UDP(7P)								       UDP(7P)

NAME    [Toc]    [Back]

     udp - Internet User Datagram Protocol

SYNOPSIS    [Toc]    [Back]

     #include <sys/socket.h>
     #include <netinet/in.h>

     s = socket(AF_INET, SOCK_DGRAM, 0);

DESCRIPTION    [Toc]    [Back]

     UDP is a simple, unreliable datagram protocol which is used to support
     the SOCK_DGRAM abstraction	for the	Internet protocol family.  UDP sockets
     are connectionless, and are normally used with the	sendto and recvfrom
     calls, though the connect(2) call may also	be used	to fix the destination
     for future	packets	(in which case the recv(2) or rea
 or
     write(2) system calls may be used).

     UDP address formats are identical to those	used by	TCP. In	particular UDP
     provides a	port identifier	in addition to the normal Internet address
     format.  Note that	the UDP	port space is separate from the	TCP port space
     (i.e., a UDP port may not be "connected" to a TCP port).

     When binding a UDP	socket,	if the local port is unspecified (i.e.,	set to
     0), the system will choose	an appropriate port number for it.  In
     addition broadcast	packets	may be sent (assuming the underlying network
     supports this) by using a reserved	"broadcast address"; this address is
     network interface dependent.

     Options at	the IP transport level may be used with	UDP; see ip(7P).

DIAGNOSTICS    [Toc]    [Back]

     A socket operation	may fail with one of the following errors returned:

     [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;

     [ENOTCONN]	    when trying	to send	a datagram, but	no destination address
		    is specified, and the socket hasn't	been connected;

     [ENOBUFS]	    when the system runs out of	memory for an internal data
		    structure;

     [EADDRINUSE]   when an attempt is made to create a	socket with a port
		    which has already been allocated;

     [EADDRNOTAVAIL]
		    when an attempt is made to create a	socket with a network
		    address for	which no network interface exists.





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UDP(7P)								       UDP(7P)

SEE ALSO    [Toc]    [Back]

     getsockopt(2), recv(2), send(2), socket(2), intro(3), inet(7F), ip(7P),
     tcp(7P)
     IRIX Network Programming Guide


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