adwald has asked for the wisdom of the Perl Monks concerning the following question:

I am needing to perform a leasequery to multiple servers. HI have tried the following code but it keeps locking on the second server. I cannot find anything online as an example. Can someone provide some assistance?

!/usr/bin/perl -w

use IO::Socket::INET;
use Net::DHCP::Packet;
use Net::DHCP::Constants;

$mac=$ARGV[0];

@dhcp = ("10.16.30.4","10.16.30.5","172.31.45.248","172.31.45.249","17
+2.31.35.248","172.31.35.249");

foreach $server (@dhcp) {

  print "$server\n";

# create a socket
  $handle = IO::Socket::INET->new(Proto => 'udp',
                                  Broadcast => 1,
                                  PeerPort => '67',
                                  LocalPort => '67',
                                  PeerAddr => $server);

# create DHCP Packet
  $inform = Net::DHCP::Packet->new(
                      op => BOOTREQUEST(),
                      Htype  => '1',
                      Hlen   => '6',
                      Ciaddr => '0',
                      Chaddr => $mac,
                      Giaddr => $handle->sockhost(),
                      Xid => int(rand(0xFFFFFFFF)),     # random xid
                      DHO_DHCP_MESSAGE_TYPE() => DHCPLEASEQUERY
                      );

# send request
  $handle->send($inform->serialize()) or die "Error sending LeaseQuery
+: $!\n";

#receive response
  $handle->recv($newmsg, 1024) or die;
  $packet = Net::DHCP::Packet->new($newmsg);
  $data = $packet->toString();

  $handle->close();

}

print "$data\n";

[download]

Replies are listed 'Best First'.
Re: UDP Client Multiple servers
by BrowserUk (Patriarch) on Oct 11, 2012 at 15:55 UTC

    What happens if you add use strict; at the top of your code and prefix your variables with my?

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    RIP Neil Armstrong
[reply]
[d/l]

      I found the answer to my problem. I needed to eval whether a response was received in an amount of time and escape out if not.

      eval {
  local $SIG{ALRM} = sub { die 'Timed Out'; };
  alarm 1;

#receive response
  $handle->recv($newmsg, 1024) or die;
  $packet = Net::DHCP::Packet->new($newmsg);
  $data = $packet->toString();

  close $handle;
  alarm 0;
};

close $handle;

      [download]
[reply]
[d/l]

        That's not really a good idea. You could just set timeout option on the socket after creating it: 

        use Socket qw(SO_RCVTIMEO);
use POSIX qw(:errno_h);
...;
my $timeout = pack 'L!L!', $sec, $usec;
$handle->sockopt(SO_RCVTIMEO, $timeout);
...;
my $res = $handle->recv(...);
unless(defined $res) {
    if($! == EAGAIN or $! == EWOULDBLOCK) {
        say "time out";
    }
}

        [download]
[reply]
[d/l]

Back to Seekers of Perl Wisdom