The purpose of the application is to listen for a specific UDP multicast and then to forward the data to any TCP clients connected to the server. The code works fine, but I have a problem with the sockets not closing after the TCP clients disconnects. A socketsniffer utility shows the the sockets remain open and all the UDP data continues to be forwarded to the clients. The problem I believe is with the "if ($write->connected())" block as it always return true, even if the TCP client is no longer connected. I use standard Windows Telnet to connect to the server and to see the data. When I close telnet, the TCP socket is suppose to close on the server.
Any reason why connected() show the connections as active even if they are not? Also, what alternative should I use then? Code: #!/usr/bin/perl use IO::Socket::Multicast; use IO::Socket; use IO::Select; my $tcp_port = "4550"; my $tcp_socket = IO::Socket::INET->new( Listen => SOMAXCONN, LocalAddr => '0.0.0.0', LocalPort => $tcp_port, Proto => 'tcp', ReuseAddr => 1, ); use Socket qw(IPPROTO_TCP TCP_NODELAY); setsockopt( $tcp_socket, IPPROTO_TCP, TCP_NODELAY, 1); use constant GROUP => '239.2.0.81'; use constant PORT => '6550'; my $udp_socket= IO::Socket::Multicast->new(Proto=>'udp',LocalPort=>PORT); $udp_socket->mcast_add(GROUP) || die "Couldn't set group: $!\n"; my $read_select = IO::Select->new(); my $write_select = IO::Select->new(); $read_select->add($tcp_socket); $read_select->add($udp_socket); ## Loop forever, reading data from the UDP socket and writing it to the ## TCP socket(s). while (1) { ## No timeout specified (see docs for IO::Select). This will block until a TCP ## client connects or we have data. my @read = $read_select->can_read(); foreach my $read (@read) { if ($read == $tcp_socket) { ## Handle connect from TCP client. Note that UDP connections are ## stateless (no accept necessary)... my $new_tcp = $read->accept(); $write_select->add($new_tcp); } elsif ($read == $udp_socket) { ## Handle data received from UDP socket... my $recv_buffer; $udp_socket->recv($recv_buffer, 1024, undef); ## Write the data read from UDP out to the TCP client(s). Again, no ## timeout. This will block until a TCP socket is writable. my @write = $write_select->can_write(); foreach my $write (@write) { ## Make sure the socket is still connected before writing. if ($write->connected()) { $write->send($recv_buffer); } else { $write_select->remove($write); close $write; } } } } }