AnyEvent-MP/MP/Transport.pm

=head1 NAME

AnyEvent::MP::Transport - actual transport protocol handler

=head1 SYNOPSIS

   use AnyEvent::MP::Transport;

=head1 DESCRIPTION

This implements the actual transport protocol for MP (it represents a
single link), most of which is considered an implementation detail.

See the "PROTOCOL" section below if you want to write another client for
this protocol.

=head1 FUNCTIONS/METHODS

=over 4

=cut

package AnyEvent::MP::Transport;

use common::sense;

use Scalar::Util ();
use List::Util ();
use MIME::Base64 ();
use Storable ();
use JSON::XS ();

use Digest::MD6 ();
use Digest::HMAC_MD6 ();

use AE ();
use AnyEvent::Socket ();
use AnyEvent::Handle 4.92 ();

use AnyEvent::MP::Config ();

our $PROTOCOL_VERSION = 0;

=item $listener = mp_listener $host, $port, <constructor-args>, $cb->($transport)

Creates a listener on the given host/port using
C<AnyEvent::Socket::tcp_server>.

See C<new>, below, for constructor arguments.

Defaults for peerhost, peerport and fh are provided.

=cut

sub mp_server($$@) {
   my $cb = pop;
   my ($host, $port, @args) = @_;

   AnyEvent::Socket::tcp_server $host, $port, sub {
      my ($fh, $host, $port) = @_;

      $cb->(new AnyEvent::MP::Transport
         fh       => $fh,
         peerhost => $host,
         peerport => $port,
         @args,
      );
   }
}

=item $guard = mp_connect $host, $port, <constructor-args>, $cb->($transport)

=cut

sub mp_connect {
   my $release = pop;
   my ($host, $port, @args) = @_;

   my $state;

   $state = AnyEvent::Socket::tcp_connect $host, $port, sub {
      my ($fh, $nhost, $nport) = @_;

      return $release->() unless $fh;

      $state = new AnyEvent::MP::Transport
         fh       => $fh,
         peername => $host,
         peerhost => $nhost,
         peerport => $nport,
         release  => $release,
         @args,
      ;
   };

   \$state
}

=item new AnyEvent::MP::Transport

   # immediately starts negotiation
   my $transport = new AnyEvent::MP::Transport
      # mandatory
      fh       => $filehandle,
      local_id => $identifier,
      on_recv  => sub { receive-callback },
      on_error => sub { error-callback },

      # optional
      on_eof   => sub { clean-close-callback },
      on_connect => sub { successful-connect-callback },
      greeting => { key => value },

      # tls support
      tls_ctx  => AnyEvent::TLS,
      peername => $peername, # for verification
   ;

=cut

sub LATENCY() { 3 } # assumed max. network latency

our @FRAMINGS = qw(json storable); # the framing types we accept and send, in order of preference
our @AUTH_SND = qw(hmac_md6_64_256); # auth types we send
our @AUTH_RCV = (@AUTH_SND, qw(cleartext)); # auth types we accept

#AnyEvent::Handle::register_write_type mp_record => sub {
#};

sub new {
   my ($class, %arg) = @_;

   my $self = bless \%arg, $class;

   $self->{queue} = [];

   {
      Scalar::Util::weaken (my $self = $self);

      my $config = AnyEvent::MP::Config::config;

      my $latency = $config->{network_latency} || LATENCY;

      $arg{secret} = $config->{secret}
         unless exists $arg{secret};

      $arg{timeout} = $config->{monitor_timeout} || $AnyEvent::MP::Kernel::MONITOR_TIMEOUT
         unless exists $arg{timeout};

      $arg{timeout} -= $latency;

      $arg{timeout} = 1 + $latency
         if $arg{timeout} < 1 + $latency;

      my $secret = $arg{secret};

      if (exists $config->{cert}) {
         $arg{tls_ctx} = {
            sslv2   => 0,
            sslv3   => 0,
            tlsv1   => 1,
            verify  => 1,
            cert    => $config->{cert},
            ca_cert => $config->{cert},
            verify_require_client_cert => 1,
         };
      }

      $self->{hdl} = new AnyEvent::Handle
         fh       => delete $arg{fh},
         autocork => 1,
         no_delay => 1,
         on_error => sub {
            $self->error ($_[2]);
         },
         rtimeout => $latency,
         peername => delete $arg{peername},
      ;

      my $greeting_kv = $self->{greeting} ||= {};

      $self->{local_node} = $AnyEvent::MP::Kernel::NODE;

      $greeting_kv->{"tls"}    = "1.0" if $arg{tls_ctx};
      $greeting_kv->{provider} = "AE-$AnyEvent::MP::Kernel::VERSION";
      $greeting_kv->{peeraddr} = AnyEvent::Socket::format_hostport $self->{peerhost}, $self->{peerport};
      $greeting_kv->{timeout}  = $arg{timeout};

      # send greeting
      my $lgreeting1 = "aemp;$PROTOCOL_VERSION"
                     . ";$self->{local_node}"
                     . ";" . (join ",", @AUTH_RCV)
                     . ";" . (join ",", @FRAMINGS)
                     . (join "", map ";$_=$greeting_kv->{$_}", keys %$greeting_kv);

      my $lgreeting2 = MIME::Base64::encode_base64 AnyEvent::MP::Kernel::nonce (66), "";

      $self->{hdl}->push_write ("$lgreeting1\012$lgreeting2\012");

      # expect greeting
      $self->{hdl}->rbuf_max (4 * 1024);
      $self->{hdl}->push_read (line => sub {
         my $rgreeting1 = $_[1];

         my ($aemp, $version, $rnode, $auths, $framings, @kv) = split /;/, $rgreeting1;

         if ($aemp ne "aemp") {
            return $self->error ("unparsable greeting");
         } elsif ($version != $PROTOCOL_VERSION) {
            return $self->error ("version mismatch (we: $PROTOCOL_VERSION, they: $version)");
         }

         my $s_auth;
         for my $auth_ (split /,/, $auths) {
            if (grep $auth_ eq $_, @AUTH_SND) {
               $s_auth = $auth_;
               last;
            }
         }

         defined $s_auth
            or return $self->error ("$auths: no common auth type supported");

         die unless $s_auth eq "hmac_md6_64_256"; # hardcoded atm.

         my $s_framing;
         for my $framing_ (split /,/, $framings) {
            if (grep $framing_ eq $_, @FRAMINGS) {
               $s_framing = $framing_;
               last;
            }
         }

         defined $s_framing
            or return $self->error ("$framings: no common framing method supported");

         $self->{remote_node} = $rnode;

         $self->{remote_greeting} = {
            map /^([^=]+)(?:=(.*))?/ ? ($1 => $2) : (),
               @kv
         };

         # read nonce
         $self->{hdl}->push_read (line => sub {
            my $rgreeting2 = $_[1];

            "$lgreeting1\012$lgreeting2" ne "$rgreeting1\012$rgreeting2" # echo attack?
               or return $self->error ("authentication error, echo attack?");

            my $key;
            my $lauth;

            if ($self->{tls_ctx} and 1 == int $self->{remote_greeting}{tls}) {
               $self->{tls} = $lgreeting2 lt $rgreeting2 ? "connect" : "accept";
               $self->{hdl}->starttls ($self->{tls}, $self->{tls_ctx});
               $s_auth = "tls";
               $lauth = "";
            } elsif (length $secret) {
               $key = Digest::MD6::md6 $secret;
               # we currently only support hmac_md6_64_256
               $lauth = Digest::HMAC_MD6::hmac_md6_hex $key, "$lgreeting1\012$lgreeting2\012$rgreeting1\012$rgreeting2\012", 64, 256;
            } else {
               return $self->error ("unable to handshake TLS and no shared secret configured");
            }

            $self->{hdl}->push_write ("$s_auth;$lauth;$s_framing\012");

            # read the authentication response
            $self->{hdl}->push_read (line => sub {
               my ($hdl, $rline) = @_;

               my ($auth_method, $rauth2, $r_framing) = split /;/, $rline;

               my $rauth =
                  $auth_method eq "hmac_md6_64_256" ? Digest::HMAC_MD6::hmac_md6_hex $key, "$rgreeting1\012$rgreeting2\012$lgreeting1\012$lgreeting2\012", 64, 256
                : $auth_method eq "cleartext"       ? unpack "H*", $secret
                : $auth_method eq "tls"             ? ($self->{tls} ? "" : "\012\012") # \012\012 never matches
                : return $self->error ("$auth_method: fatal, selected unsupported auth method");

               if ($rauth2 ne $rauth) {
                  return $self->error ("authentication failure/shared secret mismatch");
               }

               $self->{s_framing} = $s_framing;

               $hdl->rbuf_max (undef);
               my $queue = delete $self->{queue}; # we are connected

               $self->{hdl}->rtimeout ($self->{remote_greeting}{timeout});
               $self->{hdl}->wtimeout ($arg{timeout} - LATENCY);
               $self->{hdl}->on_wtimeout (sub { $self->send ([]) });

               $self->connected;

               # send queued messages
               $self->send ($_)
                  for @$queue;

               # receive handling
               my $src_node = $self->{node};

               my $rmsg; $rmsg = sub {
                  $_[0]->push_read ($r_framing => $rmsg);

                  local $AnyEvent::MP::Kernel::SRCNODE = $src_node;
                  AnyEvent::MP::Kernel::_inject (@{ $_[1] });
               };
               $hdl->push_read ($r_framing => $rmsg);
            });
         });
      });
   }

   $self
}

sub error {
   my ($self, $msg) = @_;

   $self->{node}->transport_error (transport_error => $self->{node}{noderef}, $msg)
      if $self->{node} && $self->{node}{transport} == $self;

   (delete $self->{release})->()
      if exists $self->{release};
   
   $AnyEvent::MP::Kernel::WARN->("$self->{peerhost}:$self->{peerport}: $msg");
   $self->destroy;
}

sub connected {
   my ($self) = @_;

   (delete $self->{release})->()
      if exists $self->{release};

   my $node = AnyEvent::MP::Kernel::add_node ($self->{remote_node});
   Scalar::Util::weaken ($self->{node} = $node);
   $node->transport_connect ($self);
}

sub send {
   $_[0]{hdl}->push_write ($_[0]{s_framing} => $_[1]);
}

sub destroy {
   my ($self) = @_;

   $self->{hdl}->destroy
      if $self->{hdl};
}

sub DESTROY {
   my ($self) = @_;

   $self->destroy;
}

=back

=head1 PROTOCOL

The protocol is relatively simple, and consists of three phases which are
symmetrical for both sides: greeting (followed by optionally switching to
TLS mode), authentication and packet exchange.

the protocol is designed to allow both full-text and binary streams.

The greeting consists of two text lines that are ended by either an ASCII
CR LF pair, or a single ASCII LF (recommended).

=head2 GREETING

All the lines until after authentication must not exceed 4kb in length,
including delimiter. Afterwards there is no limit on the packet size that
can be received.

=head3 First Greeting Line

Example:

   aemp;0;fec.4a7720fc;127.0.0.1:1235,[::1]:1235;hmac_md6_64_256;json,storable;provider=AE-0.0

The first line contains strings separated (not ended) by C<;>
characters. The first even ixtrings are fixed by the protocol, the
remaining strings are C<KEY=VALUE> pairs. None of them may contain C<;>
characters themselves.

The fixed strings are:

=over 4

=item protocol identification

The constant C<aemp> to identify the protocol.

=item protocol version

The protocol version supported by this end, currently C<0>. If the
versions don't match then no communication is possible. Minor extensions
are supposed to be handled through additional key-value pairs.

=item the node endpoint descriptors

for public nodes, this is a comma-separated list of protocol endpoints,
i.e., the noderef. For slave nodes, this is a unique identifier of the
form C<slave/nonce>.

=item the acceptable authentication methods

A comma-separated list of authentication methods supported by the
node. Note that AnyEvent::MP supports a C<hex_secret> authentication
method that accepts a cleartext password (hex-encoded), but will not use
this auth method itself.

The receiving side should choose the first auth method it supports.

=item the acceptable framing formats

A comma-separated list of packet encoding/framign formats understood. The
receiving side should choose the first framing format it supports for
sending packets (which might be different from the format it has to accept).

=back

The remaining arguments are C<KEY=VALUE> pairs. The following key-value
pairs are known at this time:

=over 4

=item provider=<module-version>

The software provider for this implementation. For AnyEvent::MP, this is
C<AE-0.0> or whatever version it currently is at.

=item peeraddr=<host>:<port>

The peer address (socket address of the other side) as seen locally, in the same format
as noderef endpoints.

=item tls=<major>.<minor>

Indicates that the other side supports TLS (version should be 1.0) and
wishes to do a TLS handshake.

=item timeout=<seconds>

The amount of time after which this node should be detected as dead unless
some data has been received. The node is responsible to send traffic
reasonably more often than this interval (such as every timeout minus five
seconds).

=back

=head3 Second Greeting Line

After this greeting line there will be a second line containing a
cryptographic nonce, i.e. random data of high quality. To keep the
protocol text-only, these are usually 32 base64-encoded octets, but
it could be anything that doesn't contain any ASCII CR or ASCII LF
characters.

I<< The two nonces B<must> be different, and an aemp implementation
B<must> check and fail when they are identical >>.

Example of a nonce line:

   p/I122ql7kJR8lumW3lXlXCeBnyDAvz8NQo3x5IFowE4

=head2 TLS handshake

I<< If, after the handshake, both sides indicate interest in TLS, then the
connection B<must> use TLS, or fail. >>

Both sides compare their nonces, and the side who sent the lower nonce
value ("string" comparison on the raw octet values) becomes the client,
and the one with the higher nonce the server.

=head2 AUTHENTICATION PHASE

After the greeting is received (and the optional TLS handshake),
the authentication phase begins, which consists of sending a single
C<;>-separated line with three fixed strings and any number of
C<KEY=VALUE> pairs.

The three fixed strings are:

=over 4

=item the authentication method chosen

This must be one of the methods offered by the other side in the greeting.

The currently supported authentication methods are:

=over 4

=item cleartext

This is simply the shared secret, lowercase-hex-encoded. This method is of
course very insecure, unless TLS is used, which is why this module will
accept, but not generate, cleartext auth replies.

=item hmac_md6_64_256

This method uses an MD6 HMAC with 64 bit blocksize and 256 bit hash. First, the shared secret
is hashed with MD6:

   key = MD6 (secret)

This secret is then used to generate the "local auth reply", by taking
the two local greeting lines and the two remote greeting lines (without
line endings), appending \012 to all of them, concatenating them and
calculating the MD6 HMAC with the key.

   lauth = HMAC_MD6 key, "lgreeting1\012lgreeting2\012rgreeting1\012rgreeting2\012"

This authentication token is then lowercase-hex-encoded and sent to the
other side.

Then the remote auth reply is generated using the same method, but local
and remote greeting lines swapped:

   rauth = HMAC_MD6 key, "rgreeting1\012rgreeting2\012lgreeting1\012lgreeting2\012"

This is the token that is expected from the other side.

=item tls

This type is only valid iff TLS was enabled and the TLS handshake
was successful. It has no authentication data, as the server/client
certificate was successfully verified.

Implementations supporting TLS I<must> accept this authentication type.

=back

=item the authentication data

The authentication data itself, usually base64 or hex-encoded data, see
above.

=item the framing protocol chosen

This must be one of the framing protocols offered by the other side in the
greeting. Each side must accept the choice of the other side.

=back

Example of an authentication reply:

   hmac_md6_64_256;363d5175df38bd9eaddd3f6ca18aa1c0c4aa22f0da245ac638d048398c26b8d3;json

=head2 DATA PHASE

After this, packets get exchanged using the chosen framing protocol. It is
quite possible that both sides use a different framing protocol.

=head2 FULL EXAMPLE

This is an actual protocol dump of a handshake, followed by a single data
packet. The greater than/less than lines indicate the direction of the
transfer only.

   > aemp;0;nndKd+gn;10.0.0.1:4040;hmac_md6_64_256,cleartext;json,storable;provider=AE-0.0;peeraddr=127.0.0.1:1235
   > sRG8bbc4TDbkpvH8FTP4HBs87OhepH6VuApoZqXXskuG
   < aemp;0;nmpKd+gh;127.0.0.1:1235,[::1]:1235;hmac_md6_64_256,cleartext;json,storable;provider=AE-0.0;peeraddr=127.0.0.1:58760
   < dCEUcL/LJVSTJcx8byEsOzrwhzJYOq+L3YcopA5T6EAo
   > hmac_md6_64_256;9513d4b258975accfcb2ab7532b83690e9c119a502c612203332a591c7237788;json
   < hmac_md6_64_256;0298d6ba2240faabb2b2e881cf86b97d70a113ca74a87dc006f9f1e9d3010f90;json
   > ["","lookup","pinger","10.0.0.1:4040#nndKd+gn.a","resolved"]

=head1 SEE ALSO

L<AnyEvent::MP>.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

1

Revision:	1.36
Committed:	Sat Aug 15 04:34:34 2009 UTC (14 years, 9 months ago) by root
Branch:	MAIN
Changes since 1.35:	+1 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3	root	1.13	AnyEvent::MP::Transport - actual transport protocol handler
4	root	1.1
5			=head1 SYNOPSIS
6
7			use AnyEvent::MP::Transport;
8
9			=head1 DESCRIPTION
10
11	root	1.13	This implements the actual transport protocol for MP (it represents a
12			single link), most of which is considered an implementation detail.
13	root	1.1
14	root	1.7	See the "PROTOCOL" section below if you want to write another client for
15			this protocol.
16	root	1.1
17			=head1 FUNCTIONS/METHODS
18
19			=over 4
20
21			=cut
22
23			package AnyEvent::MP::Transport;
24
25			use common::sense;
26
27	root	1.27	use Scalar::Util ();
28			use List::Util ();
29	root	1.1	use MIME::Base64 ();
30			use Storable ();
31	root	1.2	use JSON::XS ();
32	root	1.1
33	root	1.19	use Digest::MD6 ();
34			use Digest::HMAC_MD6 ();
35
36	root	1.1	use AE ();
37			use AnyEvent::Socket ();
38	root	1.27	use AnyEvent::Handle 4.92 ();
39	root	1.2
40	root	1.30	use AnyEvent::MP::Config ();
41
42	root	1.2	our $PROTOCOL_VERSION = 0;
43	root	1.1
44			=item $listener = mp_listener $host, $port, <constructor-args>, $cb->($transport)
45
46			Creates a listener on the given host/port using
47			C<AnyEvent::Socket::tcp_server>.
48
49			See C<new>, below, for constructor arguments.
50
51	root	1.10	Defaults for peerhost, peerport and fh are provided.
52	root	1.1
53			=cut
54
55			sub mp_server($$@) {
56			my $cb = pop;
57			my ($host, $port, @args) = @_;
58
59			AnyEvent::Socket::tcp_server $host, $port, sub {
60			my ($fh, $host, $port) = @_;
61
62			$cb->(new AnyEvent::MP::Transport
63			fh => $fh,
64			peerhost => $host,
65			peerport => $port,
66			@args,
67			);
68			}
69			}
70
71	root	1.2	=item $guard = mp_connect $host, $port, <constructor-args>, $cb->($transport)
72
73			=cut
74
75			sub mp_connect {
76	root	1.31	my $release = pop;
77	root	1.2	my ($host, $port, @args) = @_;
78
79	root	1.31	my $state;
80
81			$state = AnyEvent::Socket::tcp_connect $host, $port, sub {
82	root	1.2	my ($fh, $nhost, $nport) = @_;
83
84	root	1.31	return $release->() unless $fh;
85	root	1.2
86	root	1.31	$state = new AnyEvent::MP::Transport
87	root	1.2	fh => $fh,
88			peername => $host,
89			peerhost => $nhost,
90			peerport => $nport,
91	root	1.31	release => $release,
92	root	1.2	@args,
93	root	1.31	;
94			};
95
96			\$state
97	root	1.2	}
98
99	root	1.1	=item new AnyEvent::MP::Transport
100
101			# immediately starts negotiation
102			my $transport = new AnyEvent::MP::Transport
103	root	1.2	# mandatory
104	root	1.1	fh => $filehandle,
105	root	1.2	local_id => $identifier,
106	root	1.1	on_recv => sub { receive-callback },
107			on_error => sub { error-callback },
108
109			# optional
110			on_eof => sub { clean-close-callback },
111			on_connect => sub { successful-connect-callback },
112	root	1.2	greeting => { key => value },
113	root	1.1
114			# tls support
115			tls_ctx => AnyEvent::TLS,
116			peername => $peername, # for verification
117			;
118
119			=cut
120
121	root	1.27	sub LATENCY() { 3 } # assumed max. network latency
122
123	root	1.34	our @FRAMINGS = qw(json storable); # the framing types we accept and send, in order of preference
124	root	1.7	our @AUTH_SND = qw(hmac_md6_64_256); # auth types we send
125	root	1.13	our @AUTH_RCV = (@AUTH_SND, qw(cleartext)); # auth types we accept
126	root	1.7
127			#AnyEvent::Handle::register_write_type mp_record => sub {
128			#};
129	root	1.4
130	root	1.1	sub new {
131			my ($class, %arg) = @_;
132
133			my $self = bless \%arg, $class;
134
135			$self->{queue} = [];
136
137			{
138			Scalar::Util::weaken (my $self = $self);
139
140	root	1.33	my $config = AnyEvent::MP::Config::config;
141	root	1.30
142	root	1.31	my $latency = $config->{network_latency} \|\| LATENCY;
143
144	root	1.30	$arg{secret} = $config->{secret}
145	root	1.2	unless exists $arg{secret};
146
147	root	1.31	$arg{timeout} = $config->{monitor_timeout} \|\| $AnyEvent::MP::Kernel::MONITOR_TIMEOUT
148	root	1.24	unless exists $arg{timeout};
149
150	root	1.31	$arg{timeout} -= $latency;
151
152			$arg{timeout} = 1 + $latency
153			if $arg{timeout} < 1 + $latency;
154	root	1.27
155	root	1.19	my $secret = $arg{secret};
156
157	root	1.30	if (exists $config->{cert}) {
158	root	1.19	$arg{tls_ctx} = {
159			sslv2 => 0,
160			sslv3 => 0,
161			tlsv1 => 1,
162			verify => 1,
163	root	1.30	cert => $config->{cert},
164			ca_cert => $config->{cert},
165	root	1.19	verify_require_client_cert => 1,
166			};
167			}
168
169	root	1.1	$self->{hdl} = new AnyEvent::Handle
170	root	1.2	fh => delete $arg{fh},
171	root	1.4	autocork => 1,
172			no_delay => 1,
173	root	1.1	on_error => sub {
174			$self->error ($_[2]);
175			},
176	root	1.31	rtimeout => $latency,
177	root	1.1	peername => delete $arg{peername},
178			;
179
180	root	1.2	my $greeting_kv = $self->{greeting} \|\|= {};
181	root	1.24
182	root	1.31	$self->{local_node} = $AnyEvent::MP::Kernel::NODE;
183	root	1.24
184			$greeting_kv->{"tls"} = "1.0" if $arg{tls_ctx};
185	root	1.31	$greeting_kv->{provider} = "AE-$AnyEvent::MP::Kernel::VERSION";
186	root	1.7	$greeting_kv->{peeraddr} = AnyEvent::Socket::format_hostport $self->{peerhost}, $self->{peerport};
187	root	1.26	$greeting_kv->{timeout} = $arg{timeout};
188	root	1.23
189	root	1.1	# send greeting
190	root	1.12	my $lgreeting1 = "aemp;$PROTOCOL_VERSION"
191	root	1.24	. ";$self->{local_node}"
192	root	1.7	. ";" . (join ",", @AUTH_RCV)
193			. ";" . (join ",", @FRAMINGS)
194			. (join "", map ";$_=$greeting_kv->{$_}", keys %$greeting_kv);
195	root	1.12
196	root	1.31	my $lgreeting2 = MIME::Base64::encode_base64 AnyEvent::MP::Kernel::nonce (66), "";
197	root	1.1
198	root	1.7	$self->{hdl}->push_write ("$lgreeting1\012$lgreeting2\012");
199	root	1.1
200			# expect greeting
201	root	1.12	$self->{hdl}->rbuf_max (4 * 1024);
202	root	1.1	$self->{hdl}->push_read (line => sub {
203	root	1.7	my $rgreeting1 = $_[1];
204	root	1.1
205	root	1.26	my ($aemp, $version, $rnode, $auths, $framings, @kv) = split /;/, $rgreeting1;
206	root	1.1
207			if ($aemp ne "aemp") {
208			return $self->error ("unparsable greeting");
209	root	1.12	} elsif ($version != $PROTOCOL_VERSION) {
210			return $self->error ("version mismatch (we: $PROTOCOL_VERSION, they: $version)");
211	root	1.1	}
212
213	root	1.7	my $s_auth;
214			for my $auth_ (split /,/, $auths) {
215			if (grep $auth_ eq $_, @AUTH_SND) {
216			$s_auth = $auth_;
217			last;
218			}
219			}
220
221			defined $s_auth
222			or return $self->error ("$auths: no common auth type supported");
223
224			die unless $s_auth eq "hmac_md6_64_256"; # hardcoded atm.
225
226			my $s_framing;
227			for my $framing_ (split /,/, $framings) {
228			if (grep $framing_ eq $_, @FRAMINGS) {
229			$s_framing = $framing_;
230			last;
231			}
232			}
233
234			defined $s_framing
235			or return $self->error ("$framings: no common framing method supported");
236
237	root	1.2	$self->{remote_node} = $rnode;
238	root	1.1
239	root	1.2	$self->{remote_greeting} = {
240			map /^([^=]+)(?:=(.*))?/ ? ($1 => $2) : (),
241			@kv
242	root	1.1	};
243
244	root	1.7	# read nonce
245			$self->{hdl}->push_read (line => sub {
246			my $rgreeting2 = $_[1];
247
248	root	1.19	"$lgreeting1\012$lgreeting2" ne "$rgreeting1\012$rgreeting2" # echo attack?
249			or return $self->error ("authentication error, echo attack?");
250
251	root	1.30	my $key;
252	root	1.19	my $lauth;
253
254	root	1.10	if ($self->{tls_ctx} and 1 == int $self->{remote_greeting}{tls}) {
255	root	1.8	$self->{tls} = $lgreeting2 lt $rgreeting2 ? "connect" : "accept";
256			$self->{hdl}->starttls ($self->{tls}, $self->{tls_ctx});
257	root	1.19	$s_auth = "tls";
258			$lauth = "";
259	root	1.30	} elsif (length $secret) {
260			$key = Digest::MD6::md6 $secret;
261	root	1.19	# we currently only support hmac_md6_64_256
262			$lauth = Digest::HMAC_MD6::hmac_md6_hex $key, "$lgreeting1\012$lgreeting2\012$rgreeting1\012$rgreeting2\012", 64, 256;
263	root	1.30	} else {
264			return $self->error ("unable to handshake TLS and no shared secret configured");
265	root	1.8	}
266	root	1.2
267	root	1.7	$self->{hdl}->push_write ("$s_auth;$lauth;$s_framing\012");
268	root	1.2
269	root	1.19	# read the authentication response
270	root	1.7	$self->{hdl}->push_read (line => sub {
271			my ($hdl, $rline) = @_;
272	root	1.2
273	root	1.7	my ($auth_method, $rauth2, $r_framing) = split /;/, $rline;
274	root	1.1
275	root	1.19	my $rauth =
276			$auth_method eq "hmac_md6_64_256" ? Digest::HMAC_MD6::hmac_md6_hex $key, "$rgreeting1\012$rgreeting2\012$lgreeting1\012$lgreeting2\012", 64, 256
277			: $auth_method eq "cleartext" ? unpack "H*", $secret
278			: $auth_method eq "tls" ? ($self->{tls} ? "" : "\012\012") # \012\012 never matches
279			: return $self->error ("$auth_method: fatal, selected unsupported auth method");
280
281	root	1.7	if ($rauth2 ne $rauth) {
282			return $self->error ("authentication failure/shared secret mismatch");
283			}
284	root	1.1
285	root	1.7	$self->{s_framing} = $s_framing;
286	root	1.2
287	root	1.7	$hdl->rbuf_max (undef);
288			my $queue = delete $self->{queue}; # we are connected
289	root	1.1
290	root	1.27	$self->{hdl}->rtimeout ($self->{remote_greeting}{timeout});
291			$self->{hdl}->wtimeout ($arg{timeout} - LATENCY);
292	root	1.36	$self->{hdl}->on_wtimeout (sub { $self->send ([]) });
293	root	1.24
294	root	1.7	$self->connected;
295	root	1.1
296	root	1.27	# send queued messages
297	root	1.23	$self->send ($_)
298	root	1.7	for @$queue;
299	root	1.1
300	root	1.27	# receive handling
301			my $src_node = $self->{node};
302
303	root	1.22	my $rmsg; $rmsg = sub {
304	root	1.7	$_[0]->push_read ($r_framing => $rmsg);
305	root	1.1
306	root	1.31	local $AnyEvent::MP::Kernel::SRCNODE = $src_node;
307			AnyEvent::MP::Kernel::_inject (@{ $_[1] });
308	root	1.7	};
309			$hdl->push_read ($r_framing => $rmsg);
310			});
311	root	1.1	});
312			});
313			}
314
315			$self
316			}
317
318			sub error {
319			my ($self, $msg) = @_;
320
321	root	1.31	$self->{node}->transport_error (transport_error => $self->{node}{noderef}, $msg)
322			if $self->{node} && $self->{node}{transport} == $self;
323
324			(delete $self->{release})->()
325			if exists $self->{release};
326
327			$AnyEvent::MP::Kernel::WARN->("$self->{peerhost}:$self->{peerport}: $msg");
328	root	1.4	$self->destroy;
329	root	1.1	}
330
331	root	1.2	sub connected {
332			my ($self) = @_;
333
334	root	1.31	(delete $self->{release})->()
335			if exists $self->{release};
336	root	1.23
337	root	1.31	my $node = AnyEvent::MP::Kernel::add_node ($self->{remote_node});
338	root	1.4	Scalar::Util::weaken ($self->{node} = $node);
339	root	1.31	$node->transport_connect ($self);
340	root	1.2	}
341
342	root	1.1	sub send {
343	root	1.2	$_[0]{hdl}->push_write ($_[0]{s_framing} => $_[1]);
344	root	1.1	}
345
346			sub destroy {
347			my ($self) = @_;
348
349	root	1.2	$self->{hdl}->destroy
350			if $self->{hdl};
351	root	1.1	}
352
353			sub DESTROY {
354			my ($self) = @_;
355
356			$self->destroy;
357			}
358
359			=back
360
361	root	1.7	=head1 PROTOCOL
362
363			The protocol is relatively simple, and consists of three phases which are
364			symmetrical for both sides: greeting (followed by optionally switching to
365			TLS mode), authentication and packet exchange.
366
367			the protocol is designed to allow both full-text and binary streams.
368
369			The greeting consists of two text lines that are ended by either an ASCII
370			CR LF pair, or a single ASCII LF (recommended).
371
372			=head2 GREETING
373
374	root	1.15	All the lines until after authentication must not exceed 4kb in length,
375			including delimiter. Afterwards there is no limit on the packet size that
376			can be received.
377
378			=head3 First Greeting Line
379	root	1.12
380	root	1.16	Example:
381
382			aemp;0;fec.4a7720fc;127.0.0.1:1235,[::1]:1235;hmac_md6_64_256;json,storable;provider=AE-0.0
383
384			The first line contains strings separated (not ended) by C<;>
385			characters. The first even ixtrings are fixed by the protocol, the
386			remaining strings are C<KEY=VALUE> pairs. None of them may contain C<;>
387			characters themselves.
388
389	root	1.12	The fixed strings are:
390	root	1.7
391			=over 4
392
393	root	1.18	=item protocol identification
394	root	1.7
395			The constant C<aemp> to identify the protocol.
396
397			=item protocol version
398
399	root	1.12	The protocol version supported by this end, currently C<0>. If the
400			versions don't match then no communication is possible. Minor extensions
401	root	1.18	are supposed to be handled through additional key-value pairs.
402	root	1.7
403			=item the node endpoint descriptors
404
405			for public nodes, this is a comma-separated list of protocol endpoints,
406	root	1.26	i.e., the noderef. For slave nodes, this is a unique identifier of the
407			form C<slave/nonce>.
408	root	1.7
409			=item the acceptable authentication methods
410
411			A comma-separated list of authentication methods supported by the
412			node. Note that AnyEvent::MP supports a C<hex_secret> authentication
413			method that accepts a cleartext password (hex-encoded), but will not use
414			this auth method itself.
415
416			The receiving side should choose the first auth method it supports.
417
418			=item the acceptable framing formats
419
420			A comma-separated list of packet encoding/framign formats understood. The
421			receiving side should choose the first framing format it supports for
422			sending packets (which might be different from the format it has to accept).
423
424	root	1.10	=back
425	root	1.8
426			The remaining arguments are C<KEY=VALUE> pairs. The following key-value
427			pairs are known at this time:
428
429			=over 4
430
431			=item provider=<module-version>
432
433			The software provider for this implementation. For AnyEvent::MP, this is
434			C<AE-0.0> or whatever version it currently is at.
435
436			=item peeraddr=<host>:<port>
437
438			The peer address (socket address of the other side) as seen locally, in the same format
439			as noderef endpoints.
440
441			=item tls=<major>.<minor>
442
443			Indicates that the other side supports TLS (version should be 1.0) and
444			wishes to do a TLS handshake.
445
446	root	1.26	=item timeout=<seconds>
447	root	1.24
448	root	1.26	The amount of time after which this node should be detected as dead unless
449			some data has been received. The node is responsible to send traffic
450			reasonably more often than this interval (such as every timeout minus five
451			seconds).
452	root	1.24
453	root	1.8	=back
454
455	root	1.15	=head3 Second Greeting Line
456
457	root	1.8	After this greeting line there will be a second line containing a
458			cryptographic nonce, i.e. random data of high quality. To keep the
459			protocol text-only, these are usually 32 base64-encoded octets, but
460			it could be anything that doesn't contain any ASCII CR or ASCII LF
461			characters.
462
463	root	1.14	I<< The two nonces B<must> be different, and an aemp implementation
464			B<must> check and fail when they are identical >>.
465
466	root	1.16	Example of a nonce line:
467	root	1.8
468	root	1.12	p/I122ql7kJR8lumW3lXlXCeBnyDAvz8NQo3x5IFowE4
469	root	1.8
470			=head2 TLS handshake
471
472	root	1.14	I<< If, after the handshake, both sides indicate interest in TLS, then the
473	root	1.20	connection B<must> use TLS, or fail. >>
474	root	1.8
475			Both sides compare their nonces, and the side who sent the lower nonce
476			value ("string" comparison on the raw octet values) becomes the client,
477			and the one with the higher nonce the server.
478
479			=head2 AUTHENTICATION PHASE
480
481			After the greeting is received (and the optional TLS handshake),
482			the authentication phase begins, which consists of sending a single
483			C<;>-separated line with three fixed strings and any number of
484			C<KEY=VALUE> pairs.
485
486			The three fixed strings are:
487
488			=over 4
489
490			=item the authentication method chosen
491
492			This must be one of the methods offered by the other side in the greeting.
493
494	root	1.13	The currently supported authentication methods are:
495
496			=over 4
497
498			=item cleartext
499
500			This is simply the shared secret, lowercase-hex-encoded. This method is of
501			course very insecure, unless TLS is used, which is why this module will
502			accept, but not generate, cleartext auth replies.
503
504			=item hmac_md6_64_256
505
506			This method uses an MD6 HMAC with 64 bit blocksize and 256 bit hash. First, the shared secret
507			is hashed with MD6:
508
509			key = MD6 (secret)
510
511			This secret is then used to generate the "local auth reply", by taking
512			the two local greeting lines and the two remote greeting lines (without
513			line endings), appending \012 to all of them, concatenating them and
514			calculating the MD6 HMAC with the key.
515
516			lauth = HMAC_MD6 key, "lgreeting1\012lgreeting2\012rgreeting1\012rgreeting2\012"
517
518			This authentication token is then lowercase-hex-encoded and sent to the
519			other side.
520
521			Then the remote auth reply is generated using the same method, but local
522			and remote greeting lines swapped:
523
524			rauth = HMAC_MD6 key, "rgreeting1\012rgreeting2\012lgreeting1\012lgreeting2\012"
525
526			This is the token that is expected from the other side.
527
528	root	1.19	=item tls
529
530			This type is only valid iff TLS was enabled and the TLS handshake
531			was successful. It has no authentication data, as the server/client
532			certificate was successfully verified.
533
534			Implementations supporting TLS I<must> accept this authentication type.
535
536	root	1.13	=back
537
538	root	1.8	=item the authentication data
539
540	root	1.13	The authentication data itself, usually base64 or hex-encoded data, see
541			above.
542	root	1.8
543			=item the framing protocol chosen
544
545			This must be one of the framing protocols offered by the other side in the
546			greeting. Each side must accept the choice of the other side.
547
548			=back
549
550	root	1.16	Example of an authentication reply:
551	root	1.9
552	root	1.13	hmac_md6_64_256;363d5175df38bd9eaddd3f6ca18aa1c0c4aa22f0da245ac638d048398c26b8d3;json
553	root	1.9
554	root	1.8	=head2 DATA PHASE
555
556			After this, packets get exchanged using the chosen framing protocol. It is
557			quite possible that both sides use a different framing protocol.
558
559	root	1.16	=head2 FULL EXAMPLE
560
561	root	1.17	This is an actual protocol dump of a handshake, followed by a single data
562	root	1.16	packet. The greater than/less than lines indicate the direction of the
563			transfer only.
564
565			> aemp;0;nndKd+gn;10.0.0.1:4040;hmac_md6_64_256,cleartext;json,storable;provider=AE-0.0;peeraddr=127.0.0.1:1235
566			> sRG8bbc4TDbkpvH8FTP4HBs87OhepH6VuApoZqXXskuG
567			< aemp;0;nmpKd+gh;127.0.0.1:1235,[::1]:1235;hmac_md6_64_256,cleartext;json,storable;provider=AE-0.0;peeraddr=127.0.0.1:58760
568			< dCEUcL/LJVSTJcx8byEsOzrwhzJYOq+L3YcopA5T6EAo
569			> hmac_md6_64_256;9513d4b258975accfcb2ab7532b83690e9c119a502c612203332a591c7237788;json
570			< hmac_md6_64_256;0298d6ba2240faabb2b2e881cf86b97d70a113ca74a87dc006f9f1e9d3010f90;json
571	root	1.18	> ["","lookup","pinger","10.0.0.1:4040#nndKd+gn.a","resolved"]
572	root	1.16
573	root	1.1	=head1 SEE ALSO
574
575	root	1.29	L<AnyEvent::MP>.
576	root	1.1
577			=head1 AUTHOR
578
579			Marc Lehmann <schmorp@schmorp.de>
580			http://home.schmorp.de/
581
582			=cut
583
584			1
585