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Revision 1.19 by root, Sat May 24 05:57:11 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 ();	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	This module is experimental.
18
19	=cut	17	=cut
20		18
21	our $VERSION = '0.04';	19	our $VERSION = 4.45;
22		20
23	=head1 SYNOPSIS	21	=head1 SYNOPSIS
24		22
25	use AnyEvent;	23	use AnyEvent;
26	use AnyEvent::Handle;	24	use AnyEvent::Handle;
27		25
28	my $cv = AnyEvent->condvar;	26	my $cv = AnyEvent->condvar;
29		27
30	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	28	my $handle =
31
32	#TODO
33
34	# or use the constructor to pass the callback:
35
36	my $ae_fh2 =
37	AnyEvent::Handle->new (	29	AnyEvent::Handle->new (
38	fh => \*STDIN,	30	fh => \*STDIN,
39	on_eof => sub {	31	on_eof => sub {
40	$cv->broadcast;	32	$cv->send;
41	},	33	},
42	#TODO
43	);	34	);
44		35
45	$cv->wait;	36	# send some request line
		37	$handle->push_write ("getinfo\015\012");
		38
		39	# read the response line
		40	$handle->push_read (line => sub {
		41	my ($handle, $line) = @_;
		42	warn "read line <$line>\n";
		43	$cv->send;
		44	});
		45
		46	$cv->recv;
46		47
47	=head1 DESCRIPTION	48	=head1 DESCRIPTION
48		49
49	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
50	filehandles. For utility functions for doing non-blocking connects and accepts	51	filehandles. For utility functions for doing non-blocking connects and accepts
51	on sockets see L<AnyEvent::Util>.	52	on sockets see L<AnyEvent::Util>.
52		53
		54	The L<AnyEvent::Intro> tutorial contains some well-documented
		55	AnyEvent::Handle examples.
		56
53	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
54	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
55	treatment of characters applies to this module as well.	59	treatment of characters applies to this module as well.
56		60
57	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
…		…
59		63
60	=head1 METHODS	64	=head1 METHODS
61		65
62	=over 4	66	=over 4
63		67
64	=item B<new (%args)>	68	=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
65		69
66	The constructor supports these arguments (all as key => value pairs).	70	The constructor supports these arguments (all as C<< key => value >> pairs).
67		71
68	=over 4	72	=over 4
69		73
70	=item fh => $filehandle [MANDATORY]	74	=item fh => $filehandle [MANDATORY]
71		75
72	The filehandle this L<AnyEvent::Handle> object will operate on.	76	The filehandle this L<AnyEvent::Handle> object will operate on.
73		77
74	NOTE: The filehandle will be set to non-blocking (using	78	NOTE: The filehandle will be set to non-blocking mode (using
75	AnyEvent::Util::fh_nonblocking).	79	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		80	that mode.
76		81
77	=item on_eof => $cb->($self)	82	=item on_eof => $cb->($handle)
78		83
79	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.
80		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
81	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,
82	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
83	waiting for data.	95	waiting for data.
84		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
85	=item on_error => $cb->($self)	100	=item on_error => $cb->($handle, $fatal)
86		101
87	This is the fatal error callback, that is called when, well, a fatal error	102	This is the error callback, which is called when, well, some error
88	ocurs, such as not being able to resolve the hostname, failure to connect	103	occured, such as not being able to resolve the hostname, failure to
89	or a read error.	104	connect or a read error.
90		105
91	The object will not be in a usable state when this callback has been	106	Some errors are fatal (which is indicated by C<$fatal> being true). On
92	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>).
93		116
94	On callback entrance, the value of C<$!> contains the operating system	117	On callback entrance, the value of C<$!> contains the operating system
95	error (or C<ENOSPC> or C<EPIPE>).	118	error (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT> or C<EBADMSG>).
96		119
97	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
98	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
99	die.	122	C<croak>.
100		123
101	=item on_read => $cb->($self)	124	=item on_read => $cb->($handle)
102		125
103	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
104	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).
105		130
106	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 >>
107	method or acces sthe 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.
108		135
109	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
110	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
111	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
112	error will be raised (with C<$!> set to C<EPIPE>).	139	error will be raised (with C<$!> set to C<EPIPE>).
113		140
114	=item on_drain => $cb->()	141	=item on_drain => $cb->($handle)
115		142
116	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
117	(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).
118		145
119	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.
120		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
121	=item rbuf_max => <bytes>	175	=item rbuf_max => <bytes>
122		176
123	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>)
124	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
125	avoid denial-of-service attacks.	179	avoid some forms of denial-of-service attacks.
126		180
127	For example, a server accepting connections from untrusted sources should	181	For example, a server accepting connections from untrusted sources should
128	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
129	(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
130	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
131	isn't finished).	185	isn't finished).
132		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
133	=item read_size => <bytes>	213	=item read_size => <bytes>
134		214
135	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
136	on each [loop iteration). Default: C<4096>.	216	try to read during each loop iteration, which affects memory
		217	requirements). Default: C<8192>.
137		218
138	=item low_water_mark => <bytes>	219	=item low_water_mark => <bytes>
139		220
140	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
141	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
142	considered empty.	223	considered empty.
143		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
144	=item tls => "accept" | "connect" | Net::SSLeay::SSL object	248	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
145		249
146	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
147	will start making tls handshake and will transparently encrypt/decrypt	251	AnyEvent will start a TLS handshake as soon as the conenction has been
148	data.	252	established and will transparently encrypt/decrypt data afterwards.
149		253
150	For the TLS server side, use C<accept>, and for the TLS client side of a	254	TLS mode requires Net::SSLeay to be installed (it will be loaded
151	connection, use C<connect> mode.	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.
		258
		259	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		260	C<accept>, and for the TLS client side of a connection, use C<connect>
		261	mode.
152		262
153	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
154	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>
155	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
156	AnyEvent::Handle.	266	AnyEvent::Handle. Also, this module will take ownership of this connection
		267	object.
157		268
158	=item tls_ctx => $ssl_ctx	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.
159		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
		278	See the C<< ->starttls >> method for when need to start TLS negotiation later.
		279
		280	=item tls_ctx => $anyevent_tls
		281
160	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
161	(unless a connection object was specified directly). If this parameter is	283	(unless a connection object was specified directly). If this parameter is
162	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.	284	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
163		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
164	=back	301	=back
165		302
166	=cut	303	=cut
167		304
168	sub new {	305	sub new {
169	my $class = shift;	306	my $class = shift;
170
171	my $self = bless { @_ }, $class;	307	my $self = bless { @_ }, $class;
172		308
173	$self->{fh} or Carp::croak "mandatory argument fh is missing";	309	$self->{fh} or Carp::croak "mandatory argument fh is missing";
174		310
175	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	311	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
176		312
177	if ($self->{tls}) {	313	$self->{_activity} = AnyEvent->now;
178	require Net::SSLeay;	314	$self->_timeout;
		315
		316	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		317
179	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx});	318	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
180	}	319	if $self->{tls};
181		320
182	$self->on_eof (delete $self->{on_eof} ) if $self->{on_eof};
183	$self->on_error (delete $self->{on_error}) if $self->{on_error};
184	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	321	$self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
185	$self->on_read (delete $self->{on_read} ) if $self->{on_read};
186		322
187	$self->start_read;	323	$self->start_read
		324	if $self->{on_read};
188		325
189	$self	326	$self->{fh} && $self
190	}	327	}
191		328
192	sub _shutdown {	329	sub _shutdown {
193	my ($self) = @_;	330	my ($self) = @_;
194		331
195	delete $self->{rw};	332	delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
196	delete $self->{ww};	333	$self->{_eof} = 1; # tell starttls et. al to stop trying
197	delete $self->{fh};
198	}
199		334
		335	&_freetls;
		336	}
		337
200	sub error {	338	sub _error {
201	my ($self) = @_;	339	my ($self, $errno, $fatal) = @_;
202		340
203	{
204	local $!;
205	$self->_shutdown;	341	$self->_shutdown
206	}	342	if $fatal;
		343
		344	$! = $errno;
207		345
208	if ($self->{on_error}) {	346	if ($self->{on_error}) {
209	$self->{on_error}($self);	347	$self->{on_error}($self, $fatal);
210	} else {	348	} elsif ($self->{fh}) {
211	die "AnyEvent::Handle uncaught fatal error: $!";	349	Carp::croak "AnyEvent::Handle uncaught error: $!";
212	}	350	}
213	}	351	}
214		352
215	=item $fh = $handle->fh	353	=item $fh = $handle->fh
216		354
217	This method returns the filehandle of the L<AnyEvent::Handle> object.	355	This method returns the file handle used to create the L<AnyEvent::Handle> object.
218		356
219	=cut	357	=cut
220		358
221	sub fh { $_[0]->{fh} }	359	sub fh { $_[0]{fh} }
222		360
223	=item $handle->on_error ($cb)	361	=item $handle->on_error ($cb)
224		362
225	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).
226		364
…		…
238		376
239	sub on_eof {	377	sub on_eof {
240	$_[0]{on_eof} = $_[1];	378	$_[0]{on_eof} = $_[1];
241	}	379	}
242		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
243	#############################################################################	475	#############################################################################
244		476
245	=back	477	=back
246		478
247	=head2 WRITE QUEUE	479	=head2 WRITE QUEUE
…		…
250	for reading.	482	for reading.
251		483
252	The write queue is very simple: you can add data to its end, and	484	The write queue is very simple: you can add data to its end, and
253	AnyEvent::Handle will automatically try to get rid of it for you.	485	AnyEvent::Handle will automatically try to get rid of it for you.
254		486
255	When data could be writtena nd the write buffer is shorter then the low	487	When data could be written and the write buffer is shorter then the low
256	water mark, the C<on_drain> callback will be invoked.	488	water mark, the C<on_drain> callback will be invoked.
257		489
258	=over 4	490	=over 4
259		491
260	=item $handle->on_drain ($cb)	492	=item $handle->on_drain ($cb)
…		…
268	my ($self, $cb) = @_;	500	my ($self, $cb) = @_;
269		501
270	$self->{on_drain} = $cb;	502	$self->{on_drain} = $cb;
271		503
272	$cb->($self)	504	$cb->($self)
273	if $cb && $self->{low_water_mark} >= length $self->{wbuf};	505	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
274	}	506	}
275		507
276	=item $handle->push_write ($data)	508	=item $handle->push_write ($data)
277		509
278	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
…		…
282	=cut	514	=cut
283		515
284	sub _drain_wbuf {	516	sub _drain_wbuf {
285	my ($self) = @_;	517	my ($self) = @_;
286		518
287	unless ($self->{ww}) {	519	if (!$self->{_ww} && length $self->{wbuf}) {
		520
288	Scalar::Util::weaken $self;	521	Scalar::Util::weaken $self;
		522
289	my $cb = sub {	523	my $cb = sub {
290	my $len = syswrite $self->{fh}, $self->{wbuf};	524	my $len = syswrite $self->{fh}, $self->{wbuf};
291		525
292	if ($len > 0) {	526	if ($len >= 0) {
293	substr $self->{wbuf}, 0, $len, "";	527	substr $self->{wbuf}, 0, $len, "";
294		528
		529	$self->{_activity} = AnyEvent->now;
		530
295	$self->{on_drain}($self)	531	$self->{on_drain}($self)
296	if $self->{low_water_mark} >= length $self->{wbuf}	532	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
297	&& $self->{on_drain};	533	&& $self->{on_drain};
298		534
299	delete $self->{ww} unless length $self->{wbuf};	535	delete $self->{_ww} unless length $self->{wbuf};
300	} elsif ($! != EAGAIN && $! != EINTR) {	536	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
301	$self->error;	537	$self->_error ($!, 1);
302	}	538	}
303	};	539	};
304		540
		541	# try to write data immediately
		542	$cb->() unless $self->{autocork};
		543
		544	# if still data left in wbuf, we need to poll
305	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	545	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
306		546	if length $self->{wbuf};
307	$cb->($self);
308	};	547	};
		548	}
		549
		550	our %WH;
		551
		552	sub register_write_type($$) {
		553	$WH{$_[0]} = $_[1];
309	}	554	}
310		555
311	sub push_write {	556	sub push_write {
312	my $self = shift;	557	my $self = shift;
313		558
		559	if (@_ > 1) {
		560	my $type = shift;
		561
		562	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
		563	->($self, @_);
		564	}
		565
314	if ($self->{filter_w}) {	566	if ($self->{tls}) {
315	$self->{filter_w}->($self, \$_[0]);	567	$self->{_tls_wbuf} .= $_[0];
		568
		569	&_dotls ($self);
316	} else {	570	} else {
317	$self->{wbuf} .= $_[0];	571	$self->{wbuf} .= $_[0];
318	$self->_drain_wbuf;	572	$self->_drain_wbuf;
319	}	573	}
320	}	574	}
321		575
		576	=item $handle->push_write (type => @args)
		577
		578	Instead of formatting your data yourself, you can also let this module do
		579	the job by specifying a type and type-specific arguments.
		580
		581	Predefined types are (if you have ideas for additional types, feel free to
		582	drop by and tell us):
		583
		584	=over 4
		585
		586	=item netstring => $string
		587
		588	Formats the given value as netstring
		589	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		590
		591	=cut
		592
		593	register_write_type netstring => sub {
		594	my ($self, $string) = @_;
		595
		596	(length $string) . ":$string,"
		597	};
		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
		672	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
		673
		674	This function (not method) lets you add your own types to C<push_write>.
		675	Whenever the given C<type> is used, C<push_write> will invoke the code
		676	reference with the handle object and the remaining arguments.
		677
		678	The code reference is supposed to return a single octet string that will
		679	be appended to the write buffer.
		680
		681	Note that this is a function, and all types registered this way will be
		682	global, so try to use unique names.
		683
		684	=cut
		685
322	#############################################################################	686	#############################################################################
323		687
324	=back	688	=back
325		689
326	=head2 READ QUEUE	690	=head2 READ QUEUE
…		…
332	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
333	a queue.	697	a queue.
334		698
335	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
336	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
337	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
338	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).
339		704
340	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
341	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
342	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
343	below).	708	done its job (see C<push_read>, below).
344		709
345	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
346	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.
347		712
348	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
349	the specified number of bytes which give an XML datagram.	714	the specified number of bytes which give an XML datagram.
350		715
351	# in the default state, expect some header bytes	716	# in the default state, expect some header bytes
352	$handle->on_read (sub {	717	$handle->on_read (sub {
353	# 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)
354	shift->unshift_read_chunk (4, sub {	719	shift->unshift_read (chunk => 4, sub {
355	# header arrived, decode	720	# header arrived, decode
356	my $len = unpack "N", $_[1];	721	my $len = unpack "N", $_[1];
357		722
358	# now read the payload	723	# now read the payload
359	shift->unshift_read_chunk ($len, sub {	724	shift->unshift_read (chunk => $len, sub {
360	my $xml = $_[1];	725	my $xml = $_[1];
361	# handle xml	726	# handle xml
362	});	727	});
363	});	728	});
364	});	729	});
365		730
366	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"
367	"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
368	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
369	pipeline sending both requests and manipulate the queue as necessary in	734	just pipeline sending both requests and manipulate the queue as necessary
370	the callbacks:	735	in the callbacks.
371		736
372	# 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"
373	$handle->push_write ("request 1\015\012");	742	$handle->push_write ("request 1\015\012");
374		743
375	# 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
376	$handle->push_read_line (sub {	745	$handle->push_read (line => sub {
377	# if we got an "OK", we have to _prepend_ another line,	746	# if we got an "OK", we have to _prepend_ another line,
378	# 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
379	# which are already in the queue when this callback is called	748	# which are already in the queue when this callback is called
380	# we don't do this in case we got an error	749	# we don't do this in case we got an error
381	if ($_[1] eq "OK") {	750	if ($_[1] eq "OK") {
382	$_[0]->unshift_read_line (sub {	751	$_[0]->unshift_read (line => sub {
383	my $response = $_[1];	752	my $response = $_[1];
384	...	753	...
385	});	754	});
386	}	755	}
387	});	756	});
388		757
389	# request two	758	# request two, simply returns 64 octets
390	$handle->push_write ("request 2\015\012");	759	$handle->push_write ("request 2\015\012");
391		760
392	# simply read 64 bytes, always	761	# simply read 64 bytes, always
393	$handle->push_read_chunk (64, sub {	762	$handle->push_read (chunk => 64, sub {
394	my $response = $_[1];	763	my $response = $_[1];
395	...	764	...
396	});	765	});
397		766
398	=over 4	767	=over 4
399		768
400	=cut	769	=cut
401		770
402	sub _drain_rbuf {	771	sub _drain_rbuf {
403	my ($self) = @_;	772	my ($self) = @_;
		773
		774	local $self->{_in_drain} = 1;
404		775
405	if (	776	if (
406	defined $self->{rbuf_max}	777	defined $self->{rbuf_max}
407	&& $self->{rbuf_max} < length $self->{rbuf}	778	&& $self->{rbuf_max} < length $self->{rbuf}
408	) {	779	) {
409	$! = &Errno::ENOSPC; return $self->error;	780	$self->_error (&Errno::ENOSPC, 1), return;
410	}	781	}
411		782
412	return if $self->{in_drain};	783	while () {
413	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};
414		787
415	while (my $len = length $self->{rbuf}) {	788	my $len = length $self->{rbuf};
416	no strict 'refs';	789
417	if (my $cb = shift @{ $self->{queue} }) {	790	if (my $cb = shift @{ $self->{_queue} }) {
418	if (!$cb->($self)) {	791	unless ($cb->($self)) {
419	if ($self->{eof}) {	792	if ($self->{_eof}) {
420	# 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)
421	$! = &Errno::EPIPE; return $self->error;	794	$self->_error (&Errno::EPIPE, 1), return;
422	}	795	}
423		796
424	unshift @{ $self->{queue} }, $cb;	797	unshift @{ $self->{_queue} }, $cb;
425	return;	798	last;
426	}	799	}
427	} elsif ($self->{on_read}) {	800	} elsif ($self->{on_read}) {
		801	last unless $len;
		802
428	$self->{on_read}($self);	803	$self->{on_read}($self);
429		804
430	if (	805	if (
431	$self->{eof} # if no further data will arrive
432	&& $len == length $self->{rbuf} # and no data has been consumed	806	$len == length $self->{rbuf} # if no data has been consumed
433	&& !@{ $self->{queue} } # and the queue is still empty	807	&& !@{ $self->{_queue} } # and the queue is still empty
434	&& $self->{on_read} # and we still want to read data	808	&& $self->{on_read} # but we still have on_read
435	) {	809	) {
		810	# no further data will arrive
436	# then no progress can be made	811	# so no progress can be made
437	$! = &Errno::EPIPE; return $self->error;	812	$self->_error (&Errno::EPIPE, 1), return
		813	if $self->{_eof};
		814
		815	last; # more data might arrive
438	}	816	}
439	} else {	817	} else {
440	# read side becomes idle	818	# read side becomes idle
441	delete $self->{rw};	819	delete $self->{_rw} unless $self->{tls};
442	return;	820	last;
443	}	821	}
444	}	822	}
445		823
446	if ($self->{eof}) {	824	if ($self->{_eof}) {
447	$self->_shutdown;	825	if ($self->{on_eof}) {
448	$self->{on_eof}($self)	826	$self->{on_eof}($self)
449	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} };
450	}	836	}
451	}	837	}
452		838
453	=item $handle->on_read ($cb)	839	=item $handle->on_read ($cb)
454		840
…		…
460		846
461	sub on_read {	847	sub on_read {
462	my ($self, $cb) = @_;	848	my ($self, $cb) = @_;
463		849
464	$self->{on_read} = $cb;	850	$self->{on_read} = $cb;
		851	$self->_drain_rbuf if $cb && !$self->{_in_drain};
465	}	852	}
466		853
467	=item $handle->rbuf	854	=item $handle->rbuf
468		855
469	Returns the read buffer (as a modifiable lvalue).	856	Returns the read buffer (as a modifiable lvalue).
470		857
471	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} >>
472	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.
473		863
474	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>,
475	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
476	automatically manage the read buffer.	866	automatically manage the read buffer.
477		867
…		…
488	Append the given callback to the end of the queue (C<push_read>) or	878	Append the given callback to the end of the queue (C<push_read>) or
489	prepend it (C<unshift_read>).	879	prepend it (C<unshift_read>).
490		880
491	The callback is called each time some additional read data arrives.	881	The callback is called each time some additional read data arrives.
492		882
493	It must check wether enough data is in the read buffer already.	883	It must check whether enough data is in the read buffer already.
494		884
495	If not enough data is available, it must return the empty list or a false	885	If not enough data is available, it must return the empty list or a false
496	value, in which case it will be called repeatedly until enough data is	886	value, in which case it will be called repeatedly until enough data is
497	available (or an error condition is detected).	887	available (or an error condition is detected).
498		888
…		…
500	interested in (which can be none at all) and return a true value. After returning	890	interested in (which can be none at all) and return a true value. After returning
501	true, it will be removed from the queue.	891	true, it will be removed from the queue.
502		892
503	=cut	893	=cut
504		894
		895	our %RH;
		896
		897	sub register_read_type($$) {
		898	$RH{$_[0]} = $_[1];
		899	}
		900
505	sub push_read {	901	sub push_read {
506	my ($self, $cb) = @_;	902	my $self = shift;
		903	my $cb = pop;
507		904
		905	if (@_) {
		906	my $type = shift;
		907
		908	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
		909	->($self, $cb, @_);
		910	}
		911
508	push @{ $self->{queue} }, $cb;	912	push @{ $self->{_queue} }, $cb;
509	$self->_drain_rbuf;	913	$self->_drain_rbuf unless $self->{_in_drain};
510	}	914	}
511		915
512	sub unshift_read {	916	sub unshift_read {
513	my ($self, $cb) = @_;	917	my $self = shift;
		918	my $cb = pop;
514		919
		920	if (@_) {
		921	my $type = shift;
		922
		923	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
		924	->($self, $cb, @_);
		925	}
		926
		927
515	push @{ $self->{queue} }, $cb;	928	unshift @{ $self->{_queue} }, $cb;
516	$self->_drain_rbuf;	929	$self->_drain_rbuf unless $self->{_in_drain};
517	}	930	}
518		931
519	=item $handle->push_read_chunk ($len, $cb->($self, $data))	932	=item $handle->push_read (type => @args, $cb)
520		933
521	=item $handle->unshift_read_chunk ($len, $cb->($self, $data))	934	=item $handle->unshift_read (type => @args, $cb)
522		935
523	Append the given callback to the end of the queue (C<push_read_chunk>) or	936	Instead of providing a callback that parses the data itself you can chose
524	prepend it (C<unshift_read_chunk>).	937	between a number of predefined parsing formats, for chunks of data, lines
		938	etc.
525		939
526	The callback will be called only once C<$len> bytes have been read, and	940	Predefined types are (if you have ideas for additional types, feel free to
527	these C<$len> bytes will be passed to the callback.	941	drop by and tell us):
528		942
529	=cut	943	=over 4
530		944
531	sub _read_chunk($$) {	945	=item chunk => $octets, $cb->($handle, $data)
		946
		947	Invoke the callback only once C<$octets> bytes have been read. Pass the
		948	data read to the callback. The callback will never be called with less
		949	data.
		950
		951	Example: read 2 bytes.
		952
		953	$handle->push_read (chunk => 2, sub {
		954	warn "yay ", unpack "H*", $_[1];
		955	});
		956
		957	=cut
		958
		959	register_read_type chunk => sub {
532	my ($self, $len, $cb) = @_;	960	my ($self, $cb, $len) = @_;
533		961
534	sub {	962	sub {
535	$len <= length $_[0]{rbuf} or return;	963	$len <= length $_[0]{rbuf} or return;
536	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");	964	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
537	1	965	1
538	}	966	}
539	}	967	};
540		968
541	sub push_read_chunk {	969	=item line => [$eol, ]$cb->($handle, $line, $eol)
542	$_[0]->push_read (&_read_chunk);
543	}
544
545
546	sub unshift_read_chunk {
547	$_[0]->unshift_read (&_read_chunk);
548	}
549
550	=item $handle->push_read_line ([$eol, ]$cb->($self, $line, $eol))
551
552	=item $handle->unshift_read_line ([$eol, ]$cb->($self, $line, $eol))
553
554	Append the given callback to the end of the queue (C<push_read_line>) or
555	prepend it (C<unshift_read_line>).
556		970
557	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
558	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
559	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
560	the end of line marker as the third argument (C<$eol>).	974	the end of line marker as the third argument (C<$eol>).
…		…
571	Partial lines at the end of the stream will never be returned, as they are	985	Partial lines at the end of the stream will never be returned, as they are
572	not marked by the end of line marker.	986	not marked by the end of line marker.
573		987
574	=cut	988	=cut
575		989
576	sub _read_line($$) {	990	register_read_type line => sub {
577	my $self = shift;	991	my ($self, $cb, $eol) = @_;
578	my $cb = pop;
579	my $eol = @_ ? shift : qr|(\015?\012)|;
580	my $pos;
581		992
		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 {
582	$eol = quotemeta $eol unless ref $eol;	1002	$eol = quotemeta $eol unless ref $eol;
583	$eol = qr|^(.*?)($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};
584		1061
585	sub {	1062	sub {
586	$_[0]{rbuf} =~ s/$eol// or return;	1063	# accept
		1064	if ($$rbuf =~ $accept) {
		1065	$data .= substr $$rbuf, 0, $+[0], "";
		1066	$cb->($self, $data);
		1067	return 1;
		1068	}
		1069
		1070	# reject
		1071	if ($reject && $$rbuf =~ $reject) {
		1072	$self->_error (&Errno::EBADMSG);
		1073	}
587		1074
588	$cb->($_[0], $1, $2);	1075	# skip
		1076	if ($skip && $$rbuf =~ $skip) {
		1077	$data .= substr $$rbuf, 0, $+[0], "";
		1078	}
		1079
		1080	()
		1081	}
		1082	};
		1083
		1084	=item netstring => $cb->($handle, $string)
		1085
		1086	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1087
		1088	Throws an error with C<$!> set to EBADMSG on format violations.
		1089
		1090	=cut
		1091
		1092	register_read_type netstring => sub {
		1093	my ($self, $cb) = @_;
		1094
		1095	sub {
		1096	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1097	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1098	$self->_error (&Errno::EBADMSG);
		1099	}
		1100	return;
		1101	}
		1102
		1103	my $len = $1;
		1104
		1105	$self->unshift_read (chunk => $len, sub {
		1106	my $string = $_[1];
		1107	$_[0]->unshift_read (chunk => 1, sub {
		1108	if ($_[1] eq ",") {
		1109	$cb->($_[0], $string);
		1110	} else {
		1111	$self->_error (&Errno::EBADMSG);
		1112	}
		1113	});
		1114	});
		1115
589	1	1116	1
590	}	1117	}
591	}	1118	};
592		1119
593	sub push_read_line {	1120	=item packstring => $format, $cb->($handle, $string)
594	$_[0]->push_read (&_read_line);
595	}
596		1121
597	sub unshift_read_line {	1122	An octet string prefixed with an encoded length. The encoding C<$format>
598	$_[0]->unshift_read (&_read_line);	1123	uses the same format as a Perl C<pack> format, but must specify a single
599	}	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
		1267	=back
		1268
		1269	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
		1270
		1271	This function (not method) lets you add your own types to C<push_read>.
		1272
		1273	Whenever the given C<type> is used, C<push_read> will invoke the code
		1274	reference with the handle object, the callback and the remaining
		1275	arguments.
		1276
		1277	The code reference is supposed to return a callback (usually a closure)
		1278	that works as a plain read callback (see C<< ->push_read ($cb) >>).
		1279
		1280	It should invoke the passed callback when it is done reading (remember to
		1281	pass C<$handle> as first argument as all other callbacks do that).
		1282
		1283	Note that this is a function, and all types registered this way will be
		1284	global, so try to use unique names.
		1285
		1286	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
		1287	search for C<register_read_type>)).
600		1288
601	=item $handle->stop_read	1289	=item $handle->stop_read
602		1290
603	=item $handle->start_read	1291	=item $handle->start_read
604		1292
605	In rare cases you actually do not want to read anything from the	1293	In rare cases you actually do not want to read anything from the
606	socket. In this case you can call C<stop_read>. Neither C<on_read> no	1294	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
607	any queued callbacks will be executed then. To start readign again, call	1295	any queued callbacks will be executed then. To start reading again, call
608	C<start_read>.	1296	C<start_read>.
		1297
		1298	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1299	you change the C<on_read> callback or push/unshift a read callback, and it
		1300	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1301	there are any read requests in the queue.
		1302
		1303	These methods will have no effect when in TLS mode (as TLS doesn't support
		1304	half-duplex connections).
609		1305
610	=cut	1306	=cut
611		1307
612	sub stop_read {	1308	sub stop_read {
613	my ($self) = @_;	1309	my ($self) = @_;
614		1310
615	delete $self->{rw};	1311	delete $self->{_rw} unless $self->{tls};
616	}	1312	}
617		1313
618	sub start_read {	1314	sub start_read {
619	my ($self) = @_;	1315	my ($self) = @_;
620		1316
621	unless ($self->{rw} || $self->{eof}) {	1317	unless ($self->{_rw} || $self->{_eof}) {
622	Scalar::Util::weaken $self;	1318	Scalar::Util::weaken $self;
623		1319
624	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {	1320	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
625	my $rbuf = $self->{filter_r} ? \my $buf : \$self->{rbuf};	1321	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
626	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;
627		1323
628	if ($len > 0) {	1324	if ($len > 0) {
629	$self->{filter_r}	1325	$self->{_activity} = AnyEvent->now;
630	? $self->{filter_r}->($self, $rbuf)	1326
631	: $self->_drain_rbuf;	1327	if ($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	}
632		1334
633	} elsif (defined $len) {	1335	} elsif (defined $len) {
634	delete $self->{rw};	1336	delete $self->{_rw};
635	$self->{eof} = 1;	1337	$self->{_eof} = 1;
636	$self->_drain_rbuf;	1338	$self->_drain_rbuf unless $self->{_in_drain};
637		1339
638	} elsif ($! != EAGAIN && $! != EINTR) {	1340	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
639	return $self->error;	1341	return $self->_error ($!, 1);
640	}	1342	}
641	});	1343	});
642	}	1344	}
643	}	1345	}
644		1346
		1347	# poll the write BIO and send the data if applicable
645	sub _dotls {	1348	sub _dotls {
646	my ($self) = @_;	1349	my ($self) = @_;
647		1350
		1351	my $tmp;
		1352
648	if (length $self->{tls_wbuf}) {	1353	if (length $self->{_tls_wbuf}) {
649	my $len = Net::SSLeay::write ($self->{tls}, $self->{tls_wbuf});	1354	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
650	substr $self->{tls_wbuf}, 0, $len, "" if $len > 0;	1355	substr $self->{_tls_wbuf}, 0, $tmp, "";
		1356	}
651	}	1357	}
652		1358
653	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}))) {
654	$self->{wbuf} .= $buf;	1385	$self->{wbuf} .= $tmp;
655	$self->_drain_wbuf;	1386	$self->_drain_wbuf;
656	}	1387	}
657
658	if (defined (my $buf = Net::SSLeay::read ($self->{tls}))) {
659	$self->{rbuf} .= $buf;
660	$self->_drain_rbuf;
661	} elsif (
662	(my $err = Net::SSLeay::get_error ($self->{tls}, -1))
663	!= Net::SSLeay::ERROR_WANT_READ ()
664	) {
665	if ($err == Net::SSLeay::ERROR_SYSCALL ()) {
666	$self->error;
667	} elsif ($err == Net::SSLeay::ERROR_SSL ()) {
668	$! = &Errno::EIO;
669	$self->error;
670	}
671
672	# all others are fine for our purposes
673	}
674	}	1388	}
675		1389
676	# TODO: maybe document...	1390	=item $handle->starttls ($tls[, $tls_ctx])
		1391
		1392	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1393	object is created, you can also do that at a later time by calling
		1394	C<starttls>.
		1395
		1396	The first argument is the same as the C<tls> constructor argument (either
		1397	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1398
		1399	The second argument is the optional C<AnyEvent::TLS> object that is used
		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.
		1403
		1404	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1405	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1406	changed to your liking. Note that the handshake might have already started
		1407	when this function returns.
		1408
		1409	If it an error to start a TLS handshake more than once per
		1410	AnyEvent::Handle object (this is due to bugs in OpenSSL).
		1411
		1412	=cut
		1413
677	sub starttls {	1414	sub starttls {
678	my ($self, $ssl, $ctx) = @_;	1415	my ($self, $ssl, $ctx) = @_;
679		1416
680	if ($ssl eq "accept") {	1417	require Net::SSLeay;
681	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());	1418
682	Net::SSLeay::set_accept_state ($ssl);	1419	Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
683	} elsif ($ssl eq "connect") {	1420	if $self->{tls};
684	$ssl = Net::SSLeay::new ($ctx || TLS_CTX ());	1421
685	Net::SSLeay::set_connect_state ($ssl);	1422	$ctx ||= $self->{tls_ctx};
		1423
		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	}
686	}	1430
		1431	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1432	$self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self);
687		1433
688	$self->{tls} = $ssl;	1434	# basically, this is deep magic (because SSL_read should have the same issues)
		1435	# but the openssl maintainers basically said: "trust us, it just works".
		1436	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1437	# and mismaintained ssleay-module doesn't even offer them).
		1438	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1439	#
		1440	# in short: this is a mess.
		1441	#
		1442	# note that we do not try to keep the length constant between writes as we are required to do.
		1443	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1444	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1445	# have identity issues in that area.
		1446	# Net::SSLeay::CTX_set_mode ($ssl,
		1447	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		1448	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1449	Net::SSLeay::CTX_set_mode ($ssl, 1|2);
689		1450
690	$self->{tls_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());	1451	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
691	$self->{tls_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());	1452	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
692		1453
693	Net::SSLeay::set_bio ($ssl, $self->{tls_rbio}, $self->{tls_wbio});	1454	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
694		1455
695	$self->{filter_w} = sub {	1456	&_dotls; # need to trigger the initial handshake
696	$_[0]{tls_wbuf} .= ${$_[1]};	1457	$self->start_read; # make sure we actually do read
		1458	}
		1459
		1460	=item $handle->stoptls
		1461
		1462	Shuts down the SSL connection - this makes a proper EOF handshake by
		1463	sending a close notify to the other side, but since OpenSSL doesn't
		1464	support non-blocking shut downs, it is not possible to re-use the stream
		1465	afterwards.
		1466
		1467	=cut
		1468
		1469	sub stoptls {
		1470	my ($self) = @_;
		1471
		1472	if ($self->{tls}) {
		1473	Net::SSLeay::shutdown ($self->{tls});
		1474
697	&_dotls;	1475	&_dotls;
		1476
		1477	# we don't give a shit. no, we do, but we can't. no...
		1478	# we, we... have to use openssl :/
		1479	&_freetls;
698	};	1480	}
699	$self->{filter_r} = sub {	1481	}
700	Net::SSLeay::BIO_write ($_[0]{tls_rbio}, ${$_[1]});	1482
701	&_dotls;	1483	sub _freetls {
		1484	my ($self) = @_;
		1485
		1486	return unless $self->{tls};
		1487
		1488	$self->{tls_ctx}->_put_session (delete $self->{tls});
702	};	1489
		1490	delete @$self{qw(_rbio _wbio _tls_wbuf)};
703	}	1491	}
704		1492
705	sub DESTROY {	1493	sub DESTROY {
706	my $self = shift;	1494	my ($self) = @_;
707		1495
708	Net::SSLeay::free (delete $self->{tls}) if $self->{tls};	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 = ();
709	}	1544	}
710		1545
711	=item AnyEvent::Handle::TLS_CTX	1546	=item AnyEvent::Handle::TLS_CTX
712		1547
713	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
714	default for TLS mode.	1549	for TLS mode.
715		1550
716	The context is created like this:	1551	The context is created by calling L<AnyEvent::TLS> without any arguments.
717
718	Net::SSLeay::load_error_strings;
719	Net::SSLeay::SSLeay_add_ssl_algorithms;
720	Net::SSLeay::randomize;
721
722	my $CTX = Net::SSLeay::CTX_new;
723
724	Net::SSLeay::CTX_set_options $CTX, Net::SSLeay::OP_ALL
725		1552
726	=cut	1553	=cut
727		1554
728	our $TLS_CTX;	1555	our $TLS_CTX;
729		1556
730	sub TLS_CTX() {	1557	sub TLS_CTX() {
731	$TLS_CTX || do {	1558	$TLS_CTX ||= do {
732	require Net::SSLeay;	1559	require AnyEvent::TLS;
733		1560
734	Net::SSLeay::load_error_strings ();	1561	new AnyEvent::TLS
735	Net::SSLeay::SSLeay_add_ssl_algorithms ();
736	Net::SSLeay::randomize ();
737
738	$TLS_CTX = Net::SSLeay::CTX_new ();
739
740	Net::SSLeay::CTX_set_options ($TLS_CTX, Net::SSLeay::OP_ALL ());
741
742	$TLS_CTX
743	}	1562	}
744	}	1563	}
745		1564
746	=back	1565	=back
747		1566
		1567
		1568	=head1 NONFREQUENTLY ASKED QUESTIONS
		1569
		1570	=over 4
		1571
		1572	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		1573	still get further invocations!
		1574
		1575	That's because AnyEvent::Handle keeps a reference to itself when handling
		1576	read or write callbacks.
		1577
		1578	It is only safe to "forget" the reference inside EOF or error callbacks,
		1579	from within all other callbacks, you need to explicitly call the C<<
		1580	->destroy >> method.
		1581
		1582	=item I get different callback invocations in TLS mode/Why can't I pause
		1583	reading?
		1584
		1585	Unlike, say, TCP, TLS connections do not consist of two independent
		1586	communication channels, one for each direction. Or put differently. The
		1587	read and write directions are not independent of each other: you cannot
		1588	write data unless you are also prepared to read, and vice versa.
		1589
		1590	This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
		1591	callback invocations when you are not expecting any read data - the reason
		1592	is that AnyEvent::Handle always reads in TLS mode.
		1593
		1594	During the connection, you have to make sure that you always have a
		1595	non-empty read-queue, or an C<on_read> watcher. At the end of the
		1596	connection (or when you no longer want to use it) you can call the
		1597	C<destroy> method.
		1598
		1599	=item How do I read data until the other side closes the connection?
		1600
		1601	If you just want to read your data into a perl scalar, the easiest way
		1602	to achieve this is by setting an C<on_read> callback that does nothing,
		1603	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		1604	will be in C<$_[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
748	=head1 AUTHOR	1668	=head1 AUTHOR
749		1669
750	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>.
751		1671
752	=cut	1672	=cut

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