#!/usr/bin/perl

################################################################################
#
# Copyright (c) 2007-2008  Ramon Novoa  <rnovoa@artica.es>
# Copyright (c) 2007-2010  Artica Soluciones Tecnologicas S.L.
#
# tentacle_client.pl	Tentacle Client. See http://www.openideas.info/wiki for
# 			protocol description.
#
# 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; version 2 of the License.
# 
# 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.	
#
################################################################################

package tentacle::client;

=head1 NAME

tentacle_client - Tentacle Client

=head1 VERSION

Version 0.2.0

=head1 USAGE

tentacle_client [options] [file] [file] ...

=head1 DESCRIPTION

B<tentacle_client(1)> is a client for B<tentacle>, a B<client/server> file transfer protocol that aims to be:

=over

=item    * Secure by design.

=item    * Easy to use.

=item    * Versatile and cross-platform. 

=back 

Tentacle was created to replace more complex tools like SCP and FTP for simple file transfer/retrieval, and switch from authentication mechanisms like .netrc, interactive logins and SSH keys to X.509 certificates. Simple password authentication over a SSL secured connection is supported too.

The client and server (B<TCP port 41121>) are designed to be run from the command line or called from a shell script, and B<no configuration files are needed>. 

=cut

use strict;
use File::Basename;
use Getopt::Std;
use IO::Select;
use IO::Socket::INET;

# Program version
our $VERSION = '0.2.0';

# Server address
my $t_address = '127.0.0.1';

# Block size for socket read/write operations in bytes
my $t_block_size = 1024;

# Log messages, 1 enabled, 0 disabled
my $t_log = 0;

# Server port
my $t_port = 41121;

# Do not output error messages, 1 enabled, 0 disabled
my $t_quiet = 0;

# Server password
my $t_pwd = '';

# Receive mode, 1 enabled, 0 disabled
my $t_recv = 0;

# Retries for socket read/write operations
my $t_retries = 3;

# Select handler
my $t_select;

# Server socket
my $t_socket;

# Use SSL, 1 true, 0 false
my $t_ssl = 0;

# SSL ca certificate file
my $t_ssl_ca = '';

# SSL certificate file
my $t_ssl_cert = '';

# SSL private key file
my $t_ssl_key = '';

# SSL private key file password
my $t_ssl_pwd = '';

# Timeout for socket read/write operations in seconds
my $t_timeout = 1;

################################################################################
## SUB print_help
## Print help screen.
################################################################################
sub print_help {

	print ("Usage: $0 [options] [file] [file] ...\n\n");
	print ("Tentacle client v$VERSION. See http://www.openideas.info/wiki for protocol description.\n\n");
	print ("Options:\n");
	print ("\t-a address\tServer address (default $t_address).\n");
	print ("\t-c\t\tEnable SSL without a client certificate.\n");
	print ("\t-e cert\t\tOpenSSL certificate file. Enables SSL.\n");
	print ("\t-f ca\t\tVerify that the peer certificate is signed by a ca.\n");
	print ("\t-g\t\tGet files from the server.\n");
	print ("\t-h\t\tShow help.\n");
	print ("\t-k key\t\tOpenSSL private key file.\n");
	print ("\t-p port\t\tServer port (default $t_port).\n");
	print ("\t-q\t\tQuiet. Do now print error messages.\n");
	print ("\t-r number\tNumber of retries for network operations (default $t_retries).\n");
	print ("\t-t time\t\tTime-out for network operations in seconds (default ${t_timeout}s).\n");
	print ("\t-v\t\tBe verbose.\n");
	print ("\t-w\t\tPrompt for OpenSSL private key password.\n");
        print ("\t-x pwd\t\tServer password.\n\n");
}

################################################################################
## SUB parse_options
## Parse command line options and initialize global variables.
################################################################################
sub parse_options {
	my %opts;
	my $tmp;

	# Get options
	if (getopts ('a:ce:f:ghk:p:qr:t:vwx:', \%opts) == 0 || defined ($opts{'h'})) {
		print_help ();
		exit 1;
	}

	# Address
	if (defined ($opts{'a'})) {
		$t_address = $opts{'a'};
		if ($t_address !~ /^[a-zA-Z\.]+$/ && ($t_address  !~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/
			|| $1 < 0 || $1 > 255 || $2 < 0 || $2 > 255
			|| $3 < 0 || $3 > 255 || $4 < 0 || $4 > 255)) {
			error ("Address $t_address is not valid.");
		}

	}

	# Enable SSL without a client certificate
	if (defined ($opts{'c'})) {
		require IO::Socket::SSL;
		$t_ssl = 1;
	} 

	# Enable SSL
	if (defined ($opts{'e'})) {
		
		if (defined ($opts{'c'})) {
			error ("Flags -c and -e can not be used at the same time.");
		}

		require IO::Socket::SSL;

		$t_ssl_cert = $opts{'e'};
		if (! -f $t_ssl_cert) {
			error ("File $t_ssl_cert does not exist.");
		}

		$t_ssl = 1;
	}

	# Verify peer certificate
	if (defined ($opts{'f'})) {

		if (! defined ($opts{'e'})) {
			error ("Flag -e must be set to enable peer certificate verify.");
		}

		$t_ssl_ca = $opts{'f'};
		if (! -f $t_ssl_ca) {
			error ("File $t_ssl_ca does not exist.");
		}
	}

	# Get files
	if (defined ($opts{'g'})) {
		$t_recv = 1;
	}

	# SSL private key file
	if (defined ($opts{'k'})) {

		if (! defined ($opts{'e'})) {
			error ("Flag -e must be set to use a private key file.");
		}

		$t_ssl_key = $opts{'k'};
		if (! -f $t_ssl_key) {
			error ("File $t_ssl_key does not exist.");
		}
	}

	# Port
	if (defined ($opts{'p'})) {
		$t_port = $opts{'p'};
		if ($t_port !~ /^\d+$/ || $t_port < 1 || $t_port > 65535) {
			error ("Port $t_port is not valid.");
		}
	}

	# Quiet mode
	if (defined ($opts{'q'})) {
		$t_quiet = 1;
	}

	# Retries
	if (defined ($opts{'r'})) {
		$t_retries = $opts{'r'};
		if ($t_retries !~ /^\d+$/ || $t_retries < 1) {
			error ("Invalid number of retries for network operations.");
		}
	}

	# Timeout
	if (defined ($opts{'t'})) {
		$t_timeout = $opts{'t'};
		if ($t_timeout !~ /^\d+$/ || $t_timeout < 1) {
			error ("Invalid timeout for network operations.");
		}
	}

	# Be verbose
	if (defined ($opts{'v'})) {
		$t_log = 1;
	}

	# SSL private key password
	if (defined ($opts{'w'})) {

		if (! defined ($opts{'e'})) {
			error ("Flag -k must be set to provide a private key password.");
		}

		$t_ssl_pwd = ask_passwd ("Enter private key file password: ", "Enter private key file password again for confirmation: ");
	}

        # Server password
	if (defined ($opts{'x'})) {
		$t_pwd = $opts{'x'};
	}
}

################################################################################
## SUB start_client
## Open the server socket.
################################################################################
sub start_client {

	# Connect to server
	$t_socket = IO::Socket::INET->new (
	        	PeerAddr => $t_address,
			PeerPort => $t_port,
		);

	if (! defined ($t_socket)) {
		error ("Cannot connect to $t_address on port $t_port: $!.");
	}

	# Add server socket to select queue
	$t_select = IO::Select->new ();
	$t_select->add ($t_socket);

	print_log ("Connected to $t_address port $t_port");
}

################################################################################
## SUB stop_client
## Close the server socket.
################################################################################
sub stop_client {

	$t_socket->close ();
}

################################################################################
## SUB start_ssl
## Convert the server socket to an IO::Socket::SSL socket.
################################################################################
sub start_ssl {
	my $err;
	
	if ($t_ssl_cert eq ''){
		IO::Socket::SSL->start_SSL (
			$t_socket,
		);
	}
	elsif ($t_ssl_ca eq '') {
		IO::Socket::SSL->start_SSL (
			$t_socket,
			SSL_cert_file => $t_ssl_cert,
			SSL_key_file => $t_ssl_key,
			SSL_passwd_cb => sub {return $t_ssl_pwd},
			SSL_use_cert =>'1',
			# No authentication
			SSL_verify_mode => '0x00', 
		);
	}
	else {
		IO::Socket::SSL->start_SSL (
			$t_socket,
			SSL_ca_file => $t_ssl_ca,
			SSL_cert_file => $t_ssl_cert,
			SSL_key_file => $t_ssl_key,
			SSL_passwd_cb => sub {return $t_ssl_pwd},
			SSL_use_cert =>'1',
			# Verify peer
			SSL_verify_mode => '0x01', 
		);
	}

	$err = IO::Socket::SSL::errstr ();
	if ($err ne '') {
		error ($err);
	}
}

################################################################################
## SUB auth_pwd
## Authenticate client with server password.
################################################################################
sub auth_pwd {
	my $command;
	my $pwd_digest;

	require Digest::MD5;
	
	$pwd_digest = Digest::MD5::md5 ($t_pwd);
	$pwd_digest = Digest::MD5::md5_hex ($pwd_digest);

	send_data ("PASS $pwd_digest\n");

	$command = recv_command ($t_block_size);
	if ($command !~ /^PASS OK$/) {
		error ("Authentication failed.");
	}
}

################################################################################
## SUB recv_file
## Receive a file from the server
################################################################################
sub recv_file {
	my $data = '';
	my $file = $_[0];
	my $response;
	my $size;

	# Request file
	send_data ("RECV <$file>\n");

	# Wait for server response
	$response = recv_command ();
	if ($response !~ /^RECV SIZE (\d+)$/) {
		error ("Server responded $response.");
	}

	$size = $1;
	send_data ("RECV OK\n");
	
	# Receive file
	$data = recv_data_block ($size);

	# Write it to disk
	open (FILE, "> $file") || error ("Cannot open file '$file' for writing.");
	binmode (FILE);
	print (FILE $data);
	close (FILE);

	print_log ("Received file '$file'");
}

################################################################################
## SUB send_file
## Send a file to the server
################################################################################
sub send_file {
	my $base_name;
	my $data = '';
	my $response = '';
	my $retries;
	my $file = $_[0];
	my $size;
	my $written;

	$base_name = basename ($file);
	$size = -s $file;

	# Request to send file
	send_data ("SEND <$base_name> SIZE $size\n");

	print_log ("Request to send file '$base_name' size ${size}b");

	# Wait for server response
	$response = recv_command ();

	# Server rejected the file
	if ($response ne "SEND OK") {
		send_data ("QUIT\n");
		error ("Server responded $response.");
	}

	print_log ("Server responded SEND OK");

	# Send the file
	open (FILE, $file) || error ("Cannot open file '$file' for reading.");
	binmode (FILE);
	
	while ($data = <FILE>) {
		send_data ($data);
	}
	
	close (FILE);

	# Wait for server response
	$response = recv_command ();
	if ($response ne "SEND OK") {
		send_data ("QUIT\n");
		error ("Server responded $response.");
	}

	print_log ("File sent");
}

################################################################################
# Common functions
################################################################################

################################################################################
## SUB print_log
## Print log messages.
################################################################################
sub print_log {

	if ($t_log == 1) {
		print (STDOUT "[log] $_[0]\n");
	}
}

################################################################################
## SUB error
## Print an error and exit the program.
################################################################################
sub error {

	if ($t_quiet == 0) {
		print (STDERR "[err] $_[0]\n");
	}

	exit 1;
}

################################################################################
## SUB recv_data
## Read data from the client socket. Returns the number of bytes read and the
## string of bytes as a two element array.
################################################################################
sub recv_data {
	my $data;
	my $read;
	my $retries = 0;
	my $size = $_[0];

	while (1) {

		# Try to read data from the socket
		if ($t_select->can_read ($t_timeout)) {
			
			# Read at most $size bytes
			$read = sysread ($t_socket, $data, $size);

			# Read error
			if (! defined ($read)) {
				error ("Read error from " . $t_socket->sockhost () . ": $!.");
			}
	
			# EOF
			if ($read == 0) {
				error ("Connection from " . $t_socket->sockhost () . " unexpectedly closed.");
			}
	
			return ($read, $data);
		}

		# Retry
		$retries++;

		# But check for error conditions first
		if ($retries > $t_retries) {
			error ("Connection from " . $t_socket->sockhost () . " timed out.");
		}
	}
}

################################################################################
## SUB send_data
## Write data to the client socket.
################################################################################
sub send_data {
	my $data = $_[0];
	my $retries = 0;
	my $size;
	my $total = 0;
	my $written;

	$size = length ($data);

	while (1) {

		# Try to write data to the socket
		if ($t_select->can_write ($t_timeout)) {

			$written = syswrite ($t_socket, $data, $size - $total, $total);

			# Read error
			if (! defined ($written)) {
				error ("Connection error from " . $t_socket->sockhost () . ": $!.");
			}
			
			# EOF
			if ($written == 0) {
				error ("Connection from " . $t_socket->sockhost () . " unexpectedly closed.");
			}
	
		}

		$total += $written;

		# All data was written
		if ($total == $size) {
			return;
		}

		# Retry
		$retries++;

		# But check for error conditions first
		if ($retries > $t_retries) {
			error ("Connection from " . $t_socket->sockhost () . " timed out.");
		}
	}
}

################################################################################
## SUB recv_command
## Read a command from the client, ended by a new line character.
################################################################################
sub recv_command {
	my $buffer;
	my $char;
	my $command = '';
	my $read;
	my $total = 0;

	while (1) {
		
		($read, $buffer) = recv_data ($t_block_size);
		$command .= $buffer;
		$total += $read;

		# Check if the command is complete
		$char = chop ($command);
		if ($char eq "\n") {
			return $command;
		}
	
		$command .= $char;

		# Avoid overflow
		if ($total > $t_block_size) {
			error ("Received too much data from " . $t_socket->sockhost ());
		}
	}
}

################################################################################
## SUB recv_data_block
## Read $_[0] bytes of data from the client.
################################################################################
sub recv_data_block {
	my $buffer = '';
	my $data = '';
	my $read;
	my $size = $_[0];
	my $total = 0;

	while (1) {

		($read, $buffer) = recv_data ($size - $total);
		$data .= $buffer;
		$total += $read;

		# Check if all data has been read
		if ($total == $size) {
			return $data;
		}
	}
}

################################################################################
## SUB ask_passwd
## Asks the user for a password.
################################################################################
sub ask_passwd {
	my $msg1 = $_[0];
	my $msg2 = $_[1];
	my $pwd1;
	my $pwd2;

	require Term::ReadKey;

	# Disable keyboard echo
	Term::ReadKey::ReadMode('noecho');
	
	# Promt for password
	print ($msg1);
	$pwd1 = Term::ReadKey::ReadLine(0);
	print ("\n$msg2");
	$pwd2 = Term::ReadKey::ReadLine(0);
	print ("\n");

	# Restore original settings
	Term::ReadKey::ReadMode('restore');

	if ($pwd1 ne $pwd2) {
		# Call print to bypass quiet mode.
		print ("[err] Passwords do not match.\n");
		exit 1;
	}

	# Remove the trailing new line character
	chop $pwd1;

	return $pwd1;
}

################################################################################
# Main
################################################################################

my $file;

# Parse command line options
parse_options ();

# Check command line arguments
if ($t_recv == 0 && $#ARGV == -1) {
	error ("No files to send.");
}

# Connect to the server
start_client ();

# Start SSL
if ($t_ssl == 1) {
	start_ssl ();
}

# Authenticate with server
if ($t_pwd ne '') {
	auth_pwd ();
}

if ($t_recv == 0) {
	# Check that all files exist before trying to send them
	foreach $file (@ARGV) {
		if (! -f $file) {
			error ("File '$file' does not exist.");
		}
	}

	# Send the files
	foreach $file (@ARGV) {
		send_file ($file);
	}
}
else {
	# Send the files
	foreach $file (@ARGV) {
		recv_file ($file);
	}
}

# Tell the server that we are finished
send_data ("QUIT\n");

stop_client ();

exit 0;


__END__

=head1 OPTIONS

=over

=item	I<-a address>	B<Server address> (default 127.0.0.1).

=item	I<-c>			Enable B<SSL> without a client certificate.

=item	I<-e cert>		B<OpenSSL certificate> file. Enables SSL.

=item	I<-f ca>		Verify that the peer certificate is signed by a B<CA> (Certificate Authority).

=item	I<-g>			B<Get> files from the server.

=item	I<-h>			Show B<help>.

=item	I<-k key>		B<OpenSSL private key> file.

=item	I<-p port>		B<Server port> (default I<41121>).

=item	I<-q>			B<Quiet>. Do now print error messages.

=item	I<-r number>		B<Number of retries> for network operations (default I<3>).

=item	I<-t time>		B<Time-out> for network operations in seconds (default I<1s>).

=item	I<-v>			Be B<verbose>.

=item	I<-w>			Prompt for B<OpenSSL private key password>.

=item	I<-x pwd>		B<Server password>.

=back

=head1 EXIT STATUS

=over 

=item 0 on Success

=item 1 on Error

=back 

=head1 CONFIGURATION

Tentacle doesn't use any configurationf files, all the configuration is done by the options passed when it's started.

=head1 DEPENDENCIES

L<Getopt::Std>, L<IO::Select>, L<IO::Socket::INET>, L<File::Basename>

=head1 LICENSE

This is released under the GNU Lesser General Public License.

=head1 SEE ALSO

L<Getopt::Std>, L<IO::Select>, L<IO::Socket::INET>, L<File::Basename>

Protocol description and more info at: L<< http://openideas.info/wiki/index.php?title=Tentacle >>

=head1 COPYRIGHT

Copyright (c) 2005-2010 Artica Soluciones Tecnologicas S.L

=cut