UDP(4) | Device Drivers Manual | UDP(4) |
udp
— Internet
User Datagram Protocol
#include
<sys/socket.h>
#include <netinet/in.h>
int
socket
(AF_INET,
SOCK_DGRAM,
0);
int
socket
(AF_INET6,
SOCK_DGRAM,
0);
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(2) and
recvfrom(2) calls, though
the connect(2) call may also
be used to fix the destination for future packets (in which case the
recv(2) or
read(2) and
send(2) 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). 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(4) or ip6(4).
A socket operation may fail with one of the following errors returned:
EISCONN
]ENOTCONN
]ENOBUFS
]EADDRINUSE
]EADDRNOTAVAIL
]getsockopt(2), recv(2), send(2), socket(2), inet(4), inet6(4), ip(4), ip6(4), netintro(4)
The udp
protocol appeared in
4.2BSD.
May 31, 2007 | OpenBSD-5.3 |