|UDP(4)||Device Drivers Manual||UDP(4)|
udp — Internet
User Datagram Protocol
UDP is a simple, unreliable datagram protocol which is used to
SOCK_DGRAM abstraction for the Internet
protocol family. UDP sockets are connectionless, and are normally used with
the sendto and
recvfrom calls, though the
connectx(2) call may also be used to
fix the destination for future packets (in which case the
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).
Using sendmsg(2) with
IP_PKTINFO as ancillary data with a non NULL
interface index or a local address can remove the local IP address that was
assigned by a previous call to bind(2)
and leave the UDP socket in an unbound state with
INADDR_ANY as the local address.
A socket operation may fail with one of the following errors returned:
udp protocol appeared in
|March 18, 2015||BSD 4.2|