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Revision 1.34 by root, Mon May 26 03:27:52 2008 UTC vs.
Revision 1.132 by elmex, Thu Jul 2 22:25:13 2009 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 qw(WSAWOULDBLOCK);	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 file handles 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 = '0.04';	19	our $VERSION = 4.45;
20		20
21	=head1 SYNOPSIS	21	=head1 SYNOPSIS
22		22
23	use AnyEvent;	23	use AnyEvent;
24	use AnyEvent::Handle;	24	use AnyEvent::Handle;
…		…
27		27
28	my $handle =	28	my $handle =
29	AnyEvent::Handle->new (	29	AnyEvent::Handle->new (
30	fh => \*STDIN,	30	fh => \*STDIN,
31	on_eof => sub {	31	on_eof => sub {
32	$cv->broadcast;	32	$cv->send;
33	},	33	},
34	);	34	);
35		35
36	# send some request line	36	# send some request line
37	$handle->push_write ("getinfo\015\012");	37	$handle->push_write ("getinfo\015\012");
…		…
49		49
50	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
51	filehandles. For utility functions for doing non-blocking connects and accepts	51	filehandles. For utility functions for doing non-blocking connects and accepts
52	on sockets see L<AnyEvent::Util>.	52	on sockets see L<AnyEvent::Util>.
53		53
		54	The L<AnyEvent::Intro> tutorial contains some well-documented
		55	AnyEvent::Handle examples.
		56
54	In the following, when the documentation refers to of "bytes" then this	57	In the following, when the documentation refers to of "bytes" then this
55	means characters. As sysread and syswrite are used for all I/O, their	58	means characters. As sysread and syswrite are used for all I/O, their
56	treatment of characters applies to this module as well.	59	treatment of characters applies to this module as well.
57		60
58	All callbacks will be invoked with the handle object as their first	61	All callbacks will be invoked with the handle object as their first
…		…
60		63
61	=head1 METHODS	64	=head1 METHODS
62		65
63	=over 4	66	=over 4
64		67
65	=item B<new (%args)>	68	=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
66		69
67	The constructor supports these arguments (all as key => value pairs).	70	The constructor supports these arguments (all as C<< key => value >> pairs).
68		71
69	=over 4	72	=over 4
70		73
71	=item fh => $filehandle [MANDATORY]	74	=item fh => $filehandle [MANDATORY]
72		75
73	The filehandle this L<AnyEvent::Handle> object will operate on.	76	The filehandle this L<AnyEvent::Handle> object will operate on.
74		77
75	NOTE: The filehandle will be set to non-blocking (using	78	NOTE: The filehandle will be set to non-blocking mode (using
76	AnyEvent::Util::fh_nonblocking).	79	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		80	that mode.
77		81
78	=item on_eof => $cb->($self)	82	=item on_eof => $cb->($handle)
79		83
80	Set the callback to be called on EOF.	84	Set the callback to be called when an end-of-file condition is detected,
		85	i.e. in the case of a socket, when the other side has closed the
		86	connection cleanly.
81		87
		88	For sockets, this just means that the other side has stopped sending data,
		89	you can still try to write data, and, in fact, one can return from the EOF
		90	callback and continue writing data, as only the read part has been shut
		91	down.
		92
82	While not mandatory, it is highly recommended to set an eof callback,	93	While not mandatory, it is I<highly> recommended to set an EOF callback,
83	otherwise you might end up with a closed socket while you are still	94	otherwise you might end up with a closed socket while you are still
84	waiting for data.	95	waiting for data.
85		96
		97	If an EOF condition has been detected but no C<on_eof> callback has been
		98	set, then a fatal error will be raised with C<$!> set to <0>.
		99
86	=item on_error => $cb->($self)	100	=item on_error => $cb->($handle, $fatal)
87		101
88	This is the fatal error callback, that is called when, well, a fatal error	102	This is the error callback, which is called when, well, some error
89	occurs, such as not being able to resolve the hostname, failure to connect	103	occured, such as not being able to resolve the hostname, failure to
90	or a read error.	104	connect or a read error.
91		105
92	The object will not be in a usable state when this callback has been	106	Some errors are fatal (which is indicated by C<$fatal> being true). On
93	called.	107	fatal 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
		109	errors are an EOF condition with active (but unsatisifable) read watchers
		110	(C<EPIPE>) or I/O errors.
		111
		112	Non-fatal errors can be retried by simply returning, but it is recommended
		113	to simply ignore this parameter and instead abondon the handle object
		114	when this callback is invoked. Examples of non-fatal errors are timeouts
		115	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
94		116
95	On callback entrance, the value of C<$!> contains the operating system	117	On callback entrance, the value of C<$!> contains the operating system
96	error (or C<ENOSPC>, C<EPIPE> or C<EBADMSG>).	118	error (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT> or C<EBADMSG>).
97		119
98	While not mandatory, it is I<highly> recommended to set this callback, as	120	While not mandatory, it is I<highly> recommended to set this callback, as
99	you will not be notified of errors otherwise. The default simply calls	121	you will not be notified of errors otherwise. The default simply calls
100	die.	122	C<croak>.
101		123
102	=item on_read => $cb->($self)	124	=item on_read => $cb->($handle)
103		125
104	This sets the default read callback, which is called when data arrives	126	This sets the default read callback, which is called when data arrives
105	and no read request is in the queue.	127	and no read request is in the queue (unlike read queue callbacks, this
		128	callback will only be called when at least one octet of data is in the
		129	read buffer).
106		130
107	To access (and remove data from) the read buffer, use the C<< ->rbuf >>	131	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
108	method or access the C<$self->{rbuf}> member directly.	132	method or access the C<$handle->{rbuf}> member directly. Note that you
		133	must not enlarge or modify the read buffer, you can only remove data at
		134	the beginning from it.
109		135
110	When an EOF condition is detected then AnyEvent::Handle will first try to	136	When an EOF condition is detected then AnyEvent::Handle will first try to
111	feed all the remaining data to the queued callbacks and C<on_read> before	137	feed all the remaining data to the queued callbacks and C<on_read> before
112	calling the C<on_eof> callback. If no progress can be made, then a fatal	138	calling the C<on_eof> callback. If no progress can be made, then a fatal
113	error will be raised (with C<$!> set to C<EPIPE>).	139	error will be raised (with C<$!> set to C<EPIPE>).
114		140
115	=item on_drain => $cb->()	141	=item on_drain => $cb->($handle)
116		142
117	This sets the callback that is called when the write buffer becomes empty	143	This sets the callback that is called when the write buffer becomes empty
118	(or when the callback is set and the buffer is empty already).	144	(or when the callback is set and the buffer is empty already).
119		145
120	To append to the write buffer, use the C<< ->push_write >> method.	146	To append to the write buffer, use the C<< ->push_write >> method.
121		147
		148	This callback is useful when you don't want to put all of your write data
		149	into the queue at once, for example, when you want to write the contents
		150	of some file to the socket you might not want to read the whole file into
		151	memory and push it into the queue, but instead only read more data from
		152	the file when the write queue becomes empty.
		153
		154	=item timeout => $fractional_seconds
		155
		156	If non-zero, then this enables an "inactivity" timeout: whenever this many
		157	seconds pass without a successful read or write on the underlying file
		158	handle, the C<on_timeout> callback will be invoked (and if that one is
		159	missing, a non-fatal C<ETIMEDOUT> error will be raised).
		160
		161	Note that timeout processing is also active when you currently do not have
		162	any outstanding read or write requests: If you plan to keep the connection
		163	idle then you should disable the timout temporarily or ignore the timeout
		164	in the C<on_timeout> callback, in which case AnyEvent::Handle will simply
		165	restart the timeout.
		166
		167	Zero (the default) disables this timeout.
		168
		169	=item on_timeout => $cb->($handle)
		170
		171	Called whenever the inactivity timeout passes. If you return from this
		172	callback, then the timeout will be reset as if some activity had happened,
		173	so this condition is not fatal in any way.
		174
122	=item rbuf_max => <bytes>	175	=item rbuf_max => <bytes>
123		176
124	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)	177	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
125	when the read buffer ever (strictly) exceeds this size. This is useful to	178	when the read buffer ever (strictly) exceeds this size. This is useful to
126	avoid denial-of-service attacks.	179	avoid some forms of denial-of-service attacks.
127		180
128	For example, a server accepting connections from untrusted sources should	181	For example, a server accepting connections from untrusted sources should
129	be configured to accept only so-and-so much data that it cannot act on	182	be configured to accept only so-and-so much data that it cannot act on
130	(for example, when expecting a line, an attacker could send an unlimited	183	(for example, when expecting a line, an attacker could send an unlimited
131	amount of data without a callback ever being called as long as the line	184	amount of data without a callback ever being called as long as the line
132	isn't finished).	185	isn't finished).
133		186
		187	=item autocork => <boolean>
		188
		189	When disabled (the default), then C<push_write> will try to immediately
		190	write the data to the handle, if possible. This avoids having to register
		191	a write watcher and wait for the next event loop iteration, but can
		192	be inefficient if you write multiple small chunks (on the wire, this
		193	disadvantage is usually avoided by your kernel's nagle algorithm, see
		194	C<no_delay>, but this option can save costly syscalls).
		195
		196	When enabled, then writes will always be queued till the next event loop
		197	iteration. This is efficient when you do many small writes per iteration,
		198	but less efficient when you do a single write only per iteration (or when
		199	the write buffer often is full). It also increases write latency.
		200
		201	=item no_delay => <boolean>
		202
		203	When doing small writes on sockets, your operating system kernel might
		204	wait a bit for more data before actually sending it out. This is called
		205	the Nagle algorithm, and usually it is beneficial.
		206
		207	In some situations you want as low a delay as possible, which can be
		208	accomplishd by setting this option to a true value.
		209
		210	The default is your opertaing system's default behaviour (most likely
		211	enabled), this option explicitly enables or disables it, if possible.
		212
134	=item read_size => <bytes>	213	=item read_size => <bytes>
135		214
136	The default read block size (the amount of bytes this module will try to read	215	The default read block size (the amount of bytes this module will
137	on each [loop iteration). Default: C<4096>.	216	try to read during each loop iteration, which affects memory
		217	requirements). Default: C<8192>.
138		218
139	=item low_water_mark => <bytes>	219	=item low_water_mark => <bytes>
140		220
141	Sets the amount of bytes (default: C<0>) that make up an "empty" write	221	Sets the amount of bytes (default: C<0>) that make up an "empty" write
142	buffer: If the write reaches this size or gets even samller it is	222	buffer: If the write reaches this size or gets even samller it is
143	considered empty.	223	considered empty.
144		224
		225	Sometimes it can be beneficial (for performance reasons) to add data to
		226	the write buffer before it is fully drained, but this is a rare case, as
		227	the operating system kernel usually buffers data as well, so the default
		228	is good in almost all cases.
		229
		230	=item linger => <seconds>
		231
		232	If non-zero (default: C<3600>), then the destructor of the
		233	AnyEvent::Handle object will check whether there is still outstanding
		234	write data and will install a watcher that will write this data to the
		235	socket. No errors will be reported (this mostly matches how the operating
		236	system treats outstanding data at socket close time).
		237
		238	This will not work for partial TLS data that could not be encoded
		239	yet. This data will be lost. Calling the C<stoptls> method in time might
		240	help.
		241
		242	=item common_name => $string
		243
		244	The common name used by some verification methods (most notably SSL/TLS)
		245	associated with this connection. Usually this is the remote hostname used
		246	to connect, but can be almost anything.
		247
145	=item tls => "accept" | "connect" | Net::SSLeay::SSL object	248	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
146		249
147	When this parameter is given, it enables TLS (SSL) mode, that means it	250	When this parameter is given, it enables TLS (SSL) mode, that means
148	will start making tls handshake and will transparently encrypt/decrypt	251	AnyEvent will start a TLS handshake as soon as the conenction has been
149	data.	252	established and will transparently encrypt/decrypt data afterwards.
150		253
151	TLS mode requires Net::SSLeay to be installed (it will be loaded	254	TLS mode requires Net::SSLeay to be installed (it will be loaded
152	automatically when you try to create a TLS handle).	255	automatically when you try to create a TLS handle): this module doesn't
		256	have a dependency on that module, so if your module requires it, you have
		257	to add the dependency yourself.
153		258
154	For the TLS server side, use C<accept>, and for the TLS client side of a	259	Unlike TCP, TLS has a server and client side: for the TLS server side, use
155	connection, use C<connect> mode.	260	C<accept>, and for the TLS client side of a connection, use C<connect>
		261	mode.
156		262
157	You can also provide your own TLS connection object, but you have	263	You can also provide your own TLS connection object, but you have
158	to make sure that you call either C<Net::SSLeay::set_connect_state>	264	to make sure that you call either C<Net::SSLeay::set_connect_state>
159	or C<Net::SSLeay::set_accept_state> on it before you pass it to	265	or C<Net::SSLeay::set_accept_state> on it before you pass it to
160	AnyEvent::Handle.	266	AnyEvent::Handle. Also, this module will take ownership of this connection
		267	object.
161		268
		269	At some future point, AnyEvent::Handle might switch to another TLS
		270	implementation, then the option to use your own session object will go
		271	away.
		272
		273	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		274	passing in the wrong integer will lead to certain crash. This most often
		275	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		276	segmentation fault.
		277
162	See the C<starttls> method if you need to start TLs negotiation later.	278	See the C<< ->starttls >> method for when need to start TLS negotiation later.
163		279
164	=item tls_ctx => $ssl_ctx	280	=item tls_ctx => $anyevent_tls
165		281
166	Use the given Net::SSLeay::CTX object to create the new TLS connection	282	Use the given C<AnyEvent::TLS> object to create the new TLS connection
167	(unless a connection object was specified directly). If this parameter is	283	(unless a connection object was specified directly). If this parameter is
168	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.	284	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
169		285
		286	Instead of an object, you can also specify a hash reference with C<< key
		287	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		288	new TLS context object.
		289
		290	=item json => JSON or JSON::XS object
		291
		292	This is the json coder object used by the C<json> read and write types.
		293
		294	If you don't supply it, then AnyEvent::Handle will create and use a
		295	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		296	texts.
		297
		298	Note that you are responsible to depend on the JSON module if you want to
		299	use this functionality, as AnyEvent does not have a dependency itself.
		300
170	=back	301	=back
171		302
172	=cut	303	=cut
173		304
174	sub new {	305	sub new {
175	my $class = shift;	306	my $class = shift;
176
177	my $self = bless { @_ }, $class;	307	my $self = bless { @_ }, $class;
178		308
179	$self->{fh} or Carp::croak "mandatory argument fh is missing";	309	$self->{fh} or Carp::croak "mandatory argument fh is missing";
180		310
181	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	311	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
182		312
183	if ($self->{tls}) {	313	$self->{_activity} = AnyEvent->now;
184	require Net::SSLeay;	314	$self->_timeout;
		315
		316	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		317
185	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx});	318	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
186	}	319	if $self->{tls};
187		320
188	$self->on_eof (delete $self->{on_eof} ) if $self->{on_eof};
189	$self->on_error (delete $self->{on_error}) if $self->{on_error};
190	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	321	$self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
191	$self->on_read (delete $self->{on_read} ) if $self->{on_read};
192		322
193	$self->start_read;	323	$self->start_read
		324	if $self->{on_read};
194		325
195	$self	326	$self->{fh} && $self
196	}	327	}
197		328
198	sub _shutdown {	329	sub _shutdown {
199	my ($self) = @_;	330	my ($self) = @_;
200		331
201	delete $self->{rw};	332	delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
202	delete $self->{ww};	333	$self->{_eof} = 1; # tell starttls et. al to stop trying
203	delete $self->{fh};
204	}
205		334
		335	&_freetls;
		336	}
		337
206	sub error {	338	sub _error {
207	my ($self) = @_;	339	my ($self, $errno, $fatal) = @_;
208		340
209	{
210	local $!;
211	$self->_shutdown;	341	$self->_shutdown
212	}	342	if $fatal;
		343
		344	$! = $errno;
213		345
214	if ($self->{on_error}) {	346	if ($self->{on_error}) {
215	$self->{on_error}($self);	347	$self->{on_error}($self, $fatal);
216	} else {	348	} elsif ($self->{fh}) {
217	Carp::croak "AnyEvent::Handle uncaught fatal error: $!";	349	Carp::croak "AnyEvent::Handle uncaught error: $!";
218	}	350	}
219	}	351	}
220		352
221	=item $fh = $handle->fh	353	=item $fh = $handle->fh
222		354
223	This method returns the file handle of the L<AnyEvent::Handle> object.	355	This method returns the file handle used to create the L<AnyEvent::Handle> object.
224		356
225	=cut	357	=cut
226		358
227	sub fh { $_[0]->{fh} }	359	sub fh { $_[0]{fh} }
228		360
229	=item $handle->on_error ($cb)	361	=item $handle->on_error ($cb)
230		362
231	Replace the current C<on_error> callback (see the C<on_error> constructor argument).	363	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
232		364
…		…
244		376
245	sub on_eof {	377	sub on_eof {
246	$_[0]{on_eof} = $_[1];	378	$_[0]{on_eof} = $_[1];
247	}	379	}
248		380
		381	=item $handle->on_timeout ($cb)
		382
		383	Replace the current C<on_timeout> callback, or disables the callback (but
		384	not the timeout) if C<$cb> = C<undef>. See the C<timeout> constructor
		385	argument and method.
		386
		387	=cut
		388
		389	sub on_timeout {
		390	$_[0]{on_timeout} = $_[1];
		391	}
		392
		393	=item $handle->autocork ($boolean)
		394
		395	Enables or disables the current autocork behaviour (see C<autocork>
		396	constructor argument). Changes will only take effect on the next write.
		397
		398	=cut
		399
		400	sub autocork {
		401	$_[0]{autocork} = $_[1];
		402	}
		403
		404	=item $handle->no_delay ($boolean)
		405
		406	Enables or disables the C<no_delay> setting (see constructor argument of
		407	the same name for details).
		408
		409	=cut
		410
		411	sub no_delay {
		412	$_[0]{no_delay} = $_[1];
		413
		414	eval {
		415	local $SIG{__DIE__};
		416	setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
		417	};
		418	}
		419
		420	#############################################################################
		421
		422	=item $handle->timeout ($seconds)
		423
		424	Configures (or disables) the inactivity timeout.
		425
		426	=cut
		427
		428	sub timeout {
		429	my ($self, $timeout) = @_;
		430
		431	$self->{timeout} = $timeout;
		432	$self->_timeout;
		433	}
		434
		435	# reset the timeout watcher, as neccessary
		436	# also check for time-outs
		437	sub _timeout {
		438	my ($self) = @_;
		439
		440	if ($self->{timeout}) {
		441	my $NOW = AnyEvent->now;
		442
		443	# when would the timeout trigger?
		444	my $after = $self->{_activity} + $self->{timeout} - $NOW;
		445
		446	# now or in the past already?
		447	if ($after <= 0) {
		448	$self->{_activity} = $NOW;
		449
		450	if ($self->{on_timeout}) {
		451	$self->{on_timeout}($self);
		452	} else {
		453	$self->_error (&Errno::ETIMEDOUT);
		454	}
		455
		456	# callback could have changed timeout value, optimise
		457	return unless $self->{timeout};
		458
		459	# calculate new after
		460	$after = $self->{timeout};
		461	}
		462
		463	Scalar::Util::weaken $self;
		464	return unless $self; # ->error could have destroyed $self
		465
		466	$self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
		467	delete $self->{_tw};
		468	$self->_timeout;
		469	});
		470	} else {
		471	delete $self->{_tw};
		472	}
		473	}
		474
249	#############################################################################	475	#############################################################################
250		476
251	=back	477	=back
252		478
253	=head2 WRITE QUEUE	479	=head2 WRITE QUEUE
…		…
274	my ($self, $cb) = @_;	500	my ($self, $cb) = @_;
275		501
276	$self->{on_drain} = $cb;	502	$self->{on_drain} = $cb;
277		503
278	$cb->($self)	504	$cb->($self)
279	if $cb && $self->{low_water_mark} >= length $self->{wbuf};	505	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
280	}	506	}
281		507
282	=item $handle->push_write ($data)	508	=item $handle->push_write ($data)
283		509
284	Queues the given scalar to be written. You can push as much data as you	510	Queues the given scalar to be written. You can push as much data as you
…		…
288	=cut	514	=cut
289		515
290	sub _drain_wbuf {	516	sub _drain_wbuf {
291	my ($self) = @_;	517	my ($self) = @_;
292		518
293	if (!$self->{ww} && length $self->{wbuf}) {	519	if (!$self->{_ww} && length $self->{wbuf}) {
		520
294	Scalar::Util::weaken $self;	521	Scalar::Util::weaken $self;
		522
295	my $cb = sub {	523	my $cb = sub {
296	my $len = syswrite $self->{fh}, $self->{wbuf};	524	my $len = syswrite $self->{fh}, $self->{wbuf};
297		525
298	if ($len >= 0) {	526	if ($len >= 0) {
299	substr $self->{wbuf}, 0, $len, "";	527	substr $self->{wbuf}, 0, $len, "";
300		528
		529	$self->{_activity} = AnyEvent->now;
		530
301	$self->{on_drain}($self)	531	$self->{on_drain}($self)
302	if $self->{low_water_mark} >= length $self->{wbuf}	532	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
303	&& $self->{on_drain};	533	&& $self->{on_drain};
304		534
305	delete $self->{ww} unless length $self->{wbuf};	535	delete $self->{_ww} unless length $self->{wbuf};
306	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAWOULDBLOCK) {	536	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
307	$self->error;	537	$self->_error ($!, 1);
308	}	538	}
309	};	539	};
310		540
		541	# try to write data immediately
		542	$cb->() unless $self->{autocork};
		543
		544	# if still data left in wbuf, we need to poll
311	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	545	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
312		546	if length $self->{wbuf};
313	$cb->($self);
314	};	547	};
315	}	548	}
316		549
317	our %WH;	550	our %WH;
318		551
…		…
328		561
329	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")	562	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
330	->($self, @_);	563	->($self, @_);
331	}	564	}
332		565
333	if ($self->{filter_w}) {	566	if ($self->{tls}) {
334	$self->{filter_w}->($self, \$_[0]);	567	$self->{_tls_wbuf} .= $_[0];
		568
		569	&_dotls ($self);
335	} else {	570	} else {
336	$self->{wbuf} .= $_[0];	571	$self->{wbuf} .= $_[0];
337	$self->_drain_wbuf;	572	$self->_drain_wbuf;
338	}	573	}
339	}	574	}
340		575
341	=item $handle->push_write (type => @args)	576	=item $handle->push_write (type => @args)
342		577
343	=item $handle->unshift_write (type => @args)
344
345	Instead of formatting your data yourself, you can also let this module do	578	Instead of formatting your data yourself, you can also let this module do
346	the job by specifying a type and type-specific arguments.	579	the job by specifying a type and type-specific arguments.
347		580
348	Predefined types are (if you have ideas for additional types, feel free to	581	Predefined types are (if you have ideas for additional types, feel free to
349	drop by and tell us):	582	drop by and tell us):
…		…
353	=item netstring => $string	586	=item netstring => $string
354		587
355	Formats the given value as netstring	588	Formats the given value as netstring
356	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).	589	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
357		590
358	=back
359
360	=cut	591	=cut
361		592
362	register_write_type netstring => sub {	593	register_write_type netstring => sub {
363	my ($self, $string) = @_;	594	my ($self, $string) = @_;
364		595
365	sprintf "%d:%s,", (length $string), $string	596	(length $string) . ":$string,"
366	};	597	};
367		598
		599	=item packstring => $format, $data
		600
		601	An octet string prefixed with an encoded length. The encoding C<$format>
		602	uses the same format as a Perl C<pack> format, but must specify a single
		603	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		604	optional C<!>, C<< < >> or C<< > >> modifier).
		605
		606	=cut
		607
		608	register_write_type packstring => sub {
		609	my ($self, $format, $string) = @_;
		610
		611	pack "$format/a*", $string
		612	};
		613
		614	=item json => $array_or_hashref
		615
		616	Encodes the given hash or array reference into a JSON object. Unless you
		617	provide your own JSON object, this means it will be encoded to JSON text
		618	in UTF-8.
		619
		620	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		621	one end of a handle and read them at the other end without using any
		622	additional framing.
		623
		624	The generated JSON text is guaranteed not to contain any newlines: While
		625	this module doesn't need delimiters after or between JSON texts to be
		626	able to read them, many other languages depend on that.
		627
		628	A simple RPC protocol that interoperates easily with others is to send
		629	JSON arrays (or objects, although arrays are usually the better choice as
		630	they mimic how function argument passing works) and a newline after each
		631	JSON text:
		632
		633	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		634	$handle->push_write ("\012");
		635
		636	An AnyEvent::Handle receiver would simply use the C<json> read type and
		637	rely on the fact that the newline will be skipped as leading whitespace:
		638
		639	$handle->push_read (json => sub { my $array = $_[1]; ... });
		640
		641	Other languages could read single lines terminated by a newline and pass
		642	this line into their JSON decoder of choice.
		643
		644	=cut
		645
		646	register_write_type json => sub {
		647	my ($self, $ref) = @_;
		648
		649	require JSON;
		650
		651	$self->{json} ? $self->{json}->encode ($ref)
		652	: JSON::encode_json ($ref)
		653	};
		654
		655	=item storable => $reference
		656
		657	Freezes the given reference using L<Storable> and writes it to the
		658	handle. Uses the C<nfreeze> format.
		659
		660	=cut
		661
		662	register_write_type storable => sub {
		663	my ($self, $ref) = @_;
		664
		665	require Storable;
		666
		667	pack "w/a*", Storable::nfreeze ($ref)
		668	};
		669
		670	=back
		671
368	=item AnyEvent::Handle::register_write_type type => $coderef->($self, @args)	672	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
369		673
370	This function (not method) lets you add your own types to C<push_write>.	674	This function (not method) lets you add your own types to C<push_write>.
371	Whenever the given C<type> is used, C<push_write> will invoke the code	675	Whenever the given C<type> is used, C<push_write> will invoke the code
372	reference with the handle object and the remaining arguments.	676	reference with the handle object and the remaining arguments.
373		677
…		…
392	ways, the "simple" way, using only C<on_read> and the "complex" way, using	696	ways, the "simple" way, using only C<on_read> and the "complex" way, using
393	a queue.	697	a queue.
394		698
395	In the simple case, you just install an C<on_read> callback and whenever	699	In the simple case, you just install an C<on_read> callback and whenever
396	new data arrives, it will be called. You can then remove some data (if	700	new data arrives, it will be called. You can then remove some data (if
397	enough is there) from the read buffer (C<< $handle->rbuf >>) if you want	701	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
398	or not.	702	leave the data there if you want to accumulate more (e.g. when only a
		703	partial message has been received so far).
399		704
400	In the more complex case, you want to queue multiple callbacks. In this	705	In the more complex case, you want to queue multiple callbacks. In this
401	case, AnyEvent::Handle will call the first queued callback each time new	706	case, AnyEvent::Handle will call the first queued callback each time new
402	data arrives and removes it when it has done its job (see C<push_read>,	707	data arrives (also the first time it is queued) and removes it when it has
403	below).	708	done its job (see C<push_read>, below).
404		709
405	This way you can, for example, push three line-reads, followed by reading	710	This way you can, for example, push three line-reads, followed by reading
406	a chunk of data, and AnyEvent::Handle will execute them in order.	711	a chunk of data, and AnyEvent::Handle will execute them in order.
407		712
408	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by	713	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
409	the specified number of bytes which give an XML datagram.	714	the specified number of bytes which give an XML datagram.
410		715
411	# in the default state, expect some header bytes	716	# in the default state, expect some header bytes
412	$handle->on_read (sub {	717	$handle->on_read (sub {
413	# some data is here, now queue the length-header-read (4 octets)	718	# some data is here, now queue the length-header-read (4 octets)
414	shift->unshift_read_chunk (4, sub {	719	shift->unshift_read (chunk => 4, sub {
415	# header arrived, decode	720	# header arrived, decode
416	my $len = unpack "N", $_[1];	721	my $len = unpack "N", $_[1];
417		722
418	# now read the payload	723	# now read the payload
419	shift->unshift_read_chunk ($len, sub {	724	shift->unshift_read (chunk => $len, sub {
420	my $xml = $_[1];	725	my $xml = $_[1];
421	# handle xml	726	# handle xml
422	});	727	});
423	});	728	});
424	});	729	});
425		730
426	Example 2: Implement a client for a protocol that replies either with	731	Example 2: Implement a client for a protocol that replies either with "OK"
427	"OK" and another line or "ERROR" for one request, and 64 bytes for the	732	and another line or "ERROR" for the first request that is sent, and 64
428	second request. Due tot he availability of a full queue, we can just	733	bytes for the second request. Due to the availability of a queue, we can
429	pipeline sending both requests and manipulate the queue as necessary in	734	just pipeline sending both requests and manipulate the queue as necessary
430	the callbacks:	735	in the callbacks.
431		736
432	# request one	737	When the first callback is called and sees an "OK" response, it will
		738	C<unshift> another line-read. This line-read will be queued I<before> the
		739	64-byte chunk callback.
		740
		741	# request one, returns either "OK + extra line" or "ERROR"
433	$handle->push_write ("request 1\015\012");	742	$handle->push_write ("request 1\015\012");
434		743
435	# we expect "ERROR" or "OK" as response, so push a line read	744	# we expect "ERROR" or "OK" as response, so push a line read
436	$handle->push_read_line (sub {	745	$handle->push_read (line => sub {
437	# if we got an "OK", we have to _prepend_ another line,	746	# if we got an "OK", we have to _prepend_ another line,
438	# so it will be read before the second request reads its 64 bytes	747	# so it will be read before the second request reads its 64 bytes
439	# which are already in the queue when this callback is called	748	# which are already in the queue when this callback is called
440	# we don't do this in case we got an error	749	# we don't do this in case we got an error
441	if ($_[1] eq "OK") {	750	if ($_[1] eq "OK") {
442	$_[0]->unshift_read_line (sub {	751	$_[0]->unshift_read (line => sub {
443	my $response = $_[1];	752	my $response = $_[1];
444	...	753	...
445	});	754	});
446	}	755	}
447	});	756	});
448		757
449	# request two	758	# request two, simply returns 64 octets
450	$handle->push_write ("request 2\015\012");	759	$handle->push_write ("request 2\015\012");
451		760
452	# simply read 64 bytes, always	761	# simply read 64 bytes, always
453	$handle->push_read_chunk (64, sub {	762	$handle->push_read (chunk => 64, sub {
454	my $response = $_[1];	763	my $response = $_[1];
455	...	764	...
456	});	765	});
457		766
458	=over 4	767	=over 4
459		768
460	=cut	769	=cut
461		770
462	sub _drain_rbuf {	771	sub _drain_rbuf {
463	my ($self) = @_;	772	my ($self) = @_;
		773
		774	local $self->{_in_drain} = 1;
464		775
465	if (	776	if (
466	defined $self->{rbuf_max}	777	defined $self->{rbuf_max}
467	&& $self->{rbuf_max} < length $self->{rbuf}	778	&& $self->{rbuf_max} < length $self->{rbuf}
468	) {	779	) {
469	$! = &Errno::ENOSPC; return $self->error;	780	$self->_error (&Errno::ENOSPC, 1), return;
470	}	781	}
471		782
472	return if $self->{in_drain};	783	while () {
473	local $self->{in_drain} = 1;	784	# we need to use a separate tls read buffer, as we must not receive data while
		785	# we are draining the buffer, and this can only happen with TLS.
		786	$self->{rbuf} .= delete $self->{_tls_rbuf} if exists $self->{_tls_rbuf};
474		787
475	while (my $len = length $self->{rbuf}) {	788	my $len = length $self->{rbuf};
476	no strict 'refs';	789
477	if (my $cb = shift @{ $self->{queue} }) {	790	if (my $cb = shift @{ $self->{_queue} }) {
478	unless ($cb->($self)) {	791	unless ($cb->($self)) {
479	if ($self->{eof}) {	792	if ($self->{_eof}) {
480	# no progress can be made (not enough data and no data forthcoming)	793	# no progress can be made (not enough data and no data forthcoming)
481	$! = &Errno::EPIPE; return $self->error;	794	$self->_error (&Errno::EPIPE, 1), return;
482	}	795	}
483		796
484	unshift @{ $self->{queue} }, $cb;	797	unshift @{ $self->{_queue} }, $cb;
485	return;	798	last;
486	}	799	}
487	} elsif ($self->{on_read}) {	800	} elsif ($self->{on_read}) {
		801	last unless $len;
		802
488	$self->{on_read}($self);	803	$self->{on_read}($self);
489		804
490	if (	805	if (
491	$self->{eof} # if no further data will arrive
492	&& $len == length $self->{rbuf} # and no data has been consumed	806	$len == length $self->{rbuf} # if no data has been consumed
493	&& !@{ $self->{queue} } # and the queue is still empty	807	&& !@{ $self->{_queue} } # and the queue is still empty
494	&& $self->{on_read} # and we still want to read data	808	&& $self->{on_read} # but we still have on_read
495	) {	809	) {
		810	# no further data will arrive
496	# then no progress can be made	811	# so no progress can be made
497	$! = &Errno::EPIPE; return $self->error;	812	$self->_error (&Errno::EPIPE, 1), return
		813	if $self->{_eof};
		814
		815	last; # more data might arrive
498	}	816	}
499	} else {	817	} else {
500	# read side becomes idle	818	# read side becomes idle
501	delete $self->{rw};	819	delete $self->{_rw} unless $self->{tls};
502	return;	820	last;
503	}	821	}
504	}	822	}
505		823
506	if ($self->{eof}) {	824	if ($self->{_eof}) {
507	$self->_shutdown;	825	if ($self->{on_eof}) {
508	$self->{on_eof}($self)	826	$self->{on_eof}($self)
509	if $self->{on_eof};	827	} else {
		828	$self->_error (0, 1);
		829	}
		830	}
		831
		832	# may need to restart read watcher
		833	unless ($self->{_rw}) {
		834	$self->start_read
		835	if $self->{on_read} || @{ $self->{_queue} };
510	}	836	}
511	}	837	}
512		838
513	=item $handle->on_read ($cb)	839	=item $handle->on_read ($cb)
514		840
…		…
520		846
521	sub on_read {	847	sub on_read {
522	my ($self, $cb) = @_;	848	my ($self, $cb) = @_;
523		849
524	$self->{on_read} = $cb;	850	$self->{on_read} = $cb;
		851	$self->_drain_rbuf if $cb && !$self->{_in_drain};
525	}	852	}
526		853
527	=item $handle->rbuf	854	=item $handle->rbuf
528		855
529	Returns the read buffer (as a modifiable lvalue).	856	Returns the read buffer (as a modifiable lvalue).
530		857
531	You can access the read buffer directly as the C<< ->{rbuf} >> member, if	858	You can access the read buffer directly as the C<< ->{rbuf} >>
532	you want.	859	member, if you want. However, the only operation allowed on the
		860	read buffer (apart from looking at it) is removing data from its
		861	beginning. Otherwise modifying or appending to it is not allowed and will
		862	lead to hard-to-track-down bugs.
533		863
534	NOTE: The read buffer should only be used or modified if the C<on_read>,	864	NOTE: The read buffer should only be used or modified if the C<on_read>,
535	C<push_read> or C<unshift_read> methods are used. The other read methods	865	C<push_read> or C<unshift_read> methods are used. The other read methods
536	automatically manage the read buffer.	866	automatically manage the read buffer.
537		867
…		…
577		907
578	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")	908	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
579	->($self, $cb, @_);	909	->($self, $cb, @_);
580	}	910	}
581		911
582	push @{ $self->{queue} }, $cb;	912	push @{ $self->{_queue} }, $cb;
583	$self->_drain_rbuf;	913	$self->_drain_rbuf unless $self->{_in_drain};
584	}	914	}
585		915
586	sub unshift_read {	916	sub unshift_read {
587	my $self = shift;	917	my $self = shift;
588	my $cb = pop;	918	my $cb = pop;
…		…
593	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")	923	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
594	->($self, $cb, @_);	924	->($self, $cb, @_);
595	}	925	}
596		926
597		927
598	unshift @{ $self->{queue} }, $cb;	928	unshift @{ $self->{_queue} }, $cb;
599	$self->_drain_rbuf;	929	$self->_drain_rbuf unless $self->{_in_drain};
600	}	930	}
601		931
602	=item $handle->push_read (type => @args, $cb)	932	=item $handle->push_read (type => @args, $cb)
603		933
604	=item $handle->unshift_read (type => @args, $cb)	934	=item $handle->unshift_read (type => @args, $cb)
…		…
610	Predefined types are (if you have ideas for additional types, feel free to	940	Predefined types are (if you have ideas for additional types, feel free to
611	drop by and tell us):	941	drop by and tell us):
612		942
613	=over 4	943	=over 4
614		944
615	=item chunk => $octets, $cb->($self, $data)	945	=item chunk => $octets, $cb->($handle, $data)
616		946
617	Invoke the callback only once C<$octets> bytes have been read. Pass the	947	Invoke the callback only once C<$octets> bytes have been read. Pass the
618	data read to the callback. The callback will never be called with less	948	data read to the callback. The callback will never be called with less
619	data.	949	data.
620		950
…		…
634	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");	964	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
635	1	965	1
636	}	966	}
637	};	967	};
638		968
639	# compatibility with older API
640	sub push_read_chunk {
641	$_[0]->push_read (chunk => $_[1], $_[2]);
642	}
643
644	sub unshift_read_chunk {
645	$_[0]->unshift_read (chunk => $_[1], $_[2]);
646	}
647
648	=item line => [$eol, ]$cb->($self, $line, $eol)	969	=item line => [$eol, ]$cb->($handle, $line, $eol)
649		970
650	The callback will be called only once a full line (including the end of	971	The callback will be called only once a full line (including the end of
651	line marker, C<$eol>) has been read. This line (excluding the end of line	972	line marker, C<$eol>) has been read. This line (excluding the end of line
652	marker) will be passed to the callback as second argument (C<$line>), and	973	marker) will be passed to the callback as second argument (C<$line>), and
653	the end of line marker as the third argument (C<$eol>).	974	the end of line marker as the third argument (C<$eol>).
…		…
667	=cut	988	=cut
668		989
669	register_read_type line => sub {	990	register_read_type line => sub {
670	my ($self, $cb, $eol) = @_;	991	my ($self, $cb, $eol) = @_;
671		992
672	$eol = qr|(\015?\012)| if @_ < 3;	993	if (@_ < 3) {
		994	# this is more than twice as fast as the generic code below
		995	sub {
		996	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		997
		998	$cb->($_[0], $1, $2);
		999	1
		1000	}
		1001	} else {
673	$eol = quotemeta $eol unless ref $eol;	1002	$eol = quotemeta $eol unless ref $eol;
674	$eol = qr|^(.*?)($eol)|s;	1003	$eol = qr|^(.*?)($eol)|s;
		1004
		1005	sub {
		1006	$_[0]{rbuf} =~ s/$eol// or return;
		1007
		1008	$cb->($_[0], $1, $2);
		1009	1
		1010	}
		1011	}
		1012	};
		1013
		1014	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1015
		1016	Makes a regex match against the regex object C<$accept> and returns
		1017	everything up to and including the match.
		1018
		1019	Example: read a single line terminated by '\n'.
		1020
		1021	$handle->push_read (regex => qr<\n>, sub { ... });
		1022
		1023	If C<$reject> is given and not undef, then it determines when the data is
		1024	to be rejected: it is matched against the data when the C<$accept> regex
		1025	does not match and generates an C<EBADMSG> error when it matches. This is
		1026	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1027	receive buffer overflow).
		1028
		1029	Example: expect a single decimal number followed by whitespace, reject
		1030	anything else (not the use of an anchor).
		1031
		1032	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1033
		1034	If C<$skip> is given and not C<undef>, then it will be matched against
		1035	the receive buffer when neither C<$accept> nor C<$reject> match,
		1036	and everything preceding and including the match will be accepted
		1037	unconditionally. This is useful to skip large amounts of data that you
		1038	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1039	have to start matching from the beginning. This is purely an optimisation
		1040	and is usually worth only when you expect more than a few kilobytes.
		1041
		1042	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1043	expect the header to be very large (it isn't in practise, but...), we use
		1044	a skip regex to skip initial portions. The skip regex is tricky in that
		1045	it only accepts something not ending in either \015 or \012, as these are
		1046	required for the accept regex.
		1047
		1048	$handle->push_read (regex =>
		1049	qr<\015\012\015\012>,
		1050	undef, # no reject
		1051	qr<^.*[^\015\012]>,
		1052	sub { ... });
		1053
		1054	=cut
		1055
		1056	register_read_type regex => sub {
		1057	my ($self, $cb, $accept, $reject, $skip) = @_;
		1058
		1059	my $data;
		1060	my $rbuf = \$self->{rbuf};
675		1061
676	sub {	1062	sub {
677	$_[0]{rbuf} =~ s/$eol// or return;	1063	# accept
678		1064	if ($$rbuf =~ $accept) {
679	$cb->($_[0], $1, $2);	1065	$data .= substr $$rbuf, 0, $+[0], "";
		1066	$cb->($self, $data);
		1067	return 1;
		1068	}
680	1	1069
		1070	# reject
		1071	if ($reject && $$rbuf =~ $reject) {
		1072	$self->_error (&Errno::EBADMSG);
		1073	}
		1074
		1075	# skip
		1076	if ($skip && $$rbuf =~ $skip) {
		1077	$data .= substr $$rbuf, 0, $+[0], "";
		1078	}
		1079
		1080	()
681	}	1081	}
682	};	1082	};
683		1083
684	# compatibility with older API
685	sub push_read_line {
686	my $self = shift;
687	$self->push_read (line => @_);
688	}
689
690	sub unshift_read_line {
691	my $self = shift;
692	$self->unshift_read (line => @_);
693	}
694
695	=item netstring => $cb->($string)	1084	=item netstring => $cb->($handle, $string)
696		1085
697	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).	1086	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
698		1087
699	Throws an error with C<$!> set to EBADMSG on format violations.	1088	Throws an error with C<$!> set to EBADMSG on format violations.
700		1089
…		…
704	my ($self, $cb) = @_;	1093	my ($self, $cb) = @_;
705		1094
706	sub {	1095	sub {
707	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {	1096	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
708	if ($_[0]{rbuf} =~ /[^0-9]/) {	1097	if ($_[0]{rbuf} =~ /[^0-9]/) {
709	$! = &Errno::EBADMSG;	1098	$self->_error (&Errno::EBADMSG);
710	$self->error;
711	}	1099	}
712	return;	1100	return;
713	}	1101	}
714		1102
715	my $len = $1;	1103	my $len = $1;
…		…
718	my $string = $_[1];	1106	my $string = $_[1];
719	$_[0]->unshift_read (chunk => 1, sub {	1107	$_[0]->unshift_read (chunk => 1, sub {
720	if ($_[1] eq ",") {	1108	if ($_[1] eq ",") {
721	$cb->($_[0], $string);	1109	$cb->($_[0], $string);
722	} else {	1110	} else {
723	$! = &Errno::EBADMSG;	1111	$self->_error (&Errno::EBADMSG);
724	$self->error;
725	}	1112	}
726	});	1113	});
727	});	1114	});
728		1115
729	1	1116	1
730	}	1117	}
731	};	1118	};
732		1119
		1120	=item packstring => $format, $cb->($handle, $string)
		1121
		1122	An octet string prefixed with an encoded length. The encoding C<$format>
		1123	uses the same format as a Perl C<pack> format, but must specify a single
		1124	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1125	optional C<!>, C<< < >> or C<< > >> modifier).
		1126
		1127	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1128	EPP uses a prefix of C<N> (4 octtes).
		1129
		1130	Example: read a block of data prefixed by its length in BER-encoded
		1131	format (very efficient).
		1132
		1133	$handle->push_read (packstring => "w", sub {
		1134	my ($handle, $data) = @_;
		1135	});
		1136
		1137	=cut
		1138
		1139	register_read_type packstring => sub {
		1140	my ($self, $cb, $format) = @_;
		1141
		1142	sub {
		1143	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1144	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1145	or return;
		1146
		1147	$format = length pack $format, $len;
		1148
		1149	# bypass unshift if we already have the remaining chunk
		1150	if ($format + $len <= length $_[0]{rbuf}) {
		1151	my $data = substr $_[0]{rbuf}, $format, $len;
		1152	substr $_[0]{rbuf}, 0, $format + $len, "";
		1153	$cb->($_[0], $data);
		1154	} else {
		1155	# remove prefix
		1156	substr $_[0]{rbuf}, 0, $format, "";
		1157
		1158	# read remaining chunk
		1159	$_[0]->unshift_read (chunk => $len, $cb);
		1160	}
		1161
		1162	1
		1163	}
		1164	};
		1165
		1166	=item json => $cb->($handle, $hash_or_arrayref)
		1167
		1168	Reads a JSON object or array, decodes it and passes it to the
		1169	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1170
		1171	If a C<json> object was passed to the constructor, then that will be used
		1172	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1173
		1174	This read type uses the incremental parser available with JSON version
		1175	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1176	dependency on your own: this module will load the JSON module, but
		1177	AnyEvent does not depend on it itself.
		1178
		1179	Since JSON texts are fully self-delimiting, the C<json> read and write
		1180	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1181	the C<json> write type description, above, for an actual example.
		1182
		1183	=cut
		1184
		1185	register_read_type json => sub {
		1186	my ($self, $cb) = @_;
		1187
		1188	require JSON;
		1189
		1190	my $data;
		1191	my $rbuf = \$self->{rbuf};
		1192
		1193	my $json = $self->{json} ||= JSON->new->utf8;
		1194
		1195	sub {
		1196	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1197
		1198	if ($ref) {
		1199	$self->{rbuf} = $json->incr_text;
		1200	$json->incr_text = "";
		1201	$cb->($self, $ref);
		1202
		1203	1
		1204	} elsif ($@) {
		1205	# error case
		1206	$json->incr_skip;
		1207
		1208	$self->{rbuf} = $json->incr_text;
		1209	$json->incr_text = "";
		1210
		1211	$self->_error (&Errno::EBADMSG);
		1212
		1213	()
		1214	} else {
		1215	$self->{rbuf} = "";
		1216
		1217	()
		1218	}
		1219	}
		1220	};
		1221
		1222	=item storable => $cb->($handle, $ref)
		1223
		1224	Deserialises a L<Storable> frozen representation as written by the
		1225	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1226	data).
		1227
		1228	Raises C<EBADMSG> error if the data could not be decoded.
		1229
		1230	=cut
		1231
		1232	register_read_type storable => sub {
		1233	my ($self, $cb) = @_;
		1234
		1235	require Storable;
		1236
		1237	sub {
		1238	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1239	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1240	or return;
		1241
		1242	my $format = length pack "w", $len;
		1243
		1244	# bypass unshift if we already have the remaining chunk
		1245	if ($format + $len <= length $_[0]{rbuf}) {
		1246	my $data = substr $_[0]{rbuf}, $format, $len;
		1247	substr $_[0]{rbuf}, 0, $format + $len, "";
		1248	$cb->($_[0], Storable::thaw ($data));
		1249	} else {
		1250	# remove prefix
		1251	substr $_[0]{rbuf}, 0, $format, "";
		1252
		1253	# read remaining chunk
		1254	$_[0]->unshift_read (chunk => $len, sub {
		1255	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1256	$cb->($_[0], $ref);
		1257	} else {
		1258	$self->_error (&Errno::EBADMSG);
		1259	}
		1260	});
		1261	}
		1262
		1263	1
		1264	}
		1265	};
		1266
733	=back	1267	=back
734		1268
735	=item AnyEvent::Handle::register_read_type type => $coderef->($self, $cb, @args)	1269	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
736		1270
737	This function (not method) lets you add your own types to C<push_read>.	1271	This function (not method) lets you add your own types to C<push_read>.
738		1272
739	Whenever the given C<type> is used, C<push_read> will invoke the code	1273	Whenever the given C<type> is used, C<push_read> will invoke the code
740	reference with the handle object, the callback and the remaining	1274	reference with the handle object, the callback and the remaining
…		…
742		1276
743	The code reference is supposed to return a callback (usually a closure)	1277	The code reference is supposed to return a callback (usually a closure)
744	that works as a plain read callback (see C<< ->push_read ($cb) >>).	1278	that works as a plain read callback (see C<< ->push_read ($cb) >>).
745		1279
746	It should invoke the passed callback when it is done reading (remember to	1280	It should invoke the passed callback when it is done reading (remember to
747	pass C<$self> as first argument as all other callbacks do that).	1281	pass C<$handle> as first argument as all other callbacks do that).
748		1282
749	Note that this is a function, and all types registered this way will be	1283	Note that this is a function, and all types registered this way will be
750	global, so try to use unique names.	1284	global, so try to use unique names.
751		1285
752	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,	1286	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
…		…
755	=item $handle->stop_read	1289	=item $handle->stop_read
756		1290
757	=item $handle->start_read	1291	=item $handle->start_read
758		1292
759	In rare cases you actually do not want to read anything from the	1293	In rare cases you actually do not want to read anything from the
760	socket. In this case you can call C<stop_read>. Neither C<on_read> no	1294	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
761	any queued callbacks will be executed then. To start reading again, call	1295	any queued callbacks will be executed then. To start reading again, call
762	C<start_read>.	1296	C<start_read>.
763		1297
		1298	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1299	you change the C<on_read> callback or push/unshift a read callback, and it
		1300	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1301	there are any read requests in the queue.
		1302
		1303	These methods will have no effect when in TLS mode (as TLS doesn't support
		1304	half-duplex connections).
		1305
764	=cut	1306	=cut
765		1307
766	sub stop_read {	1308	sub stop_read {
767	my ($self) = @_;	1309	my ($self) = @_;
768		1310
769	delete $self->{rw};	1311	delete $self->{_rw} unless $self->{tls};
770	}	1312	}
771		1313
772	sub start_read {	1314	sub start_read {
773	my ($self) = @_;	1315	my ($self) = @_;
774		1316
775	unless ($self->{rw} || $self->{eof}) {	1317	unless ($self->{_rw} || $self->{_eof}) {
776	Scalar::Util::weaken $self;	1318	Scalar::Util::weaken $self;
777		1319
778	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {	1320	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
779	my $rbuf = $self->{filter_r} ? \my $buf : \$self->{rbuf};	1321	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
780	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;	1322	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
781		1323
782	if ($len > 0) {	1324	if ($len > 0) {
783	$self->{filter_r}	1325	$self->{_activity} = AnyEvent->now;
784	? $self->{filter_r}->($self, $rbuf)	1326
785	: $self->_drain_rbuf;	1327	if ($self->{tls}) {
		1328	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
		1329
		1330	&_dotls ($self);
		1331	} else {
		1332	$self->_drain_rbuf unless $self->{_in_drain};
		1333	}
786		1334
787	} elsif (defined $len) {	1335	} elsif (defined $len) {
788	delete $self->{rw};	1336	delete $self->{_rw};
789	$self->{eof} = 1;	1337	$self->{_eof} = 1;
790	$self->_drain_rbuf;	1338	$self->_drain_rbuf unless $self->{_in_drain};
791		1339
792	} elsif ($! != EAGAIN && $! != EINTR && $! != &AnyEvent::Util::WSAWOULDBLOCK) {	1340	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
793	return $self->error;	1341	return $self->_error ($!, 1);
794	}	1342	}
795	});	1343	});
796	}	1344	}
797	}	1345	}
798		1346
		1347	# poll the write BIO and send the data if applicable
799	sub _dotls {	1348	sub _dotls {
800	my ($self) = @_;	1349	my ($self) = @_;
801		1350
		1351	my $tmp;
		1352
802	if (length $self->{tls_wbuf}) {	1353	if (length $self->{_tls_wbuf}) {
803	while ((my $len = Net::SSLeay::write ($self->{tls}, $self->{tls_wbuf})) > 0) {	1354	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
804	substr $self->{tls_wbuf}, 0, $len, "";	1355	substr $self->{_tls_wbuf}, 0, $tmp, "";
805	}	1356	}
806	}	1357	}
807		1358
808	if (defined (my $buf = Net::SSLeay::BIO_read ($self->{tls_wbio}))) {	1359	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		1360	unless (length $tmp) {
		1361	# let's treat SSL-eof as we treat normal EOF
		1362	delete $self->{_rw};
		1363	$self->{_eof} = 1;
		1364	&_freetls;
		1365	}
		1366
		1367	$self->{_tls_rbuf} .= $tmp;
		1368	$self->_drain_rbuf unless $self->{_in_drain};
		1369	$self->{tls} or return; # tls session might have gone away in callback
		1370	}
		1371
		1372	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
		1373
		1374	if ($tmp != Net::SSLeay::ERROR_WANT_READ ()) {
		1375	if ($tmp == Net::SSLeay::ERROR_SYSCALL ()) {
		1376	return $self->_error ($!, 1);
		1377	} elsif ($tmp == Net::SSLeay::ERROR_SSL ()) {
		1378	return $self->_error (&Errno::EIO, 1);
		1379	}
		1380
		1381	# all other errors are fine for our purposes
		1382	}
		1383
		1384	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
809	$self->{wbuf} .= $buf;	1385	$self->{wbuf} .= $tmp;
810	$self->_drain_wbuf;	1386	$self->_drain_wbuf;
811	}
812
813	while (defined (my $buf = Net::SSLeay::read ($self->{tls}))) {
814	$self->{rbuf} .= $buf;
815	$self->_drain_rbuf;
816	}
817
818	my $err = Net::SSLeay::get_error ($self->{tls}, -1);
819
820	if ($err!= Net::SSLeay::ERROR_WANT_READ ()) {
821	if ($err == Net::SSLeay::ERROR_SYSCALL ()) {
822	$self->error;
823	} elsif ($err == Net::SSLeay::ERROR_SSL ()) {
824	$! = &Errno::EIO;
825	$self->error;
826	}
827
828	# all others are fine for our purposes
829	}	1387	}
830	}	1388	}
831		1389
832	=item $handle->starttls ($tls[, $tls_ctx])	1390	=item $handle->starttls ($tls[, $tls_ctx])
833		1391
…		…
836	C<starttls>.	1394	C<starttls>.
837		1395
838	The first argument is the same as the C<tls> constructor argument (either	1396	The first argument is the same as the C<tls> constructor argument (either
839	C<"connect">, C<"accept"> or an existing Net::SSLeay object).	1397	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
840		1398
841	The second argument is the optional C<Net::SSLeay::CTX> object that is	1399	The second argument is the optional C<AnyEvent::TLS> object that is used
842	used when AnyEvent::Handle has to create its own TLS connection object.	1400	when AnyEvent::Handle has to create its own TLS connection object, or
		1401	a hash reference with C<< key => value >> pairs that will be used to
		1402	construct a new context.
843		1403
844	=cut	1404	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1405	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1406	changed to your liking. Note that the handshake might have already started
		1407	when this function returns.
845		1408
846	# TODO: maybe document...	1409	If it an error to start a TLS handshake more than once per
		1410	AnyEvent::Handle object (this is due to bugs in OpenSSL).
		1411
		1412	=cut
		1413
847	sub starttls {	1414	sub starttls {
848	my ($self, $ssl, $ctx) = @_;	1415	my ($self, $ssl, $ctx) = @_;
849		1416
850	$self->stoptls;	1417	require Net::SSLeay;
851		1418
852	if ($ssl eq "accept") {	1419	Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
853	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());	1420	if $self->{tls};
854	Net::SSLeay::set_accept_state ($ssl);	1421
855	} elsif ($ssl eq "connect") {	1422	$ctx ||= $self->{tls_ctx};
856	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());	1423
857	Net::SSLeay::set_connect_state ($ssl);	1424	if ("HASH" eq ref $ctx) {
		1425	require AnyEvent::TLS;
		1426
		1427	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
		1428	$ctx = new AnyEvent::TLS %$ctx;
		1429	}
858	}	1430
859		1431	$self->{tls_ctx} = $ctx || TLS_CTX ();
860	$self->{tls} = $ssl;	1432	$self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self);
861		1433
862	# basically, this is deep magic (because SSL_read should have the same issues)	1434	# basically, this is deep magic (because SSL_read should have the same issues)
863	# but the openssl maintainers basically said: "trust us, it just works".	1435	# but the openssl maintainers basically said: "trust us, it just works".
864	# (unfortunately, we have to hardcode constants because the abysmally misdesigned	1436	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
865	# and mismaintained ssleay-module doesn't even offer them).	1437	# and mismaintained ssleay-module doesn't even offer them).
866	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html	1438	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1439	#
		1440	# in short: this is a mess.
		1441	#
		1442	# note that we do not try to keep the length constant between writes as we are required to do.
		1443	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1444	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1445	# have identity issues in that area.
867	Net::SSLeay::CTX_set_mode ($self->{tls},	1446	# Net::SSLeay::CTX_set_mode ($ssl,
868	(eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)	1447	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
869	| (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));	1448	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1449	Net::SSLeay::CTX_set_mode ($ssl, 1|2);
870		1450
871	$self->{tls_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());	1451	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
872	$self->{tls_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());	1452	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
873		1453
874	Net::SSLeay::set_bio ($ssl, $self->{tls_rbio}, $self->{tls_wbio});	1454	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
875		1455
876	$self->{filter_w} = sub {	1456	&_dotls; # need to trigger the initial handshake
877	$_[0]{tls_wbuf} .= ${$_[1]};	1457	$self->start_read; # make sure we actually do read
878	&_dotls;
879	};
880	$self->{filter_r} = sub {
881	Net::SSLeay::BIO_write ($_[0]{tls_rbio}, ${$_[1]});
882	&_dotls;
883	};
884	}	1458	}
885		1459
886	=item $handle->stoptls	1460	=item $handle->stoptls
887		1461
888	Destroys the SSL connection, if any. Partial read or write data will be	1462	Shuts down the SSL connection - this makes a proper EOF handshake by
889	lost.	1463	sending a close notify to the other side, but since OpenSSL doesn't
		1464	support non-blocking shut downs, it is not possible to re-use the stream
		1465	afterwards.
890		1466
891	=cut	1467	=cut
892		1468
893	sub stoptls {	1469	sub stoptls {
894	my ($self) = @_;	1470	my ($self) = @_;
895		1471
896	Net::SSLeay::free (delete $self->{tls}) if $self->{tls};	1472	if ($self->{tls}) {
897	delete $self->{tls_rbio};	1473	Net::SSLeay::shutdown ($self->{tls});
898	delete $self->{tls_wbio};	1474
899	delete $self->{tls_wbuf};	1475	&_dotls;
900	delete $self->{filter_r};	1476
901	delete $self->{filter_w};	1477	# we don't give a shit. no, we do, but we can't. no...
		1478	# we, we... have to use openssl :/
		1479	&_freetls;
		1480	}
		1481	}
		1482
		1483	sub _freetls {
		1484	my ($self) = @_;
		1485
		1486	return unless $self->{tls};
		1487
		1488	$self->{tls_ctx}->_put_session (delete $self->{tls});
		1489
		1490	delete @$self{qw(_rbio _wbio _tls_wbuf)};
902	}	1491	}
903		1492
904	sub DESTROY {	1493	sub DESTROY {
905	my $self = shift;	1494	my ($self) = @_;
906		1495
907	$self->stoptls;	1496	&_freetls;
		1497
		1498	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		1499
		1500	if ($linger && length $self->{wbuf}) {
		1501	my $fh = delete $self->{fh};
		1502	my $wbuf = delete $self->{wbuf};
		1503
		1504	my @linger;
		1505
		1506	push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
		1507	my $len = syswrite $fh, $wbuf, length $wbuf;
		1508
		1509	if ($len > 0) {
		1510	substr $wbuf, 0, $len, "";
		1511	} else {
		1512	@linger = (); # end
		1513	}
		1514	});
		1515	push @linger, AnyEvent->timer (after => $linger, cb => sub {
		1516	@linger = ();
		1517	});
		1518	}
		1519	}
		1520
		1521	=item $handle->destroy
		1522
		1523	Shuts down the handle object as much as possible - this call ensures that
		1524	no further callbacks will be invoked and resources will be freed as much
		1525	as possible. You must not call any methods on the object afterwards.
		1526
		1527	Normally, you can just "forget" any references to an AnyEvent::Handle
		1528	object and it will simply shut down. This works in fatal error and EOF
		1529	callbacks, as well as code outside. It does I<NOT> work in a read or write
		1530	callback, so when you want to destroy the AnyEvent::Handle object from
		1531	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		1532	that case.
		1533
		1534	The handle might still linger in the background and write out remaining
		1535	data, as specified by the C<linger> option, however.
		1536
		1537	=cut
		1538
		1539	sub destroy {
		1540	my ($self) = @_;
		1541
		1542	$self->DESTROY;
		1543	%$self = ();
908	}	1544	}
909		1545
910	=item AnyEvent::Handle::TLS_CTX	1546	=item AnyEvent::Handle::TLS_CTX
911		1547
912	This function creates and returns the Net::SSLeay::CTX object used by	1548	This function creates and returns the AnyEvent::TLS object used by default
913	default for TLS mode.	1549	for TLS mode.
914		1550
915	The context is created like this:	1551	The context is created by calling L<AnyEvent::TLS> without any arguments.
916
917	Net::SSLeay::load_error_strings;
918	Net::SSLeay::SSLeay_add_ssl_algorithms;
919	Net::SSLeay::randomize;
920
921	my $CTX = Net::SSLeay::CTX_new;
922
923	Net::SSLeay::CTX_set_options $CTX, Net::SSLeay::OP_ALL
924		1552
925	=cut	1553	=cut
926		1554
927	our $TLS_CTX;	1555	our $TLS_CTX;
928		1556
929	sub TLS_CTX() {	1557	sub TLS_CTX() {
930	$TLS_CTX || do {	1558	$TLS_CTX ||= do {
931	require Net::SSLeay;	1559	require AnyEvent::TLS;
932		1560
933	Net::SSLeay::load_error_strings ();	1561	new AnyEvent::TLS
934	Net::SSLeay::SSLeay_add_ssl_algorithms ();
935	Net::SSLeay::randomize ();
936
937	$TLS_CTX = Net::SSLeay::CTX_new ();
938
939	Net::SSLeay::CTX_set_options ($TLS_CTX, Net::SSLeay::OP_ALL ());
940
941	$TLS_CTX
942	}	1562	}
943	}	1563	}
944		1564
945	=back	1565	=back
946		1566
		1567
		1568	=head1 NONFREQUENTLY ASKED QUESTIONS
		1569
		1570	=over 4
		1571
		1572	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		1573	still get further invocations!
		1574
		1575	That's because AnyEvent::Handle keeps a reference to itself when handling
		1576	read or write callbacks.
		1577
		1578	It is only safe to "forget" the reference inside EOF or error callbacks,
		1579	from within all other callbacks, you need to explicitly call the C<<
		1580	->destroy >> method.
		1581
		1582	=item I get different callback invocations in TLS mode/Why can't I pause
		1583	reading?
		1584
		1585	Unlike, say, TCP, TLS connections do not consist of two independent
		1586	communication channels, one for each direction. Or put differently. The
		1587	read and write directions are not independent of each other: you cannot
		1588	write data unless you are also prepared to read, and vice versa.
		1589
		1590	This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
		1591	callback invocations when you are not expecting any read data - the reason
		1592	is that AnyEvent::Handle always reads in TLS mode.
		1593
		1594	During the connection, you have to make sure that you always have a
		1595	non-empty read-queue, or an C<on_read> watcher. At the end of the
		1596	connection (or when you no longer want to use it) you can call the
		1597	C<destroy> method.
		1598
		1599	=item How do I read data until the other side closes the connection?
		1600
		1601	If you just want to read your data into a perl scalar, the easiest way
		1602	to achieve this is by setting an C<on_read> callback that does nothing,
		1603	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		1604	will be in C<$_[0]{rbuf}>:
		1605
		1606	$handle->on_read (sub { });
		1607	$handle->on_eof (undef);
		1608	$handle->on_error (sub {
		1609	my $data = delete $_[0]{rbuf};
		1610	undef $handle;
		1611	});
		1612
		1613	The reason to use C<on_error> is that TCP connections, due to latencies
		1614	and packets loss, might get closed quite violently with an error, when in
		1615	fact, all data has been received.
		1616
		1617	It is usually better to use acknowledgements when transferring data,
		1618	to make sure the other side hasn't just died and you got the data
		1619	intact. This is also one reason why so many internet protocols have an
		1620	explicit QUIT command.
		1621
		1622	=item I don't want to destroy the handle too early - how do I wait until
		1623	all data has been written?
		1624
		1625	After writing your last bits of data, set the C<on_drain> callback
		1626	and destroy the handle in there - with the default setting of
		1627	C<low_water_mark> this will be called precisely when all data has been
		1628	written to the socket:
		1629
		1630	$handle->push_write (...);
		1631	$handle->on_drain (sub {
		1632	warn "all data submitted to the kernel\n";
		1633	undef $handle;
		1634	});
		1635
		1636	=back
		1637
		1638
		1639	=head1 SUBCLASSING AnyEvent::Handle
		1640
		1641	In many cases, you might want to subclass AnyEvent::Handle.
		1642
		1643	To make this easier, a given version of AnyEvent::Handle uses these
		1644	conventions:
		1645
		1646	=over 4
		1647
		1648	=item * all constructor arguments become object members.
		1649
		1650	At least initially, when you pass a C<tls>-argument to the constructor it
		1651	will end up in C<< $handle->{tls} >>. Those members might be changed or
		1652	mutated later on (for example C<tls> will hold the TLS connection object).
		1653
		1654	=item * other object member names are prefixed with an C<_>.
		1655
		1656	All object members not explicitly documented (internal use) are prefixed
		1657	with an underscore character, so the remaining non-C<_>-namespace is free
		1658	for use for subclasses.
		1659
		1660	=item * all members not documented here and not prefixed with an underscore
		1661	are free to use in subclasses.
		1662
		1663	Of course, new versions of AnyEvent::Handle may introduce more "public"
		1664	member variables, but thats just life, at least it is documented.
		1665
		1666	=back
		1667
947	=head1 AUTHOR	1668	=head1 AUTHOR
948		1669
949	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.	1670	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
950		1671
951	=cut	1672	=cut

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