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Revision: 1.19
Committed: Tue Aug 4 21:36:28 2009 UTC (14 years, 9 months ago) by root
Branch: MAIN
Changes since 1.18: +44 -27 lines
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File Contents

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