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423 lines
9.9 KiB
423 lines
9.9 KiB
#!/usr/bin/perl
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#
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# Copyright (c) 2006-2009 by Karl J. Runge <runge@karlrunge.com>
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#
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# connect_switch is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or (at
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# your option) any later version.
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#
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# connect_switch is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with connect_switch; if not, write to the Free Software
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# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA
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# or see <http://www.gnu.org/licenses/>.
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#
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#
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# connect_switch:
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#
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# A kludge script that sits between web clients and a mod_ssl (https)
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# enabled apache webserver.
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#
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# If an incoming web client connection makes a proxy CONNECT request
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# it is handled directly by this script (apache is not involved).
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# Otherwise, all other connections are forwarded to the apache webserver.
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#
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# This can be useful for VNC redirection using an existing https (port
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# 443) webserver, thereby not requiring a 2nd (non-https) port open on
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# the firewall for the CONNECT requests.
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#
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# It does not seem possible (to me) to achieve this entirely within apache
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# because the CONNECT request appears to be forwarded encrypted to
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# the remote host and so the SSL dies immediately.
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#
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# Note: There is no need to use this script for a non-ssl apache webserver
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# port because mod_proxy works fine for doing the switching all inside
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# apache (see ProxyRequests and AllowCONNECT parameters).
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#
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# Apache configuration:
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#
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# The mod_ssl configuration is often in a file named ssl.conf. In the
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# simplest case you change something like this:
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#
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# From:
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#
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# Listen 443
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#
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# <VirtualHost _default_:443>
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# ...
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# </VirtualHost>
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#
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# To:
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#
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# Listen 127.0.0.1:443
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#
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# <VirtualHost _default_:443>
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# ...
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# </VirtualHost>
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#
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# (i.e. just change the Listen directive).
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#
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# If you have mod_ssl listening on a different internal port, you do
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# not need to specify the localhost Listen address.
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#
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# It is probably a good idea to set $listen_host below to the known
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# IP address you want the service to listen on (to avoid localhost where
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# apache is listening).
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############################################################################
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# The defaults for hosts and ports (you can override them below if needed):
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#
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# Look below for these environment variables that let you set the various
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# parameters without needing to edit this script:
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#
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# CONNECT_SWITCH_LISTEN
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# CONNECT_SWITCH_HTTPD
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# CONNECT_SWITCH_ALLOWED
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# CONNECT_SWITCH_ALLOW_FILE
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# CONNECT_SWITCH_VERBOSE
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# CONNECT_SWITCH_APPLY_VNC_OFFSET
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# CONNECT_SWITCH_VNC_OFFSET
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my $hostname = `hostname`;
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chomp $hostname;
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my $listen_host = $hostname;
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my $listen_port = 443;
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if (exists $ENV{CONNECT_SWITCH_LISTEN}) {
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# E.g. CONNECT_SWITCH_LISTEN=192.168.0.32:443
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($listen_host, $listen_port) = split(/:/, $ENV{CONNECT_SWITCH_LISTEN});
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}
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my $httpd_host = 'localhost';
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my $httpd_port = 443;
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if (exists $ENV{CONNECT_SWITCH_HTTPD}) {
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# E.g. CONNECT_SWITCH_HTTPD=127.0.0.1:443
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($httpd_host, $httpd_port) = split(/:/, $ENV{CONNECT_SWITCH_HTTPD});
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}
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############################################################################
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# You can/should override the host/port settings here:
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#
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#$listen_host = '23.45.67.89'; # set to your interface IP number.
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#$listen_port = 555; # and/or nonstandard port.
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#$httpd_host = 'somehost'; # maybe you redir https to another machine.
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#$httpd_port = 666; # and/or nonstandard port.
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# You must set the allowed host:port CONNECT redirection list.
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# Only these host:port pairs will be redirected to.
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#
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my @allowed = qw(
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machine1:5915
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machine2:5900
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);
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if (exists $ENV{CONNECT_SWITCH_ALLOWED}) {
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#
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# E.g. CONNECT_SWITCH_ALLOWED=machine1:5915,machine2:5900
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#
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@allowed = split(/,/, $ENV{CONNECT_SWITCH_ALLOWED});
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}
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# Or you could also use an external "allow file".
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# They get added to the @allowed list.
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# The file is re-read for each new connection.
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#
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# Format of $allow_file:
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#
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# host1 vncdisp
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# host2 vncdisp
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#
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# where, e.g. vncdisp = 15 => port 5915, say
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#
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# joesbox 15
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# fredsbox 15
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# rupert 1
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my $allow_file = '/dist/apache/2.0/conf/vnc.hosts';
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$allow_file = '';
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if (exists $ENV{CONNECT_SWITCH_ALLOW_FILE}) {
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# E.g. CONNECT_SWITCH_ALLOW_FILE=/usr/local/etc/allow.txt
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$allow_file = $ENV{CONNECT_SWITCH_ALLOW_FILE};
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}
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# Set to 1 to re-map to vnc port, e.g. 'hostname 15' to 'hostname 5915'
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# i.e. assume a port 0 <= port < 200 is actually a VNC display
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# and add 5900 to it. Set to 0 to not do the mapping.
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# Note that negative ports, e.g. 'joesbox -22' go directly to -port.
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#
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my $apply_vnc_offset = 1;
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my $vnc_offset = 5900;
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if (exists $ENV{CONNECT_SWITCH_APPLY_VNC_OFFSET}) {
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# E.g. CONNECT_SWITCH_APPLY_VNC_OFFSET=0
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$apply_vnc_offset = $ENV{CONNECT_SWITCH_APPLY_VNC_OFFSET};
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}
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if (exists $ENV{CONNECT_SWITCH_VNC_OFFSET}) {
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# E.g. CONNECT_SWITCH_VNC_OFFSET=6000
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$vnc_offset = $ENV{CONNECT_SWITCH_VNC_OFFSET};
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}
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# Set to 1 for more debugging output:
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#
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my $verbose = 0;
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if (exists $ENV{CONNECT_SWITCH_VERBOSE}) {
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# E.g. CONNECT_SWITCH_VERBOSE=1
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$verbose = $ENV{CONNECT_SWITCH_VERBOSE};
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}
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############################################################################
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# No need for any changes below here.
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use IO::Socket::INET;
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use strict;
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use warnings;
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my $killpid = 1;
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setpgrp(0, 0);
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my $listen_sock = IO::Socket::INET->new(
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Listen => 10,
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LocalAddr => $listen_host,
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LocalPort => $listen_port,
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Proto => "tcp"
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);
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if (! $listen_sock) {
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die "connect_switch: $!\n";
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}
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my $current_fh1 = '';
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my $current_fh2 = '';
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my $conn = 0;
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while (1) {
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$conn++;
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print STDERR "listening for connection: $conn\n" if $verbose;
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my ($client, $ip) = $listen_sock->accept();
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if (! $client) {
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fsleep(0.5);
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next;
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}
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print STDERR "conn: $conn -- ", $client->peerhost(), "\n" if $verbose;
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my $pid = fork();
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if (! defined $pid) {
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die "connect_switch: $!\n";
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} elsif ($pid) {
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wait;
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next;
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} else {
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close $listen_sock;
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if (fork) {
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exit 0;
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}
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setpgrp(0, 0);
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handle_conn($client);
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}
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}
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exit 0;
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sub handle_conn {
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my $client = shift;
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my $start = time();
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my @allow = @allowed;
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if ($allow_file && -f $allow_file) {
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if (open(ALLOW, "<$allow_file")) {
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while (<ALLOW>) {
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next if /^\s*#/;
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next if /^\s*$/;
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chomp;
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my ($host, $dpy) = split(' ', $_);
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next if ! defined $host;
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next if ! defined $dpy;
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if ($dpy < 0) {
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$dpy = -$dpy;
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} elsif ($apply_vnc_offset) {
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$dpy += $vnc_offset if $dpy < 200;
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}
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push @allow, "$host:$dpy";
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}
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close(ALLOW);
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} else {
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warn "$allow_file: $!\n";
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}
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}
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my $str = '';
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my $N = 0;
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my $isconn = 1;
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for (my $i = 0; $i < 7; $i++) {
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my $b;
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sysread($client, $b, 1);
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$str .= $b;
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$N++;
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print STDERR "read: '$str'\n" if $verbose;
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my $cstr = substr('CONNECT', 0, $i+1);
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if ($str ne $cstr) {
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$isconn = 0;
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last;
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}
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}
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my $sock = '';
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if ($isconn) {
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while ($str !~ /\r\n\r\n/) {
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my $b;
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sysread($client, $b, 1);
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$str .= $b;
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}
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print STDERR "read: $str\n" if $verbose;
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my $ok = 0;
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my $hostport = '';
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my $http_vers = '1.0';
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if ($str =~ /^CONNECT\s+(\S+)\s+HTTP\/(\S+)/) {
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$hostport = $1;
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$http_vers = $2;
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foreach my $hp (@allow) {
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if ($hp eq $hostport) {
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$ok = 1;
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last;
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}
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}
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}
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if (! $ok) {
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close $client;
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exit 0;
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}
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my ($host, $port) = split(/:/, $hostport);
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print STDERR "connecting to: $host:$port\n" if $verbose;
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$sock = IO::Socket::INET->new(
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PeerAddr => $host,
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PeerPort => $port,
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Proto => "tcp"
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);
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my $msg;
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if ($sock) {
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$msg = "HTTP/$http_vers 200 Connection Established\r\n"
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. "Proxy-agent: connect_switch v0.2\r\n\r\n";
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} else {
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$msg = "HTTP/$http_vers 502 Bad Gateway\r\n"
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. "Connection: close\r\n\r\n";
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}
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syswrite($client, $msg, length($msg));
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$str = '';
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} else {
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print STDERR "connecting to: $httpd_host:$httpd_port\n"
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if $verbose;
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$sock = IO::Socket::INET->new(
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PeerAddr => $httpd_host,
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PeerPort => $httpd_port,
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Proto => "tcp"
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);
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}
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if (! $sock) {
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close $client;
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die "connect_switch: $!\n";
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}
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$current_fh1 = $client;
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$current_fh2 = $sock;
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$SIG{TERM} = sub {print STDERR "got sigterm\[$$]\n" if $verbose; close $current_fh1; close $current_fh2; exit 0};
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my $parent = $$;
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if (my $child = fork()) {
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xfer($sock, $client, 'S->C');
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if ($killpid) {
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fsleep(0.5);
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kill 'TERM', $child;
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}
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} else {
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if ($str ne '' && $N > 0) {
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syswrite($sock, $str, $N);
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}
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xfer($client, $sock, 'C->S');
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if ($killpid) {
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fsleep(0.75);
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kill 'TERM', $parent;
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}
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}
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if ($verbose) {
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my $dt = time() - $start;
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print STDERR "dt\[$$]: $dt\n";
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}
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exit 0;
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}
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sub xfer {
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my($in, $out, $lab) = @_;
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my ($RIN, $WIN, $EIN, $ROUT);
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$RIN = $WIN = $EIN = "";
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$ROUT = "";
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vec($RIN, fileno($in), 1) = 1;
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vec($WIN, fileno($in), 1) = 1;
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$EIN = $RIN | $WIN;
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my $buf;
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while (1) {
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my $nf = 0;
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while (! $nf) {
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$nf = select($ROUT=$RIN, undef, undef, undef);
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}
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my $len = sysread($in, $buf, 8192);
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if (! defined($len)) {
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next if $! =~ /^Interrupted/;
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print STDERR "connect_switch\[$lab/$conn/$$]: $!\n";
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last;
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} elsif ($len == 0) {
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print STDERR "connect_switch\[$lab/$conn/$$]: "
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. "Input is EOF.\n";
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last;
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}
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if (0) {
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# verbose debugging of data:
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syswrite(STDERR , "\n$lab: ", 6);
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syswrite(STDERR , $buf, $len);
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}
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my $offset = 0;
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my $quit = 0;
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while ($len) {
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my $written = syswrite($out, $buf, $len, $offset);
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if (! defined $written) {
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print STDERR "connect_switch\[$lab/$conn/$$]: "
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. "Output is EOF. $!\n";
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$quit = 1;
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last;
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}
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$len -= $written;
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$offset += $written;
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}
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last if $quit;
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}
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close($in);
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close($out);
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}
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sub fsleep {
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my ($time) = @_;
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select(undef, undef, undef, $time) if $time;
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}
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