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Revision 1.8 by root, Fri May 2 15:36:10 2008 UTC vs.
Revision 1.82 by root, Thu Aug 21 18:45:16 2008 UTC

1	package AnyEvent::Handle;	1	package AnyEvent::Handle;
2		2
3	no warnings;	3	no warnings;
4	use strict;	4	use strict qw(subs vars);
5		5
6	use AnyEvent ();	6	use AnyEvent ();
7	use AnyEvent::Util ();	7	use AnyEvent::Util qw(WSAEWOULDBLOCK);
8	use Scalar::Util ();	8	use Scalar::Util ();
9	use Carp ();	9	use Carp ();
10	use Fcntl ();	10	use Fcntl ();
11	use Errno qw/EAGAIN EINTR/;	11	use Errno qw(EAGAIN EINTR);
12		12
13	=head1 NAME	13	=head1 NAME
14		14
15	AnyEvent::Handle - non-blocking I/O on filehandles via AnyEvent	15	AnyEvent::Handle - non-blocking I/O on file handles via AnyEvent
16		16
17	=cut	17	=cut
18		18
19	our $VERSION = '0.02';	19	our $VERSION = 4.232;
20		20
21	=head1 SYNOPSIS	21	=head1 SYNOPSIS
22		22
23	use AnyEvent;	23	use AnyEvent;
24	use AnyEvent::Handle;	24	use AnyEvent::Handle;
25		25
26	my $cv = AnyEvent->condvar;	26	my $cv = AnyEvent->condvar;
27		27
28	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	28	my $handle =
29
30	#TODO
31
32	# or use the constructor to pass the callback:
33
34	my $ae_fh2 =
35	AnyEvent::Handle->new (	29	AnyEvent::Handle->new (
36	fh => \*STDIN,	30	fh => \*STDIN,
37	on_eof => sub {	31	on_eof => sub {
38	$cv->broadcast;	32	$cv->broadcast;
39	},	33	},
40	#TODO
41	);	34	);
42		35
43	$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;
44		47
45	=head1 DESCRIPTION	48	=head1 DESCRIPTION
46		49
47	This module is a helper module to make it easier to do event-based I/O on	50	This module is a helper module to make it easier to do event-based I/O on
48	filehandles (and sockets, see L<AnyEvent::Socket> for an easy way to make	51	filehandles. For utility functions for doing non-blocking connects and accepts
49	non-blocking resolves and connects).	52	on sockets see L<AnyEvent::Util>.
50		53
51	In the following, when the documentation refers to of "bytes" then this	54	In the following, when the documentation refers to of "bytes" then this
52	means characters. As sysread and syswrite are used for all I/O, their	55	means characters. As sysread and syswrite are used for all I/O, their
53	treatment of characters applies to this module as well.	56	treatment of characters applies to this module as well.
54		57
…		…
70	The filehandle this L<AnyEvent::Handle> object will operate on.	73	The filehandle this L<AnyEvent::Handle> object will operate on.
71		74
72	NOTE: The filehandle will be set to non-blocking (using	75	NOTE: The filehandle will be set to non-blocking (using
73	AnyEvent::Util::fh_nonblocking).	76	AnyEvent::Util::fh_nonblocking).
74		77
75	=item on_error => $cb->($self) [MANDATORY]	78	=item on_eof => $cb->($handle)
76		79
77	This is the fatal error callback, that is called when a fatal error ocurs,	80	Set the callback to be called when an end-of-file condition is detected,
		81	i.e. in the case of a socket, when the other side has closed the
		82	connection cleanly.
		83
		84	For sockets, this just means that the other side has stopped sending data,
		85	you can still try to write data, and, in fact, one can return from the eof
		86	callback and continue writing data, as only the read part has been shut
		87	down.
		88
		89	While not mandatory, it is I<highly> recommended to set an eof callback,
		90	otherwise you might end up with a closed socket while you are still
		91	waiting for data.
		92
		93	If an EOF condition has been detected but no C<on_eof> callback has been
		94	set, then a fatal error will be raised with C<$!> set to <0>.
		95
		96	=item on_error => $cb->($handle, $fatal)
		97
		98	This is the error callback, which is called when, well, some error
78	such as not being able to resolve the hostname, failure to connect or a	99	occured, such as not being able to resolve the hostname, failure to
79	read error.	100	connect or a read error.
80		101
81	The object will not be in a usable state when this callback has been	102	Some errors are fatal (which is indicated by C<$fatal> being true). On
82	called.	103	fatal errors the handle object will be shut down and will not be usable
		104	(but you are free to look at the current C< ->rbuf >). Examples of fatal
		105	errors are an EOF condition with active (but unsatisifable) read watchers
		106	(C<EPIPE>) or I/O errors.
83		107
		108	Non-fatal errors can be retried by simply returning, but it is recommended
		109	to simply ignore this parameter and instead abondon the handle object
		110	when this callback is invoked. Examples of non-fatal errors are timeouts
		111	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
		112
84	On callback entrance, the value of C<$!> contains the opertaing system	113	On callback entrance, the value of C<$!> contains the operating system
85	error (or C<ENOSPC> or C<EPIPE>).	114	error (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT> or C<EBADMSG>).
86		115
87	=item on_eof => $cb->($self) [MANDATORY]	116	While not mandatory, it is I<highly> recommended to set this callback, as
		117	you will not be notified of errors otherwise. The default simply calls
		118	C<croak>.
88		119
89	Set the callback to be called on EOF.
90
91	=item on_read => $cb->($self)	120	=item on_read => $cb->($handle)
92		121
93	This sets the default read callback, which is called when data arrives	122	This sets the default read callback, which is called when data arrives
94	and no read request is in the queue. If the read callback is C<undef>	123	and no read request is in the queue (unlike read queue callbacks, this
95	or has never been set, than AnyEvent::Handle will cease reading from the	124	callback will only be called when at least one octet of data is in the
96	filehandle.	125	read buffer).
97		126
98	To access (and remove data from) the read buffer, use the C<< ->rbuf >>	127	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
99	method or acces sthe C<$self->{rbuf}> member directly.	128	method or access the C<$handle->{rbuf}> member directly.
100		129
101	When an EOF condition is detected then AnyEvent::Handle will first try to	130	When an EOF condition is detected then AnyEvent::Handle will first try to
102	feed all the remaining data to the queued callbacks and C<on_read> before	131	feed all the remaining data to the queued callbacks and C<on_read> before
103	calling the C<on_eof> callback. If no progress can be made, then a fatal	132	calling the C<on_eof> callback. If no progress can be made, then a fatal
104	error will be raised (with C<$!> set to C<EPIPE>).	133	error will be raised (with C<$!> set to C<EPIPE>).
105		134
106	=item on_drain => $cb->()	135	=item on_drain => $cb->($handle)
107		136
108	This sets the callback that is called when the write buffer becomes empty	137	This sets the callback that is called when the write buffer becomes empty
109	(or when the callback is set and the buffer is empty already).	138	(or when the callback is set and the buffer is empty already).
110		139
111	To append to the write buffer, use the C<< ->push_write >> method.	140	To append to the write buffer, use the C<< ->push_write >> method.
		141
		142	This callback is useful when you don't want to put all of your write data
		143	into the queue at once, for example, when you want to write the contents
		144	of some file to the socket you might not want to read the whole file into
		145	memory and push it into the queue, but instead only read more data from
		146	the file when the write queue becomes empty.
		147
		148	=item timeout => $fractional_seconds
		149
		150	If non-zero, then this enables an "inactivity" timeout: whenever this many
		151	seconds pass without a successful read or write on the underlying file
		152	handle, the C<on_timeout> callback will be invoked (and if that one is
		153	missing, an C<ETIMEDOUT> error will be raised).
		154
		155	Note that timeout processing is also active when you currently do not have
		156	any outstanding read or write requests: If you plan to keep the connection
		157	idle then you should disable the timout temporarily or ignore the timeout
		158	in the C<on_timeout> callback.
		159
		160	Zero (the default) disables this timeout.
		161
		162	=item on_timeout => $cb->($handle)
		163
		164	Called whenever the inactivity timeout passes. If you return from this
		165	callback, then the timeout will be reset as if some activity had happened,
		166	so this condition is not fatal in any way.
112		167
113	=item rbuf_max => <bytes>	168	=item rbuf_max => <bytes>
114		169
115	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)	170	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
116	when the read buffer ever (strictly) exceeds this size. This is useful to	171	when the read buffer ever (strictly) exceeds this size. This is useful to
…		…
120	be configured to accept only so-and-so much data that it cannot act on	175	be configured to accept only so-and-so much data that it cannot act on
121	(for example, when expecting a line, an attacker could send an unlimited	176	(for example, when expecting a line, an attacker could send an unlimited
122	amount of data without a callback ever being called as long as the line	177	amount of data without a callback ever being called as long as the line
123	isn't finished).	178	isn't finished).
124		179
		180	=item autocork => <boolean>
		181
		182	When disabled (the default), then C<push_write> will try to immediately
		183	write the data to the handle if possible. This avoids having to register
		184	a write watcher and wait for the next event loop iteration, but can be
		185	inefficient if you write multiple small chunks (this disadvantage is
		186	usually avoided by your kernel's nagle algorithm, see C<low_delay>).
		187
		188	When enabled, then writes will always be queued till the next event loop
		189	iteration. This is efficient when you do many small writes per iteration,
		190	but less efficient when you do a single write only.
		191
		192	=item no_delay => <boolean>
		193
		194	When doing small writes on sockets, your operating system kernel might
		195	wait a bit for more data before actually sending it out. This is called
		196	the Nagle algorithm, and usually it is beneficial.
		197
		198	In some situations you want as low a delay as possible, which cna be
		199	accomplishd by setting this option to true.
		200
		201	The default is your opertaing system's default behaviour, this option
		202	explicitly enables or disables it, if possible.
		203
125	=item read_size => <bytes>	204	=item read_size => <bytes>
126		205
127	The default read block size (the amount of bytes this module will try to read	206	The default read block size (the amount of bytes this module will try to read
128	on each [loop iteration). Default: C<4096>.	207	during each (loop iteration). Default: C<8192>.
129		208
130	=item low_water_mark => <bytes>	209	=item low_water_mark => <bytes>
131		210
132	Sets the amount of bytes (default: C<0>) that make up an "empty" write	211	Sets the amount of bytes (default: C<0>) that make up an "empty" write
133	buffer: If the write reaches this size or gets even samller it is	212	buffer: If the write reaches this size or gets even samller it is
134	considered empty.	213	considered empty.
135		214
		215	=item linger => <seconds>
		216
		217	If non-zero (default: C<3600>), then the destructor of the
		218	AnyEvent::Handle object will check wether there is still outstanding write
		219	data and will install a watcher that will write out this data. No errors
		220	will be reported (this mostly matches how the operating system treats
		221	outstanding data at socket close time).
		222
		223	This will not work for partial TLS data that could not yet been
		224	encoded. This data will be lost.
		225
		226	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		227
		228	When this parameter is given, it enables TLS (SSL) mode, that means it
		229	will start making tls handshake and will transparently encrypt/decrypt
		230	data.
		231
		232	TLS mode requires Net::SSLeay to be installed (it will be loaded
		233	automatically when you try to create a TLS handle).
		234
		235	For the TLS server side, use C<accept>, and for the TLS client side of a
		236	connection, use C<connect> mode.
		237
		238	You can also provide your own TLS connection object, but you have
		239	to make sure that you call either C<Net::SSLeay::set_connect_state>
		240	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		241	AnyEvent::Handle.
		242
		243	See the C<starttls> method if you need to start TLS negotiation later.
		244
		245	=item tls_ctx => $ssl_ctx
		246
		247	Use the given Net::SSLeay::CTX object to create the new TLS connection
		248	(unless a connection object was specified directly). If this parameter is
		249	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
		250
		251	=item json => JSON or JSON::XS object
		252
		253	This is the json coder object used by the C<json> read and write types.
		254
		255	If you don't supply it, then AnyEvent::Handle will create and use a
		256	suitable one, which will write and expect UTF-8 encoded JSON texts.
		257
		258	Note that you are responsible to depend on the JSON module if you want to
		259	use this functionality, as AnyEvent does not have a dependency itself.
		260
		261	=item filter_r => $cb
		262
		263	=item filter_w => $cb
		264
		265	These exist, but are undocumented at this time.
		266
136	=back	267	=back
137		268
138	=cut	269	=cut
139		270
140	sub new {	271	sub new {
…		…
144		275
145	$self->{fh} or Carp::croak "mandatory argument fh is missing";	276	$self->{fh} or Carp::croak "mandatory argument fh is missing";
146		277
147	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	278	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
148		279
149	$self->on_error ((delete $self->{on_error}) or Carp::croak "mandatory argument on_error is missing");	280	if ($self->{tls}) {
150	$self->on_eof ((delete $self->{on_eof} ) or Carp::croak "mandatory argument on_eof is missing");	281	require Net::SSLeay;
		282	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx});
		283	}
151		284
		285	$self->{_activity} = AnyEvent->now;
		286	$self->_timeout;
		287
152	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	288	$self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
153	$self->on_read (delete $self->{on_read} ) if $self->{on_read};	289	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		290
		291	$self->start_read
		292	if $self->{on_read};
154		293
155	$self	294	$self
156	}	295	}
157		296
158	sub _shutdown {	297	sub _shutdown {
159	my ($self) = @_;	298	my ($self) = @_;
160		299
		300	delete $self->{_tw};
161	delete $self->{rw};	301	delete $self->{_rw};
162	delete $self->{ww};	302	delete $self->{_ww};
163	delete $self->{fh};	303	delete $self->{fh};
164	}
165		304
		305	$self->stoptls;
		306
		307	delete $self->{on_read};
		308	delete $self->{_queue};
		309	}
		310
166	sub error {	311	sub _error {
167	my ($self) = @_;	312	my ($self, $errno, $fatal) = @_;
168		313
169	{
170	local $!;
171	$self->_shutdown;	314	$self->_shutdown
172	}	315	if $fatal;
173		316
		317	$! = $errno;
		318
		319	if ($self->{on_error}) {
174	$self->{on_error}($self);	320	$self->{on_error}($self, $fatal);
		321	} else {
		322	Carp::croak "AnyEvent::Handle uncaught error: $!";
		323	}
175	}	324	}
176		325
177	=item $fh = $handle->fh	326	=item $fh = $handle->fh
178		327
179	This method returns the filehandle of the L<AnyEvent::Handle> object.	328	This method returns the file handle of the L<AnyEvent::Handle> object.
180		329
181	=cut	330	=cut
182		331
183	sub fh { $_[0]->{fh} }	332	sub fh { $_[0]{fh} }
184		333
185	=item $handle->on_error ($cb)	334	=item $handle->on_error ($cb)
186		335
187	Replace the current C<on_error> callback (see the C<on_error> constructor argument).	336	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
188		337
…		…
196		345
197	Replace the current C<on_eof> callback (see the C<on_eof> constructor argument).	346	Replace the current C<on_eof> callback (see the C<on_eof> constructor argument).
198		347
199	=cut	348	=cut
200		349
201	#############################################################################
202
203	sub on_eof {	350	sub on_eof {
204	$_[0]{on_eof} = $_[1];	351	$_[0]{on_eof} = $_[1];
205	}	352	}
		353
		354	=item $handle->on_timeout ($cb)
		355
		356	Replace the current C<on_timeout> callback, or disables the callback
		357	(but not the timeout) if C<$cb> = C<undef>. See C<timeout> constructor
		358	argument.
		359
		360	=cut
		361
		362	sub on_timeout {
		363	$_[0]{on_timeout} = $_[1];
		364	}
		365
		366	=item $handle->autocork ($boolean)
		367
		368	Enables or disables the current autocork behaviour (see C<autocork>
		369	constructor argument).
		370
		371	=cut
		372
		373	=item $handle->no_delay ($boolean)
		374
		375	Enables or disables the C<no_delay> setting (see constructor argument of
		376	the same name for details).
		377
		378	=cut
		379
		380	sub no_delay {
		381	$_[0]{no_delay} = $_[1];
		382
		383	eval {
		384	local $SIG{__DIE__};
		385	setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
		386	};
		387	}
		388
		389	#############################################################################
		390
		391	=item $handle->timeout ($seconds)
		392
		393	Configures (or disables) the inactivity timeout.
		394
		395	=cut
		396
		397	sub timeout {
		398	my ($self, $timeout) = @_;
		399
		400	$self->{timeout} = $timeout;
		401	$self->_timeout;
		402	}
		403
		404	# reset the timeout watcher, as neccessary
		405	# also check for time-outs
		406	sub _timeout {
		407	my ($self) = @_;
		408
		409	if ($self->{timeout}) {
		410	my $NOW = AnyEvent->now;
		411
		412	# when would the timeout trigger?
		413	my $after = $self->{_activity} + $self->{timeout} - $NOW;
		414
		415	# now or in the past already?
		416	if ($after <= 0) {
		417	$self->{_activity} = $NOW;
		418
		419	if ($self->{on_timeout}) {
		420	$self->{on_timeout}($self);
		421	} else {
		422	$self->_error (&Errno::ETIMEDOUT);
		423	}
		424
		425	# callback could have changed timeout value, optimise
		426	return unless $self->{timeout};
		427
		428	# calculate new after
		429	$after = $self->{timeout};
		430	}
		431
		432	Scalar::Util::weaken $self;
		433	return unless $self; # ->error could have destroyed $self
		434
		435	$self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
		436	delete $self->{_tw};
		437	$self->_timeout;
		438	});
		439	} else {
		440	delete $self->{_tw};
		441	}
		442	}
		443
		444	#############################################################################
		445
		446	=back
		447
		448	=head2 WRITE QUEUE
		449
		450	AnyEvent::Handle manages two queues per handle, one for writing and one
		451	for reading.
		452
		453	The write queue is very simple: you can add data to its end, and
		454	AnyEvent::Handle will automatically try to get rid of it for you.
		455
		456	When data could be written and the write buffer is shorter then the low
		457	water mark, the C<on_drain> callback will be invoked.
		458
		459	=over 4
206		460
207	=item $handle->on_drain ($cb)	461	=item $handle->on_drain ($cb)
208		462
209	Sets the C<on_drain> callback or clears it (see the description of	463	Sets the C<on_drain> callback or clears it (see the description of
210	C<on_drain> in the constructor).	464	C<on_drain> in the constructor).
…		…
226	want (only limited by the available memory), as C<AnyEvent::Handle>	480	want (only limited by the available memory), as C<AnyEvent::Handle>
227	buffers it independently of the kernel.	481	buffers it independently of the kernel.
228		482
229	=cut	483	=cut
230		484
231	sub push_write {	485	sub _drain_wbuf {
232	my ($self, $data) = @_;	486	my ($self) = @_;
233		487
234	$self->{wbuf} .= $data;	488	if (!$self->{_ww} && length $self->{wbuf}) {
235		489
236	unless ($self->{ww}) {
237	Scalar::Util::weaken $self;	490	Scalar::Util::weaken $self;
		491
238	my $cb = sub {	492	my $cb = sub {
239	my $len = syswrite $self->{fh}, $self->{wbuf};	493	my $len = syswrite $self->{fh}, $self->{wbuf};
240		494
241	if ($len > 0) {	495	if ($len >= 0) {
242	substr $self->{wbuf}, 0, $len, "";	496	substr $self->{wbuf}, 0, $len, "";
243		497
		498	$self->{_activity} = AnyEvent->now;
244		499
245	$self->{on_drain}($self)	500	$self->{on_drain}($self)
246	if $self->{low_water_mark} >= length $self->{wbuf}	501	if $self->{low_water_mark} >= length $self->{wbuf}
247	&& $self->{on_drain};	502	&& $self->{on_drain};
248		503
249	delete $self->{ww} unless length $self->{wbuf};	504	delete $self->{_ww} unless length $self->{wbuf};
250	} elsif ($! != EAGAIN && $! != EINTR) {	505	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
251	$self->error;	506	$self->_error ($!, 1);
252	}	507	}
253	};	508	};
254		509
		510	# try to write data immediately
		511	$cb->() unless $self->{autocork};
		512
		513	# if still data left in wbuf, we need to poll
255	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	514	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
256		515	if length $self->{wbuf};
257	$cb->($self);
258	};	516	};
259	}	517	}
260		518
		519	our %WH;
		520
		521	sub register_write_type($$) {
		522	$WH{$_[0]} = $_[1];
		523	}
		524
		525	sub push_write {
		526	my $self = shift;
		527
		528	if (@_ > 1) {
		529	my $type = shift;
		530
		531	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
		532	->($self, @_);
		533	}
		534
		535	if ($self->{filter_w}) {
		536	$self->{filter_w}($self, \$_[0]);
		537	} else {
		538	$self->{wbuf} .= $_[0];
		539	$self->_drain_wbuf;
		540	}
		541	}
		542
		543	=item $handle->push_write (type => @args)
		544
		545	Instead of formatting your data yourself, you can also let this module do
		546	the job by specifying a type and type-specific arguments.
		547
		548	Predefined types are (if you have ideas for additional types, feel free to
		549	drop by and tell us):
		550
		551	=over 4
		552
		553	=item netstring => $string
		554
		555	Formats the given value as netstring
		556	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		557
		558	=cut
		559
		560	register_write_type netstring => sub {
		561	my ($self, $string) = @_;
		562
		563	sprintf "%d:%s,", (length $string), $string
		564	};
		565
		566	=item packstring => $format, $data
		567
		568	An octet string prefixed with an encoded length. The encoding C<$format>
		569	uses the same format as a Perl C<pack> format, but must specify a single
		570	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		571	optional C<!>, C<< < >> or C<< > >> modifier).
		572
		573	=cut
		574
		575	register_write_type packstring => sub {
		576	my ($self, $format, $string) = @_;
		577
		578	pack "$format/a*", $string
		579	};
		580
		581	=item json => $array_or_hashref
		582
		583	Encodes the given hash or array reference into a JSON object. Unless you
		584	provide your own JSON object, this means it will be encoded to JSON text
		585	in UTF-8.
		586
		587	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		588	one end of a handle and read them at the other end without using any
		589	additional framing.
		590
		591	The generated JSON text is guaranteed not to contain any newlines: While
		592	this module doesn't need delimiters after or between JSON texts to be
		593	able to read them, many other languages depend on that.
		594
		595	A simple RPC protocol that interoperates easily with others is to send
		596	JSON arrays (or objects, although arrays are usually the better choice as
		597	they mimic how function argument passing works) and a newline after each
		598	JSON text:
		599
		600	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		601	$handle->push_write ("\012");
		602
		603	An AnyEvent::Handle receiver would simply use the C<json> read type and
		604	rely on the fact that the newline will be skipped as leading whitespace:
		605
		606	$handle->push_read (json => sub { my $array = $_[1]; ... });
		607
		608	Other languages could read single lines terminated by a newline and pass
		609	this line into their JSON decoder of choice.
		610
		611	=cut
		612
		613	register_write_type json => sub {
		614	my ($self, $ref) = @_;
		615
		616	require JSON;
		617
		618	$self->{json} ? $self->{json}->encode ($ref)
		619	: JSON::encode_json ($ref)
		620	};
		621
		622	=item storable => $reference
		623
		624	Freezes the given reference using L<Storable> and writes it to the
		625	handle. Uses the C<nfreeze> format.
		626
		627	=cut
		628
		629	register_write_type storable => sub {
		630	my ($self, $ref) = @_;
		631
		632	require Storable;
		633
		634	pack "w/a*", Storable::nfreeze ($ref)
		635	};
		636
		637	=back
		638
		639	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
		640
		641	This function (not method) lets you add your own types to C<push_write>.
		642	Whenever the given C<type> is used, C<push_write> will invoke the code
		643	reference with the handle object and the remaining arguments.
		644
		645	The code reference is supposed to return a single octet string that will
		646	be appended to the write buffer.
		647
		648	Note that this is a function, and all types registered this way will be
		649	global, so try to use unique names.
		650
		651	=cut
		652
261	#############################################################################	653	#############################################################################
		654
		655	=back
		656
		657	=head2 READ QUEUE
		658
		659	AnyEvent::Handle manages two queues per handle, one for writing and one
		660	for reading.
		661
		662	The read queue is more complex than the write queue. It can be used in two
		663	ways, the "simple" way, using only C<on_read> and the "complex" way, using
		664	a queue.
		665
		666	In the simple case, you just install an C<on_read> callback and whenever
		667	new data arrives, it will be called. You can then remove some data (if
		668	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
		669	leave the data there if you want to accumulate more (e.g. when only a
		670	partial message has been received so far).
		671
		672	In the more complex case, you want to queue multiple callbacks. In this
		673	case, AnyEvent::Handle will call the first queued callback each time new
		674	data arrives (also the first time it is queued) and removes it when it has
		675	done its job (see C<push_read>, below).
		676
		677	This way you can, for example, push three line-reads, followed by reading
		678	a chunk of data, and AnyEvent::Handle will execute them in order.
		679
		680	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
		681	the specified number of bytes which give an XML datagram.
		682
		683	# in the default state, expect some header bytes
		684	$handle->on_read (sub {
		685	# some data is here, now queue the length-header-read (4 octets)
		686	shift->unshift_read (chunk => 4, sub {
		687	# header arrived, decode
		688	my $len = unpack "N", $_[1];
		689
		690	# now read the payload
		691	shift->unshift_read (chunk => $len, sub {
		692	my $xml = $_[1];
		693	# handle xml
		694	});
		695	});
		696	});
		697
		698	Example 2: Implement a client for a protocol that replies either with "OK"
		699	and another line or "ERROR" for the first request that is sent, and 64
		700	bytes for the second request. Due to the availability of a queue, we can
		701	just pipeline sending both requests and manipulate the queue as necessary
		702	in the callbacks.
		703
		704	When the first callback is called and sees an "OK" response, it will
		705	C<unshift> another line-read. This line-read will be queued I<before> the
		706	64-byte chunk callback.
		707
		708	# request one, returns either "OK + extra line" or "ERROR"
		709	$handle->push_write ("request 1\015\012");
		710
		711	# we expect "ERROR" or "OK" as response, so push a line read
		712	$handle->push_read (line => sub {
		713	# if we got an "OK", we have to _prepend_ another line,
		714	# so it will be read before the second request reads its 64 bytes
		715	# which are already in the queue when this callback is called
		716	# we don't do this in case we got an error
		717	if ($_[1] eq "OK") {
		718	$_[0]->unshift_read (line => sub {
		719	my $response = $_[1];
		720	...
		721	});
		722	}
		723	});
		724
		725	# request two, simply returns 64 octets
		726	$handle->push_write ("request 2\015\012");
		727
		728	# simply read 64 bytes, always
		729	$handle->push_read (chunk => 64, sub {
		730	my $response = $_[1];
		731	...
		732	});
		733
		734	=over 4
		735
		736	=cut
262		737
263	sub _drain_rbuf {	738	sub _drain_rbuf {
264	my ($self) = @_;	739	my ($self) = @_;
265		740
266	return if exists $self->{in_drain};
267	local $self->{in_drain} = 1;	741	local $self->{_in_drain} = 1;
268		742
		743	if (
		744	defined $self->{rbuf_max}
		745	&& $self->{rbuf_max} < length $self->{rbuf}
		746	) {
		747	$self->_error (&Errno::ENOSPC, 1), return;
		748	}
		749
		750	while () {
269	while (my $len = length $self->{rbuf}) {	751	my $len = length $self->{rbuf};
270	no strict 'refs';	752
271	if (@{ $self->{queue} }) {	753	if (my $cb = shift @{ $self->{_queue} }) {
272	if ($self->{queue}[0]($self)) {	754	unless ($cb->($self)) {
273	shift @{ $self->{queue} };
274	} elsif ($self->{eof}) {	755	if ($self->{_eof}) {
275	# no progress can be made (not enough data and no data forthcoming)	756	# no progress can be made (not enough data and no data forthcoming)
276	$! = &Errno::EPIPE; return $self->error;	757	$self->_error (&Errno::EPIPE, 1), return;
277	} else {	758	}
		759
		760	unshift @{ $self->{_queue} }, $cb;
278	return;	761	last;
279	}	762	}
280	} elsif ($self->{on_read}) {	763	} elsif ($self->{on_read}) {
		764	last unless $len;
		765
281	$self->{on_read}($self);	766	$self->{on_read}($self);
282		767
283	if (	768	if (
284	$self->{eof} # if no further data will arrive
285	&& $len == length $self->{rbuf} # and no data has been consumed	769	$len == length $self->{rbuf} # if no data has been consumed
286	&& !@{ $self->{queue} } # and the queue is still empty	770	&& !@{ $self->{_queue} } # and the queue is still empty
287	&& $self->{on_read} # and we still want to read data	771	&& $self->{on_read} # but we still have on_read
288	) {	772	) {
		773	# no further data will arrive
289	# then no progress can be made	774	# so no progress can be made
290	$! = &Errno::EPIPE; return $self->error;	775	$self->_error (&Errno::EPIPE, 1), return
		776	if $self->{_eof};
		777
		778	last; # more data might arrive
291	}	779	}
292	} else {	780	} else {
293	# read side becomes idle	781	# read side becomes idle
294	delete $self->{rw};	782	delete $self->{_rw};
295	return;	783	last;
296	}	784	}
297	}	785	}
298		786
299	if ($self->{eof}) {	787	if ($self->{_eof}) {
300	$self->_shutdown;	788	if ($self->{on_eof}) {
301	$self->{on_eof}($self);	789	$self->{on_eof}($self)
		790	} else {
		791	$self->_error (0, 1);
		792	}
		793	}
		794
		795	# may need to restart read watcher
		796	unless ($self->{_rw}) {
		797	$self->start_read
		798	if $self->{on_read} || @{ $self->{_queue} };
302	}	799	}
303	}	800	}
304		801
305	=item $handle->on_read ($cb)	802	=item $handle->on_read ($cb)
306		803
…		…
312		809
313	sub on_read {	810	sub on_read {
314	my ($self, $cb) = @_;	811	my ($self, $cb) = @_;
315		812
316	$self->{on_read} = $cb;	813	$self->{on_read} = $cb;
317		814	$self->_drain_rbuf if $cb && !$self->{_in_drain};
318	unless ($self->{rw} || $self->{eof}) {
319	Scalar::Util::weaken $self;
320
321	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
322	my $len = sysread $self->{fh}, $self->{rbuf}, $self->{read_size} || 8192, length $self->{rbuf};
323
324	if ($len > 0) {
325	if (exists $self->{rbuf_max}) {
326	if ($self->{rbuf_max} < length $self->{rbuf}) {
327	$! = &Errno::ENOSPC; return $self->error;
328	}
329	}
330
331	} elsif (defined $len) {
332	$self->{eof} = 1;
333	delete $self->{rw};
334
335	} elsif ($! != EAGAIN && $! != EINTR) {
336	return $self->error;
337	}
338
339	$self->_drain_rbuf;
340	});
341	}
342	}	815	}
343		816
344	=item $handle->rbuf	817	=item $handle->rbuf
345		818
346	Returns the read buffer (as a modifiable lvalue).	819	Returns the read buffer (as a modifiable lvalue).
…		…
365	Append the given callback to the end of the queue (C<push_read>) or	838	Append the given callback to the end of the queue (C<push_read>) or
366	prepend it (C<unshift_read>).	839	prepend it (C<unshift_read>).
367		840
368	The callback is called each time some additional read data arrives.	841	The callback is called each time some additional read data arrives.
369		842
370	It must check wether enough data is in the read buffer already.	843	It must check whether enough data is in the read buffer already.
371		844
372	If not enough data is available, it must return the empty list or a false	845	If not enough data is available, it must return the empty list or a false
373	value, in which case it will be called repeatedly until enough data is	846	value, in which case it will be called repeatedly until enough data is
374	available (or an error condition is detected).	847	available (or an error condition is detected).
375		848
…		…
377	interested in (which can be none at all) and return a true value. After returning	850	interested in (which can be none at all) and return a true value. After returning
378	true, it will be removed from the queue.	851	true, it will be removed from the queue.
379		852
380	=cut	853	=cut
381		854
		855	our %RH;
		856
		857	sub register_read_type($$) {
		858	$RH{$_[0]} = $_[1];
		859	}
		860
382	sub push_read {	861	sub push_read {
383	my ($self, $cb) = @_;	862	my $self = shift;
		863	my $cb = pop;
384		864
		865	if (@_) {
		866	my $type = shift;
		867
		868	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
		869	->($self, $cb, @_);
		870	}
		871
385	push @{ $self->{queue} }, $cb;	872	push @{ $self->{_queue} }, $cb;
386	$self->_drain_rbuf;	873	$self->_drain_rbuf unless $self->{_in_drain};
387	}	874	}
388		875
389	sub unshift_read {	876	sub unshift_read {
390	my ($self, $cb) = @_;	877	my $self = shift;
		878	my $cb = pop;
391		879
		880	if (@_) {
		881	my $type = shift;
		882
		883	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
		884	->($self, $cb, @_);
		885	}
		886
		887
392	push @{ $self->{queue} }, $cb;	888	unshift @{ $self->{_queue} }, $cb;
393	$self->_drain_rbuf;	889	$self->_drain_rbuf unless $self->{_in_drain};
394	}	890	}
395		891
396	=item $handle->push_read_chunk ($len, $cb->($self, $data))	892	=item $handle->push_read (type => @args, $cb)
397		893
398	=item $handle->unshift_read_chunk ($len, $cb->($self, $data))	894	=item $handle->unshift_read (type => @args, $cb)
399		895
400	Append the given callback to the end of the queue (C<push_read_chunk>) or	896	Instead of providing a callback that parses the data itself you can chose
401	prepend it (C<unshift_read_chunk>).	897	between a number of predefined parsing formats, for chunks of data, lines
		898	etc.
402		899
403	The callback will be called only once C<$len> bytes have been read, and	900	Predefined types are (if you have ideas for additional types, feel free to
404	these C<$len> bytes will be passed to the callback.	901	drop by and tell us):
405		902
406	=cut	903	=over 4
407		904
408	sub _read_chunk($$) {	905	=item chunk => $octets, $cb->($handle, $data)
409	my ($len, $cb) = @_;	906
		907	Invoke the callback only once C<$octets> bytes have been read. Pass the
		908	data read to the callback. The callback will never be called with less
		909	data.
		910
		911	Example: read 2 bytes.
		912
		913	$handle->push_read (chunk => 2, sub {
		914	warn "yay ", unpack "H*", $_[1];
		915	});
		916
		917	=cut
		918
		919	register_read_type chunk => sub {
		920	my ($self, $cb, $len) = @_;
410		921
411	sub {	922	sub {
412	$len <= length $_[0]{rbuf} or return;	923	$len <= length $_[0]{rbuf} or return;
413	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");	924	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
414	1	925	1
415	}	926	}
416	}	927	};
417		928
418	sub push_read_chunk {	929	=item line => [$eol, ]$cb->($handle, $line, $eol)
419	my ($self, $len, $cb) = @_;
420
421	$self->push_read (_read_chunk $len, $cb);
422	}
423
424
425	sub unshift_read_chunk {
426	my ($self, $len, $cb) = @_;
427
428	$self->unshift_read (_read_chunk $len, $cb);
429	}
430
431	=item $handle->push_read_line ([$eol, ]$cb->($self, $line, $eol))
432
433	=item $handle->unshift_read_line ([$eol, ]$cb->($self, $line, $eol))
434
435	Append the given callback to the end of the queue (C<push_read_line>) or
436	prepend it (C<unshift_read_line>).
437		930
438	The callback will be called only once a full line (including the end of	931	The callback will be called only once a full line (including the end of
439	line marker, C<$eol>) has been read. This line (excluding the end of line	932	line marker, C<$eol>) has been read. This line (excluding the end of line
440	marker) will be passed to the callback as second argument (C<$line>), and	933	marker) will be passed to the callback as second argument (C<$line>), and
441	the end of line marker as the third argument (C<$eol>).	934	the end of line marker as the third argument (C<$eol>).
…		…
452	Partial lines at the end of the stream will never be returned, as they are	945	Partial lines at the end of the stream will never be returned, as they are
453	not marked by the end of line marker.	946	not marked by the end of line marker.
454		947
455	=cut	948	=cut
456		949
457	sub _read_line($$) {	950	register_read_type line => sub {
458	my $cb = pop;	951	my ($self, $cb, $eol) = @_;
459	my $eol = @_ ? shift : qr|(\015?\012)|;
460	my $pos;
461		952
		953	if (@_ < 3) {
		954	# this is more than twice as fast as the generic code below
		955	sub {
		956	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		957
		958	$cb->($_[0], $1, $2);
		959	1
		960	}
		961	} else {
462	$eol = qr|(\Q$eol\E)| unless ref $eol;	962	$eol = quotemeta $eol unless ref $eol;
463	$eol = qr|^(.*?)($eol)|;	963	$eol = qr|^(.*?)($eol)|s;
		964
		965	sub {
		966	$_[0]{rbuf} =~ s/$eol// or return;
		967
		968	$cb->($_[0], $1, $2);
		969	1
		970	}
		971	}
		972	};
		973
		974	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		975
		976	Makes a regex match against the regex object C<$accept> and returns
		977	everything up to and including the match.
		978
		979	Example: read a single line terminated by '\n'.
		980
		981	$handle->push_read (regex => qr<\n>, sub { ... });
		982
		983	If C<$reject> is given and not undef, then it determines when the data is
		984	to be rejected: it is matched against the data when the C<$accept> regex
		985	does not match and generates an C<EBADMSG> error when it matches. This is
		986	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		987	receive buffer overflow).
		988
		989	Example: expect a single decimal number followed by whitespace, reject
		990	anything else (not the use of an anchor).
		991
		992	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		993
		994	If C<$skip> is given and not C<undef>, then it will be matched against
		995	the receive buffer when neither C<$accept> nor C<$reject> match,
		996	and everything preceding and including the match will be accepted
		997	unconditionally. This is useful to skip large amounts of data that you
		998	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		999	have to start matching from the beginning. This is purely an optimisation
		1000	and is usually worth only when you expect more than a few kilobytes.
		1001
		1002	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1003	expect the header to be very large (it isn't in practise, but...), we use
		1004	a skip regex to skip initial portions. The skip regex is tricky in that
		1005	it only accepts something not ending in either \015 or \012, as these are
		1006	required for the accept regex.
		1007
		1008	$handle->push_read (regex =>
		1009	qr<\015\012\015\012>,
		1010	undef, # no reject
		1011	qr<^.*[^\015\012]>,
		1012	sub { ... });
		1013
		1014	=cut
		1015
		1016	register_read_type regex => sub {
		1017	my ($self, $cb, $accept, $reject, $skip) = @_;
		1018
		1019	my $data;
		1020	my $rbuf = \$self->{rbuf};
464		1021
465	sub {	1022	sub {
466	$_[0]{rbuf} =~ s/$eol// or return;	1023	# accept
		1024	if ($$rbuf =~ $accept) {
		1025	$data .= substr $$rbuf, 0, $+[0], "";
		1026	$cb->($self, $data);
		1027	return 1;
		1028	}
		1029
		1030	# reject
		1031	if ($reject && $$rbuf =~ $reject) {
		1032	$self->_error (&Errno::EBADMSG);
		1033	}
467		1034
468	$cb->($1, $2);	1035	# skip
		1036	if ($skip && $$rbuf =~ $skip) {
		1037	$data .= substr $$rbuf, 0, $+[0], "";
		1038	}
		1039
		1040	()
		1041	}
		1042	};
		1043
		1044	=item netstring => $cb->($handle, $string)
		1045
		1046	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1047
		1048	Throws an error with C<$!> set to EBADMSG on format violations.
		1049
		1050	=cut
		1051
		1052	register_read_type netstring => sub {
		1053	my ($self, $cb) = @_;
		1054
		1055	sub {
		1056	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1057	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1058	$self->_error (&Errno::EBADMSG);
		1059	}
		1060	return;
		1061	}
		1062
		1063	my $len = $1;
		1064
		1065	$self->unshift_read (chunk => $len, sub {
		1066	my $string = $_[1];
		1067	$_[0]->unshift_read (chunk => 1, sub {
		1068	if ($_[1] eq ",") {
		1069	$cb->($_[0], $string);
		1070	} else {
		1071	$self->_error (&Errno::EBADMSG);
		1072	}
		1073	});
		1074	});
		1075
469	1	1076	1
470	}	1077	}
471	}	1078	};
472		1079
473	sub push_read_line {	1080	=item packstring => $format, $cb->($handle, $string)
		1081
		1082	An octet string prefixed with an encoded length. The encoding C<$format>
		1083	uses the same format as a Perl C<pack> format, but must specify a single
		1084	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1085	optional C<!>, C<< < >> or C<< > >> modifier).
		1086
		1087	DNS over TCP uses a prefix of C<n>, EPP uses a prefix of C<N>.
		1088
		1089	Example: read a block of data prefixed by its length in BER-encoded
		1090	format (very efficient).
		1091
		1092	$handle->push_read (packstring => "w", sub {
		1093	my ($handle, $data) = @_;
		1094	});
		1095
		1096	=cut
		1097
		1098	register_read_type packstring => sub {
		1099	my ($self, $cb, $format) = @_;
		1100
		1101	sub {
		1102	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1103	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1104	or return;
		1105
		1106	$format = length pack $format, $len;
		1107
		1108	# bypass unshift if we already have the remaining chunk
		1109	if ($format + $len <= length $_[0]{rbuf}) {
		1110	my $data = substr $_[0]{rbuf}, $format, $len;
		1111	substr $_[0]{rbuf}, 0, $format + $len, "";
		1112	$cb->($_[0], $data);
		1113	} else {
		1114	# remove prefix
		1115	substr $_[0]{rbuf}, 0, $format, "";
		1116
		1117	# read remaining chunk
		1118	$_[0]->unshift_read (chunk => $len, $cb);
		1119	}
		1120
		1121	1
		1122	}
		1123	};
		1124
		1125	=item json => $cb->($handle, $hash_or_arrayref)
		1126
		1127	Reads a JSON object or array, decodes it and passes it to the callback.
		1128
		1129	If a C<json> object was passed to the constructor, then that will be used
		1130	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1131
		1132	This read type uses the incremental parser available with JSON version
		1133	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1134	dependency on your own: this module will load the JSON module, but
		1135	AnyEvent does not depend on it itself.
		1136
		1137	Since JSON texts are fully self-delimiting, the C<json> read and write
		1138	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1139	the C<json> write type description, above, for an actual example.
		1140
		1141	=cut
		1142
		1143	register_read_type json => sub {
		1144	my ($self, $cb) = @_;
		1145
		1146	require JSON;
		1147
		1148	my $data;
		1149	my $rbuf = \$self->{rbuf};
		1150
		1151	my $json = $self->{json} ||= JSON->new->utf8;
		1152
		1153	sub {
		1154	my $ref = $json->incr_parse ($self->{rbuf});
		1155
		1156	if ($ref) {
		1157	$self->{rbuf} = $json->incr_text;
		1158	$json->incr_text = "";
		1159	$cb->($self, $ref);
		1160
		1161	1
		1162	} else {
		1163	$self->{rbuf} = "";
		1164	()
		1165	}
		1166	}
		1167	};
		1168
		1169	=item storable => $cb->($handle, $ref)
		1170
		1171	Deserialises a L<Storable> frozen representation as written by the
		1172	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1173	data).
		1174
		1175	Raises C<EBADMSG> error if the data could not be decoded.
		1176
		1177	=cut
		1178
		1179	register_read_type storable => sub {
		1180	my ($self, $cb) = @_;
		1181
		1182	require Storable;
		1183
		1184	sub {
		1185	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1186	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1187	or return;
		1188
		1189	my $format = length pack "w", $len;
		1190
		1191	# bypass unshift if we already have the remaining chunk
		1192	if ($format + $len <= length $_[0]{rbuf}) {
		1193	my $data = substr $_[0]{rbuf}, $format, $len;
		1194	substr $_[0]{rbuf}, 0, $format + $len, "";
		1195	$cb->($_[0], Storable::thaw ($data));
		1196	} else {
		1197	# remove prefix
		1198	substr $_[0]{rbuf}, 0, $format, "";
		1199
		1200	# read remaining chunk
		1201	$_[0]->unshift_read (chunk => $len, sub {
		1202	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1203	$cb->($_[0], $ref);
		1204	} else {
		1205	$self->_error (&Errno::EBADMSG);
		1206	}
		1207	});
		1208	}
		1209
		1210	1
		1211	}
		1212	};
		1213
		1214	=back
		1215
		1216	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
		1217
		1218	This function (not method) lets you add your own types to C<push_read>.
		1219
		1220	Whenever the given C<type> is used, C<push_read> will invoke the code
		1221	reference with the handle object, the callback and the remaining
		1222	arguments.
		1223
		1224	The code reference is supposed to return a callback (usually a closure)
		1225	that works as a plain read callback (see C<< ->push_read ($cb) >>).
		1226
		1227	It should invoke the passed callback when it is done reading (remember to
		1228	pass C<$handle> as first argument as all other callbacks do that).
		1229
		1230	Note that this is a function, and all types registered this way will be
		1231	global, so try to use unique names.
		1232
		1233	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
		1234	search for C<register_read_type>)).
		1235
		1236	=item $handle->stop_read
		1237
		1238	=item $handle->start_read
		1239
		1240	In rare cases you actually do not want to read anything from the
		1241	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
		1242	any queued callbacks will be executed then. To start reading again, call
		1243	C<start_read>.
		1244
		1245	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1246	you change the C<on_read> callback or push/unshift a read callback, and it
		1247	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1248	there are any read requests in the queue.
		1249
		1250	=cut
		1251
		1252	sub stop_read {
		1253	my ($self) = @_;
		1254
		1255	delete $self->{_rw};
		1256	}
		1257
		1258	sub start_read {
		1259	my ($self) = @_;
		1260
		1261	unless ($self->{_rw} || $self->{_eof}) {
		1262	Scalar::Util::weaken $self;
		1263
		1264	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
		1265	my $rbuf = $self->{filter_r} ? \my $buf : \$self->{rbuf};
		1266	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
		1267
		1268	if ($len > 0) {
		1269	$self->{_activity} = AnyEvent->now;
		1270
		1271	$self->{filter_r}
		1272	? $self->{filter_r}($self, $rbuf)
		1273	: $self->{_in_drain} || $self->_drain_rbuf;
		1274
		1275	} elsif (defined $len) {
		1276	delete $self->{_rw};
		1277	$self->{_eof} = 1;
		1278	$self->_drain_rbuf unless $self->{_in_drain};
		1279
		1280	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		1281	return $self->_error ($!, 1);
		1282	}
		1283	});
		1284	}
		1285	}
		1286
		1287	sub _dotls {
		1288	my ($self) = @_;
		1289
		1290	my $buf;
		1291
		1292	if (length $self->{_tls_wbuf}) {
		1293	while ((my $len = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1294	substr $self->{_tls_wbuf}, 0, $len, "";
		1295	}
		1296	}
		1297
		1298	if (length ($buf = Net::SSLeay::BIO_read ($self->{_wbio}))) {
		1299	$self->{wbuf} .= $buf;
		1300	$self->_drain_wbuf;
		1301	}
		1302
		1303	while (defined ($buf = Net::SSLeay::read ($self->{tls}))) {
		1304	if (length $buf) {
		1305	$self->{rbuf} .= $buf;
		1306	$self->_drain_rbuf unless $self->{_in_drain};
		1307	} else {
		1308	# let's treat SSL-eof as we treat normal EOF
		1309	$self->{_eof} = 1;
		1310	$self->_shutdown;
		1311	return;
		1312	}
		1313	}
		1314
		1315	my $err = Net::SSLeay::get_error ($self->{tls}, -1);
		1316
		1317	if ($err!= Net::SSLeay::ERROR_WANT_READ ()) {
		1318	if ($err == Net::SSLeay::ERROR_SYSCALL ()) {
		1319	return $self->_error ($!, 1);
		1320	} elsif ($err == Net::SSLeay::ERROR_SSL ()) {
		1321	return $self->_error (&Errno::EIO, 1);
		1322	}
		1323
		1324	# all others are fine for our purposes
		1325	}
		1326	}
		1327
		1328	=item $handle->starttls ($tls[, $tls_ctx])
		1329
		1330	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1331	object is created, you can also do that at a later time by calling
		1332	C<starttls>.
		1333
		1334	The first argument is the same as the C<tls> constructor argument (either
		1335	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1336
		1337	The second argument is the optional C<Net::SSLeay::CTX> object that is
		1338	used when AnyEvent::Handle has to create its own TLS connection object.
		1339
		1340	The TLS connection object will end up in C<< $handle->{tls} >> after this
		1341	call and can be used or changed to your liking. Note that the handshake
		1342	might have already started when this function returns.
		1343
		1344	=cut
		1345
		1346	sub starttls {
		1347	my ($self, $ssl, $ctx) = @_;
		1348
		1349	$self->stoptls;
		1350
		1351	if ($ssl eq "accept") {
		1352	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());
		1353	Net::SSLeay::set_accept_state ($ssl);
		1354	} elsif ($ssl eq "connect") {
		1355	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());
		1356	Net::SSLeay::set_connect_state ($ssl);
		1357	}
		1358
		1359	$self->{tls} = $ssl;
		1360
		1361	# basically, this is deep magic (because SSL_read should have the same issues)
		1362	# but the openssl maintainers basically said: "trust us, it just works".
		1363	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1364	# and mismaintained ssleay-module doesn't even offer them).
		1365	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1366	Net::SSLeay::CTX_set_mode ($self->{tls},
		1367	(eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		1368	| (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1369
		1370	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1371	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1372
		1373	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
		1374
		1375	$self->{filter_w} = sub {
		1376	$_[0]{_tls_wbuf} .= ${$_[1]};
		1377	&_dotls;
		1378	};
		1379	$self->{filter_r} = sub {
		1380	Net::SSLeay::BIO_write ($_[0]{_rbio}, ${$_[1]});
		1381	&_dotls;
		1382	};
		1383	}
		1384
		1385	=item $handle->stoptls
		1386
		1387	Destroys the SSL connection, if any. Partial read or write data will be
		1388	lost.
		1389
		1390	=cut
		1391
		1392	sub stoptls {
		1393	my ($self) = @_;
		1394
		1395	Net::SSLeay::free (delete $self->{tls}) if $self->{tls};
		1396
		1397	delete $self->{_rbio};
		1398	delete $self->{_wbio};
		1399	delete $self->{_tls_wbuf};
		1400	delete $self->{filter_r};
		1401	delete $self->{filter_w};
		1402	}
		1403
		1404	sub DESTROY {
474	my $self = shift;	1405	my $self = shift;
475		1406
476	$self->push_read (&_read_line);	1407	$self->stoptls;
477	}
478		1408
479	sub unshift_read_line {	1409	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
480	my $self = shift;
481		1410
482	$self->unshift_read (&_read_line);	1411	if ($linger && length $self->{wbuf}) {
		1412	my $fh = delete $self->{fh};
		1413	my $wbuf = delete $self->{wbuf};
		1414
		1415	my @linger;
		1416
		1417	push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
		1418	my $len = syswrite $fh, $wbuf, length $wbuf;
		1419
		1420	if ($len > 0) {
		1421	substr $wbuf, 0, $len, "";
		1422	} else {
		1423	@linger = (); # end
		1424	}
		1425	});
		1426	push @linger, AnyEvent->timer (after => $linger, cb => sub {
		1427	@linger = ();
		1428	});
		1429	}
		1430	}
		1431
		1432	=item AnyEvent::Handle::TLS_CTX
		1433
		1434	This function creates and returns the Net::SSLeay::CTX object used by
		1435	default for TLS mode.
		1436
		1437	The context is created like this:
		1438
		1439	Net::SSLeay::load_error_strings;
		1440	Net::SSLeay::SSLeay_add_ssl_algorithms;
		1441	Net::SSLeay::randomize;
		1442
		1443	my $CTX = Net::SSLeay::CTX_new;
		1444
		1445	Net::SSLeay::CTX_set_options $CTX, Net::SSLeay::OP_ALL
		1446
		1447	=cut
		1448
		1449	our $TLS_CTX;
		1450
		1451	sub TLS_CTX() {
		1452	$TLS_CTX || do {
		1453	require Net::SSLeay;
		1454
		1455	Net::SSLeay::load_error_strings ();
		1456	Net::SSLeay::SSLeay_add_ssl_algorithms ();
		1457	Net::SSLeay::randomize ();
		1458
		1459	$TLS_CTX = Net::SSLeay::CTX_new ();
		1460
		1461	Net::SSLeay::CTX_set_options ($TLS_CTX, Net::SSLeay::OP_ALL ());
		1462
		1463	$TLS_CTX
		1464	}
483	}	1465	}
484		1466
485	=back	1467	=back
486		1468
		1469	=head1 SUBCLASSING AnyEvent::Handle
		1470
		1471	In many cases, you might want to subclass AnyEvent::Handle.
		1472
		1473	To make this easier, a given version of AnyEvent::Handle uses these
		1474	conventions:
		1475
		1476	=over 4
		1477
		1478	=item * all constructor arguments become object members.
		1479
		1480	At least initially, when you pass a C<tls>-argument to the constructor it
		1481	will end up in C<< $handle->{tls} >>. Those members might be changed or
		1482	mutated later on (for example C<tls> will hold the TLS connection object).
		1483
		1484	=item * other object member names are prefixed with an C<_>.
		1485
		1486	All object members not explicitly documented (internal use) are prefixed
		1487	with an underscore character, so the remaining non-C<_>-namespace is free
		1488	for use for subclasses.
		1489
		1490	=item * all members not documented here and not prefixed with an underscore
		1491	are free to use in subclasses.
		1492
		1493	Of course, new versions of AnyEvent::Handle may introduce more "public"
		1494	member variables, but thats just life, at least it is documented.
		1495
		1496	=back
		1497
487	=head1 AUTHOR	1498	=head1 AUTHOR
488		1499
489	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.	1500	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
490		1501
491	=cut	1502	=cut

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