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