package Echolot::Chain;

#
#
# This file is part of Echolot - a Pinger for anonymous remailers.
#
# Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2012, 2014 Peter Palfrader <peter@palfrader.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, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
#

=pod

=head1 Name

Echolot::Chain - actual sending and receiving of Chain-Pings.

=head1 DESCRIPTION

This package provides functions for sending out and receiving chain-pings.

=cut

use strict;
use English;
use Echolot::Log;
use Echolot::Pinger::Mix;
use Echolot::Pinger::CPunk;

my %INTENSIVE_CARE;

sub do_mix_chainping($$$$$$$$) {
	my ($addr1, $type1, $keyid1, $addr2, $type2, $keyid2, $to, $body) = @_;

	($type1 eq 'mix' && $type2 eq 'mix') or
		Echolot::Log::warn("both types should really be mix ($type1, $type2)."),
		return 0;

	my %key1 = Echolot::Globals::get()->{'storage'}->get_key($addr1, $type1, $keyid1);
	my %key2 = Echolot::Globals::get()->{'storage'}->get_key($addr2, $type2, $keyid2);
	Echolot::Pinger::Mix::ping(
		$body,
		$to,
		0,
		[ $key1{'nick'}    , $key2{'nick'}     ],
		{ $keyid1 => \%key1, $keyid2 => \%key2 } ) or
		return 0;

	return 1;
};

sub do_cpunk_chainping($$$$$$$$) {
	my ($addr1, $type1, $keyid1, $addr2, $type2, $keyid2, $to, $body) = @_;

	my $keyhash = {};
	if ($type1 ne 'cpunk-clear') {
		my %key = Echolot::Globals::get()->{'storage'}->get_key($addr1, $type1, $keyid1);
		$keyhash->{$keyid1} = \%key;
	};
	if ($type2 ne 'cpunk-clear') {
		my %key = Echolot::Globals::get()->{'storage'}->get_key($addr2, $type2, $keyid2);
		$keyhash->{$keyid2} = \%key;
	};
	Echolot::Pinger::CPunk::ping(
		$body,
		$to,
		0,
		[ { address    => $addr1,
		    keyid      => $keyid1,
		    encrypt    => ($type1 ne 'cpunk-clear'),
		    pgp2compat => ($type1 eq 'cpunk-rsa') },
		  { address    => $addr2,
		    keyid      => $keyid2,
		    encrypt    => ($type2 ne 'cpunk-clear'),
		    pgp2compat => ($type2 eq 'cpunk-rsa') } ],
		$keyhash ) or
		return 0;

	return 1;
};

sub do_chainping($$$$$$$) {
	my ($chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2) = @_;
	
	my $now = time();
	my $token = join(':', $chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2, $now);
	my $mac = Echolot::Tools::make_mac($token);
	my $body = "chaintype: $chaintype\n".
		"remailer1: $addr1\n".
		"type1: $type1\n".
		"key1: $key1\n".
		"remailer2: $addr2\n".
		"type2: $type2\n".
		"key2: $key2\n".
		"sent: $now\n".
		"mac: $mac\n".
		Echolot::Tools::make_garbage();
	$body = Echolot::Tools::crypt_symmetrically($body, 'encrypt');
		
	my $to = Echolot::Tools::make_address('chainping');
	if ($chaintype eq 'mix') {
		do_mix_chainping($addr1, $type1, $key1, $addr2, $type2, $key2, $to, $body);
	} elsif ($chaintype eq 'cpunk') {
		do_cpunk_chainping($addr1, $type1, $key1, $addr2, $type2, $key2, $to, $body);
	} else {
		Echolot::Log::warn("Don't know how to handle chain ping type $chaintype.");
		return 0;
	};

	Echolot::Globals::get()->{'storage'}->register_chainpingout($chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2, $now);
	return 1;
};

sub send_pings($;$$) {
	return 1 unless Echolot::Config::get()->{'do_chainpings'};

	my ($scheduled_for, $which1, $which2) = @_;

	$which1 = '' unless defined $which1;
	$which2 = '' unless defined $which2;

	my $call_intervall = Echolot::Config::get()->{'chainpinger_interval'};
	my $send_every_n_calls = Echolot::Config::get()->{'chainping_every_nth_time'};

	my $timemod = int ($scheduled_for / $call_intervall);
	my $this_call_id = $timemod % $send_every_n_calls;
	my $session_id = int ($scheduled_for / ($call_intervall * $send_every_n_calls));

	# Same thing for Intensive Care -- yet unknown or already broken chains
	my $send_every_n_calls_ic = Echolot::Config::get()->{'chainping_ic_every_nth_time'};

	my $timemod_ic = int ($scheduled_for / $call_intervall);
	my $this_call_id_ic = $timemod_ic % $send_every_n_calls_ic;
	my $session_id_ic = int ($scheduled_for / ($call_intervall * $send_every_n_calls_ic));

	my @remailers = Echolot::Globals::get()->{'storage'}->get_addresses();
	for my $chaintype (keys %{Echolot::Config::get()->{'which_chainpings'}}) {

		my @thisrems;
		for my $rem (@remailers) {
			next unless $rem->{'pingit'};
			my $addr = $rem->{'address'};
			my $type;
			my %supports = map { $_ => 1 } Echolot::Globals::get()->{'storage'}->get_types($addr);
			for my $thistype (@{Echolot::Config::get()->{'which_chainpings'}->{$chaintype}}) {
				$type = $thistype, last if $supports{$thistype};
			};
			next unless $type;
			my $key;
			my $latest = 0;
			for my $keyid (Echolot::Globals::get()->{'storage'}->get_keys($addr, $type)) {
				my %key = Echolot::Globals::get()->{'storage'}->get_key($addr, $type, $keyid);
				$key = $keyid, $latest = $key{'last_update'} if $latest < $key{'last_update'};
			};
			push @thisrems, { addr => $addr, type => $type, key => $key };
		};

		for my $rem1 (@thisrems) {
			my $addr1 = $rem1->{'addr'};

			next unless (
				$which1 eq 'all' ||
				$which1 eq $addr1 ||
				$which1 eq '');

			my $type1 = $rem1->{'type'};
			my $key1  = $rem1->{'key'};

			for my $rem2 (@thisrems) {
				my $addr2 = $rem2->{'addr'};
				next if $rem1 eq $rem2 && (! ($which1 eq $addr2 && $which2 eq $addr2));

				next unless (
					$which2 eq 'all' ||
					$which2 eq $addr2 ||
					$which2 eq '');

				my $type2 = $rem2->{'type'};
				my $key2  = $rem2->{'key'};

				my $call_id    = Echolot::Tools::makeShortNumHash($addr1.$addr2.$chaintype.$session_id   ) % $send_every_n_calls;
				my $call_id_ic = Echolot::Tools::makeShortNumHash($addr1.$addr2.$chaintype.$session_id_ic) % $send_every_n_calls_ic;
				next unless (
					(($which1 eq $addr1 || $which1 eq 'all' ) && ($which2 eq $addr2 ||  $which2 eq 'all')) ||
					(($which1 eq '' && $which2 eq '') && (
						$this_call_id eq $call_id ||
						(defined $INTENSIVE_CARE{$chaintype}->{$addr1.' '.$addr2} && $this_call_id_ic eq $call_id_ic))));

				Echolot::Log::debug("chainping calling $chaintype, $addr1 ($type1, $key1) - $addr2 ($type2, $key2)");
				do_chainping($chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2);
			};
		};
	};
	return 1;
};

sub set_intensive_care($@) {
	my ($chaintype, $intensive_care) = @_;

	%{$INTENSIVE_CARE{$chaintype}} = map { ($_->{'addr1'}.' '.$_->{'addr2'}) => $_->{'reason'} } @$intensive_care;
	if (scalar @$intensive_care) {
		Echolot::Log::debug("intensive care $chaintype:\n" . join("\n", sort { $a cmp $b } map { "$_: $INTENSIVE_CARE{$chaintype}->{$_}" } keys %{$INTENSIVE_CARE{$chaintype}} ));
	} else {
		Echolot::Log::debug("intensive care $chaintype: (none)");
	};
};

sub receive($$$$) {
	my ($header, $msg, $token, $timestamp) = @_;

	my $now = time();

	my $body;
	if ($msg =~ /^-----BEGIN PGP MESSAGE-----/m) {
		# work around borken middleman remailers that have a problem with some
		# sort of end of line characters and randhopping them through reliable
		# remailers..
		# they add an empty line between each usefull line
		$msg =~ s/(\r?\n)\r?\n/$1/g if ($msg =~ /^-----BEGIN PGP MESSAGE-----\r?\n\r?\n/m);
		$body = Echolot::Tools::crypt_symmetrically($msg, 'decrypt');
	};
	$body = $msg unless defined $body;

	my ($chaintype) = $body =~ /^chaintype: (.*)$/m;
	my ($addr1) = $body =~ /^remailer1: (.*)$/m;
	my ($type1) = $body =~ /^type1: (.*)$/m;
	my ($key1) = $body =~ /^key1: (.*)$/m;
	my ($addr2) = $body =~ /^remailer2: (.*)$/m;
	my ($type2) = $body =~ /^type2: (.*)$/m;
	my ($key2) = $body =~ /^key2: (.*)$/m;
	my ($sent) = $body =~ /^sent: (.*)$/m;
	my ($mac) = $body =~ /^mac: (.*)$/m;

	my @values = ($chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2, $sent, $mac);
	my $cleanstring = join ":", map { defined() ? $_ : "undef" } @values;

	(grep { ! defined() } @values) and
		Echolot::Log::warn("Received chainping at $timestamp has undefined values: $cleanstring."),
		return 0;

	pop @values;
	Echolot::Tools::verify_mac(join(':', @values), $mac) or
		Echolot::Log::warn("Received chainping at $timestamp has wrong mac; $cleanstring."),
		return 0;

	Echolot::Globals::get()->{'storage'}->register_chainpingdone($chaintype, $addr1, $type1, $key1, $addr2, $type2, $key2, $sent, $now - $sent) or
		return 0;
	
	return 1;
};

1;
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