS
                     50: A socket operation may fail with one of the following errors returned:
                     51: .TP 15
                     52: [EISCONN]
                     53: when trying to establish a connection on a socket which
                     54: already has one, or when trying to send a datagram with the destination
                     55: address specified and the socket is already connected;
                     56: .TP 15
                     57: [ENOTCONN]
                     58: when trying to send a datagram, but
                     59: no destination address is specified, and the socket hasn't been
                     60: connected;
                     61: .TP 15
                     62: [ENOBUFS]
                     63: when the system runs out of memory for
                     64: an internal data structure;
                     65: .TP 15
                     66: [EADDRINUSE]
                     67: when an attempt
                     68: is made to create a socket with a port which has already been
                     69: allocated;
                     70: .TP 15
                     71: [EADDRNOTAVAIL]
                     72: when an attempt is made to create a 
                     73: socket with a network address for which no network interface
                     74: exists.
                     75: .SH SEE ALSO
                     76: getsockopt(2), recv(2), send(2), socket(2), intro(4N), inet(4F), ip(4P)

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