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Revision 1.29 by root, Sat May 24 23:10:18 2008 UTC vs.
Revision 1.137 by root, Sat Jul 4 23:58:52 2009 UTC

1package AnyEvent::Handle; 1package AnyEvent::Handle;
2 2
3no warnings; 3no warnings;
4use strict; 4use strict qw(subs vars);
5 5
6use AnyEvent (); 6use AnyEvent ();
7use AnyEvent::Util (); 7use AnyEvent::Util qw(WSAEWOULDBLOCK);
8use Scalar::Util (); 8use Scalar::Util ();
9use Carp (); 9use Carp ();
10use Fcntl (); 10use Fcntl ();
11use Errno qw/EAGAIN EINTR/; 11use Errno qw(EAGAIN EINTR);
12 12
13=head1 NAME 13=head1 NAME
14 14
15AnyEvent::Handle - non-blocking I/O on file handles via AnyEvent 15AnyEvent::Handle - non-blocking I/O on file handles via AnyEvent
16 16
17This module is experimental.
18
19=cut 17=cut
20 18
21our $VERSION = '0.04'; 19our $VERSION = 4.452;
22 20
23=head1 SYNOPSIS 21=head1 SYNOPSIS
24 22
25 use AnyEvent; 23 use AnyEvent;
26 use AnyEvent::Handle; 24 use AnyEvent::Handle;
27 25
28 my $cv = AnyEvent->condvar; 26 my $cv = AnyEvent->condvar;
29 27
30 my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN); 28 my $handle =
31
32 #TODO
33
34 # or use the constructor to pass the callback:
35
36 my $ae_fh2 =
37 AnyEvent::Handle->new ( 29 AnyEvent::Handle->new (
38 fh => \*STDIN, 30 fh => \*STDIN,
39 on_eof => sub { 31 on_eof => sub {
40 $cv->broadcast; 32 $cv->send;
41 }, 33 },
42 #TODO
43 ); 34 );
44 35
45 $cv->wait; 36 # send some request line
37 $handle->push_write ("getinfo\015\012");
38
39 # read the response line
40 $handle->push_read (line => sub {
41 my ($handle, $line) = @_;
42 warn "read line <$line>\n";
43 $cv->send;
44 });
45
46 $cv->recv;
46 47
47=head1 DESCRIPTION 48=head1 DESCRIPTION
48 49
49This module is a helper module to make it easier to do event-based I/O on 50This module is a helper module to make it easier to do event-based I/O on
50filehandles. For utility functions for doing non-blocking connects and accepts 51filehandles. For utility functions for doing non-blocking connects and accepts
51on sockets see L<AnyEvent::Util>. 52on sockets see L<AnyEvent::Util>.
52 53
54The L<AnyEvent::Intro> tutorial contains some well-documented
55AnyEvent::Handle examples.
56
53In the following, when the documentation refers to of "bytes" then this 57In the following, when the documentation refers to of "bytes" then this
54means characters. As sysread and syswrite are used for all I/O, their 58means characters. As sysread and syswrite are used for all I/O, their
55treatment of characters applies to this module as well. 59treatment of characters applies to this module as well.
56 60
57All callbacks will be invoked with the handle object as their first 61All callbacks will be invoked with the handle object as their first
59 63
60=head1 METHODS 64=head1 METHODS
61 65
62=over 4 66=over 4
63 67
64=item B<new (%args)> 68=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
65 69
66The constructor supports these arguments (all as key => value pairs). 70The constructor supports these arguments (all as C<< key => value >> pairs).
67 71
68=over 4 72=over 4
69 73
70=item fh => $filehandle [MANDATORY] 74=item fh => $filehandle [MANDATORY]
71 75
72The filehandle this L<AnyEvent::Handle> object will operate on. 76The filehandle this L<AnyEvent::Handle> object will operate on.
73 77
74NOTE: The filehandle will be set to non-blocking (using 78NOTE: The filehandle will be set to non-blocking mode (using
75AnyEvent::Util::fh_nonblocking). 79C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
80that mode.
76 81
77=item on_eof => $cb->($self) 82=item on_eof => $cb->($handle)
78 83
79Set the callback to be called on EOF. 84Set the callback to be called when an end-of-file condition is detected,
85i.e. in the case of a socket, when the other side has closed the
86connection cleanly.
80 87
88For sockets, this just means that the other side has stopped sending data,
89you can still try to write data, and, in fact, one can return from the EOF
90callback and continue writing data, as only the read part has been shut
91down.
92
81While not mandatory, it is highly recommended to set an eof callback, 93While not mandatory, it is I<highly> recommended to set an EOF callback,
82otherwise you might end up with a closed socket while you are still 94otherwise you might end up with a closed socket while you are still
83waiting for data. 95waiting for data.
84 96
85=item on_error => $cb->($self) 97If an EOF condition has been detected but no C<on_eof> callback has been
98set, then a fatal error will be raised with C<$!> set to <0>.
86 99
100=item on_error => $cb->($handle, $fatal, $message)
101
87This is the fatal error callback, that is called when, well, a fatal error 102This is the error callback, which is called when, well, some error
88occurs, such as not being able to resolve the hostname, failure to connect 103occured, such as not being able to resolve the hostname, failure to
89or a read error. 104connect or a read error.
90 105
91The object will not be in a usable state when this callback has been 106Some errors are fatal (which is indicated by C<$fatal> being true). On
92called. 107fatal errors the handle object will be shut down and will not be usable
108(but you are free to look at the current C<< ->rbuf >>). Examples of fatal
109errors are an EOF condition with active (but unsatisifable) read watchers
110(C<EPIPE>) or I/O errors.
111
112AnyEvent::Handle tries to find an appropriate error code for you to check
113against, but in some cases (TLS errors), this does not work well. It is
114recommended to always output the C<$message> argument in human-readable
115error messages (it's usually the same as C<"$!">).
116
117Non-fatal errors can be retried by simply returning, but it is recommended
118to simply ignore this parameter and instead abondon the handle object
119when this callback is invoked. Examples of non-fatal errors are timeouts
120C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
93 121
94On callback entrance, the value of C<$!> contains the operating system 122On callback entrance, the value of C<$!> contains the operating system
95error (or C<ENOSPC>, C<EPIPE> or C<EBADMSG>). 123error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
124C<EPROTO>).
96 125
97While not mandatory, it is I<highly> recommended to set this callback, as 126While not mandatory, it is I<highly> recommended to set this callback, as
98you will not be notified of errors otherwise. The default simply calls 127you will not be notified of errors otherwise. The default simply calls
99die. 128C<croak>.
100 129
101=item on_read => $cb->($self) 130=item on_read => $cb->($handle)
102 131
103This sets the default read callback, which is called when data arrives 132This sets the default read callback, which is called when data arrives
104and no read request is in the queue. 133and no read request is in the queue (unlike read queue callbacks, this
134callback will only be called when at least one octet of data is in the
135read buffer).
105 136
106To access (and remove data from) the read buffer, use the C<< ->rbuf >> 137To access (and remove data from) the read buffer, use the C<< ->rbuf >>
107method or access the C<$self->{rbuf}> member directly. 138method or access the C<$handle->{rbuf}> member directly. Note that you
139must not enlarge or modify the read buffer, you can only remove data at
140the beginning from it.
108 141
109When an EOF condition is detected then AnyEvent::Handle will first try to 142When an EOF condition is detected then AnyEvent::Handle will first try to
110feed all the remaining data to the queued callbacks and C<on_read> before 143feed all the remaining data to the queued callbacks and C<on_read> before
111calling the C<on_eof> callback. If no progress can be made, then a fatal 144calling the C<on_eof> callback. If no progress can be made, then a fatal
112error will be raised (with C<$!> set to C<EPIPE>). 145error will be raised (with C<$!> set to C<EPIPE>).
113 146
114=item on_drain => $cb->() 147=item on_drain => $cb->($handle)
115 148
116This sets the callback that is called when the write buffer becomes empty 149This sets the callback that is called when the write buffer becomes empty
117(or when the callback is set and the buffer is empty already). 150(or when the callback is set and the buffer is empty already).
118 151
119To append to the write buffer, use the C<< ->push_write >> method. 152To append to the write buffer, use the C<< ->push_write >> method.
120 153
154This callback is useful when you don't want to put all of your write data
155into the queue at once, for example, when you want to write the contents
156of some file to the socket you might not want to read the whole file into
157memory and push it into the queue, but instead only read more data from
158the file when the write queue becomes empty.
159
160=item timeout => $fractional_seconds
161
162If non-zero, then this enables an "inactivity" timeout: whenever this many
163seconds pass without a successful read or write on the underlying file
164handle, the C<on_timeout> callback will be invoked (and if that one is
165missing, a non-fatal C<ETIMEDOUT> error will be raised).
166
167Note that timeout processing is also active when you currently do not have
168any outstanding read or write requests: If you plan to keep the connection
169idle then you should disable the timout temporarily or ignore the timeout
170in the C<on_timeout> callback, in which case AnyEvent::Handle will simply
171restart the timeout.
172
173Zero (the default) disables this timeout.
174
175=item on_timeout => $cb->($handle)
176
177Called whenever the inactivity timeout passes. If you return from this
178callback, then the timeout will be reset as if some activity had happened,
179so this condition is not fatal in any way.
180
121=item rbuf_max => <bytes> 181=item rbuf_max => <bytes>
122 182
123If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>) 183If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
124when the read buffer ever (strictly) exceeds this size. This is useful to 184when the read buffer ever (strictly) exceeds this size. This is useful to
125avoid denial-of-service attacks. 185avoid some forms of denial-of-service attacks.
126 186
127For example, a server accepting connections from untrusted sources should 187For example, a server accepting connections from untrusted sources should
128be configured to accept only so-and-so much data that it cannot act on 188be configured to accept only so-and-so much data that it cannot act on
129(for example, when expecting a line, an attacker could send an unlimited 189(for example, when expecting a line, an attacker could send an unlimited
130amount of data without a callback ever being called as long as the line 190amount of data without a callback ever being called as long as the line
131isn't finished). 191isn't finished).
132 192
193=item autocork => <boolean>
194
195When disabled (the default), then C<push_write> will try to immediately
196write the data to the handle, if possible. This avoids having to register
197a write watcher and wait for the next event loop iteration, but can
198be inefficient if you write multiple small chunks (on the wire, this
199disadvantage is usually avoided by your kernel's nagle algorithm, see
200C<no_delay>, but this option can save costly syscalls).
201
202When enabled, then writes will always be queued till the next event loop
203iteration. This is efficient when you do many small writes per iteration,
204but less efficient when you do a single write only per iteration (or when
205the write buffer often is full). It also increases write latency.
206
207=item no_delay => <boolean>
208
209When doing small writes on sockets, your operating system kernel might
210wait a bit for more data before actually sending it out. This is called
211the Nagle algorithm, and usually it is beneficial.
212
213In some situations you want as low a delay as possible, which can be
214accomplishd by setting this option to a true value.
215
216The default is your opertaing system's default behaviour (most likely
217enabled), this option explicitly enables or disables it, if possible.
218
133=item read_size => <bytes> 219=item read_size => <bytes>
134 220
135The default read block size (the amount of bytes this module will try to read 221The default read block size (the amount of bytes this module will
136on each [loop iteration). Default: C<4096>. 222try to read during each loop iteration, which affects memory
223requirements). Default: C<8192>.
137 224
138=item low_water_mark => <bytes> 225=item low_water_mark => <bytes>
139 226
140Sets the amount of bytes (default: C<0>) that make up an "empty" write 227Sets the amount of bytes (default: C<0>) that make up an "empty" write
141buffer: If the write reaches this size or gets even samller it is 228buffer: If the write reaches this size or gets even samller it is
142considered empty. 229considered empty.
143 230
231Sometimes it can be beneficial (for performance reasons) to add data to
232the write buffer before it is fully drained, but this is a rare case, as
233the operating system kernel usually buffers data as well, so the default
234is good in almost all cases.
235
236=item linger => <seconds>
237
238If non-zero (default: C<3600>), then the destructor of the
239AnyEvent::Handle object will check whether there is still outstanding
240write data and will install a watcher that will write this data to the
241socket. No errors will be reported (this mostly matches how the operating
242system treats outstanding data at socket close time).
243
244This will not work for partial TLS data that could not be encoded
245yet. This data will be lost. Calling the C<stoptls> method in time might
246help.
247
248=item peername => $string
249
250A string used to identify the remote site - usually the DNS hostname
251(I<not> IDN!) used to create the connection, rarely the IP address.
252
253Apart from being useful in error messages, this string is also used in TLS
254common name verification (see C<verify_cn> in L<AnyEvent::TLS>).
255
144=item tls => "accept" | "connect" | Net::SSLeay::SSL object 256=item tls => "accept" | "connect" | Net::SSLeay::SSL object
145 257
146When this parameter is given, it enables TLS (SSL) mode, that means it 258When this parameter is given, it enables TLS (SSL) mode, that means
147will start making tls handshake and will transparently encrypt/decrypt 259AnyEvent will start a TLS handshake as soon as the conenction has been
148data. 260established and will transparently encrypt/decrypt data afterwards.
261
262All TLS protocol errors will be signalled as C<EPROTO>, with an
263appropriate error message.
149 264
150TLS mode requires Net::SSLeay to be installed (it will be loaded 265TLS mode requires Net::SSLeay to be installed (it will be loaded
151automatically when you try to create a TLS handle). 266automatically when you try to create a TLS handle): this module doesn't
267have a dependency on that module, so if your module requires it, you have
268to add the dependency yourself.
152 269
153For the TLS server side, use C<accept>, and for the TLS client side of a 270Unlike TCP, TLS has a server and client side: for the TLS server side, use
154connection, use C<connect> mode. 271C<accept>, and for the TLS client side of a connection, use C<connect>
272mode.
155 273
156You can also provide your own TLS connection object, but you have 274You can also provide your own TLS connection object, but you have
157to make sure that you call either C<Net::SSLeay::set_connect_state> 275to make sure that you call either C<Net::SSLeay::set_connect_state>
158or C<Net::SSLeay::set_accept_state> on it before you pass it to 276or C<Net::SSLeay::set_accept_state> on it before you pass it to
159AnyEvent::Handle. 277AnyEvent::Handle. Also, this module will take ownership of this connection
278object.
160 279
280At some future point, AnyEvent::Handle might switch to another TLS
281implementation, then the option to use your own session object will go
282away.
283
284B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
285passing in the wrong integer will lead to certain crash. This most often
286happens when one uses a stylish C<< tls => 1 >> and is surprised about the
287segmentation fault.
288
161See the C<starttls> method if you need to start TLs negotiation later. 289See the C<< ->starttls >> method for when need to start TLS negotiation later.
162 290
163=item tls_ctx => $ssl_ctx 291=item tls_ctx => $anyevent_tls
164 292
165Use the given Net::SSLeay::CTX object to create the new TLS connection 293Use the given C<AnyEvent::TLS> object to create the new TLS connection
166(unless a connection object was specified directly). If this parameter is 294(unless a connection object was specified directly). If this parameter is
167missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>. 295missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
168 296
297Instead of an object, you can also specify a hash reference with C<< key
298=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
299new TLS context object.
300
301=item json => JSON or JSON::XS object
302
303This is the json coder object used by the C<json> read and write types.
304
305If you don't supply it, then AnyEvent::Handle will create and use a
306suitable one (on demand), which will write and expect UTF-8 encoded JSON
307texts.
308
309Note that you are responsible to depend on the JSON module if you want to
310use this functionality, as AnyEvent does not have a dependency itself.
311
169=back 312=back
170 313
171=cut 314=cut
172
173our (%RH, %WH);
174
175sub register_read_type($$) {
176 $RH{$_[0]} = $_[1];
177}
178
179sub register_write_type($$) {
180 $WH{$_[0]} = $_[1];
181}
182 315
183sub new { 316sub new {
184 my $class = shift; 317 my $class = shift;
185
186 my $self = bless { @_ }, $class; 318 my $self = bless { @_ }, $class;
187 319
188 $self->{fh} or Carp::croak "mandatory argument fh is missing"; 320 $self->{fh} or Carp::croak "mandatory argument fh is missing";
189 321
190 AnyEvent::Util::fh_nonblocking $self->{fh}, 1; 322 AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
191 323
192 if ($self->{tls}) { 324 $self->{_activity} = AnyEvent->now;
193 require Net::SSLeay; 325 $self->_timeout;
326
327 $self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
328
194 $self->starttls (delete $self->{tls}, delete $self->{tls_ctx}); 329 $self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
195 } 330 if $self->{tls};
196 331
197 $self->on_eof (delete $self->{on_eof} ) if $self->{on_eof};
198 $self->on_error (delete $self->{on_error}) if $self->{on_error};
199 $self->on_drain (delete $self->{on_drain}) if $self->{on_drain}; 332 $self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
200 $self->on_read (delete $self->{on_read} ) if $self->{on_read};
201 333
202 $self->start_read; 334 $self->start_read
335 if $self->{on_read};
203 336
204 $self 337 $self->{fh} && $self
205} 338}
206 339
207sub _shutdown { 340sub _shutdown {
208 my ($self) = @_; 341 my ($self) = @_;
209 342
210 delete $self->{rw}; 343 delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
211 delete $self->{ww}; 344 $self->{_eof} = 1; # tell starttls et. al to stop trying
212 delete $self->{fh};
213}
214 345
346 &_freetls;
347}
348
215sub error { 349sub _error {
216 my ($self) = @_; 350 my ($self, $errno, $fatal, $message) = @_;
217 351
218 {
219 local $!;
220 $self->_shutdown; 352 $self->_shutdown
221 } 353 if $fatal;
354
355 $! = $errno;
356 $message ||= "$!";
222 357
223 if ($self->{on_error}) { 358 if ($self->{on_error}) {
224 $self->{on_error}($self); 359 $self->{on_error}($self, $fatal, $message);
225 } else { 360 } elsif ($self->{fh}) {
226 Carp::croak "AnyEvent::Handle uncaught fatal error: $!"; 361 Carp::croak "AnyEvent::Handle uncaught error: $message";
227 } 362 }
228} 363}
229 364
230=item $fh = $handle->fh 365=item $fh = $handle->fh
231 366
232This method returns the file handle of the L<AnyEvent::Handle> object. 367This method returns the file handle used to create the L<AnyEvent::Handle> object.
233 368
234=cut 369=cut
235 370
236sub fh { $_[0]->{fh} } 371sub fh { $_[0]{fh} }
237 372
238=item $handle->on_error ($cb) 373=item $handle->on_error ($cb)
239 374
240Replace the current C<on_error> callback (see the C<on_error> constructor argument). 375Replace the current C<on_error> callback (see the C<on_error> constructor argument).
241 376
253 388
254sub on_eof { 389sub on_eof {
255 $_[0]{on_eof} = $_[1]; 390 $_[0]{on_eof} = $_[1];
256} 391}
257 392
393=item $handle->on_timeout ($cb)
394
395Replace the current C<on_timeout> callback, or disables the callback (but
396not the timeout) if C<$cb> = C<undef>. See the C<timeout> constructor
397argument and method.
398
399=cut
400
401sub on_timeout {
402 $_[0]{on_timeout} = $_[1];
403}
404
405=item $handle->autocork ($boolean)
406
407Enables or disables the current autocork behaviour (see C<autocork>
408constructor argument). Changes will only take effect on the next write.
409
410=cut
411
412sub autocork {
413 $_[0]{autocork} = $_[1];
414}
415
416=item $handle->no_delay ($boolean)
417
418Enables or disables the C<no_delay> setting (see constructor argument of
419the same name for details).
420
421=cut
422
423sub no_delay {
424 $_[0]{no_delay} = $_[1];
425
426 eval {
427 local $SIG{__DIE__};
428 setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
429 };
430}
431
432#############################################################################
433
434=item $handle->timeout ($seconds)
435
436Configures (or disables) the inactivity timeout.
437
438=cut
439
440sub timeout {
441 my ($self, $timeout) = @_;
442
443 $self->{timeout} = $timeout;
444 $self->_timeout;
445}
446
447# reset the timeout watcher, as neccessary
448# also check for time-outs
449sub _timeout {
450 my ($self) = @_;
451
452 if ($self->{timeout}) {
453 my $NOW = AnyEvent->now;
454
455 # when would the timeout trigger?
456 my $after = $self->{_activity} + $self->{timeout} - $NOW;
457
458 # now or in the past already?
459 if ($after <= 0) {
460 $self->{_activity} = $NOW;
461
462 if ($self->{on_timeout}) {
463 $self->{on_timeout}($self);
464 } else {
465 $self->_error (&Errno::ETIMEDOUT);
466 }
467
468 # callback could have changed timeout value, optimise
469 return unless $self->{timeout};
470
471 # calculate new after
472 $after = $self->{timeout};
473 }
474
475 Scalar::Util::weaken $self;
476 return unless $self; # ->error could have destroyed $self
477
478 $self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
479 delete $self->{_tw};
480 $self->_timeout;
481 });
482 } else {
483 delete $self->{_tw};
484 }
485}
486
258############################################################################# 487#############################################################################
259 488
260=back 489=back
261 490
262=head2 WRITE QUEUE 491=head2 WRITE QUEUE
283 my ($self, $cb) = @_; 512 my ($self, $cb) = @_;
284 513
285 $self->{on_drain} = $cb; 514 $self->{on_drain} = $cb;
286 515
287 $cb->($self) 516 $cb->($self)
288 if $cb && $self->{low_water_mark} >= length $self->{wbuf}; 517 if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
289} 518}
290 519
291=item $handle->push_write ($data) 520=item $handle->push_write ($data)
292 521
293Queues the given scalar to be written. You can push as much data as you 522Queues the given scalar to be written. You can push as much data as you
297=cut 526=cut
298 527
299sub _drain_wbuf { 528sub _drain_wbuf {
300 my ($self) = @_; 529 my ($self) = @_;
301 530
302 if (!$self->{ww} && length $self->{wbuf}) { 531 if (!$self->{_ww} && length $self->{wbuf}) {
532
303 Scalar::Util::weaken $self; 533 Scalar::Util::weaken $self;
534
304 my $cb = sub { 535 my $cb = sub {
305 my $len = syswrite $self->{fh}, $self->{wbuf}; 536 my $len = syswrite $self->{fh}, $self->{wbuf};
306 537
307 if ($len >= 0) { 538 if ($len >= 0) {
308 substr $self->{wbuf}, 0, $len, ""; 539 substr $self->{wbuf}, 0, $len, "";
309 540
541 $self->{_activity} = AnyEvent->now;
542
310 $self->{on_drain}($self) 543 $self->{on_drain}($self)
311 if $self->{low_water_mark} >= length $self->{wbuf} 544 if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
312 && $self->{on_drain}; 545 && $self->{on_drain};
313 546
314 delete $self->{ww} unless length $self->{wbuf}; 547 delete $self->{_ww} unless length $self->{wbuf};
315 } elsif ($! != EAGAIN && $! != EINTR) { 548 } elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
316 $self->error; 549 $self->_error ($!, 1);
317 } 550 }
318 }; 551 };
319 552
553 # try to write data immediately
554 $cb->() unless $self->{autocork};
555
556 # if still data left in wbuf, we need to poll
320 $self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb); 557 $self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
321 558 if length $self->{wbuf};
322 $cb->($self);
323 }; 559 };
560}
561
562our %WH;
563
564sub register_write_type($$) {
565 $WH{$_[0]} = $_[1];
324} 566}
325 567
326sub push_write { 568sub push_write {
327 my $self = shift; 569 my $self = shift;
328 570
331 573
332 @_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write") 574 @_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
333 ->($self, @_); 575 ->($self, @_);
334 } 576 }
335 577
336 if ($self->{filter_w}) { 578 if ($self->{tls}) {
337 $self->{filter_w}->($self, \$_[0]); 579 $self->{_tls_wbuf} .= $_[0];
580
581 &_dotls ($self);
338 } else { 582 } else {
339 $self->{wbuf} .= $_[0]; 583 $self->{wbuf} .= $_[0];
340 $self->_drain_wbuf; 584 $self->_drain_wbuf;
341 } 585 }
342} 586}
343 587
344=item $handle->push_write (type => @args) 588=item $handle->push_write (type => @args)
345 589
346=item $handle->unshift_write (type => @args)
347
348Instead of formatting your data yourself, you can also let this module do 590Instead of formatting your data yourself, you can also let this module do
349the job by specifying a type and type-specific arguments. 591the job by specifying a type and type-specific arguments.
350 592
351Predefined types are: 593Predefined types are (if you have ideas for additional types, feel free to
594drop by and tell us):
352 595
353=over 4 596=over 4
354 597
355=item netstring => $string 598=item netstring => $string
356 599
360=cut 603=cut
361 604
362register_write_type netstring => sub { 605register_write_type netstring => sub {
363 my ($self, $string) = @_; 606 my ($self, $string) = @_;
364 607
365 sprintf "%d:%s,", (length $string), $string 608 (length $string) . ":$string,"
366}; 609};
367 610
611=item packstring => $format, $data
612
613An octet string prefixed with an encoded length. The encoding C<$format>
614uses the same format as a Perl C<pack> format, but must specify a single
615integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
616optional C<!>, C<< < >> or C<< > >> modifier).
617
618=cut
619
620register_write_type packstring => sub {
621 my ($self, $format, $string) = @_;
622
623 pack "$format/a*", $string
624};
625
626=item json => $array_or_hashref
627
628Encodes the given hash or array reference into a JSON object. Unless you
629provide your own JSON object, this means it will be encoded to JSON text
630in UTF-8.
631
632JSON objects (and arrays) are self-delimiting, so you can write JSON at
633one end of a handle and read them at the other end without using any
634additional framing.
635
636The generated JSON text is guaranteed not to contain any newlines: While
637this module doesn't need delimiters after or between JSON texts to be
638able to read them, many other languages depend on that.
639
640A simple RPC protocol that interoperates easily with others is to send
641JSON arrays (or objects, although arrays are usually the better choice as
642they mimic how function argument passing works) and a newline after each
643JSON text:
644
645 $handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
646 $handle->push_write ("\012");
647
648An AnyEvent::Handle receiver would simply use the C<json> read type and
649rely on the fact that the newline will be skipped as leading whitespace:
650
651 $handle->push_read (json => sub { my $array = $_[1]; ... });
652
653Other languages could read single lines terminated by a newline and pass
654this line into their JSON decoder of choice.
655
656=cut
657
658register_write_type json => sub {
659 my ($self, $ref) = @_;
660
661 require JSON;
662
663 $self->{json} ? $self->{json}->encode ($ref)
664 : JSON::encode_json ($ref)
665};
666
667=item storable => $reference
668
669Freezes the given reference using L<Storable> and writes it to the
670handle. Uses the C<nfreeze> format.
671
672=cut
673
674register_write_type storable => sub {
675 my ($self, $ref) = @_;
676
677 require Storable;
678
679 pack "w/a*", Storable::nfreeze ($ref)
680};
681
368=back 682=back
369 683
370=cut 684=item $handle->push_shutdown
371 685
686Sometimes you know you want to close the socket after writing your data
687before it was actually written. One way to do that is to replace your
688C<on_drain> handler by a callback that shuts down the socket. This method
689is a shorthand for just that, and replaces the C<on_drain> callback with:
372 690
691 sub { shutdown $_[0]{fh}, 1 } # for push_shutdown
692
693This simply shuts down the write side and signals an EOF condition to the
694the peer.
695
696You can rely on the normal read queue and C<on_eof> handling
697afterwards. This is the cleanest way to close a connection.
698
699=cut
700
701sub push_shutdown {
702 $_[0]->{on_drain} = sub { shutdown $_[0]{fh}, 1 };
703}
704
705=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
706
707This function (not method) lets you add your own types to C<push_write>.
708Whenever the given C<type> is used, C<push_write> will invoke the code
709reference with the handle object and the remaining arguments.
710
711The code reference is supposed to return a single octet string that will
712be appended to the write buffer.
713
714Note that this is a function, and all types registered this way will be
715global, so try to use unique names.
716
717=cut
373 718
374############################################################################# 719#############################################################################
375 720
376=back 721=back
377 722
384ways, the "simple" way, using only C<on_read> and the "complex" way, using 729ways, the "simple" way, using only C<on_read> and the "complex" way, using
385a queue. 730a queue.
386 731
387In the simple case, you just install an C<on_read> callback and whenever 732In the simple case, you just install an C<on_read> callback and whenever
388new data arrives, it will be called. You can then remove some data (if 733new data arrives, it will be called. You can then remove some data (if
389enough is there) from the read buffer (C<< $handle->rbuf >>) if you want 734enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
390or not. 735leave the data there if you want to accumulate more (e.g. when only a
736partial message has been received so far).
391 737
392In the more complex case, you want to queue multiple callbacks. In this 738In the more complex case, you want to queue multiple callbacks. In this
393case, AnyEvent::Handle will call the first queued callback each time new 739case, AnyEvent::Handle will call the first queued callback each time new
394data arrives and removes it when it has done its job (see C<push_read>, 740data arrives (also the first time it is queued) and removes it when it has
395below). 741done its job (see C<push_read>, below).
396 742
397This way you can, for example, push three line-reads, followed by reading 743This way you can, for example, push three line-reads, followed by reading
398a chunk of data, and AnyEvent::Handle will execute them in order. 744a chunk of data, and AnyEvent::Handle will execute them in order.
399 745
400Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by 746Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
401the specified number of bytes which give an XML datagram. 747the specified number of bytes which give an XML datagram.
402 748
403 # in the default state, expect some header bytes 749 # in the default state, expect some header bytes
404 $handle->on_read (sub { 750 $handle->on_read (sub {
405 # some data is here, now queue the length-header-read (4 octets) 751 # some data is here, now queue the length-header-read (4 octets)
406 shift->unshift_read_chunk (4, sub { 752 shift->unshift_read (chunk => 4, sub {
407 # header arrived, decode 753 # header arrived, decode
408 my $len = unpack "N", $_[1]; 754 my $len = unpack "N", $_[1];
409 755
410 # now read the payload 756 # now read the payload
411 shift->unshift_read_chunk ($len, sub { 757 shift->unshift_read (chunk => $len, sub {
412 my $xml = $_[1]; 758 my $xml = $_[1];
413 # handle xml 759 # handle xml
414 }); 760 });
415 }); 761 });
416 }); 762 });
417 763
418Example 2: Implement a client for a protocol that replies either with 764Example 2: Implement a client for a protocol that replies either with "OK"
419"OK" and another line or "ERROR" for one request, and 64 bytes for the 765and another line or "ERROR" for the first request that is sent, and 64
420second request. Due tot he availability of a full queue, we can just 766bytes for the second request. Due to the availability of a queue, we can
421pipeline sending both requests and manipulate the queue as necessary in 767just pipeline sending both requests and manipulate the queue as necessary
422the callbacks: 768in the callbacks.
423 769
424 # request one 770When the first callback is called and sees an "OK" response, it will
771C<unshift> another line-read. This line-read will be queued I<before> the
77264-byte chunk callback.
773
774 # request one, returns either "OK + extra line" or "ERROR"
425 $handle->push_write ("request 1\015\012"); 775 $handle->push_write ("request 1\015\012");
426 776
427 # we expect "ERROR" or "OK" as response, so push a line read 777 # we expect "ERROR" or "OK" as response, so push a line read
428 $handle->push_read_line (sub { 778 $handle->push_read (line => sub {
429 # if we got an "OK", we have to _prepend_ another line, 779 # if we got an "OK", we have to _prepend_ another line,
430 # so it will be read before the second request reads its 64 bytes 780 # so it will be read before the second request reads its 64 bytes
431 # which are already in the queue when this callback is called 781 # which are already in the queue when this callback is called
432 # we don't do this in case we got an error 782 # we don't do this in case we got an error
433 if ($_[1] eq "OK") { 783 if ($_[1] eq "OK") {
434 $_[0]->unshift_read_line (sub { 784 $_[0]->unshift_read (line => sub {
435 my $response = $_[1]; 785 my $response = $_[1];
436 ... 786 ...
437 }); 787 });
438 } 788 }
439 }); 789 });
440 790
441 # request two 791 # request two, simply returns 64 octets
442 $handle->push_write ("request 2\015\012"); 792 $handle->push_write ("request 2\015\012");
443 793
444 # simply read 64 bytes, always 794 # simply read 64 bytes, always
445 $handle->push_read_chunk (64, sub { 795 $handle->push_read (chunk => 64, sub {
446 my $response = $_[1]; 796 my $response = $_[1];
447 ... 797 ...
448 }); 798 });
449 799
450=over 4 800=over 4
451 801
452=cut 802=cut
453 803
454sub _drain_rbuf { 804sub _drain_rbuf {
455 my ($self) = @_; 805 my ($self) = @_;
806
807 local $self->{_in_drain} = 1;
456 808
457 if ( 809 if (
458 defined $self->{rbuf_max} 810 defined $self->{rbuf_max}
459 && $self->{rbuf_max} < length $self->{rbuf} 811 && $self->{rbuf_max} < length $self->{rbuf}
460 ) { 812 ) {
461 $! = &Errno::ENOSPC; return $self->error; 813 $self->_error (&Errno::ENOSPC, 1), return;
462 } 814 }
463 815
464 return if $self->{in_drain}; 816 while () {
465 local $self->{in_drain} = 1; 817 # we need to use a separate tls read buffer, as we must not receive data while
818 # we are draining the buffer, and this can only happen with TLS.
819 $self->{rbuf} .= delete $self->{_tls_rbuf} if exists $self->{_tls_rbuf};
466 820
467 while (my $len = length $self->{rbuf}) { 821 my $len = length $self->{rbuf};
468 no strict 'refs'; 822
469 if (my $cb = shift @{ $self->{queue} }) { 823 if (my $cb = shift @{ $self->{_queue} }) {
470 unless ($cb->($self)) { 824 unless ($cb->($self)) {
471 if ($self->{eof}) { 825 if ($self->{_eof}) {
472 # no progress can be made (not enough data and no data forthcoming) 826 # no progress can be made (not enough data and no data forthcoming)
473 $! = &Errno::EPIPE; return $self->error; 827 $self->_error (&Errno::EPIPE, 1), return;
474 } 828 }
475 829
476 unshift @{ $self->{queue} }, $cb; 830 unshift @{ $self->{_queue} }, $cb;
477 return; 831 last;
478 } 832 }
479 } elsif ($self->{on_read}) { 833 } elsif ($self->{on_read}) {
834 last unless $len;
835
480 $self->{on_read}($self); 836 $self->{on_read}($self);
481 837
482 if ( 838 if (
483 $self->{eof} # if no further data will arrive
484 && $len == length $self->{rbuf} # and no data has been consumed 839 $len == length $self->{rbuf} # if no data has been consumed
485 && !@{ $self->{queue} } # and the queue is still empty 840 && !@{ $self->{_queue} } # and the queue is still empty
486 && $self->{on_read} # and we still want to read data 841 && $self->{on_read} # but we still have on_read
487 ) { 842 ) {
843 # no further data will arrive
488 # then no progress can be made 844 # so no progress can be made
489 $! = &Errno::EPIPE; return $self->error; 845 $self->_error (&Errno::EPIPE, 1), return
846 if $self->{_eof};
847
848 last; # more data might arrive
490 } 849 }
491 } else { 850 } else {
492 # read side becomes idle 851 # read side becomes idle
493 delete $self->{rw}; 852 delete $self->{_rw} unless $self->{tls};
494 return; 853 last;
495 } 854 }
496 } 855 }
497 856
498 if ($self->{eof}) { 857 if ($self->{_eof}) {
499 $self->_shutdown; 858 if ($self->{on_eof}) {
500 $self->{on_eof}($self) 859 $self->{on_eof}($self)
501 if $self->{on_eof}; 860 } else {
861 $self->_error (0, 1);
862 }
863 }
864
865 # may need to restart read watcher
866 unless ($self->{_rw}) {
867 $self->start_read
868 if $self->{on_read} || @{ $self->{_queue} };
502 } 869 }
503} 870}
504 871
505=item $handle->on_read ($cb) 872=item $handle->on_read ($cb)
506 873
512 879
513sub on_read { 880sub on_read {
514 my ($self, $cb) = @_; 881 my ($self, $cb) = @_;
515 882
516 $self->{on_read} = $cb; 883 $self->{on_read} = $cb;
884 $self->_drain_rbuf if $cb && !$self->{_in_drain};
517} 885}
518 886
519=item $handle->rbuf 887=item $handle->rbuf
520 888
521Returns the read buffer (as a modifiable lvalue). 889Returns the read buffer (as a modifiable lvalue).
522 890
523You can access the read buffer directly as the C<< ->{rbuf} >> member, if 891You can access the read buffer directly as the C<< ->{rbuf} >>
524you want. 892member, if you want. However, the only operation allowed on the
893read buffer (apart from looking at it) is removing data from its
894beginning. Otherwise modifying or appending to it is not allowed and will
895lead to hard-to-track-down bugs.
525 896
526NOTE: The read buffer should only be used or modified if the C<on_read>, 897NOTE: The read buffer should only be used or modified if the C<on_read>,
527C<push_read> or C<unshift_read> methods are used. The other read methods 898C<push_read> or C<unshift_read> methods are used. The other read methods
528automatically manage the read buffer. 899automatically manage the read buffer.
529 900
552interested in (which can be none at all) and return a true value. After returning 923interested in (which can be none at all) and return a true value. After returning
553true, it will be removed from the queue. 924true, it will be removed from the queue.
554 925
555=cut 926=cut
556 927
928our %RH;
929
930sub register_read_type($$) {
931 $RH{$_[0]} = $_[1];
932}
933
557sub push_read { 934sub push_read {
558 my $self = shift; 935 my $self = shift;
559 my $cb = pop; 936 my $cb = pop;
560 937
561 if (@_) { 938 if (@_) {
563 940
564 $cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read") 941 $cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
565 ->($self, $cb, @_); 942 ->($self, $cb, @_);
566 } 943 }
567 944
568 push @{ $self->{queue} }, $cb; 945 push @{ $self->{_queue} }, $cb;
569 $self->_drain_rbuf; 946 $self->_drain_rbuf unless $self->{_in_drain};
570} 947}
571 948
572sub unshift_read { 949sub unshift_read {
573 my $self = shift; 950 my $self = shift;
574 my $cb = pop; 951 my $cb = pop;
579 $cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read") 956 $cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
580 ->($self, $cb, @_); 957 ->($self, $cb, @_);
581 } 958 }
582 959
583 960
584 unshift @{ $self->{queue} }, $cb; 961 unshift @{ $self->{_queue} }, $cb;
585 $self->_drain_rbuf; 962 $self->_drain_rbuf unless $self->{_in_drain};
586} 963}
587 964
588=item $handle->push_read (type => @args, $cb) 965=item $handle->push_read (type => @args, $cb)
589 966
590=item $handle->unshift_read (type => @args, $cb) 967=item $handle->unshift_read (type => @args, $cb)
591 968
592Instead of providing a callback that parses the data itself you can chose 969Instead of providing a callback that parses the data itself you can chose
593between a number of predefined parsing formats, for chunks of data, lines 970between a number of predefined parsing formats, for chunks of data, lines
594etc. 971etc.
595 972
596The types currently supported are: 973Predefined types are (if you have ideas for additional types, feel free to
974drop by and tell us):
597 975
598=over 4 976=over 4
599 977
600=item chunk => $octets, $cb->($self, $data) 978=item chunk => $octets, $cb->($handle, $data)
601 979
602Invoke the callback only once C<$octets> bytes have been read. Pass the 980Invoke the callback only once C<$octets> bytes have been read. Pass the
603data read to the callback. The callback will never be called with less 981data read to the callback. The callback will never be called with less
604data. 982data.
605 983
619 $cb->($_[0], substr $_[0]{rbuf}, 0, $len, ""); 997 $cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
620 1 998 1
621 } 999 }
622}; 1000};
623 1001
624# compatibility with older API
625sub push_read_chunk {
626 $_[0]->push_read (chunk => $_[1], $_[2]);
627}
628
629sub unshift_read_chunk {
630 $_[0]->unshift_read (chunk => $_[1], $_[2]);
631}
632
633=item line => [$eol, ]$cb->($self, $line, $eol) 1002=item line => [$eol, ]$cb->($handle, $line, $eol)
634 1003
635The callback will be called only once a full line (including the end of 1004The callback will be called only once a full line (including the end of
636line marker, C<$eol>) has been read. This line (excluding the end of line 1005line marker, C<$eol>) has been read. This line (excluding the end of line
637marker) will be passed to the callback as second argument (C<$line>), and 1006marker) will be passed to the callback as second argument (C<$line>), and
638the end of line marker as the third argument (C<$eol>). 1007the end of line marker as the third argument (C<$eol>).
652=cut 1021=cut
653 1022
654register_read_type line => sub { 1023register_read_type line => sub {
655 my ($self, $cb, $eol) = @_; 1024 my ($self, $cb, $eol) = @_;
656 1025
657 $eol = qr|(\015?\012)| if @_ < 3; 1026 if (@_ < 3) {
1027 # this is more than twice as fast as the generic code below
1028 sub {
1029 $_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
1030
1031 $cb->($_[0], $1, $2);
1032 1
1033 }
1034 } else {
658 $eol = quotemeta $eol unless ref $eol; 1035 $eol = quotemeta $eol unless ref $eol;
659 $eol = qr|^(.*?)($eol)|s; 1036 $eol = qr|^(.*?)($eol)|s;
1037
1038 sub {
1039 $_[0]{rbuf} =~ s/$eol// or return;
1040
1041 $cb->($_[0], $1, $2);
1042 1
1043 }
1044 }
1045};
1046
1047=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
1048
1049Makes a regex match against the regex object C<$accept> and returns
1050everything up to and including the match.
1051
1052Example: read a single line terminated by '\n'.
1053
1054 $handle->push_read (regex => qr<\n>, sub { ... });
1055
1056If C<$reject> is given and not undef, then it determines when the data is
1057to be rejected: it is matched against the data when the C<$accept> regex
1058does not match and generates an C<EBADMSG> error when it matches. This is
1059useful to quickly reject wrong data (to avoid waiting for a timeout or a
1060receive buffer overflow).
1061
1062Example: expect a single decimal number followed by whitespace, reject
1063anything else (not the use of an anchor).
1064
1065 $handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
1066
1067If C<$skip> is given and not C<undef>, then it will be matched against
1068the receive buffer when neither C<$accept> nor C<$reject> match,
1069and everything preceding and including the match will be accepted
1070unconditionally. This is useful to skip large amounts of data that you
1071know cannot be matched, so that the C<$accept> or C<$reject> regex do not
1072have to start matching from the beginning. This is purely an optimisation
1073and is usually worth only when you expect more than a few kilobytes.
1074
1075Example: expect a http header, which ends at C<\015\012\015\012>. Since we
1076expect the header to be very large (it isn't in practise, but...), we use
1077a skip regex to skip initial portions. The skip regex is tricky in that
1078it only accepts something not ending in either \015 or \012, as these are
1079required for the accept regex.
1080
1081 $handle->push_read (regex =>
1082 qr<\015\012\015\012>,
1083 undef, # no reject
1084 qr<^.*[^\015\012]>,
1085 sub { ... });
1086
1087=cut
1088
1089register_read_type regex => sub {
1090 my ($self, $cb, $accept, $reject, $skip) = @_;
1091
1092 my $data;
1093 my $rbuf = \$self->{rbuf};
660 1094
661 sub { 1095 sub {
662 $_[0]{rbuf} =~ s/$eol// or return; 1096 # accept
663 1097 if ($$rbuf =~ $accept) {
664 $cb->($_[0], $1, $2); 1098 $data .= substr $$rbuf, 0, $+[0], "";
1099 $cb->($self, $data);
1100 return 1;
1101 }
665 1 1102
1103 # reject
1104 if ($reject && $$rbuf =~ $reject) {
1105 $self->_error (&Errno::EBADMSG);
1106 }
1107
1108 # skip
1109 if ($skip && $$rbuf =~ $skip) {
1110 $data .= substr $$rbuf, 0, $+[0], "";
1111 }
1112
1113 ()
666 } 1114 }
667}; 1115};
668 1116
669# compatibility with older API
670sub push_read_line {
671 my $self = shift;
672 $self->push_read (line => @_);
673}
674
675sub unshift_read_line {
676 my $self = shift;
677 $self->unshift_read (line => @_);
678}
679
680=item netstring => $cb->($string) 1117=item netstring => $cb->($handle, $string)
681 1118
682A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement). 1119A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
683 1120
684Throws an error with C<$!> set to EBADMSG on format violations. 1121Throws an error with C<$!> set to EBADMSG on format violations.
685 1122
689 my ($self, $cb) = @_; 1126 my ($self, $cb) = @_;
690 1127
691 sub { 1128 sub {
692 unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) { 1129 unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
693 if ($_[0]{rbuf} =~ /[^0-9]/) { 1130 if ($_[0]{rbuf} =~ /[^0-9]/) {
694 $! = &Errno::EBADMSG; 1131 $self->_error (&Errno::EBADMSG);
695 $self->error;
696 } 1132 }
697 return; 1133 return;
698 } 1134 }
699 1135
700 my $len = $1; 1136 my $len = $1;
703 my $string = $_[1]; 1139 my $string = $_[1];
704 $_[0]->unshift_read (chunk => 1, sub { 1140 $_[0]->unshift_read (chunk => 1, sub {
705 if ($_[1] eq ",") { 1141 if ($_[1] eq ",") {
706 $cb->($_[0], $string); 1142 $cb->($_[0], $string);
707 } else { 1143 } else {
708 $! = &Errno::EBADMSG; 1144 $self->_error (&Errno::EBADMSG);
709 $self->error;
710 } 1145 }
711 }); 1146 });
712 }); 1147 });
713 1148
714 1 1149 1
715 } 1150 }
716}; 1151};
717 1152
1153=item packstring => $format, $cb->($handle, $string)
1154
1155An octet string prefixed with an encoded length. The encoding C<$format>
1156uses the same format as a Perl C<pack> format, but must specify a single
1157integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
1158optional C<!>, C<< < >> or C<< > >> modifier).
1159
1160For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
1161EPP uses a prefix of C<N> (4 octtes).
1162
1163Example: read a block of data prefixed by its length in BER-encoded
1164format (very efficient).
1165
1166 $handle->push_read (packstring => "w", sub {
1167 my ($handle, $data) = @_;
1168 });
1169
1170=cut
1171
1172register_read_type packstring => sub {
1173 my ($self, $cb, $format) = @_;
1174
1175 sub {
1176 # when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
1177 defined (my $len = eval { unpack $format, $_[0]{rbuf} })
1178 or return;
1179
1180 $format = length pack $format, $len;
1181
1182 # bypass unshift if we already have the remaining chunk
1183 if ($format + $len <= length $_[0]{rbuf}) {
1184 my $data = substr $_[0]{rbuf}, $format, $len;
1185 substr $_[0]{rbuf}, 0, $format + $len, "";
1186 $cb->($_[0], $data);
1187 } else {
1188 # remove prefix
1189 substr $_[0]{rbuf}, 0, $format, "";
1190
1191 # read remaining chunk
1192 $_[0]->unshift_read (chunk => $len, $cb);
1193 }
1194
1195 1
1196 }
1197};
1198
1199=item json => $cb->($handle, $hash_or_arrayref)
1200
1201Reads a JSON object or array, decodes it and passes it to the
1202callback. When a parse error occurs, an C<EBADMSG> error will be raised.
1203
1204If a C<json> object was passed to the constructor, then that will be used
1205for the final decode, otherwise it will create a JSON coder expecting UTF-8.
1206
1207This read type uses the incremental parser available with JSON version
12082.09 (and JSON::XS version 2.2) and above. You have to provide a
1209dependency on your own: this module will load the JSON module, but
1210AnyEvent does not depend on it itself.
1211
1212Since JSON texts are fully self-delimiting, the C<json> read and write
1213types are an ideal simple RPC protocol: just exchange JSON datagrams. See
1214the C<json> write type description, above, for an actual example.
1215
1216=cut
1217
1218register_read_type json => sub {
1219 my ($self, $cb) = @_;
1220
1221 my $json = $self->{json} ||=
1222 eval { require JSON::XS; JSON::XS->new->utf8 }
1223 || do { require JSON; JSON->new->utf8 };
1224
1225 my $data;
1226 my $rbuf = \$self->{rbuf};
1227
1228 sub {
1229 my $ref = eval { $json->incr_parse ($self->{rbuf}) };
1230
1231 if ($ref) {
1232 $self->{rbuf} = $json->incr_text;
1233 $json->incr_text = "";
1234 $cb->($self, $ref);
1235
1236 1
1237 } elsif ($@) {
1238 # error case
1239 $json->incr_skip;
1240
1241 $self->{rbuf} = $json->incr_text;
1242 $json->incr_text = "";
1243
1244 $self->_error (&Errno::EBADMSG);
1245
1246 ()
1247 } else {
1248 $self->{rbuf} = "";
1249
1250 ()
1251 }
1252 }
1253};
1254
1255=item storable => $cb->($handle, $ref)
1256
1257Deserialises a L<Storable> frozen representation as written by the
1258C<storable> write type (BER-encoded length prefix followed by nfreeze'd
1259data).
1260
1261Raises C<EBADMSG> error if the data could not be decoded.
1262
1263=cut
1264
1265register_read_type storable => sub {
1266 my ($self, $cb) = @_;
1267
1268 require Storable;
1269
1270 sub {
1271 # when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
1272 defined (my $len = eval { unpack "w", $_[0]{rbuf} })
1273 or return;
1274
1275 my $format = length pack "w", $len;
1276
1277 # bypass unshift if we already have the remaining chunk
1278 if ($format + $len <= length $_[0]{rbuf}) {
1279 my $data = substr $_[0]{rbuf}, $format, $len;
1280 substr $_[0]{rbuf}, 0, $format + $len, "";
1281 $cb->($_[0], Storable::thaw ($data));
1282 } else {
1283 # remove prefix
1284 substr $_[0]{rbuf}, 0, $format, "";
1285
1286 # read remaining chunk
1287 $_[0]->unshift_read (chunk => $len, sub {
1288 if (my $ref = eval { Storable::thaw ($_[1]) }) {
1289 $cb->($_[0], $ref);
1290 } else {
1291 $self->_error (&Errno::EBADMSG);
1292 }
1293 });
1294 }
1295
1296 1
1297 }
1298};
1299
718=back 1300=back
719 1301
1302=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
1303
1304This function (not method) lets you add your own types to C<push_read>.
1305
1306Whenever the given C<type> is used, C<push_read> will invoke the code
1307reference with the handle object, the callback and the remaining
1308arguments.
1309
1310The code reference is supposed to return a callback (usually a closure)
1311that works as a plain read callback (see C<< ->push_read ($cb) >>).
1312
1313It should invoke the passed callback when it is done reading (remember to
1314pass C<$handle> as first argument as all other callbacks do that).
1315
1316Note that this is a function, and all types registered this way will be
1317global, so try to use unique names.
1318
1319For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
1320search for C<register_read_type>)).
1321
720=item $handle->stop_read 1322=item $handle->stop_read
721 1323
722=item $handle->start_read 1324=item $handle->start_read
723 1325
724In rare cases you actually do not want to read anything from the 1326In rare cases you actually do not want to read anything from the
725socket. In this case you can call C<stop_read>. Neither C<on_read> no 1327socket. In this case you can call C<stop_read>. Neither C<on_read> nor
726any queued callbacks will be executed then. To start reading again, call 1328any queued callbacks will be executed then. To start reading again, call
727C<start_read>. 1329C<start_read>.
728 1330
1331Note that AnyEvent::Handle will automatically C<start_read> for you when
1332you change the C<on_read> callback or push/unshift a read callback, and it
1333will automatically C<stop_read> for you when neither C<on_read> is set nor
1334there are any read requests in the queue.
1335
1336These methods will have no effect when in TLS mode (as TLS doesn't support
1337half-duplex connections).
1338
729=cut 1339=cut
730 1340
731sub stop_read { 1341sub stop_read {
732 my ($self) = @_; 1342 my ($self) = @_;
733 1343
734 delete $self->{rw}; 1344 delete $self->{_rw} unless $self->{tls};
735} 1345}
736 1346
737sub start_read { 1347sub start_read {
738 my ($self) = @_; 1348 my ($self) = @_;
739 1349
740 unless ($self->{rw} || $self->{eof}) { 1350 unless ($self->{_rw} || $self->{_eof}) {
741 Scalar::Util::weaken $self; 1351 Scalar::Util::weaken $self;
742 1352
743 $self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub { 1353 $self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
744 my $rbuf = $self->{filter_r} ? \my $buf : \$self->{rbuf}; 1354 my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
745 my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf; 1355 my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
746 1356
747 if ($len > 0) { 1357 if ($len > 0) {
748 $self->{filter_r} 1358 $self->{_activity} = AnyEvent->now;
749 ? $self->{filter_r}->($self, $rbuf) 1359
750 : $self->_drain_rbuf; 1360 if ($self->{tls}) {
1361 Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
1362
1363 &_dotls ($self);
1364 } else {
1365 $self->_drain_rbuf unless $self->{_in_drain};
1366 }
751 1367
752 } elsif (defined $len) { 1368 } elsif (defined $len) {
753 delete $self->{rw}; 1369 delete $self->{_rw};
754 $self->{eof} = 1; 1370 $self->{_eof} = 1;
755 $self->_drain_rbuf; 1371 $self->_drain_rbuf unless $self->{_in_drain};
756 1372
757 } elsif ($! != EAGAIN && $! != EINTR) { 1373 } elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
758 return $self->error; 1374 return $self->_error ($!, 1);
759 } 1375 }
760 }); 1376 });
761 } 1377 }
762} 1378}
763 1379
1380our $ERROR_SYSCALL;
1381our $ERROR_WANT_READ;
1382our $ERROR_ZERO_RETURN;
1383
1384sub _tls_error {
1385 my ($self, $err) = @_;
1386
1387 return $self->_error ($!, 1)
1388 if $err == Net::SSLeay::ERROR_SYSCALL ();
1389
1390 my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
1391
1392 # reduce error string to look less scary
1393 $err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
1394
1395 $self->_error (&Errno::EPROTO, 1, $err);
1396}
1397
1398# poll the write BIO and send the data if applicable
1399# also decode read data if possible
1400# this is basiclaly our TLS state machine
1401# more efficient implementations are possible with openssl,
1402# but not with the buggy and incomplete Net::SSLeay.
764sub _dotls { 1403sub _dotls {
765 my ($self) = @_; 1404 my ($self) = @_;
766 1405
1406 my $tmp;
1407
767 if (length $self->{tls_wbuf}) { 1408 if (length $self->{_tls_wbuf}) {
768 while ((my $len = Net::SSLeay::write ($self->{tls}, $self->{tls_wbuf})) > 0) { 1409 while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
769 substr $self->{tls_wbuf}, 0, $len, ""; 1410 substr $self->{_tls_wbuf}, 0, $tmp, "";
770 } 1411 }
771 }
772 1412
1413 $tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
1414 return $self->_tls_error ($tmp)
1415 if $tmp != $ERROR_WANT_READ
1416 && ($tmp != $ERROR_SYSCALL || $!)
1417 && $tmp != $ERROR_ZERO_RETURN;
1418 }
1419
773 if (defined (my $buf = Net::SSLeay::BIO_read ($self->{tls_wbio}))) { 1420 while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
1421 unless (length $tmp) {
1422 # let's treat SSL-eof as we treat normal EOF
1423 delete $self->{_rw};
1424 $self->{_eof} = 1;
1425 &_freetls;
1426 }
1427
1428 $self->{_tls_rbuf} .= $tmp;
1429 $self->_drain_rbuf unless $self->{_in_drain};
1430 $self->{tls} or return; # tls session might have gone away in callback
1431 }
1432
1433 $tmp = Net::SSLeay::get_error ($self->{tls}, -1);
1434 return $self->_tls_error ($tmp)
1435 if $tmp != $ERROR_WANT_READ
1436 && ($tmp != $ERROR_SYSCALL || $!)
1437 && $tmp != $ERROR_ZERO_RETURN;
1438
1439 while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
774 $self->{wbuf} .= $buf; 1440 $self->{wbuf} .= $tmp;
775 $self->_drain_wbuf; 1441 $self->_drain_wbuf;
776 }
777
778 while (defined (my $buf = Net::SSLeay::read ($self->{tls}))) {
779 $self->{rbuf} .= $buf;
780 $self->_drain_rbuf;
781 }
782
783 my $err = Net::SSLeay::get_error ($self->{tls}, -1);
784
785 if ($err!= Net::SSLeay::ERROR_WANT_READ ()) {
786 if ($err == Net::SSLeay::ERROR_SYSCALL ()) {
787 $self->error;
788 } elsif ($err == Net::SSLeay::ERROR_SSL ()) {
789 $! = &Errno::EIO;
790 $self->error;
791 }
792
793 # all others are fine for our purposes
794 } 1442 }
795} 1443}
796 1444
797=item $handle->starttls ($tls[, $tls_ctx]) 1445=item $handle->starttls ($tls[, $tls_ctx])
798 1446
801C<starttls>. 1449C<starttls>.
802 1450
803The first argument is the same as the C<tls> constructor argument (either 1451The first argument is the same as the C<tls> constructor argument (either
804C<"connect">, C<"accept"> or an existing Net::SSLeay object). 1452C<"connect">, C<"accept"> or an existing Net::SSLeay object).
805 1453
806The second argument is the optional C<Net::SSLeay::CTX> object that is 1454The second argument is the optional C<AnyEvent::TLS> object that is used
807used when AnyEvent::Handle has to create its own TLS connection object. 1455when AnyEvent::Handle has to create its own TLS connection object, or
1456a hash reference with C<< key => value >> pairs that will be used to
1457construct a new context.
808 1458
809=cut 1459The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
1460context in C<< $handle->{tls_ctx} >> after this call and can be used or
1461changed to your liking. Note that the handshake might have already started
1462when this function returns.
810 1463
811# TODO: maybe document... 1464If it an error to start a TLS handshake more than once per
1465AnyEvent::Handle object (this is due to bugs in OpenSSL).
1466
1467=cut
1468
1469our %TLS_CACHE; #TODO not yet documented, should we?
1470
812sub starttls { 1471sub starttls {
813 my ($self, $ssl, $ctx) = @_; 1472 my ($self, $ssl, $ctx) = @_;
814 1473
815 $self->stoptls; 1474 require Net::SSLeay;
816 1475
817 if ($ssl eq "accept") { 1476 Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
818 $ssl = Net::SSLeay::new ($ctx || TLS_CTX ()); 1477 if $self->{tls};
819 Net::SSLeay::set_accept_state ($ssl); 1478
820 } elsif ($ssl eq "connect") { 1479 $ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
821 $ssl = Net::SSLeay::new ($ctx || TLS_CTX ()); 1480 $ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
822 Net::SSLeay::set_connect_state ($ssl); 1481 $ERROR_ZERO_RETURN = Net::SSLeay::ERROR_ZERO_RETURN ();
1482
1483 $ctx ||= $self->{tls_ctx};
1484
1485 if ("HASH" eq ref $ctx) {
1486 require AnyEvent::TLS;
1487
1488 local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
1489
1490 if ($ctx->{cache}) {
1491 my $key = $ctx+0;
1492 $ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
1493 } else {
1494 $ctx = new AnyEvent::TLS %$ctx;
1495 }
1496 }
823 } 1497
824 1498 $self->{tls_ctx} = $ctx || TLS_CTX ();
825 $self->{tls} = $ssl; 1499 $self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self, $self->{peername});
826 1500
827 # basically, this is deep magic (because SSL_read should have the same issues) 1501 # basically, this is deep magic (because SSL_read should have the same issues)
828 # but the openssl maintainers basically said: "trust us, it just works". 1502 # but the openssl maintainers basically said: "trust us, it just works".
829 # (unfortunately, we have to hardcode constants because the abysmally misdesigned 1503 # (unfortunately, we have to hardcode constants because the abysmally misdesigned
830 # and mismaintained ssleay-module doesn't even offer them). 1504 # and mismaintained ssleay-module doesn't even offer them).
831 # http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html 1505 # http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
1506 #
1507 # in short: this is a mess.
1508 #
1509 # note that we do not try to keep the length constant between writes as we are required to do.
1510 # we assume that most (but not all) of this insanity only applies to non-blocking cases,
1511 # and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
1512 # have identity issues in that area.
832 Net::SSLeay::CTX_set_mode ($self->{tls}, 1513# Net::SSLeay::CTX_set_mode ($ssl,
833 (eval { Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1) 1514# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
834 | (eval { Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2)); 1515# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
1516 Net::SSLeay::CTX_set_mode ($ssl, 1|2);
835 1517
836 $self->{tls_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ()); 1518 $self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
837 $self->{tls_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ()); 1519 $self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
838 1520
839 Net::SSLeay::set_bio ($ssl, $self->{tls_rbio}, $self->{tls_wbio}); 1521 Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
840 1522
841 $self->{filter_w} = sub { 1523 &_dotls; # need to trigger the initial handshake
842 $_[0]{tls_wbuf} .= ${$_[1]}; 1524 $self->start_read; # make sure we actually do read
843 &_dotls;
844 };
845 $self->{filter_r} = sub {
846 Net::SSLeay::BIO_write ($_[0]{tls_rbio}, ${$_[1]});
847 &_dotls;
848 };
849} 1525}
850 1526
851=item $handle->stoptls 1527=item $handle->stoptls
852 1528
853Destroys the SSL connection, if any. Partial read or write data will be 1529Shuts down the SSL connection - this makes a proper EOF handshake by
854lost. 1530sending a close notify to the other side, but since OpenSSL doesn't
1531support non-blocking shut downs, it is not possible to re-use the stream
1532afterwards.
855 1533
856=cut 1534=cut
857 1535
858sub stoptls { 1536sub stoptls {
859 my ($self) = @_; 1537 my ($self) = @_;
860 1538
861 Net::SSLeay::free (delete $self->{tls}) if $self->{tls}; 1539 if ($self->{tls}) {
862 delete $self->{tls_rbio}; 1540 Net::SSLeay::shutdown ($self->{tls});
863 delete $self->{tls_wbio}; 1541
864 delete $self->{tls_wbuf}; 1542 &_dotls;
865 delete $self->{filter_r}; 1543
866 delete $self->{filter_w}; 1544 # we don't give a shit. no, we do, but we can't. no...
1545 # we, we... have to use openssl :/
1546 &_freetls;
1547 }
1548}
1549
1550sub _freetls {
1551 my ($self) = @_;
1552
1553 return unless $self->{tls};
1554
1555 $self->{tls_ctx}->_put_session (delete $self->{tls});
1556
1557 delete @$self{qw(_rbio _wbio _tls_wbuf)};
867} 1558}
868 1559
869sub DESTROY { 1560sub DESTROY {
870 my $self = shift; 1561 my ($self) = @_;
871 1562
872 $self->stoptls; 1563 &_freetls;
1564
1565 my $linger = exists $self->{linger} ? $self->{linger} : 3600;
1566
1567 if ($linger && length $self->{wbuf}) {
1568 my $fh = delete $self->{fh};
1569 my $wbuf = delete $self->{wbuf};
1570
1571 my @linger;
1572
1573 push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
1574 my $len = syswrite $fh, $wbuf, length $wbuf;
1575
1576 if ($len > 0) {
1577 substr $wbuf, 0, $len, "";
1578 } else {
1579 @linger = (); # end
1580 }
1581 });
1582 push @linger, AnyEvent->timer (after => $linger, cb => sub {
1583 @linger = ();
1584 });
1585 }
1586}
1587
1588=item $handle->destroy
1589
1590Shuts down the handle object as much as possible - this call ensures that
1591no further callbacks will be invoked and resources will be freed as much
1592as possible. You must not call any methods on the object afterwards.
1593
1594Normally, you can just "forget" any references to an AnyEvent::Handle
1595object and it will simply shut down. This works in fatal error and EOF
1596callbacks, as well as code outside. It does I<NOT> work in a read or write
1597callback, so when you want to destroy the AnyEvent::Handle object from
1598within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
1599that case.
1600
1601The handle might still linger in the background and write out remaining
1602data, as specified by the C<linger> option, however.
1603
1604=cut
1605
1606sub destroy {
1607 my ($self) = @_;
1608
1609 $self->DESTROY;
1610 %$self = ();
873} 1611}
874 1612
875=item AnyEvent::Handle::TLS_CTX 1613=item AnyEvent::Handle::TLS_CTX
876 1614
877This function creates and returns the Net::SSLeay::CTX object used by 1615This function creates and returns the AnyEvent::TLS object used by default
878default for TLS mode. 1616for TLS mode.
879 1617
880The context is created like this: 1618The context is created by calling L<AnyEvent::TLS> without any arguments.
881
882 Net::SSLeay::load_error_strings;
883 Net::SSLeay::SSLeay_add_ssl_algorithms;
884 Net::SSLeay::randomize;
885
886 my $CTX = Net::SSLeay::CTX_new;
887
888 Net::SSLeay::CTX_set_options $CTX, Net::SSLeay::OP_ALL
889 1619
890=cut 1620=cut
891 1621
892our $TLS_CTX; 1622our $TLS_CTX;
893 1623
894sub TLS_CTX() { 1624sub TLS_CTX() {
895 $TLS_CTX || do { 1625 $TLS_CTX ||= do {
896 require Net::SSLeay; 1626 require AnyEvent::TLS;
897 1627
898 Net::SSLeay::load_error_strings (); 1628 new AnyEvent::TLS
899 Net::SSLeay::SSLeay_add_ssl_algorithms ();
900 Net::SSLeay::randomize ();
901
902 $TLS_CTX = Net::SSLeay::CTX_new ();
903
904 Net::SSLeay::CTX_set_options ($TLS_CTX, Net::SSLeay::OP_ALL ());
905
906 $TLS_CTX
907 } 1629 }
908} 1630}
909 1631
910=back 1632=back
911 1633
1634
1635=head1 NONFREQUENTLY ASKED QUESTIONS
1636
1637=over 4
1638
1639=item I C<undef> the AnyEvent::Handle reference inside my callback and
1640still get further invocations!
1641
1642That's because AnyEvent::Handle keeps a reference to itself when handling
1643read or write callbacks.
1644
1645It is only safe to "forget" the reference inside EOF or error callbacks,
1646from within all other callbacks, you need to explicitly call the C<<
1647->destroy >> method.
1648
1649=item I get different callback invocations in TLS mode/Why can't I pause
1650reading?
1651
1652Unlike, say, TCP, TLS connections do not consist of two independent
1653communication channels, one for each direction. Or put differently. The
1654read and write directions are not independent of each other: you cannot
1655write data unless you are also prepared to read, and vice versa.
1656
1657This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
1658callback invocations when you are not expecting any read data - the reason
1659is that AnyEvent::Handle always reads in TLS mode.
1660
1661During the connection, you have to make sure that you always have a
1662non-empty read-queue, or an C<on_read> watcher. At the end of the
1663connection (or when you no longer want to use it) you can call the
1664C<destroy> method.
1665
1666=item How do I read data until the other side closes the connection?
1667
1668If you just want to read your data into a perl scalar, the easiest way
1669to achieve this is by setting an C<on_read> callback that does nothing,
1670clearing the C<on_eof> callback and in the C<on_error> callback, the data
1671will be in C<$_[0]{rbuf}>:
1672
1673 $handle->on_read (sub { });
1674 $handle->on_eof (undef);
1675 $handle->on_error (sub {
1676 my $data = delete $_[0]{rbuf};
1677 undef $handle;
1678 });
1679
1680The reason to use C<on_error> is that TCP connections, due to latencies
1681and packets loss, might get closed quite violently with an error, when in
1682fact, all data has been received.
1683
1684It is usually better to use acknowledgements when transferring data,
1685to make sure the other side hasn't just died and you got the data
1686intact. This is also one reason why so many internet protocols have an
1687explicit QUIT command.
1688
1689=item I don't want to destroy the handle too early - how do I wait until
1690all data has been written?
1691
1692After writing your last bits of data, set the C<on_drain> callback
1693and destroy the handle in there - with the default setting of
1694C<low_water_mark> this will be called precisely when all data has been
1695written to the socket:
1696
1697 $handle->push_write (...);
1698 $handle->on_drain (sub {
1699 warn "all data submitted to the kernel\n";
1700 undef $handle;
1701 });
1702
1703=back
1704
1705
1706=head1 SUBCLASSING AnyEvent::Handle
1707
1708In many cases, you might want to subclass AnyEvent::Handle.
1709
1710To make this easier, a given version of AnyEvent::Handle uses these
1711conventions:
1712
1713=over 4
1714
1715=item * all constructor arguments become object members.
1716
1717At least initially, when you pass a C<tls>-argument to the constructor it
1718will end up in C<< $handle->{tls} >>. Those members might be changed or
1719mutated later on (for example C<tls> will hold the TLS connection object).
1720
1721=item * other object member names are prefixed with an C<_>.
1722
1723All object members not explicitly documented (internal use) are prefixed
1724with an underscore character, so the remaining non-C<_>-namespace is free
1725for use for subclasses.
1726
1727=item * all members not documented here and not prefixed with an underscore
1728are free to use in subclasses.
1729
1730Of course, new versions of AnyEvent::Handle may introduce more "public"
1731member variables, but thats just life, at least it is documented.
1732
1733=back
1734
912=head1 AUTHOR 1735=head1 AUTHOR
913 1736
914Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>. 1737Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
915 1738
916=cut 1739=cut

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