#!/opt/net/GNU/bin/perl -w
#
#      receives numbered UDP datagrams from a remote host.
#
#      Usage:
#          udp-recv [-p <port_number>]
#
#          <port_number> defaults to 9870.
#
# Renaud Waldura # Mon Sep 18 17:30:18 1995
#

require 'getopts.pl';


## parse options

&Getopts('p:');

$port = ($opt_p) ? $opt_p : 9870;


## create a UDP socket

$sockaddr = 'S n a4 x8';	# magic
$family   = 2;			# AF_INET (system dependent !)
$socktype = 1;			# SOCK_DGRAM (system dependent !)

($name, $aliases, $proto) = getprotobyname('udp');
$me = pack($sockaddr, $family, $port, "\0\0\0\0");

# make the socket and  bind it to the protocol

print "name $name aliases $aliases proto $proto\n";
socket(S, $family, $socktype, $proto) || die "Unable to create socket: $!";
bind(S, $me) || die "Unable to bind socket: $!";


## receive numbered datagrams and print their values

$sender = "";
$datagram = "";
for ($n = 1; ; $n++)
{
    $sender = recv(S, $datagram, 1024, 0);

    print "Received datagram $n, length = ", length($datagram), 
	", number = ", (split(/:/, $datagram))[1], "\n";

#    ($af, $port, $inetaddr) = unpack($sockaddr, $sender);
#    @inetaddr = unpack('C4', $inetaddr);
#    print "\tfrom { $af, $port, @inetaddr }\n";
}


## die
close(S);