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#!/usr/bin/perl -w
# Simple WEB server.
#
# Inspired by some examples from the perlipc and other perl manual pages.
#
# Copyright (C) 2009 Michael Adam <obnox@samba.org>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, see <http://www.gnu.org/licenses/>.
use strict;
use IO::Socket;
use IO::Select;
use Carp;
use POSIX qw(setsid :sys_wait_h);
use Errno;
use Getopt::Long;
use Pod::Usage;
use Fcntl ':flock'; # import LOCK_* constants
my $VERSION = "0.1";
my $EOL = "\015\012";
my $port = 2345;
my $proto = getprotobyname('tcp');
my $pid_file = "/tmp/webserver.pid";
my $log_dir = "/tmp";
my $access_log_file;
my $error_log_file;
my $document_root = "/tmp";
my $help = 0;
sub create_child($$$);
sub logmsg {
print STDERR "[", scalar localtime, ", $$] $0: @_\n";
}
sub start_server($$) {
my $proto = shift;
my $port = shift;
my $server;
$server = IO::Socket::INET->new(Proto => $proto,
LocalPort => $port,
Listen => SOMAXCONN,
Reuse => 1);
logmsg "server started listening on port $port";
return $server;
}
sub REAPER {
local $!; # don't let waitpid() overwrite current error
while ((my $pid = waitpid(-1,WNOHANG)) > 0 && WIFEXITED($?)) {
logmsg "reaped $pid" . ($? ? " with exit code $?" : '');
}
$SIG{CHLD} = \&REAPER;
}
sub parse_request($) {
my $client = shift;
my $request = "";
while (my $request_line = <$client>) {
$request .= $request_line;
last if ($request_line eq $EOL);
}
logmsg "request:\n" .
"------------------------------\n" .
"$request" .
"------------------------------";
return $request;
}
sub child_action($) {
my $client = shift;
my $client_ip = shift;
logmsg "client_action: client $client_ip";
$client->autoflush();
my $fortune_bin = "/usr/games/fortune";
my $fortune = "";
if ( -x $fortune_bin) {
$fortune = qx(/usr/games/fortune);
$fortune =~ s/\n/$EOL/g;
}
my $request = parse_request($client);
print $client "HTTP/1.0 200 OK$EOL";
print $client "Server: Tinyproxy-Test-Web-Server/$VERSION$EOL";
print $client "Content-Type: text/html$EOL";
print $client "$EOL";
print $client "<html>$EOL";
print $client "<h1>Tinyproxy test WEB server</h1>$EOL";
print $client "<h2>Fortune</h2>$EOL";
if ($fortune) {
print $client "<pre>$fortune</pre>$EOL";
} else {
print $client "Sorry, no $fortune_bin not found.$EOL";
}
print $client "<h2>Your request:</h2>$EOL";
print $client "<pre>$request<pre>$EOL";
print $client "</html>$EOL";
close $client;
return 0;
}
sub create_child($$$) {
my $client = shift;
my $action = shift;
my $client_ip = shift;
unless (@_ == 0 && $action && ref($action) eq 'CODE') {
confess "internal error. create_child needs code reference as argument";
}
my $pid = fork();
if (not defined($pid)) {
# error
logmsg "cannot fork: $!";
return;
} elsif ($pid) {
# parent
logmsg "child process created with pid $pid";
return;
} else {
# child
exit &$action($client, $client_ip);
}
}
sub process_options() {
my $result = GetOptions("help|?" => \$help,
"port=s" => \$port,
"pid-file=s" => \$pid_file,
"log-dir=s" => \$log_dir,
"root|document-root=s" => \$document_root);
die "Error reading cmdline options! $!" unless $result;
pod2usage(1) if $help;
# some post-processing:
($port) = $port =~ /^(\d+)$/ or die "invalid port";
$access_log_file = "$log_dir/webserver.access_log";
$error_log_file = "$log_dir/webserver.error_log";
}
sub daemonize() {
umask 0;
chdir "/" or die "daemonize: can't chdir to /: $!";
open STDIN, "/dev/null" or
die "daemonize: Can't read from /dev/null: $!";
my $pid = fork();
die "daemonize: can't fork: $!" if not defined($pid);
exit(0) if $pid != 0; # parent
# child (daemon)
setsid or die "damonize: Can't create a new session: $!";
}
sub reopen_logs() {
open STDOUT, ">> $access_log_file" or
die "daemonize: Can't write to '$access_log_file': $!";
open STDERR, ">> $error_log_file" or
die "daemonize: Can't write to '$error_log_file': $!";
}
sub get_pid_lock() {
# first make sure the file exists
open(LOCKFILE_W, ">> $pid_file") or
die "Error opening pid file '$pid_file' for writing: $!";
# open for reading and try to lock:
open(LOCKFILE, "< $pid_file") or
die "Error opening pid file '$pid_file' for reading: $!";
unless (flock(LOCKFILE, LOCK_EX|LOCK_NB)) {
print "pid file '$pid_file' is already locked.\n";
my $other_pid = <LOCKFILE>;
if (!defined($other_pid)) {
print "Error reading from pid file.\n";
} else {
chomp($other_pid);
if (!$other_pid) {
print "pid file is empty.\n";
} else {
print "Webserver is already running with pid '$other_pid'.\n";
}
}
close LOCKFILE;
exit(0);
}
# now re-open for recreating the file and write our pid
close(LOCKFILE_W);
open(LOCKFILE_W, "> $pid_file") or
die "Error opening pid file '$pid_file' for writing: $!";
LOCKFILE_W->autoflush(1);
print LOCKFILE_W "$$";
close(LOCKFILE_W);
}
sub release_pid_lock() {
flock(LOCKFILE, LOCK_UN);
close LOCKFILE;
}
# "main" ...
$|=1; # autoflush
process_options();
daemonize();
get_pid_lock();
reopen_logs();
$SIG{CHLD} = \&REAPER;
my $server = start_server($proto, $port);
my $slct = IO::Select->new($server);
while (1) {
my @ready_for_reading = $slct->can_read();
foreach my $fh (@ready_for_reading) {
if ($fh != $server) {
logmsg "select: fh ready for reading but not server",
"don't know what to do...";
}
# new connection:
my $client = $server->accept() or do {
# try again if accept() returned because
# a signal was received
if ($!{EINTR}) {
logmsg "accept: got signal EINTR ...";
next;
}
die "accept: $!";
};
my $client_ip = inet_ntoa($client->peeraddr);
logmsg "connection from $client_ip at port " . $client->peerport;
create_child($client, \&child_action, $client_ip);
close $client;
}
}
# never reached...
logmsg "Server done - ooops!\n";
release_pid_lock();
exit(0);
__END__
=head1 webserver.pl
A simple WEB server written in perl.
=head1 SYNOPSIS
webserver.pl [options]
=head1 OPTIONS
=over 8
=item B<--help>
Print a brief help message and exit.
=item B<--port>
Specify the port number for the server to listen on.
=item B<--root|--document-root>
Specify the document root directory from which to serve web content.
=item B<--log-dir>
Specify the directory where the log files should be stored.
=item B<--pid-file>
Specify the location of the pid lock file.
=back
=head1 DESCRIPTION
This is a very simple web server. It currently does not deliver the specific web
page requested, but constructs the same kind of answer for each request, citing
a fortune if fortune is available, and printing the originating request.
=cut
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