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UDP_OPEN(3)		   libdill Library Functions		   UDP_OPEN(3)

NAME
       udp_open	- opens	an UDP socket

SYNOPSIS
	      #include <libdill.h>

	      int udp_open(
		  struct ipaddr* local,
		  struct ipaddr* remote);

DESCRIPTION
       UDP  is	an  unreliable message-based protocol defined in RFC 768.  The
       size of the message is limited.	The protocol has no initial or	termi-
       nal handshake.  A single	socket can be used to different	destinations.

       This function creates an	UDP socket.

       local: IP address to be used to set source IP address in	outgoing pack-
       ets.   Also,  the socket	will receive packets sent to this address.  If
       port in the address is set to zero an ephemeral port will be chosen and
       filled into the local address.

       remote: IP address used as default destination  for  outbound  packets.
       It  is  used  when  destination	address	in udp_send function is	set to
       NULL.  It is also used by msend and mrecv functions which  don't	 allow
       to  specify the destination address explicitly.	Furthermore, if	remote
       address is set, all the packets arriving	from different addresses  will
       be silently dropped.

       To close	this socket use	hclose function.

       This  function  is  not	available  if  libdill is compiled with	--dis-
       able-sockets option.

RETURN VALUE
       In case of success the function returns newly  created  socket  handle.
       In  case	of error it returns -1 and sets	errno to one of	the values be-
       low.

ERRORS
       • EADDRINUSE: The local address is already in use.

       • EADDRNOTAVAIL:	The specified address is not available from the	 local
	 machine.

       • EINVAL: Invalid argument.

       • EMFILE: The maximum number of file descriptors	in the process are al-
	 ready open.

       • ENFILE:  The maximum number of	file descriptors in the	system are al-
	 ready open.

       • ENOMEM: Not enough memory.

EXAMPLE
	      struct ipaddr local;
	      ipaddr_local(&local, NULL, 5555, 0);
	      struct ipaddr remote;
	      ipaddr_remote(&remote, "server.example.org", 5555, 0, -1);
	      int s = udp_open(&local, &remote);
	      udp_send(s1, NULL, "ABC",	3);
	      char buf[2000];
	      ssize_t sz = udp_recv(s, NULL, buf, sizeof(buf), -1);
	      hclose(s);

SEE ALSO
       hclose(3)  mrecv(3)  mrecvl(3)	msend(3)   msendl(3)   udp_open_mem(3)
       udp_recv(3) udp_recvl(3)	udp_send(3) udp_sendl(3)

libdill								   UDP_OPEN(3)

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