1 |
=head1 NAME |
2 |
|
3 |
AnyEvent::MP::Transport - actual transport protocol handler |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use AnyEvent::MP::Transport; |
8 |
|
9 |
=head1 DESCRIPTION |
10 |
|
11 |
This module implements (and documents) the actual transport protocol for |
12 |
AEMP. |
13 |
|
14 |
See the "PROTOCOL" section below if you want to write another client for |
15 |
this protocol. |
16 |
|
17 |
=head1 FUNCTIONS/METHODS |
18 |
|
19 |
=over 4 |
20 |
|
21 |
=cut |
22 |
|
23 |
package AnyEvent::MP::Transport; |
24 |
|
25 |
use common::sense; |
26 |
|
27 |
use Scalar::Util (); |
28 |
use List::Util (); |
29 |
use MIME::Base64 (); |
30 |
use Storable (); |
31 |
use JSON::XS (); |
32 |
|
33 |
use Digest::MD6 (); |
34 |
use Digest::HMAC_MD6 (); |
35 |
|
36 |
use AE (); |
37 |
use AnyEvent::Socket (); |
38 |
use AnyEvent::Handle 4.92 (); |
39 |
|
40 |
use AnyEvent::MP::Config (); |
41 |
|
42 |
our $PROTOCOL_VERSION = 1; |
43 |
|
44 |
our @HOOK_GREET; # called at connect/accept time |
45 |
our @HOOK_GREETED; # called at greeting1 time |
46 |
our @HOOK_CONNECT; # called at data phase |
47 |
our @HOOK_DESTROY; # called at destroy time |
48 |
our %HOOK_PROTOCOL = ( |
49 |
"aemp-dataconn" => sub { |
50 |
require AnyEvent::MP::DataConn; |
51 |
&AnyEvent::MP::DataConn::_inject; |
52 |
}, |
53 |
); |
54 |
|
55 |
=item $listener = mp_server $host, $port, <constructor-args> |
56 |
|
57 |
Creates a listener on the given host/port using |
58 |
C<AnyEvent::Socket::tcp_server>. |
59 |
|
60 |
See C<new>, below, for constructor arguments. |
61 |
|
62 |
Defaults for peerhost, peerport and fh are provided. |
63 |
|
64 |
=cut |
65 |
|
66 |
sub mp_server($$;%) { |
67 |
my ($host, $port, %arg) = @_; |
68 |
|
69 |
AnyEvent::Socket::tcp_server $host, $port, sub { |
70 |
my ($fh, $host, $port) = @_; |
71 |
|
72 |
my $tp = new AnyEvent::MP::Transport |
73 |
fh => $fh, |
74 |
peerhost => $host, |
75 |
peerport => $port, |
76 |
%arg, |
77 |
; |
78 |
$tp->{keepalive} = $tp; |
79 |
}, delete $arg{prepare} |
80 |
} |
81 |
|
82 |
=item $guard = mp_connect $host, $port, <constructor-args>, $cb->($transport) |
83 |
|
84 |
=cut |
85 |
|
86 |
sub mp_connect { |
87 |
my $release = pop; |
88 |
my ($host, $port, @args) = @_; |
89 |
|
90 |
new AnyEvent::MP::Transport |
91 |
connect => [$host, $port], |
92 |
peerhost => $host, |
93 |
peerport => $port, |
94 |
release => $release, |
95 |
@args, |
96 |
; |
97 |
} |
98 |
|
99 |
=item new AnyEvent::MP::Transport |
100 |
|
101 |
Create a new transport - usually used via C<mp_server> or C<mp_connect> |
102 |
instead. |
103 |
|
104 |
# immediately starts negotiation |
105 |
my $transport = new AnyEvent::MP::Transport |
106 |
# mandatory |
107 |
fh => $filehandle, |
108 |
local_id => $identifier, |
109 |
on_recv => sub { receive-callback }, |
110 |
on_error => sub { error-callback }, |
111 |
|
112 |
# optional |
113 |
on_greet => sub { before sending greeting }, |
114 |
on_greeted => sub { after receiving greeting }, |
115 |
on_connect => sub { successful-connect-callback }, |
116 |
greeting => { key => value }, |
117 |
|
118 |
# tls support |
119 |
tls_ctx => AnyEvent::TLS, |
120 |
peername => $peername, # for verification |
121 |
; |
122 |
|
123 |
=cut |
124 |
|
125 |
sub new { |
126 |
my ($class, %arg) = @_; |
127 |
|
128 |
my $self = bless \%arg, $class; |
129 |
|
130 |
{ |
131 |
Scalar::Util::weaken (my $self = $self); |
132 |
|
133 |
my $config = $AnyEvent::MP::Kernel::CONFIG; |
134 |
|
135 |
my $timeout = $config->{monitor_timeout}; |
136 |
my $lframing = $config->{framing_format}; |
137 |
my $auth_snd = $config->{auth_offer}; |
138 |
my $auth_rcv = $config->{auth_accept}; |
139 |
|
140 |
$self->{secret} = $config->{secret} |
141 |
unless exists $self->{secret}; |
142 |
|
143 |
my $secret = $self->{secret}; |
144 |
|
145 |
if (exists $config->{cert}) { |
146 |
$self->{tls_ctx} = { |
147 |
sslv2 => 0, |
148 |
sslv3 => 0, |
149 |
tlsv1 => 1, |
150 |
verify => 1, |
151 |
cert => $config->{cert}, |
152 |
ca_cert => $config->{cert}, |
153 |
verify_require_client_cert => 1, |
154 |
}; |
155 |
} |
156 |
|
157 |
$self->{hdl} = new AnyEvent::Handle |
158 |
+($self->{fh} ? (fh => $self->{fh}) : (connect => $self->{connect})), |
159 |
autocork => $config->{autocork}, |
160 |
no_delay => exists $config->{nodelay} ? $config->{nodelay} : 1, |
161 |
keepalive => 1, |
162 |
on_error => sub { |
163 |
$self->error ($_[2]); |
164 |
}, |
165 |
rtimeout => $timeout, |
166 |
; |
167 |
|
168 |
my $greeting_kv = $self->{local_greeting} ||= {}; |
169 |
|
170 |
$greeting_kv->{tls} = "1.0" if $self->{tls_ctx}; |
171 |
$greeting_kv->{provider} = "AE-$AnyEvent::MP::Config::VERSION"; |
172 |
$greeting_kv->{peeraddr} = AnyEvent::Socket::format_hostport $self->{peerhost}, $self->{peerport}; |
173 |
|
174 |
my $protocol = $self->{protocol} || "aemp"; |
175 |
|
176 |
# can modify greeting_kv |
177 |
$_->($self) for $protocol eq "aemp" ? @HOOK_GREET : (); |
178 |
(delete $self->{on_greet})->($self) |
179 |
if exists $self->{on_greet}; |
180 |
|
181 |
# send greeting |
182 |
my $lgreeting1 = "$protocol;$PROTOCOL_VERSION" |
183 |
. ";$AnyEvent::MP::Kernel::NODE" |
184 |
. ";" . (join ",", @$auth_rcv) |
185 |
. ";" . (join ",", @$lframing) |
186 |
. (join "", map ";$_=$greeting_kv->{$_}", keys %$greeting_kv); |
187 |
|
188 |
my $lgreeting2 = MIME::Base64::encode_base64 AnyEvent::MP::Kernel::nonce (66), ""; |
189 |
|
190 |
$self->{hdl}->push_write ("$lgreeting1\012$lgreeting2\012"); |
191 |
return unless $self; |
192 |
|
193 |
# expect greeting |
194 |
$self->{hdl}->rbuf_max (4 * 1024); |
195 |
$self->{hdl}->push_read (line => sub { |
196 |
my $rgreeting1 = $_[1]; |
197 |
|
198 |
my ($aemp, $version, $rnode, $auths, $framings, @kv) = split /;/, $rgreeting1; |
199 |
|
200 |
$self->{remote_node} = $rnode; |
201 |
|
202 |
$self->{remote_greeting} = { |
203 |
map /^([^=]+)(?:=(.*))?/ ? ($1 => $2) : (), |
204 |
@kv |
205 |
}; |
206 |
|
207 |
# maybe upgrade the protocol |
208 |
if ($protocol eq "aemp" and $aemp =~ /^aemp-\w+$/) { |
209 |
# maybe check for existence of the protocol handler? |
210 |
$self->{protocol} = $protocol = $aemp; |
211 |
} |
212 |
|
213 |
$_->($self) for $protocol eq "aemp" ? @HOOK_GREETED : (); |
214 |
(delete $self->{on_greeted})->($self) |
215 |
if exists $self->{on_greeted}; |
216 |
|
217 |
if ($aemp ne $protocol and $aemp ne "aemp") { |
218 |
return $self->error ("unparsable greeting, expected '$protocol', got '$aemp'"); |
219 |
} elsif ($version != $PROTOCOL_VERSION) { |
220 |
return $self->error ("version mismatch (we: $PROTOCOL_VERSION, they: $version)"); |
221 |
} elsif ($protocol eq "aemp") { |
222 |
if ($rnode eq $AnyEvent::MP::Kernel::NODE) { |
223 |
return $self->error ("I refuse to talk to myself"); |
224 |
} elsif ($AnyEvent::MP::Kernel::NODE{$rnode} && $AnyEvent::MP::Kernel::NODE{$rnode}{transport}) { |
225 |
return $self->error ("$rnode already connected, not connecting again."); |
226 |
} |
227 |
} |
228 |
|
229 |
# read nonce |
230 |
$self->{hdl}->push_read (line => sub { |
231 |
my $rgreeting2 = $_[1]; |
232 |
|
233 |
"$lgreeting1\012$lgreeting2" ne "$rgreeting1\012$rgreeting2" # echo attack? |
234 |
or return $self->error ("authentication error, echo attack?"); |
235 |
|
236 |
my $tls = $self->{tls_ctx} && 1 == int $self->{remote_greeting}{tls}; |
237 |
|
238 |
my $s_auth; |
239 |
for my $auth_ (split /,/, $auths) { |
240 |
if (grep $auth_ eq $_, @$auth_snd and ($auth_ !~ /^tls_/ or $tls)) { |
241 |
$s_auth = $auth_; |
242 |
last; |
243 |
} |
244 |
} |
245 |
|
246 |
defined $s_auth |
247 |
or return $self->error ("$auths: no common auth type supported"); |
248 |
|
249 |
my $s_framing; |
250 |
for my $framing_ (split /,/, $framings) { |
251 |
if (grep $framing_ eq $_, @$lframing) { |
252 |
$s_framing = $framing_; |
253 |
last; |
254 |
} |
255 |
} |
256 |
|
257 |
defined $s_framing |
258 |
or return $self->error ("$framings: no common framing method supported"); |
259 |
|
260 |
my $key; |
261 |
my $lauth; |
262 |
|
263 |
if ($tls) { |
264 |
$self->{tls} = $lgreeting2 lt $rgreeting2 ? "connect" : "accept"; |
265 |
$self->{hdl}->starttls ($self->{tls}, $self->{tls_ctx}); |
266 |
return unless $self->{hdl}; # starttls might destruct us |
267 |
|
268 |
$lauth = |
269 |
$s_auth eq "tls_anon" ? "" |
270 |
: $s_auth eq "tls_md6_64_256" ? Digest::MD6::md6_hex "$lgreeting1\012$lgreeting2\012$rgreeting1\012$rgreeting2\012" |
271 |
: return $self->error ("$s_auth: fatal, selected unsupported snd auth method"); |
272 |
|
273 |
} elsif (length $secret) { |
274 |
return $self->error ("$s_auth: fatal, selected unsupported snd auth method") |
275 |
unless $s_auth eq "hmac_md6_64_256"; # hardcoded atm. |
276 |
|
277 |
$key = Digest::MD6::md6 $secret; |
278 |
# we currently only support hmac_md6_64_256 |
279 |
$lauth = Digest::HMAC_MD6::hmac_md6_hex $key, "$lgreeting1\012$lgreeting2\012$rgreeting1\012$rgreeting2\012", 64, 256; |
280 |
|
281 |
} else { |
282 |
return $self->error ("unable to handshake TLS and no shared secret configured"); |
283 |
} |
284 |
|
285 |
$self->{hdl}->push_write ("$s_auth;$lauth;$s_framing\012"); |
286 |
return unless $self; |
287 |
|
288 |
# read the authentication response |
289 |
$self->{hdl}->push_read (line => sub { |
290 |
my ($hdl, $rline) = @_; |
291 |
|
292 |
my ($auth_method, $rauth2, $r_framing) = split /;/, $rline; |
293 |
|
294 |
my $rauth = |
295 |
$auth_method eq "hmac_md6_64_256" ? Digest::HMAC_MD6::hmac_md6_hex $key, "$rgreeting1\012$rgreeting2\012$lgreeting1\012$lgreeting2\012", 64, 256 |
296 |
: $auth_method eq "cleartext" ? unpack "H*", $secret |
297 |
: $auth_method eq "tls_anon" ? ($tls ? "" : "\012\012") # \012\012 never matches |
298 |
: $auth_method eq "tls_md6_64_256" ? ($tls ? Digest::MD6::md6_hex "$rgreeting1\012$rgreeting2\012$lgreeting1\012$lgreeting2\012" : "\012\012") |
299 |
: return $self->error ("$auth_method: fatal, selected unsupported rcv auth method"); |
300 |
|
301 |
if ($rauth2 ne $rauth) { |
302 |
return $self->error ("authentication failure/shared secret mismatch"); |
303 |
} |
304 |
|
305 |
$self->{s_framing} = $s_framing; |
306 |
|
307 |
$hdl->rbuf_max (undef); |
308 |
|
309 |
# we rely on TCP retransmit timeouts and keepalives |
310 |
$self->{hdl}->rtimeout (undef); |
311 |
|
312 |
$self->{remote_greeting}{untrusted} = 1 |
313 |
if $auth_method eq "tls_anon"; |
314 |
|
315 |
if ($protocol eq "aemp" and $self->{hdl}) { |
316 |
# listener-less node need to continuously probe |
317 |
unless (@$AnyEvent::MP::Kernel::LISTENER) { |
318 |
$self->{hdl}->wtimeout ($timeout); |
319 |
$self->{hdl}->on_wtimeout (sub { $self->{send}->([]) }); |
320 |
} |
321 |
|
322 |
# receive handling |
323 |
|
324 |
my $push_write = $hdl->can ("push_write"); |
325 |
my $push_read = $hdl->can ("push_read"); |
326 |
|
327 |
if ($s_framing eq "json") { |
328 |
$self->{send} = sub { |
329 |
$push_write->($hdl, JSON::XS::encode_json $_[0]); |
330 |
}; |
331 |
} else { |
332 |
$self->{send} = sub { |
333 |
$push_write->($hdl, $s_framing => $_[0]); |
334 |
}; |
335 |
} |
336 |
|
337 |
if ($r_framing eq "json") { |
338 |
my $coder = JSON::XS->new->utf8; |
339 |
|
340 |
$hdl->on_read (sub { |
341 |
local $AnyEvent::MP::Kernel::SRCNODE = $self->{node}; |
342 |
|
343 |
AnyEvent::MP::Kernel::_inject (@$_) |
344 |
for $coder->incr_parse (delete $_[0]{rbuf}); |
345 |
|
346 |
() |
347 |
}); |
348 |
} else { |
349 |
my $rmsg; $rmsg = $self->{rmsg} = sub { |
350 |
$push_read->($_[0], $r_framing => $rmsg); |
351 |
|
352 |
local $AnyEvent::MP::Kernel::SRCNODE = $self->{node}; |
353 |
AnyEvent::MP::Kernel::_inject (@{ $_[1] }); |
354 |
}; |
355 |
eval { |
356 |
$push_read->($_[0], $r_framing => $rmsg); |
357 |
}; |
358 |
Scalar::Util::weaken $rmsg; |
359 |
return $self->error ("$r_framing: unusable remote framing") |
360 |
if $@; |
361 |
} |
362 |
} |
363 |
|
364 |
$self->connected; |
365 |
}); |
366 |
}); |
367 |
}); |
368 |
} |
369 |
|
370 |
$self |
371 |
} |
372 |
|
373 |
sub error { |
374 |
my ($self, $msg) = @_; |
375 |
|
376 |
delete $self->{keepalive}; |
377 |
|
378 |
if ($self->{protocol}) { |
379 |
$HOOK_PROTOCOL{$self->{protocol}}->($self, $msg); |
380 |
} else { |
381 |
$AnyEvent::MP::Kernel::WARN->(9, "$self->{peerhost}:$self->{peerport} $msg");#d# |
382 |
|
383 |
$self->{node}->transport_error (transport_error => $self->{node}{id}, $msg) |
384 |
if $self->{node} && $self->{node}{transport} == $self; |
385 |
} |
386 |
|
387 |
(delete $self->{release})->() |
388 |
if exists $self->{release}; |
389 |
|
390 |
# $AnyEvent::MP::Kernel::WARN->(7, "$self->{peerhost}:$self->{peerport}: $msg"); |
391 |
$self->destroy; |
392 |
} |
393 |
|
394 |
sub connected { |
395 |
my ($self) = @_; |
396 |
|
397 |
delete $self->{keepalive}; |
398 |
|
399 |
if ($self->{protocol}) { |
400 |
$self->{hdl}->on_error (undef); |
401 |
$HOOK_PROTOCOL{$self->{protocol}}->($self, undef); |
402 |
} else { |
403 |
$AnyEvent::MP::Kernel::WARN->(9, "$self->{peerhost}:$self->{peerport} connected as $self->{remote_node}"); |
404 |
|
405 |
my $node = AnyEvent::MP::Kernel::add_node ($self->{remote_node}); |
406 |
Scalar::Util::weaken ($self->{node} = $node); |
407 |
$node->transport_connect ($self); |
408 |
|
409 |
$_->($self) for @HOOK_CONNECT; |
410 |
} |
411 |
|
412 |
(delete $self->{release})->() |
413 |
if exists $self->{release}; |
414 |
|
415 |
(delete $self->{on_connect})->($self) |
416 |
if exists $self->{on_connect}; |
417 |
} |
418 |
|
419 |
sub destroy { |
420 |
my ($self) = @_; |
421 |
|
422 |
(delete $self->{release})->() |
423 |
if exists $self->{release}; |
424 |
|
425 |
$self->{hdl}->destroy |
426 |
if $self->{hdl}; |
427 |
|
428 |
(delete $self->{on_destroy})->($self) |
429 |
if exists $self->{on_destroy}; |
430 |
$_->($self) for $self->{protocol} ? () : @HOOK_DESTROY; |
431 |
|
432 |
$self->{protocol} = "destroyed"; # to keep hooks from invoked twice. |
433 |
} |
434 |
|
435 |
sub DESTROY { |
436 |
my ($self) = @_; |
437 |
|
438 |
$self->destroy; |
439 |
} |
440 |
|
441 |
=back |
442 |
|
443 |
=head1 PROTOCOL |
444 |
|
445 |
The AEMP protocol is comparatively simple, and consists of three phases |
446 |
which are symmetrical for both sides: greeting (followed by optionally |
447 |
switching to TLS mode), authentication and packet exchange. |
448 |
|
449 |
The protocol is designed to allow both full-text and binary streams. |
450 |
|
451 |
The greeting consists of two text lines that are ended by either an ASCII |
452 |
CR LF pair, or a single ASCII LF (recommended). |
453 |
|
454 |
=head2 GREETING |
455 |
|
456 |
All the lines until after authentication must not exceed 4kb in length, |
457 |
including line delimiter. Afterwards there is no limit on the packet size |
458 |
that can be received. |
459 |
|
460 |
=head3 First Greeting Line |
461 |
|
462 |
Example: |
463 |
|
464 |
aemp;0;rain;tls_md6_64_256,hmac_md6_64_256,tls_anon,cleartext;json,storable;timeout=12;peeraddr=10.0.0.1:48082 |
465 |
|
466 |
The first line contains strings separated (not ended) by C<;> |
467 |
characters. The first five strings are fixed by the protocol, the |
468 |
remaining strings are C<KEY=VALUE> pairs. None of them may contain C<;> |
469 |
characters themselves (when escaping is needed, use C<%3b> to represent |
470 |
C<;> and C<%25> to represent C<%>)- |
471 |
|
472 |
The fixed strings are: |
473 |
|
474 |
=over 4 |
475 |
|
476 |
=item protocol identification |
477 |
|
478 |
The constant C<aemp> to identify this protocol. |
479 |
|
480 |
=item protocol version |
481 |
|
482 |
The protocol version supported by this end, currently C<1>. If the |
483 |
versions don't match then no communication is possible. Minor extensions |
484 |
are supposed to be handled through additional key-value pairs. |
485 |
|
486 |
=item the node ID |
487 |
|
488 |
This is the node ID of the connecting node. |
489 |
|
490 |
=item the acceptable authentication methods |
491 |
|
492 |
A comma-separated list of authentication methods supported by the |
493 |
node. Note that AnyEvent::MP supports a C<hex_secret> authentication |
494 |
method that accepts a clear-text password (hex-encoded), but will not use |
495 |
this authentication method itself. |
496 |
|
497 |
The receiving side should choose the first authentication method it |
498 |
supports. |
499 |
|
500 |
=item the acceptable framing formats |
501 |
|
502 |
A comma-separated list of packet encoding/framing formats understood. The |
503 |
receiving side should choose the first framing format it supports for |
504 |
sending packets (which might be different from the format it has to accept). |
505 |
|
506 |
=back |
507 |
|
508 |
The remaining arguments are C<KEY=VALUE> pairs. The following key-value |
509 |
pairs are known at this time: |
510 |
|
511 |
=over 4 |
512 |
|
513 |
=item provider=<module-version> |
514 |
|
515 |
The software provider for this implementation. For AnyEvent::MP, this is |
516 |
C<AE-0.0> or whatever version it currently is at. |
517 |
|
518 |
=item peeraddr=<host>:<port> |
519 |
|
520 |
The peer address (socket address of the other side) as seen locally. |
521 |
|
522 |
=item tls=<major>.<minor> |
523 |
|
524 |
Indicates that the other side supports TLS (version should be 1.0) and |
525 |
wishes to do a TLS handshake. |
526 |
|
527 |
=back |
528 |
|
529 |
=head3 Second Greeting Line |
530 |
|
531 |
After this greeting line there will be a second line containing a |
532 |
cryptographic nonce, i.e. random data of high quality. To keep the |
533 |
protocol text-only, these are usually 32 base64-encoded octets, but |
534 |
it could be anything that doesn't contain any ASCII CR or ASCII LF |
535 |
characters. |
536 |
|
537 |
I<< The two nonces B<must> be different, and an aemp implementation |
538 |
B<must> check and fail when they are identical >>. |
539 |
|
540 |
Example of a nonce line (yes, it's random-looking because it is random |
541 |
data): |
542 |
|
543 |
2XYhdG7/O6epFa4wuP0ujAEx1rXYWRcOypjUYK7eF6yWAQr7gwIN9m/2+mVvBrTPXz5GJDgfGm9d8QRABAbmAP/s |
544 |
|
545 |
=head2 TLS handshake |
546 |
|
547 |
I<< If, after the handshake, both sides indicate interest in TLS, then the |
548 |
connection B<must> use TLS, or fail to continue. >> |
549 |
|
550 |
Both sides compare their nonces, and the side who sent the lower nonce |
551 |
value ("string" comparison on the raw octet values) becomes the client, |
552 |
and the one with the higher nonce the server. |
553 |
|
554 |
=head2 AUTHENTICATION PHASE |
555 |
|
556 |
After the greeting is received (and the optional TLS handshake), |
557 |
the authentication phase begins, which consists of sending a single |
558 |
C<;>-separated line with three fixed strings and any number of |
559 |
C<KEY=VALUE> pairs. |
560 |
|
561 |
The three fixed strings are: |
562 |
|
563 |
=over 4 |
564 |
|
565 |
=item the authentication method chosen |
566 |
|
567 |
This must be one of the methods offered by the other side in the greeting. |
568 |
|
569 |
Note that all methods starting with C<tls_> are only valid I<iff> TLS was |
570 |
successfully handshaked (and to be secure the implementation must enforce |
571 |
this). |
572 |
|
573 |
The currently supported authentication methods are: |
574 |
|
575 |
=over 4 |
576 |
|
577 |
=item cleartext |
578 |
|
579 |
This is simply the shared secret, lowercase-hex-encoded. This method is of |
580 |
course very insecure if TLS is not used (and not completely secure even |
581 |
if TLS is used), which is why this module will accept, but not generate, |
582 |
cleartext auth replies. |
583 |
|
584 |
=item hmac_md6_64_256 |
585 |
|
586 |
This method uses an MD6 HMAC with 64 bit blocksize and 256 bit hash, and |
587 |
requires a shared secret. It is the preferred auth method when a shared |
588 |
secret is available. |
589 |
|
590 |
First, the shared secret is hashed with MD6: |
591 |
|
592 |
key = MD6 (secret) |
593 |
|
594 |
This secret is then used to generate the "local auth reply", by taking |
595 |
the two local greeting lines and the two remote greeting lines (without |
596 |
line endings), appending \012 to all of them, concatenating them and |
597 |
calculating the MD6 HMAC with the key: |
598 |
|
599 |
lauth = HMAC_MD6 key, "lgreeting1\012lgreeting2\012rgreeting1\012rgreeting2\012" |
600 |
|
601 |
This authentication token is then lowercase-hex-encoded and sent to the |
602 |
other side. |
603 |
|
604 |
Then the remote auth reply is generated using the same method, but local |
605 |
and remote greeting lines swapped: |
606 |
|
607 |
rauth = HMAC_MD6 key, "rgreeting1\012rgreeting2\012lgreeting1\012lgreeting2\012" |
608 |
|
609 |
This is the token that is expected from the other side. |
610 |
|
611 |
=item tls_anon |
612 |
|
613 |
This type is only valid I<iff> TLS was enabled and the TLS handshake |
614 |
was successful. It has no authentication data, as the server/client |
615 |
certificate was successfully verified. |
616 |
|
617 |
This authentication type is somewhat insecure, as it allows a |
618 |
man-in-the-middle attacker to change some of the connection parameters |
619 |
(such as the framing format), although there is no known attack that |
620 |
exploits this in a way that is worse than just denying the service. |
621 |
|
622 |
By default, this implementation accepts but never generates this auth |
623 |
reply. |
624 |
|
625 |
=item tls_md6_64_256 |
626 |
|
627 |
This type is only valid I<iff> TLS was enabled and the TLS handshake was |
628 |
successful. |
629 |
|
630 |
This authentication type simply calculates: |
631 |
|
632 |
lauth = MD6 "rgreeting1\012rgreeting2\012lgreeting1\012lgreeting2\012" |
633 |
|
634 |
and lowercase-hex encodes the result and sends it as authentication |
635 |
data. No shared secret is required (authentication is done by TLS). The |
636 |
checksum exists only to make tinkering with the greeting hard. |
637 |
|
638 |
=back |
639 |
|
640 |
=item the authentication data |
641 |
|
642 |
The authentication data itself, usually base64 or hex-encoded data, see |
643 |
above. |
644 |
|
645 |
=item the framing protocol chosen |
646 |
|
647 |
This must be one of the framing protocols offered by the other side in the |
648 |
greeting. Each side must accept the choice of the other side, and generate |
649 |
packets in the format it chose itself. |
650 |
|
651 |
=back |
652 |
|
653 |
Example of an authentication reply: |
654 |
|
655 |
hmac_md6_64_256;363d5175df38bd9eaddd3f6ca18aa1c0c4aa22f0da245ac638d048398c26b8d3;json |
656 |
|
657 |
=head2 DATA PHASE |
658 |
|
659 |
After this, packets get exchanged using the chosen framing protocol. It is |
660 |
quite possible that both sides use a different framing protocol. |
661 |
|
662 |
=head2 FULL EXAMPLE |
663 |
|
664 |
This is an actual protocol dump of a handshake, followed by a single data |
665 |
packet. The greater than/less than lines indicate the direction of the |
666 |
transfer only. |
667 |
|
668 |
> aemp;0;anon/57Cs1CggVJjzYaQp13XXg4;tls_md6_64_256,hmac_md6_64_256,tls_anon,cleartext;json,storable;provider=AE-0.8;timeout=12;peeraddr=10.0.0.17:4040 |
669 |
> yLgdG1ov/02shVkVQer3wzeuywZK+oraTdEQBmIqWHaegxSGDG4g+HqogLQbvdypFOsoDWJ1Sh4ImV4DMhvUBwTK |
670 |
|
671 |
< aemp;0;ruth;tls_md6_64_256,hmac_md6_64_256,tls_anon,cleartext;json,storable;provider=AE-0.8;timeout=12;peeraddr=10.0.0.1:37108 |
672 |
< +xMQXP8ElfNmuvEhsmcp+s2wCJOuQAsPxSg3d2Ewhs6gBnJz+ypVdWJ/wAVrXqlIJfLeVS/CBy4gEGkyWHSuVb1L |
673 |
|
674 |
> hmac_md6_64_256;5ad913855742ae5a03a5aeb7eafa4c78629de136bed6acd73eea36c9e98df44a;json |
675 |
|
676 |
< hmac_md6_64_256;84cd590976f794914c2ca26dac3a207a57a6798b9171289c114de07cf0c20401;json |
677 |
< ["","AnyEvent::MP::_spawn","57Cs1CggVJjzYaQp13XXg4.c","AnyEvent::MP::Global::connect",0,"anon/57Cs1CggVJjzYaQp13XXg4"] |
678 |
... |
679 |
|
680 |
The shared secret in use was C<8ugxrtw6H5tKnfPWfaSr4HGhE8MoJXmzTT1BWq7sLutNcD0IbXprQlZjIbl7MBKoeklG3IEfY9GlJthC0pENzk>. |
681 |
|
682 |
=head2 SIMPLE HANDSHAKE FOR NON-PERL NODES |
683 |
|
684 |
Implementing the full set of options for handshaking can be a daunting |
685 |
task. |
686 |
|
687 |
If security is not so important (because you only connect locally and |
688 |
control the host, a common case), and you want to interface with an AEMP |
689 |
node from another programming language, then you can also implement a |
690 |
simplified handshake. |
691 |
|
692 |
For example, in a simple implementation you could decide to simply not |
693 |
check the authenticity of the other side and use cleartext authentication |
694 |
yourself. The the handshake is as simple as sending three lines of text, |
695 |
reading three lines of text, and then you can exchange JSON-formatted |
696 |
messages: |
697 |
|
698 |
aemp;1;<nodename>;hmac_md6_64_256;json |
699 |
<nonce> |
700 |
cleartext;<hexencoded secret>;json |
701 |
|
702 |
The nodename should be unique within the network, preferably unique with |
703 |
every connection, the <nonce> could be empty or some random data, and the |
704 |
hexencoded secret would be the shared secret, in lowercase hex (e.g. if |
705 |
the secret is "geheim", the hex-encoded version would be "67656865696d"). |
706 |
|
707 |
Note that apart from the low-level handshake and framing protocol, there |
708 |
is a high-level protocol, e.g. for monitoring, building the mesh or |
709 |
spawning. All these messages are sent to the node port (the empty string) |
710 |
and can safely be ignored if you do not need the relevant functionality. |
711 |
|
712 |
=head3 USEFUL HINTS |
713 |
|
714 |
Since taking part in the global protocol to find port groups is |
715 |
nontrivial, hardcoding port names should be considered as well, i.e. the |
716 |
non-Perl node could simply listen to messages for a few well-known ports. |
717 |
|
718 |
Alternatively, the non-Perl node could call a (already loaded) function |
719 |
in the Perl node by sending it a special message: |
720 |
|
721 |
["", "Some::Function::name", "myownport", 1, 2, 3] |
722 |
|
723 |
This would call the function C<Some::Function::name> with the string |
724 |
C<myownport> and some additional arguments. |
725 |
|
726 |
=head2 MONITORING |
727 |
|
728 |
Monitoring the connection itself is transport-specific. For TCP, all |
729 |
connection monitoring is currently left to TCP retransmit time-outs |
730 |
on a busy link, and TCP keepalive (which should be enabled) for idle |
731 |
connections. |
732 |
|
733 |
This is not sufficient for listener-less nodes, however: they need |
734 |
to regularly send data (30 seconds, or the monitoring interval, is |
735 |
recommended), so TCP actively probes. |
736 |
|
737 |
Future implementations of AnyEvent::MP::Transport might query the kernel TCP |
738 |
buffer after a write timeout occurs, and if it is non-empty, shut down the |
739 |
connections, but this is an area of future research :) |
740 |
|
741 |
=head2 NODE PROTOCOL |
742 |
|
743 |
The transport simply transfers messages, but to implement a full node, a |
744 |
special node port must exist that understands a number of requests. |
745 |
|
746 |
If you are interested in implementing this, drop us a note so we finish |
747 |
the documentation. |
748 |
|
749 |
=head1 SEE ALSO |
750 |
|
751 |
L<AnyEvent::MP>. |
752 |
|
753 |
=head1 AUTHOR |
754 |
|
755 |
Marc Lehmann <schmorp@schmorp.de> |
756 |
http://home.schmorp.de/ |
757 |
|
758 |
=cut |
759 |
|
760 |
1 |
761 |
|