NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | ATTRIBUTES | SEE ALSO
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>int socket(AF_INET, SOCK_DGRAM, 0);
The UDP datagram protocol is used to support the SOCK_DGRAM abstraction for the Internet protocol family. UDP sockets are connectionless, and are normally used with the sendto(2POSIX) and recvfrom(2POSIX) calls. The connect(2POSIX) call may also be used to fix the destination for future packets (in which case the recv(2POSIX) or read(2POSIX) and send(2POSIX) or write(2POSIX) 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 (a UDP port cannot be "connected" to a TCP port). 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).
A socket operation may fail and return one of the following error conditions:
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;
when trying to send a datagram, but no destination address is specified, and the socket hasn't been connected;
when the system runs out of memory for an internal data structure;
when an attempt is made to create a socket with a port which has already been allocated;
when an attempt is made to create a socket with a network address for which no network interface exists.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
---|---|
Interface Stability | Evolving |
NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | ATTRIBUTES | SEE ALSO