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Revision 1.10 by root, Sat May 3 12:17:35 2008 UTC vs.
Revision 1.144 by root, Mon Jul 6 21:38:25 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	=cut	17	=cut
18		18
19	our $VERSION = '0.02';	19	our $VERSION = 4.452;
20		20
21	=head1 SYNOPSIS	21	=head1 SYNOPSIS
22		22
23	use AnyEvent;	23	use AnyEvent;
24	use AnyEvent::Handle;	24	use AnyEvent::Handle;
25		25
26	my $cv = AnyEvent->condvar;	26	my $cv = AnyEvent->condvar;
27		27
28	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	28	my $handle =
29
30	#TODO
31
32	# or use the constructor to pass the callback:
33
34	my $ae_fh2 =
35	AnyEvent::Handle->new (	29	AnyEvent::Handle->new (
36	fh => \*STDIN,	30	fh => \*STDIN,
37	on_eof => sub {	31	on_eof => sub {
38	$cv->broadcast;	32	$cv->send;
39	},	33	},
40	#TODO
41	);	34	);
42		35
43	$cv->wait;	36	# send some request line
		37	$handle->push_write ("getinfo\015\012");
		38
		39	# read the response line
		40	$handle->push_read (line => sub {
		41	my ($handle, $line) = @_;
		42	warn "read line <$line>\n";
		43	$cv->send;
		44	});
		45
		46	$cv->recv;
44		47
45	=head1 DESCRIPTION	48	=head1 DESCRIPTION
46		49
47	This module is a helper module to make it easier to do event-based I/O on	50	This module is a helper module to make it easier to do event-based I/O on
48	filehandles (and sockets, see L<AnyEvent::Socket> for an easy way to make	51	filehandles. For utility functions for doing non-blocking connects and accepts
49	non-blocking resolves and connects).	52	on sockets see L<AnyEvent::Util>.
		53
		54	The L<AnyEvent::Intro> tutorial contains some well-documented
		55	AnyEvent::Handle examples.
50		56
51	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
52	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
53	treatment of characters applies to this module as well.	59	treatment of characters applies to this module as well.
54		60
…		…
57		63
58	=head1 METHODS	64	=head1 METHODS
59		65
60	=over 4	66	=over 4
61		67
62	=item B<new (%args)>	68	=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
63		69
64	The constructor supports these arguments (all as key => value pairs).	70	The constructor supports these arguments (all as C<< key => value >> pairs).
65		71
66	=over 4	72	=over 4
67		73
68	=item fh => $filehandle [MANDATORY]	74	=item fh => $filehandle [MANDATORY]
69		75
70	The filehandle this L<AnyEvent::Handle> object will operate on.	76	The filehandle this L<AnyEvent::Handle> object will operate on.
71		77
72	NOTE: The filehandle will be set to non-blocking (using	78	NOTE: The filehandle will be set to non-blocking mode (using
73	AnyEvent::Util::fh_nonblocking).	79	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		80	that mode.
74		81
75	=item on_eof => $cb->($self) [MANDATORY]
76
77	Set the callback to be called on EOF.
78
79	=item on_error => $cb->($self)	82	=item on_eof => $cb->($handle)
80		83
		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.
		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
		93	While not mandatory, it is I<highly> recommended to set an EOF callback,
		94	otherwise you might end up with a closed socket while you are still
		95	waiting for data.
		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
		100	=item on_error => $cb->($handle, $fatal, $message)
		101
81	This is the fatal error callback, that is called when, well, a fatal error	102	This is the error callback, which is called when, well, some error
82	ocurs, such as not being able to resolve the hostname, failure to connect	103	occured, such as not being able to resolve the hostname, failure to
83	or a read error.	104	connect or a read error.
84		105
85	The object will not be in a usable state when this callback has been	106	Some errors are fatal (which is indicated by C<$fatal> being true). On
86	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	AnyEvent::Handle tries to find an appropriate error code for you to check
		113	against, but in some cases (TLS errors), this does not work well. It is
		114	recommended to always output the C<$message> argument in human-readable
		115	error messages (it's usually the same as C<"$!">).
		116
		117	Non-fatal errors can be retried by simply returning, but it is recommended
		118	to simply ignore this parameter and instead abondon the handle object
		119	when this callback is invoked. Examples of non-fatal errors are timeouts
		120	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
87		121
88	On callback entrance, the value of C<$!> contains the operating system	122	On callback entrance, the value of C<$!> contains the operating system
89	error (or C<ENOSPC> or C<EPIPE>).	123	error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		124	C<EPROTO>).
90		125
91	While not mandatory, it is I<highly> recommended to set this callback, as	126	While not mandatory, it is I<highly> recommended to set this callback, as
92	you will not be notified of errors otherwise. The default simply calls	127	you will not be notified of errors otherwise. The default simply calls
93	die.	128	C<croak>.
94		129
95	=item on_read => $cb->($self)	130	=item on_read => $cb->($handle)
96		131
97	This sets the default read callback, which is called when data arrives	132	This sets the default read callback, which is called when data arrives
98	and no read request is in the queue.	133	and no read request is in the queue (unlike read queue callbacks, this
		134	callback will only be called when at least one octet of data is in the
		135	read buffer).
99		136
100	To access (and remove data from) the read buffer, use the C<< ->rbuf >>	137	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
101	method or acces sthe C<$self->{rbuf}> member directly.	138	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		139	must not enlarge or modify the read buffer, you can only remove data at
		140	the beginning from it.
102		141
103	When an EOF condition is detected then AnyEvent::Handle will first try to	142	When an EOF condition is detected then AnyEvent::Handle will first try to
104	feed all the remaining data to the queued callbacks and C<on_read> before	143	feed all the remaining data to the queued callbacks and C<on_read> before
105	calling the C<on_eof> callback. If no progress can be made, then a fatal	144	calling the C<on_eof> callback. If no progress can be made, then a fatal
106	error will be raised (with C<$!> set to C<EPIPE>).	145	error will be raised (with C<$!> set to C<EPIPE>).
107		146
108	=item on_drain => $cb->()	147	=item on_drain => $cb->($handle)
109		148
110	This sets the callback that is called when the write buffer becomes empty	149	This sets the callback that is called when the write buffer becomes empty
111	(or when the callback is set and the buffer is empty already).	150	(or when the callback is set and the buffer is empty already).
112		151
113	To append to the write buffer, use the C<< ->push_write >> method.	152	To append to the write buffer, use the C<< ->push_write >> method.
114		153
		154	This callback is useful when you don't want to put all of your write data
		155	into the queue at once, for example, when you want to write the contents
		156	of some file to the socket you might not want to read the whole file into
		157	memory and push it into the queue, but instead only read more data from
		158	the file when the write queue becomes empty.
		159
		160	=item timeout => $fractional_seconds
		161
		162	If non-zero, then this enables an "inactivity" timeout: whenever this many
		163	seconds pass without a successful read or write on the underlying file
		164	handle, the C<on_timeout> callback will be invoked (and if that one is
		165	missing, a non-fatal C<ETIMEDOUT> error will be raised).
		166
		167	Note that timeout processing is also active when you currently do not have
		168	any outstanding read or write requests: If you plan to keep the connection
		169	idle then you should disable the timout temporarily or ignore the timeout
		170	in the C<on_timeout> callback, in which case AnyEvent::Handle will simply
		171	restart the timeout.
		172
		173	Zero (the default) disables this timeout.
		174
		175	=item on_timeout => $cb->($handle)
		176
		177	Called whenever the inactivity timeout passes. If you return from this
		178	callback, then the timeout will be reset as if some activity had happened,
		179	so this condition is not fatal in any way.
		180
115	=item rbuf_max => <bytes>	181	=item rbuf_max => <bytes>
116		182
117	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)	183	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
118	when the read buffer ever (strictly) exceeds this size. This is useful to	184	when the read buffer ever (strictly) exceeds this size. This is useful to
119	avoid denial-of-service attacks.	185	avoid some forms of denial-of-service attacks.
120		186
121	For example, a server accepting connections from untrusted sources should	187	For example, a server accepting connections from untrusted sources should
122	be configured to accept only so-and-so much data that it cannot act on	188	be configured to accept only so-and-so much data that it cannot act on
123	(for example, when expecting a line, an attacker could send an unlimited	189	(for example, when expecting a line, an attacker could send an unlimited
124	amount of data without a callback ever being called as long as the line	190	amount of data without a callback ever being called as long as the line
125	isn't finished).	191	isn't finished).
126		192
		193	=item autocork => <boolean>
		194
		195	When disabled (the default), then C<push_write> will try to immediately
		196	write the data to the handle, if possible. This avoids having to register
		197	a write watcher and wait for the next event loop iteration, but can
		198	be inefficient if you write multiple small chunks (on the wire, this
		199	disadvantage is usually avoided by your kernel's nagle algorithm, see
		200	C<no_delay>, but this option can save costly syscalls).
		201
		202	When enabled, then writes will always be queued till the next event loop
		203	iteration. This is efficient when you do many small writes per iteration,
		204	but less efficient when you do a single write only per iteration (or when
		205	the write buffer often is full). It also increases write latency.
		206
		207	=item no_delay => <boolean>
		208
		209	When doing small writes on sockets, your operating system kernel might
		210	wait a bit for more data before actually sending it out. This is called
		211	the Nagle algorithm, and usually it is beneficial.
		212
		213	In some situations you want as low a delay as possible, which can be
		214	accomplishd by setting this option to a true value.
		215
		216	The default is your opertaing system's default behaviour (most likely
		217	enabled), this option explicitly enables or disables it, if possible.
		218
127	=item read_size => <bytes>	219	=item read_size => <bytes>
128		220
129	The default read block size (the amount of bytes this module will try to read	221	The default read block size (the amount of bytes this module will
130	on each [loop iteration). Default: C<4096>.	222	try to read during each loop iteration, which affects memory
		223	requirements). Default: C<8192>.
131		224
132	=item low_water_mark => <bytes>	225	=item low_water_mark => <bytes>
133		226
134	Sets the amount of bytes (default: C<0>) that make up an "empty" write	227	Sets the amount of bytes (default: C<0>) that make up an "empty" write
135	buffer: If the write reaches this size or gets even samller it is	228	buffer: If the write reaches this size or gets even samller it is
136	considered empty.	229	considered empty.
137		230
		231	Sometimes it can be beneficial (for performance reasons) to add data to
		232	the write buffer before it is fully drained, but this is a rare case, as
		233	the operating system kernel usually buffers data as well, so the default
		234	is good in almost all cases.
		235
		236	=item linger => <seconds>
		237
		238	If non-zero (default: C<3600>), then the destructor of the
		239	AnyEvent::Handle object will check whether there is still outstanding
		240	write data and will install a watcher that will write this data to the
		241	socket. No errors will be reported (this mostly matches how the operating
		242	system treats outstanding data at socket close time).
		243
		244	This will not work for partial TLS data that could not be encoded
		245	yet. This data will be lost. Calling the C<stoptls> method in time might
		246	help.
		247
		248	=item peername => $string
		249
		250	A string used to identify the remote site - usually the DNS hostname
		251	(I<not> IDN!) used to create the connection, rarely the IP address.
		252
		253	Apart from being useful in error messages, this string is also used in TLS
		254	peername verification (see C<verify_peername> in L<AnyEvent::TLS>). This
		255	verification will be skipped when C<peername> is not specified or
		256	C<undef>.
		257
		258	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		259
		260	When this parameter is given, it enables TLS (SSL) mode, that means
		261	AnyEvent will start a TLS handshake as soon as the conenction has been
		262	established and will transparently encrypt/decrypt data afterwards.
		263
		264	All TLS protocol errors will be signalled as C<EPROTO>, with an
		265	appropriate error message.
		266
		267	TLS mode requires Net::SSLeay to be installed (it will be loaded
		268	automatically when you try to create a TLS handle): this module doesn't
		269	have a dependency on that module, so if your module requires it, you have
		270	to add the dependency yourself.
		271
		272	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		273	C<accept>, and for the TLS client side of a connection, use C<connect>
		274	mode.
		275
		276	You can also provide your own TLS connection object, but you have
		277	to make sure that you call either C<Net::SSLeay::set_connect_state>
		278	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		279	AnyEvent::Handle. Also, this module will take ownership of this connection
		280	object.
		281
		282	At some future point, AnyEvent::Handle might switch to another TLS
		283	implementation, then the option to use your own session object will go
		284	away.
		285
		286	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		287	passing in the wrong integer will lead to certain crash. This most often
		288	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		289	segmentation fault.
		290
		291	See the C<< ->starttls >> method for when need to start TLS negotiation later.
		292
		293	=item tls_ctx => $anyevent_tls
		294
		295	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		296	(unless a connection object was specified directly). If this parameter is
		297	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
		298
		299	Instead of an object, you can also specify a hash reference with C<< key
		300	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		301	new TLS context object.
		302
		303	=item on_starttls => $cb->($handle, $success[, $error_message])
		304
		305	This callback will be invoked when the TLS/SSL handshake has finished. If
		306	C<$success> is true, then the TLS handshake succeeded, otherwise it failed
		307	(C<on_stoptls> will not be called in this case).
		308
		309	The session in C<< $handle->{tls} >> can still be examined in this
		310	callback, even when the handshake was not successful.
		311
		312	TLS handshake failures will not cause C<on_error> to be invoked when this
		313	callback is in effect, instead, the error message will be passed to C<on_starttls>.
		314
		315	Without this callback, handshake failures lead to C<on_error> being
		316	called, as normal.
		317
		318	Note that you cannot call C<starttls> right again in this callback. If you
		319	need to do that, start an zero-second timer instead whose callback can
		320	then call C<< ->starttls >> again.
		321
		322	=item on_stoptls => $cb->($handle)
		323
		324	When a SSLv3/TLS shutdown/close notify/EOF is detected and this callback is
		325	set, then it will be invoked after freeing the TLS session. If it is not,
		326	then a TLS shutdown condition will be treated like a normal EOF condition
		327	on the handle.
		328
		329	The session in C<< $handle->{tls} >> can still be examined in this
		330	callback.
		331
		332	This callback will only be called on TLS shutdowns, not when the
		333	underlying handle signals EOF.
		334
		335	=item json => JSON or JSON::XS object
		336
		337	This is the json coder object used by the C<json> read and write types.
		338
		339	If you don't supply it, then AnyEvent::Handle will create and use a
		340	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		341	texts.
		342
		343	Note that you are responsible to depend on the JSON module if you want to
		344	use this functionality, as AnyEvent does not have a dependency itself.
		345
138	=back	346	=back
139		347
140	=cut	348	=cut
141		349
142	sub new {	350	sub new {
143	my $class = shift;	351	my $class = shift;
144
145	my $self = bless { @_ }, $class;	352	my $self = bless { @_ }, $class;
146		353
147	$self->{fh} or Carp::croak "mandatory argument fh is missing";	354	$self->{fh} or Carp::croak "mandatory argument fh is missing";
148		355
149	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	356	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
150		357
151	$self->on_eof ((delete $self->{on_eof} ) or Carp::croak "mandatory argument on_eof is missing");	358	$self->{_activity} = AnyEvent->now;
		359	$self->_timeout;
152		360
153	$self->on_error (delete $self->{on_error}) if $self->{on_error};	361	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		362
		363	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		364	if $self->{tls};
		365
154	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	366	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};
155	$self->on_read (delete $self->{on_read} ) if $self->{on_read};
156		367
157	$self->start_read;	368	$self->start_read
		369	if $self->{on_read};
158		370
159	$self	371	$self->{fh} && $self
160	}	372	}
161		373
162	sub _shutdown {	374	sub _shutdown {
163	my ($self) = @_;	375	my ($self) = @_;
164		376
165	delete $self->{rw};	377	delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
166	delete $self->{ww};	378	$self->{_eof} = 1; # tell starttls et. al to stop trying
167	delete $self->{fh};
168	}
169		379
		380	&_freetls;
		381	}
		382
170	sub error {	383	sub _error {
171	my ($self) = @_;	384	my ($self, $errno, $fatal, $message) = @_;
172		385
173	{
174	local $!;
175	$self->_shutdown;	386	$self->_shutdown
176	}	387	if $fatal;
		388
		389	$! = $errno;
		390	$message ||= "$!";
177		391
178	if ($self->{on_error}) {	392	if ($self->{on_error}) {
179	$self->{on_error}($self);	393	$self->{on_error}($self, $fatal, $message);
180	} else {	394	} elsif ($self->{fh}) {
181	die "AnyEvent::Handle uncaught fatal error: $!";	395	Carp::croak "AnyEvent::Handle uncaught error: $message";
182	}	396	}
183	}	397	}
184		398
185	=item $fh = $handle->fh	399	=item $fh = $handle->fh
186		400
187	This method returns the filehandle of the L<AnyEvent::Handle> object.	401	This method returns the file handle used to create the L<AnyEvent::Handle> object.
188		402
189	=cut	403	=cut
190		404
191	sub fh { $_[0]->{fh} }	405	sub fh { $_[0]{fh} }
192		406
193	=item $handle->on_error ($cb)	407	=item $handle->on_error ($cb)
194		408
195	Replace the current C<on_error> callback (see the C<on_error> constructor argument).	409	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
196		410
…		…
208		422
209	sub on_eof {	423	sub on_eof {
210	$_[0]{on_eof} = $_[1];	424	$_[0]{on_eof} = $_[1];
211	}	425	}
212		426
		427	=item $handle->on_timeout ($cb)
		428
		429	Replace the current C<on_timeout> callback, or disables the callback (but
		430	not the timeout) if C<$cb> = C<undef>. See the C<timeout> constructor
		431	argument and method.
		432
		433	=cut
		434
		435	sub on_timeout {
		436	$_[0]{on_timeout} = $_[1];
		437	}
		438
		439	=item $handle->autocork ($boolean)
		440
		441	Enables or disables the current autocork behaviour (see C<autocork>
		442	constructor argument). Changes will only take effect on the next write.
		443
		444	=cut
		445
		446	sub autocork {
		447	$_[0]{autocork} = $_[1];
		448	}
		449
		450	=item $handle->no_delay ($boolean)
		451
		452	Enables or disables the C<no_delay> setting (see constructor argument of
		453	the same name for details).
		454
		455	=cut
		456
		457	sub no_delay {
		458	$_[0]{no_delay} = $_[1];
		459
		460	eval {
		461	local $SIG{__DIE__};
		462	setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
		463	};
		464	}
		465
		466	=item $handle->on_starttls ($cb)
		467
		468	Replace the current C<on_starttls> callback (see the C<on_starttls> constructor argument).
		469
		470	=cut
		471
		472	sub on_starttls {
		473	$_[0]{on_starttls} = $_[1];
		474	}
		475
		476	=item $handle->on_stoptls ($cb)
		477
		478	Replace the current C<on_stoptls> callback (see the C<on_stoptls> constructor argument).
		479
		480	=cut
		481
		482	sub on_starttls {
		483	$_[0]{on_stoptls} = $_[1];
		484	}
		485
		486	#############################################################################
		487
		488	=item $handle->timeout ($seconds)
		489
		490	Configures (or disables) the inactivity timeout.
		491
		492	=cut
		493
		494	sub timeout {
		495	my ($self, $timeout) = @_;
		496
		497	$self->{timeout} = $timeout;
		498	$self->_timeout;
		499	}
		500
		501	# reset the timeout watcher, as neccessary
		502	# also check for time-outs
		503	sub _timeout {
		504	my ($self) = @_;
		505
		506	if ($self->{timeout}) {
		507	my $NOW = AnyEvent->now;
		508
		509	# when would the timeout trigger?
		510	my $after = $self->{_activity} + $self->{timeout} - $NOW;
		511
		512	# now or in the past already?
		513	if ($after <= 0) {
		514	$self->{_activity} = $NOW;
		515
		516	if ($self->{on_timeout}) {
		517	$self->{on_timeout}($self);
		518	} else {
		519	$self->_error (&Errno::ETIMEDOUT);
		520	}
		521
		522	# callback could have changed timeout value, optimise
		523	return unless $self->{timeout};
		524
		525	# calculate new after
		526	$after = $self->{timeout};
		527	}
		528
		529	Scalar::Util::weaken $self;
		530	return unless $self; # ->error could have destroyed $self
		531
		532	$self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
		533	delete $self->{_tw};
		534	$self->_timeout;
		535	});
		536	} else {
		537	delete $self->{_tw};
		538	}
		539	}
		540
213	#############################################################################	541	#############################################################################
214		542
215	=back	543	=back
216		544
217	=head2 WRITE QUEUE	545	=head2 WRITE QUEUE
…		…
220	for reading.	548	for reading.
221		549
222	The write queue is very simple: you can add data to its end, and	550	The write queue is very simple: you can add data to its end, and
223	AnyEvent::Handle will automatically try to get rid of it for you.	551	AnyEvent::Handle will automatically try to get rid of it for you.
224		552
225	When data could be writtena nd the write buffer is shorter then the low	553	When data could be written and the write buffer is shorter then the low
226	water mark, the C<on_drain> callback will be invoked.	554	water mark, the C<on_drain> callback will be invoked.
227		555
228	=over 4	556	=over 4
229		557
230	=item $handle->on_drain ($cb)	558	=item $handle->on_drain ($cb)
…		…
238	my ($self, $cb) = @_;	566	my ($self, $cb) = @_;
239		567
240	$self->{on_drain} = $cb;	568	$self->{on_drain} = $cb;
241		569
242	$cb->($self)	570	$cb->($self)
243	if $cb && $self->{low_water_mark} >= length $self->{wbuf};	571	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
244	}	572	}
245		573
246	=item $handle->push_write ($data)	574	=item $handle->push_write ($data)
247		575
248	Queues the given scalar to be written. You can push as much data as you	576	Queues the given scalar to be written. You can push as much data as you
249	want (only limited by the available memory), as C<AnyEvent::Handle>	577	want (only limited by the available memory), as C<AnyEvent::Handle>
250	buffers it independently of the kernel.	578	buffers it independently of the kernel.
251		579
252	=cut	580	=cut
253		581
254	sub push_write {	582	sub _drain_wbuf {
255	my ($self, $data) = @_;	583	my ($self) = @_;
256		584
257	$self->{wbuf} .= $data;	585	if (!$self->{_ww} && length $self->{wbuf}) {
258		586
259	unless ($self->{ww}) {
260	Scalar::Util::weaken $self;	587	Scalar::Util::weaken $self;
		588
261	my $cb = sub {	589	my $cb = sub {
262	my $len = syswrite $self->{fh}, $self->{wbuf};	590	my $len = syswrite $self->{fh}, $self->{wbuf};
263		591
264	if ($len > 0) {	592	if ($len >= 0) {
265	substr $self->{wbuf}, 0, $len, "";	593	substr $self->{wbuf}, 0, $len, "";
266		594
		595	$self->{_activity} = AnyEvent->now;
267		596
268	$self->{on_drain}($self)	597	$self->{on_drain}($self)
269	if $self->{low_water_mark} >= length $self->{wbuf}	598	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
270	&& $self->{on_drain};	599	&& $self->{on_drain};
271		600
272	delete $self->{ww} unless length $self->{wbuf};	601	delete $self->{_ww} unless length $self->{wbuf};
273	} elsif ($! != EAGAIN && $! != EINTR) {	602	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
274	$self->error;	603	$self->_error ($!, 1);
275	}	604	}
276	};	605	};
277		606
		607	# try to write data immediately
		608	$cb->() unless $self->{autocork};
		609
		610	# if still data left in wbuf, we need to poll
278	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	611	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
279		612	if length $self->{wbuf};
280	$cb->($self);
281	};	613	};
282	}	614	}
		615
		616	our %WH;
		617
		618	sub register_write_type($$) {
		619	$WH{$_[0]} = $_[1];
		620	}
		621
		622	sub push_write {
		623	my $self = shift;
		624
		625	if (@_ > 1) {
		626	my $type = shift;
		627
		628	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
		629	->($self, @_);
		630	}
		631
		632	if ($self->{tls}) {
		633	$self->{_tls_wbuf} .= $_[0];
		634
		635	&_dotls ($self);
		636	} else {
		637	$self->{wbuf} .= $_[0];
		638	$self->_drain_wbuf;
		639	}
		640	}
		641
		642	=item $handle->push_write (type => @args)
		643
		644	Instead of formatting your data yourself, you can also let this module do
		645	the job by specifying a type and type-specific arguments.
		646
		647	Predefined types are (if you have ideas for additional types, feel free to
		648	drop by and tell us):
		649
		650	=over 4
		651
		652	=item netstring => $string
		653
		654	Formats the given value as netstring
		655	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		656
		657	=cut
		658
		659	register_write_type netstring => sub {
		660	my ($self, $string) = @_;
		661
		662	(length $string) . ":$string,"
		663	};
		664
		665	=item packstring => $format, $data
		666
		667	An octet string prefixed with an encoded length. The encoding C<$format>
		668	uses the same format as a Perl C<pack> format, but must specify a single
		669	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		670	optional C<!>, C<< < >> or C<< > >> modifier).
		671
		672	=cut
		673
		674	register_write_type packstring => sub {
		675	my ($self, $format, $string) = @_;
		676
		677	pack "$format/a*", $string
		678	};
		679
		680	=item json => $array_or_hashref
		681
		682	Encodes the given hash or array reference into a JSON object. Unless you
		683	provide your own JSON object, this means it will be encoded to JSON text
		684	in UTF-8.
		685
		686	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		687	one end of a handle and read them at the other end without using any
		688	additional framing.
		689
		690	The generated JSON text is guaranteed not to contain any newlines: While
		691	this module doesn't need delimiters after or between JSON texts to be
		692	able to read them, many other languages depend on that.
		693
		694	A simple RPC protocol that interoperates easily with others is to send
		695	JSON arrays (or objects, although arrays are usually the better choice as
		696	they mimic how function argument passing works) and a newline after each
		697	JSON text:
		698
		699	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		700	$handle->push_write ("\012");
		701
		702	An AnyEvent::Handle receiver would simply use the C<json> read type and
		703	rely on the fact that the newline will be skipped as leading whitespace:
		704
		705	$handle->push_read (json => sub { my $array = $_[1]; ... });
		706
		707	Other languages could read single lines terminated by a newline and pass
		708	this line into their JSON decoder of choice.
		709
		710	=cut
		711
		712	register_write_type json => sub {
		713	my ($self, $ref) = @_;
		714
		715	require JSON;
		716
		717	$self->{json} ? $self->{json}->encode ($ref)
		718	: JSON::encode_json ($ref)
		719	};
		720
		721	=item storable => $reference
		722
		723	Freezes the given reference using L<Storable> and writes it to the
		724	handle. Uses the C<nfreeze> format.
		725
		726	=cut
		727
		728	register_write_type storable => sub {
		729	my ($self, $ref) = @_;
		730
		731	require Storable;
		732
		733	pack "w/a*", Storable::nfreeze ($ref)
		734	};
		735
		736	=back
		737
		738	=item $handle->push_shutdown
		739
		740	Sometimes you know you want to close the socket after writing your data
		741	before it was actually written. One way to do that is to replace your
		742	C<on_drain> handler by a callback that shuts down the socket (and set
		743	C<low_water_mark> to C<0>). This method is a shorthand for just that, and
		744	replaces the C<on_drain> callback with:
		745
		746	sub { shutdown $_[0]{fh}, 1 } # for push_shutdown
		747
		748	This simply shuts down the write side and signals an EOF condition to the
		749	the peer.
		750
		751	You can rely on the normal read queue and C<on_eof> handling
		752	afterwards. This is the cleanest way to close a connection.
		753
		754	=cut
		755
		756	sub push_shutdown {
		757	my ($self) = @_;
		758
		759	delete $self->{low_water_mark};
		760	$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
		761	}
		762
		763	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
		764
		765	This function (not method) lets you add your own types to C<push_write>.
		766	Whenever the given C<type> is used, C<push_write> will invoke the code
		767	reference with the handle object and the remaining arguments.
		768
		769	The code reference is supposed to return a single octet string that will
		770	be appended to the write buffer.
		771
		772	Note that this is a function, and all types registered this way will be
		773	global, so try to use unique names.
		774
		775	=cut
283		776
284	#############################################################################	777	#############################################################################
285		778
286	=back	779	=back
287		780
…		…
294	ways, the "simple" way, using only C<on_read> and the "complex" way, using	787	ways, the "simple" way, using only C<on_read> and the "complex" way, using
295	a queue.	788	a queue.
296		789
297	In the simple case, you just install an C<on_read> callback and whenever	790	In the simple case, you just install an C<on_read> callback and whenever
298	new data arrives, it will be called. You can then remove some data (if	791	new data arrives, it will be called. You can then remove some data (if
299	enough is there) from the read buffer (C<< $handle->rbuf >>) if you want	792	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
300	or not.	793	leave the data there if you want to accumulate more (e.g. when only a
		794	partial message has been received so far).
301		795
302	In the more complex case, you want to queue multiple callbacks. In this	796	In the more complex case, you want to queue multiple callbacks. In this
303	case, AnyEvent::Handle will call the first queued callback each time new	797	case, AnyEvent::Handle will call the first queued callback each time new
304	data arrives and removes it when it has done its job (see C<push_read>,	798	data arrives (also the first time it is queued) and removes it when it has
305	below).	799	done its job (see C<push_read>, below).
306		800
307	This way you can, for example, push three line-reads, followed by reading	801	This way you can, for example, push three line-reads, followed by reading
308	a chunk of data, and AnyEvent::Handle will execute them in order.	802	a chunk of data, and AnyEvent::Handle will execute them in order.
309		803
310	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by	804	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
311	the specified number of bytes which give an XML datagram.	805	the specified number of bytes which give an XML datagram.
312		806
313	# in the default state, expect some header bytes	807	# in the default state, expect some header bytes
314	$handle->on_read (sub {	808	$handle->on_read (sub {
315	# some data is here, now queue the length-header-read (4 octets)	809	# some data is here, now queue the length-header-read (4 octets)
316	shift->unshift_read_chunk (4, sub {	810	shift->unshift_read (chunk => 4, sub {
317	# header arrived, decode	811	# header arrived, decode
318	my $len = unpack "N", $_[1];	812	my $len = unpack "N", $_[1];
319		813
320	# now read the payload	814	# now read the payload
321	shift->unshift_read_chunk ($len, sub {	815	shift->unshift_read (chunk => $len, sub {
322	my $xml = $_[1];	816	my $xml = $_[1];
323	# handle xml	817	# handle xml
324	});	818	});
325	});	819	});
326	});	820	});
327		821
328	Example 2: Implement a client for a protocol that replies either with	822	Example 2: Implement a client for a protocol that replies either with "OK"
329	"OK" and another line or "ERROR" for one request, and 64 bytes for the	823	and another line or "ERROR" for the first request that is sent, and 64
330	second request. Due tot he availability of a full queue, we can just	824	bytes for the second request. Due to the availability of a queue, we can
331	pipeline sending both requests and manipulate the queue as necessary in	825	just pipeline sending both requests and manipulate the queue as necessary
332	the callbacks:	826	in the callbacks.
333		827
334	# request one	828	When the first callback is called and sees an "OK" response, it will
		829	C<unshift> another line-read. This line-read will be queued I<before> the
		830	64-byte chunk callback.
		831
		832	# request one, returns either "OK + extra line" or "ERROR"
335	$handle->push_write ("request 1\015\012");	833	$handle->push_write ("request 1\015\012");
336		834
337	# we expect "ERROR" or "OK" as response, so push a line read	835	# we expect "ERROR" or "OK" as response, so push a line read
338	$handle->push_read_line (sub {	836	$handle->push_read (line => sub {
339	# if we got an "OK", we have to _prepend_ another line,	837	# if we got an "OK", we have to _prepend_ another line,
340	# so it will be read before the second request reads its 64 bytes	838	# so it will be read before the second request reads its 64 bytes
341	# which are already in the queue when this callback is called	839	# which are already in the queue when this callback is called
342	# we don't do this in case we got an error	840	# we don't do this in case we got an error
343	if ($_[1] eq "OK") {	841	if ($_[1] eq "OK") {
344	$_[0]->unshift_read_line (sub {	842	$_[0]->unshift_read (line => sub {
345	my $response = $_[1];	843	my $response = $_[1];
346	...	844	...
347	});	845	});
348	}	846	}
349	});	847	});
350		848
351	# request two	849	# request two, simply returns 64 octets
352	$handle->push_write ("request 2\015\012");	850	$handle->push_write ("request 2\015\012");
353		851
354	# simply read 64 bytes, always	852	# simply read 64 bytes, always
355	$handle->push_read_chunk (64, sub {	853	$handle->push_read (chunk => 64, sub {
356	my $response = $_[1];	854	my $response = $_[1];
357	...	855	...
358	});	856	});
359		857
360	=over 4	858	=over 4
…		…
362	=cut	860	=cut
363		861
364	sub _drain_rbuf {	862	sub _drain_rbuf {
365	my ($self) = @_;	863	my ($self) = @_;
366		864
367	return if exists $self->{in_drain};
368	local $self->{in_drain} = 1;	865	local $self->{_in_drain} = 1;
369		866
		867	if (
		868	defined $self->{rbuf_max}
		869	&& $self->{rbuf_max} < length $self->{rbuf}
		870	) {
		871	$self->_error (&Errno::ENOSPC, 1), return;
		872	}
		873
		874	while () {
		875	# we need to use a separate tls read buffer, as we must not receive data while
		876	# we are draining the buffer, and this can only happen with TLS.
		877	$self->{rbuf} .= delete $self->{_tls_rbuf} if exists $self->{_tls_rbuf};
		878
370	while (my $len = length $self->{rbuf}) {	879	my $len = length $self->{rbuf};
371	no strict 'refs';	880
372	if (my $cb = shift @{ $self->{queue} }) {	881	if (my $cb = shift @{ $self->{_queue} }) {
373	if (!$cb->($self)) {	882	unless ($cb->($self)) {
374	if ($self->{eof}) {	883	if ($self->{_eof}) {
375	# no progress can be made (not enough data and no data forthcoming)	884	# no progress can be made (not enough data and no data forthcoming)
376	$! = &Errno::EPIPE; return $self->error;	885	$self->_error (&Errno::EPIPE, 1), return;
377	}	886	}
378		887
379	unshift @{ $self->{queue} }, $cb;	888	unshift @{ $self->{_queue} }, $cb;
380	return;	889	last;
381	}	890	}
382	} elsif ($self->{on_read}) {	891	} elsif ($self->{on_read}) {
		892	last unless $len;
		893
383	$self->{on_read}($self);	894	$self->{on_read}($self);
384		895
385	if (	896	if (
386	$self->{eof} # if no further data will arrive
387	&& $len == length $self->{rbuf} # and no data has been consumed	897	$len == length $self->{rbuf} # if no data has been consumed
388	&& !@{ $self->{queue} } # and the queue is still empty	898	&& !@{ $self->{_queue} } # and the queue is still empty
389	&& $self->{on_read} # and we still want to read data	899	&& $self->{on_read} # but we still have on_read
390	) {	900	) {
		901	# no further data will arrive
391	# then no progress can be made	902	# so no progress can be made
392	$! = &Errno::EPIPE; return $self->error;	903	$self->_error (&Errno::EPIPE, 1), return
		904	if $self->{_eof};
		905
		906	last; # more data might arrive
393	}	907	}
394	} else {	908	} else {
395	# read side becomes idle	909	# read side becomes idle
396	delete $self->{rw};	910	delete $self->{_rw} unless $self->{tls};
397	return;	911	last;
398	}	912	}
399	}	913	}
400		914
401	if ($self->{eof}) {	915	if ($self->{_eof}) {
402	$self->_shutdown;	916	if ($self->{on_eof}) {
403	$self->{on_eof}($self);	917	$self->{on_eof}($self)
		918	} else {
		919	$self->_error (0, 1, "Unexpected end-of-file");
		920	}
		921	}
		922
		923	# may need to restart read watcher
		924	unless ($self->{_rw}) {
		925	$self->start_read
		926	if $self->{on_read} || @{ $self->{_queue} };
404	}	927	}
405	}	928	}
406		929
407	=item $handle->on_read ($cb)	930	=item $handle->on_read ($cb)
408		931
…		…
414		937
415	sub on_read {	938	sub on_read {
416	my ($self, $cb) = @_;	939	my ($self, $cb) = @_;
417		940
418	$self->{on_read} = $cb;	941	$self->{on_read} = $cb;
		942	$self->_drain_rbuf if $cb && !$self->{_in_drain};
419	}	943	}
420		944
421	=item $handle->rbuf	945	=item $handle->rbuf
422		946
423	Returns the read buffer (as a modifiable lvalue).	947	Returns the read buffer (as a modifiable lvalue).
424		948
425	You can access the read buffer directly as the C<< ->{rbuf} >> member, if	949	You can access the read buffer directly as the C<< ->{rbuf} >>
426	you want.	950	member, if you want. However, the only operation allowed on the
		951	read buffer (apart from looking at it) is removing data from its
		952	beginning. Otherwise modifying or appending to it is not allowed and will
		953	lead to hard-to-track-down bugs.
427		954
428	NOTE: The read buffer should only be used or modified if the C<on_read>,	955	NOTE: The read buffer should only be used or modified if the C<on_read>,
429	C<push_read> or C<unshift_read> methods are used. The other read methods	956	C<push_read> or C<unshift_read> methods are used. The other read methods
430	automatically manage the read buffer.	957	automatically manage the read buffer.
431		958
…		…
442	Append the given callback to the end of the queue (C<push_read>) or	969	Append the given callback to the end of the queue (C<push_read>) or
443	prepend it (C<unshift_read>).	970	prepend it (C<unshift_read>).
444		971
445	The callback is called each time some additional read data arrives.	972	The callback is called each time some additional read data arrives.
446		973
447	It must check wether enough data is in the read buffer already.	974	It must check whether enough data is in the read buffer already.
448		975
449	If not enough data is available, it must return the empty list or a false	976	If not enough data is available, it must return the empty list or a false
450	value, in which case it will be called repeatedly until enough data is	977	value, in which case it will be called repeatedly until enough data is
451	available (or an error condition is detected).	978	available (or an error condition is detected).
452		979
…		…
454	interested in (which can be none at all) and return a true value. After returning	981	interested in (which can be none at all) and return a true value. After returning
455	true, it will be removed from the queue.	982	true, it will be removed from the queue.
456		983
457	=cut	984	=cut
458		985
		986	our %RH;
		987
		988	sub register_read_type($$) {
		989	$RH{$_[0]} = $_[1];
		990	}
		991
459	sub push_read {	992	sub push_read {
460	my ($self, $cb) = @_;	993	my $self = shift;
		994	my $cb = pop;
461		995
		996	if (@_) {
		997	my $type = shift;
		998
		999	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
		1000	->($self, $cb, @_);
		1001	}
		1002
462	push @{ $self->{queue} }, $cb;	1003	push @{ $self->{_queue} }, $cb;
463	$self->_drain_rbuf;	1004	$self->_drain_rbuf unless $self->{_in_drain};
464	}	1005	}
465		1006
466	sub unshift_read {	1007	sub unshift_read {
467	my ($self, $cb) = @_;	1008	my $self = shift;
		1009	my $cb = pop;
468		1010
		1011	if (@_) {
		1012	my $type = shift;
		1013
		1014	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
		1015	->($self, $cb, @_);
		1016	}
		1017
		1018
469	push @{ $self->{queue} }, $cb;	1019	unshift @{ $self->{_queue} }, $cb;
470	$self->_drain_rbuf;	1020	$self->_drain_rbuf unless $self->{_in_drain};
471	}	1021	}
472		1022
473	=item $handle->push_read_chunk ($len, $cb->($self, $data))	1023	=item $handle->push_read (type => @args, $cb)
474		1024
475	=item $handle->unshift_read_chunk ($len, $cb->($self, $data))	1025	=item $handle->unshift_read (type => @args, $cb)
476		1026
477	Append the given callback to the end of the queue (C<push_read_chunk>) or	1027	Instead of providing a callback that parses the data itself you can chose
478	prepend it (C<unshift_read_chunk>).	1028	between a number of predefined parsing formats, for chunks of data, lines
		1029	etc.
479		1030
480	The callback will be called only once C<$len> bytes have been read, and	1031	Predefined types are (if you have ideas for additional types, feel free to
481	these C<$len> bytes will be passed to the callback.	1032	drop by and tell us):
482		1033
483	=cut	1034	=over 4
484		1035
485	sub _read_chunk($$) {	1036	=item chunk => $octets, $cb->($handle, $data)
		1037
		1038	Invoke the callback only once C<$octets> bytes have been read. Pass the
		1039	data read to the callback. The callback will never be called with less
		1040	data.
		1041
		1042	Example: read 2 bytes.
		1043
		1044	$handle->push_read (chunk => 2, sub {
		1045	warn "yay ", unpack "H*", $_[1];
		1046	});
		1047
		1048	=cut
		1049
		1050	register_read_type chunk => sub {
486	my ($self, $len, $cb) = @_;	1051	my ($self, $cb, $len) = @_;
487		1052
488	sub {	1053	sub {
489	$len <= length $_[0]{rbuf} or return;	1054	$len <= length $_[0]{rbuf} or return;
490	$cb->($self, $_[0], substr $_[0]{rbuf}, 0, $len, "");	1055	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
491	1	1056	1
492	}	1057	}
493	}	1058	};
494		1059
495	sub push_read_chunk {	1060	=item line => [$eol, ]$cb->($handle, $line, $eol)
496	$_[0]->push_read (&_read_chunk);
497	}
498
499
500	sub unshift_read_chunk {
501	$_[0]->unshift_read (&_read_chunk);
502	}
503
504	=item $handle->push_read_line ([$eol, ]$cb->($self, $line, $eol))
505
506	=item $handle->unshift_read_line ([$eol, ]$cb->($self, $line, $eol))
507
508	Append the given callback to the end of the queue (C<push_read_line>) or
509	prepend it (C<unshift_read_line>).
510		1061
511	The callback will be called only once a full line (including the end of	1062	The callback will be called only once a full line (including the end of
512	line marker, C<$eol>) has been read. This line (excluding the end of line	1063	line marker, C<$eol>) has been read. This line (excluding the end of line
513	marker) will be passed to the callback as second argument (C<$line>), and	1064	marker) will be passed to the callback as second argument (C<$line>), and
514	the end of line marker as the third argument (C<$eol>).	1065	the end of line marker as the third argument (C<$eol>).
…		…
525	Partial lines at the end of the stream will never be returned, as they are	1076	Partial lines at the end of the stream will never be returned, as they are
526	not marked by the end of line marker.	1077	not marked by the end of line marker.
527		1078
528	=cut	1079	=cut
529		1080
530	sub _read_line($$) {	1081	register_read_type line => sub {
531	my $self = shift;	1082	my ($self, $cb, $eol) = @_;
532	my $cb = pop;
533	my $eol = @_ ? shift : qr|(\015?\012)|;
534	my $pos;
535		1083
		1084	if (@_ < 3) {
		1085	# this is more than twice as fast as the generic code below
		1086	sub {
		1087	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		1088
		1089	$cb->($_[0], $1, $2);
		1090	1
		1091	}
		1092	} else {
536	$eol = qr|(\Q$eol\E)| unless ref $eol;	1093	$eol = quotemeta $eol unless ref $eol;
537	$eol = qr|^(.*?)($eol)|;	1094	$eol = qr|^(.*?)($eol)|s;
		1095
		1096	sub {
		1097	$_[0]{rbuf} =~ s/$eol// or return;
		1098
		1099	$cb->($_[0], $1, $2);
		1100	1
		1101	}
		1102	}
		1103	};
		1104
		1105	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1106
		1107	Makes a regex match against the regex object C<$accept> and returns
		1108	everything up to and including the match.
		1109
		1110	Example: read a single line terminated by '\n'.
		1111
		1112	$handle->push_read (regex => qr<\n>, sub { ... });
		1113
		1114	If C<$reject> is given and not undef, then it determines when the data is
		1115	to be rejected: it is matched against the data when the C<$accept> regex
		1116	does not match and generates an C<EBADMSG> error when it matches. This is
		1117	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1118	receive buffer overflow).
		1119
		1120	Example: expect a single decimal number followed by whitespace, reject
		1121	anything else (not the use of an anchor).
		1122
		1123	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1124
		1125	If C<$skip> is given and not C<undef>, then it will be matched against
		1126	the receive buffer when neither C<$accept> nor C<$reject> match,
		1127	and everything preceding and including the match will be accepted
		1128	unconditionally. This is useful to skip large amounts of data that you
		1129	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1130	have to start matching from the beginning. This is purely an optimisation
		1131	and is usually worth only when you expect more than a few kilobytes.
		1132
		1133	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1134	expect the header to be very large (it isn't in practise, but...), we use
		1135	a skip regex to skip initial portions. The skip regex is tricky in that
		1136	it only accepts something not ending in either \015 or \012, as these are
		1137	required for the accept regex.
		1138
		1139	$handle->push_read (regex =>
		1140	qr<\015\012\015\012>,
		1141	undef, # no reject
		1142	qr<^.*[^\015\012]>,
		1143	sub { ... });
		1144
		1145	=cut
		1146
		1147	register_read_type regex => sub {
		1148	my ($self, $cb, $accept, $reject, $skip) = @_;
		1149
		1150	my $data;
		1151	my $rbuf = \$self->{rbuf};
538		1152
539	sub {	1153	sub {
540	$_[0]{rbuf} =~ s/$eol// or return;	1154	# accept
541		1155	if ($$rbuf =~ $accept) {
		1156	$data .= substr $$rbuf, 0, $+[0], "";
542	$cb->($self, $1, $2);	1157	$cb->($self, $data);
		1158	return 1;
		1159	}
		1160
		1161	# reject
		1162	if ($reject && $$rbuf =~ $reject) {
		1163	$self->_error (&Errno::EBADMSG);
		1164	}
		1165
		1166	# skip
		1167	if ($skip && $$rbuf =~ $skip) {
		1168	$data .= substr $$rbuf, 0, $+[0], "";
		1169	}
		1170
		1171	()
		1172	}
		1173	};
		1174
		1175	=item netstring => $cb->($handle, $string)
		1176
		1177	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1178
		1179	Throws an error with C<$!> set to EBADMSG on format violations.
		1180
		1181	=cut
		1182
		1183	register_read_type netstring => sub {
		1184	my ($self, $cb) = @_;
		1185
		1186	sub {
		1187	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1188	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1189	$self->_error (&Errno::EBADMSG);
		1190	}
		1191	return;
		1192	}
		1193
		1194	my $len = $1;
		1195
		1196	$self->unshift_read (chunk => $len, sub {
		1197	my $string = $_[1];
		1198	$_[0]->unshift_read (chunk => 1, sub {
		1199	if ($_[1] eq ",") {
		1200	$cb->($_[0], $string);
		1201	} else {
		1202	$self->_error (&Errno::EBADMSG);
		1203	}
		1204	});
		1205	});
		1206
543	1	1207	1
544	}	1208	}
545	}	1209	};
546		1210
547	sub push_read_line {	1211	=item packstring => $format, $cb->($handle, $string)
548	$_[0]->push_read (&_read_line);
549	}
550		1212
551	sub unshift_read_line {	1213	An octet string prefixed with an encoded length. The encoding C<$format>
552	$_[0]->unshift_read (&_read_line);	1214	uses the same format as a Perl C<pack> format, but must specify a single
553	}	1215	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1216	optional C<!>, C<< < >> or C<< > >> modifier).
		1217
		1218	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1219	EPP uses a prefix of C<N> (4 octtes).
		1220
		1221	Example: read a block of data prefixed by its length in BER-encoded
		1222	format (very efficient).
		1223
		1224	$handle->push_read (packstring => "w", sub {
		1225	my ($handle, $data) = @_;
		1226	});
		1227
		1228	=cut
		1229
		1230	register_read_type packstring => sub {
		1231	my ($self, $cb, $format) = @_;
		1232
		1233	sub {
		1234	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1235	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1236	or return;
		1237
		1238	$format = length pack $format, $len;
		1239
		1240	# bypass unshift if we already have the remaining chunk
		1241	if ($format + $len <= length $_[0]{rbuf}) {
		1242	my $data = substr $_[0]{rbuf}, $format, $len;
		1243	substr $_[0]{rbuf}, 0, $format + $len, "";
		1244	$cb->($_[0], $data);
		1245	} else {
		1246	# remove prefix
		1247	substr $_[0]{rbuf}, 0, $format, "";
		1248
		1249	# read remaining chunk
		1250	$_[0]->unshift_read (chunk => $len, $cb);
		1251	}
		1252
		1253	1
		1254	}
		1255	};
		1256
		1257	=item json => $cb->($handle, $hash_or_arrayref)
		1258
		1259	Reads a JSON object or array, decodes it and passes it to the
		1260	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1261
		1262	If a C<json> object was passed to the constructor, then that will be used
		1263	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1264
		1265	This read type uses the incremental parser available with JSON version
		1266	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1267	dependency on your own: this module will load the JSON module, but
		1268	AnyEvent does not depend on it itself.
		1269
		1270	Since JSON texts are fully self-delimiting, the C<json> read and write
		1271	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1272	the C<json> write type description, above, for an actual example.
		1273
		1274	=cut
		1275
		1276	register_read_type json => sub {
		1277	my ($self, $cb) = @_;
		1278
		1279	my $json = $self->{json} ||=
		1280	eval { require JSON::XS; JSON::XS->new->utf8 }
		1281	|| do { require JSON; JSON->new->utf8 };
		1282
		1283	my $data;
		1284	my $rbuf = \$self->{rbuf};
		1285
		1286	sub {
		1287	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1288
		1289	if ($ref) {
		1290	$self->{rbuf} = $json->incr_text;
		1291	$json->incr_text = "";
		1292	$cb->($self, $ref);
		1293
		1294	1
		1295	} elsif ($@) {
		1296	# error case
		1297	$json->incr_skip;
		1298
		1299	$self->{rbuf} = $json->incr_text;
		1300	$json->incr_text = "";
		1301
		1302	$self->_error (&Errno::EBADMSG);
		1303
		1304	()
		1305	} else {
		1306	$self->{rbuf} = "";
		1307
		1308	()
		1309	}
		1310	}
		1311	};
		1312
		1313	=item storable => $cb->($handle, $ref)
		1314
		1315	Deserialises a L<Storable> frozen representation as written by the
		1316	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1317	data).
		1318
		1319	Raises C<EBADMSG> error if the data could not be decoded.
		1320
		1321	=cut
		1322
		1323	register_read_type storable => sub {
		1324	my ($self, $cb) = @_;
		1325
		1326	require Storable;
		1327
		1328	sub {
		1329	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1330	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1331	or return;
		1332
		1333	my $format = length pack "w", $len;
		1334
		1335	# bypass unshift if we already have the remaining chunk
		1336	if ($format + $len <= length $_[0]{rbuf}) {
		1337	my $data = substr $_[0]{rbuf}, $format, $len;
		1338	substr $_[0]{rbuf}, 0, $format + $len, "";
		1339	$cb->($_[0], Storable::thaw ($data));
		1340	} else {
		1341	# remove prefix
		1342	substr $_[0]{rbuf}, 0, $format, "";
		1343
		1344	# read remaining chunk
		1345	$_[0]->unshift_read (chunk => $len, sub {
		1346	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1347	$cb->($_[0], $ref);
		1348	} else {
		1349	$self->_error (&Errno::EBADMSG);
		1350	}
		1351	});
		1352	}
		1353
		1354	1
		1355	}
		1356	};
		1357
		1358	=back
		1359
		1360	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
		1361
		1362	This function (not method) lets you add your own types to C<push_read>.
		1363
		1364	Whenever the given C<type> is used, C<push_read> will invoke the code
		1365	reference with the handle object, the callback and the remaining
		1366	arguments.
		1367
		1368	The code reference is supposed to return a callback (usually a closure)
		1369	that works as a plain read callback (see C<< ->push_read ($cb) >>).
		1370
		1371	It should invoke the passed callback when it is done reading (remember to
		1372	pass C<$handle> as first argument as all other callbacks do that).
		1373
		1374	Note that this is a function, and all types registered this way will be
		1375	global, so try to use unique names.
		1376
		1377	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
		1378	search for C<register_read_type>)).
554		1379
555	=item $handle->stop_read	1380	=item $handle->stop_read
556		1381
557	=item $handle->start_read	1382	=item $handle->start_read
558		1383
559	In rare cases you actually do not want to read anything form the	1384	In rare cases you actually do not want to read anything from the
560	socket. In this case you can call C<stop_read>. Neither C<on_read> no	1385	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
561	any queued callbacks will be executed then. To start readign again, call	1386	any queued callbacks will be executed then. To start reading again, call
562	C<start_read>.	1387	C<start_read>.
		1388
		1389	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1390	you change the C<on_read> callback or push/unshift a read callback, and it
		1391	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1392	there are any read requests in the queue.
		1393
		1394	These methods will have no effect when in TLS mode (as TLS doesn't support
		1395	half-duplex connections).
563		1396
564	=cut	1397	=cut
565		1398
566	sub stop_read {	1399	sub stop_read {
567	my ($self) = @_;	1400	my ($self) = @_;
568		1401
569	delete $self->{rw};	1402	delete $self->{_rw} unless $self->{tls};
570	}	1403	}
571		1404
572	sub start_read {	1405	sub start_read {
573	my ($self) = @_;	1406	my ($self) = @_;
574		1407
575	unless ($self->{rw} || $self->{eof}) {	1408	unless ($self->{_rw} || $self->{_eof}) {
576	Scalar::Util::weaken $self;	1409	Scalar::Util::weaken $self;
577		1410
578	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {	1411	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
		1412	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
579	my $len = sysread $self->{fh}, $self->{rbuf}, $self->{read_size} || 8192, length $self->{rbuf};	1413	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
580		1414
581	if ($len > 0) {	1415	if ($len > 0) {
		1416	$self->{_activity} = AnyEvent->now;
		1417
582	if (exists $self->{rbuf_max}) {	1418	if ($self->{tls}) {
583	if ($self->{rbuf_max} < length $self->{rbuf}) {	1419	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
584	$! = &Errno::ENOSPC; return $self->error;	1420
585	}	1421	&_dotls ($self);
		1422	} else {
		1423	$self->_drain_rbuf unless $self->{_in_drain};
586	}	1424	}
587		1425
588	} elsif (defined $len) {	1426	} elsif (defined $len) {
589	$self->{eof} = 1;
590	delete $self->{rw};	1427	delete $self->{_rw};
		1428	$self->{_eof} = 1;
		1429	$self->_drain_rbuf unless $self->{_in_drain};
591		1430
592	} elsif ($! != EAGAIN && $! != EINTR) {	1431	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
593	return $self->error;	1432	return $self->_error ($!, 1);
594	}	1433	}
595
596	$self->_drain_rbuf;
597	});	1434	});
598	}	1435	}
599	}	1436	}
600		1437
		1438	our $ERROR_SYSCALL;
		1439	our $ERROR_WANT_READ;
		1440
		1441	sub _tls_error {
		1442	my ($self, $err) = @_;
		1443
		1444	return $self->_error ($!, 1)
		1445	if $err == Net::SSLeay::ERROR_SYSCALL ();
		1446
		1447	my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
		1448
		1449	# reduce error string to look less scary
		1450	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
		1451
		1452	if ($self->{_on_starttls}) {
		1453	(delete $self->{_on_starttls})->($self, undef, $err);
		1454	&_freetls;
		1455	} else {
		1456	&_freetls;
		1457	$self->_error (&Errno::EPROTO, 1, $err);
		1458	}
		1459	}
		1460
		1461	# poll the write BIO and send the data if applicable
		1462	# also decode read data if possible
		1463	# this is basiclaly our TLS state machine
		1464	# more efficient implementations are possible with openssl,
		1465	# but not with the buggy and incomplete Net::SSLeay.
		1466	sub _dotls {
		1467	my ($self) = @_;
		1468
		1469	my $tmp;
		1470
		1471	if (length $self->{_tls_wbuf}) {
		1472	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1473	substr $self->{_tls_wbuf}, 0, $tmp, "";
		1474	}
		1475
		1476	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		1477	return $self->_tls_error ($tmp)
		1478	if $tmp != $ERROR_WANT_READ
		1479	&& ($tmp != $ERROR_SYSCALL || $!);
		1480	}
		1481
		1482	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		1483	unless (length $tmp) {
		1484	$self->{_on_starttls}
		1485	and (delete $self->{_on_starttls})->($self, undef, "EOF during handshake"); # ???
		1486	&_freetls;
		1487
		1488	if ($self->{on_stoptls}) {
		1489	$self->{on_stoptls}($self);
		1490	return;
		1491	} else {
		1492	# let's treat SSL-eof as we treat normal EOF
		1493	delete $self->{_rw};
		1494	$self->{_eof} = 1;
		1495	}
		1496	}
		1497
		1498	$self->{_tls_rbuf} .= $tmp;
		1499	$self->_drain_rbuf unless $self->{_in_drain};
		1500	$self->{tls} or return; # tls session might have gone away in callback
		1501	}
		1502
		1503	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
		1504	return $self->_tls_error ($tmp)
		1505	if $tmp != $ERROR_WANT_READ
		1506	&& ($tmp != $ERROR_SYSCALL || $!);
		1507
		1508	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
		1509	$self->{wbuf} .= $tmp;
		1510	$self->_drain_wbuf;
		1511	}
		1512
		1513	$self->{_on_starttls}
		1514	and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
		1515	and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
		1516	}
		1517
		1518	=item $handle->starttls ($tls[, $tls_ctx])
		1519
		1520	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1521	object is created, you can also do that at a later time by calling
		1522	C<starttls>.
		1523
		1524	The first argument is the same as the C<tls> constructor argument (either
		1525	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1526
		1527	The second argument is the optional C<AnyEvent::TLS> object that is used
		1528	when AnyEvent::Handle has to create its own TLS connection object, or
		1529	a hash reference with C<< key => value >> pairs that will be used to
		1530	construct a new context.
		1531
		1532	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1533	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1534	changed to your liking. Note that the handshake might have already started
		1535	when this function returns.
		1536
		1537	If it an error to start a TLS handshake more than once per
		1538	AnyEvent::Handle object (this is due to bugs in OpenSSL).
		1539
		1540	=cut
		1541
		1542	our %TLS_CACHE; #TODO not yet documented, should we?
		1543
		1544	sub starttls {
		1545	my ($self, $ssl, $ctx) = @_;
		1546
		1547	require Net::SSLeay;
		1548
		1549	Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
		1550	if $self->{tls};
		1551
		1552	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		1553	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		1554
		1555	$ctx ||= $self->{tls_ctx};
		1556
		1557	if ("HASH" eq ref $ctx) {
		1558	require AnyEvent::TLS;
		1559
		1560	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
		1561
		1562	if ($ctx->{cache}) {
		1563	my $key = $ctx+0;
		1564	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
		1565	} else {
		1566	$ctx = new AnyEvent::TLS %$ctx;
		1567	}
		1568	}
		1569
		1570	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1571	$self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self, $self->{peername});
		1572
		1573	# basically, this is deep magic (because SSL_read should have the same issues)
		1574	# but the openssl maintainers basically said: "trust us, it just works".
		1575	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1576	# and mismaintained ssleay-module doesn't even offer them).
		1577	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1578	#
		1579	# in short: this is a mess.
		1580	#
		1581	# note that we do not try to keep the length constant between writes as we are required to do.
		1582	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1583	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1584	# have identity issues in that area.
		1585	# Net::SSLeay::CTX_set_mode ($ssl,
		1586	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		1587	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1588	Net::SSLeay::CTX_set_mode ($ssl, 1|2);
		1589
		1590	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1591	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1592
		1593	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
		1594
		1595	$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
		1596	if $self->{on_starttls};
		1597
		1598	&_dotls; # need to trigger the initial handshake
		1599	$self->start_read; # make sure we actually do read
		1600	}
		1601
		1602	=item $handle->stoptls
		1603
		1604	Shuts down the SSL connection - this makes a proper EOF handshake by
		1605	sending a close notify to the other side, but since OpenSSL doesn't
		1606	support non-blocking shut downs, it is not possible to re-use the stream
		1607	afterwards.
		1608
		1609	=cut
		1610
		1611	sub stoptls {
		1612	my ($self) = @_;
		1613
		1614	if ($self->{tls}) {
		1615	Net::SSLeay::shutdown ($self->{tls});
		1616
		1617	&_dotls;
		1618
		1619	# # we don't give a shit. no, we do, but we can't. no...#d#
		1620	# # we, we... have to use openssl :/#d#
		1621	# &_freetls;#d#
		1622	}
		1623	}
		1624
		1625	sub _freetls {
		1626	my ($self) = @_;
		1627
		1628	return unless $self->{tls};
		1629
		1630	$self->{tls_ctx}->_put_session (delete $self->{tls});
		1631
		1632	delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
		1633	}
		1634
		1635	sub DESTROY {
		1636	my ($self) = @_;
		1637
		1638	&_freetls;
		1639
		1640	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		1641
		1642	if ($linger && length $self->{wbuf}) {
		1643	my $fh = delete $self->{fh};
		1644	my $wbuf = delete $self->{wbuf};
		1645
		1646	my @linger;
		1647
		1648	push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
		1649	my $len = syswrite $fh, $wbuf, length $wbuf;
		1650
		1651	if ($len > 0) {
		1652	substr $wbuf, 0, $len, "";
		1653	} else {
		1654	@linger = (); # end
		1655	}
		1656	});
		1657	push @linger, AnyEvent->timer (after => $linger, cb => sub {
		1658	@linger = ();
		1659	});
		1660	}
		1661	}
		1662
		1663	=item $handle->destroy
		1664
		1665	Shuts down the handle object as much as possible - this call ensures that
		1666	no further callbacks will be invoked and as many resources as possible
		1667	will be freed. You must not call any methods on the object afterwards.
		1668
		1669	Normally, you can just "forget" any references to an AnyEvent::Handle
		1670	object and it will simply shut down. This works in fatal error and EOF
		1671	callbacks, as well as code outside. It does I<NOT> work in a read or write
		1672	callback, so when you want to destroy the AnyEvent::Handle object from
		1673	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		1674	that case.
		1675
		1676	The handle might still linger in the background and write out remaining
		1677	data, as specified by the C<linger> option, however.
		1678
		1679	=cut
		1680
		1681	sub destroy {
		1682	my ($self) = @_;
		1683
		1684	$self->DESTROY;
		1685	%$self = ();
		1686	}
		1687
		1688	=item AnyEvent::Handle::TLS_CTX
		1689
		1690	This function creates and returns the AnyEvent::TLS object used by default
		1691	for TLS mode.
		1692
		1693	The context is created by calling L<AnyEvent::TLS> without any arguments.
		1694
		1695	=cut
		1696
		1697	our $TLS_CTX;
		1698
		1699	sub TLS_CTX() {
		1700	$TLS_CTX ||= do {
		1701	require AnyEvent::TLS;
		1702
		1703	new AnyEvent::TLS
		1704	}
		1705	}
		1706
601	=back	1707	=back
602		1708
		1709
		1710	=head1 NONFREQUENTLY ASKED QUESTIONS
		1711
		1712	=over 4
		1713
		1714	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		1715	still get further invocations!
		1716
		1717	That's because AnyEvent::Handle keeps a reference to itself when handling
		1718	read or write callbacks.
		1719
		1720	It is only safe to "forget" the reference inside EOF or error callbacks,
		1721	from within all other callbacks, you need to explicitly call the C<<
		1722	->destroy >> method.
		1723
		1724	=item I get different callback invocations in TLS mode/Why can't I pause
		1725	reading?
		1726
		1727	Unlike, say, TCP, TLS connections do not consist of two independent
		1728	communication channels, one for each direction. Or put differently. The
		1729	read and write directions are not independent of each other: you cannot
		1730	write data unless you are also prepared to read, and vice versa.
		1731
		1732	This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
		1733	callback invocations when you are not expecting any read data - the reason
		1734	is that AnyEvent::Handle always reads in TLS mode.
		1735
		1736	During the connection, you have to make sure that you always have a
		1737	non-empty read-queue, or an C<on_read> watcher. At the end of the
		1738	connection (or when you no longer want to use it) you can call the
		1739	C<destroy> method.
		1740
		1741	=item How do I read data until the other side closes the connection?
		1742
		1743	If you just want to read your data into a perl scalar, the easiest way
		1744	to achieve this is by setting an C<on_read> callback that does nothing,
		1745	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		1746	will be in C<$_[0]{rbuf}>:
		1747
		1748	$handle->on_read (sub { });
		1749	$handle->on_eof (undef);
		1750	$handle->on_error (sub {
		1751	my $data = delete $_[0]{rbuf};
		1752	undef $handle;
		1753	});
		1754
		1755	The reason to use C<on_error> is that TCP connections, due to latencies
		1756	and packets loss, might get closed quite violently with an error, when in
		1757	fact, all data has been received.
		1758
		1759	It is usually better to use acknowledgements when transferring data,
		1760	to make sure the other side hasn't just died and you got the data
		1761	intact. This is also one reason why so many internet protocols have an
		1762	explicit QUIT command.
		1763
		1764	=item I don't want to destroy the handle too early - how do I wait until
		1765	all data has been written?
		1766
		1767	After writing your last bits of data, set the C<on_drain> callback
		1768	and destroy the handle in there - with the default setting of
		1769	C<low_water_mark> this will be called precisely when all data has been
		1770	written to the socket:
		1771
		1772	$handle->push_write (...);
		1773	$handle->on_drain (sub {
		1774	warn "all data submitted to the kernel\n";
		1775	undef $handle;
		1776	});
		1777
		1778	If you just want to queue some data and then signal EOF to the other side,
		1779	consider using C<< ->push_shutdown >> instead.
		1780
		1781	=item I want to contact a TLS/SSL server, I don't care about security.
		1782
		1783	If your TLS server is a pure TLS server (e.g. HTTPS) that only speaks TLS,
		1784	simply connect to it and then create the AnyEvent::Handle with the C<tls>
		1785	parameter:
		1786
		1787	tcp_connect $host, $port, sub {
		1788	my ($fh) = @_;
		1789
		1790	my $handle = new AnyEvent::Handle
		1791	fh => $fh,
		1792	tls => "connect",
		1793	on_error => sub { ... };
		1794
		1795	$handle->push_write (...);
		1796	};
		1797
		1798	=item I want to contact a TLS/SSL server, I do care about security.
		1799
		1800	Then you should additionally enable certificate verification, including
		1801	peername verification, if the protocol you use supports it (see
		1802	L<AnyEvent::TLS>, C<verify_peername>).
		1803
		1804	E.g. for HTTPS:
		1805
		1806	tcp_connect $host, $port, sub {
		1807	my ($fh) = @_;
		1808
		1809	my $handle = new AnyEvent::Handle
		1810	fh => $fh,
		1811	peername => $host,
		1812	tls => "connect",
		1813	tls_ctx => { verify => 1, verify_peername => "https" },
		1814	...
		1815
		1816	Note that you must specify the hostname you connected to (or whatever
		1817	"peername" the protocol needs) as the C<peername> argument, otherwise no
		1818	peername verification will be done.
		1819
		1820	The above will use the system-dependent default set of trusted CA
		1821	certificates. If you want to check against a specific CA, add the
		1822	C<ca_file> (or C<ca_cert>) arguments to C<tls_ctx>:
		1823
		1824	tls_ctx => {
		1825	verify => 1,
		1826	verify_peername => "https",
		1827	ca_file => "my-ca-cert.pem",
		1828	},
		1829
		1830	=item I want to create a TLS/SSL server, how do I do that?
		1831
		1832	Well, you first need to get a server certificate and key. You have
		1833	three options: a) ask a CA (buy one, use cacert.org etc.) b) create a
		1834	self-signed certificate (cheap. check the search engine of your choice,
		1835	there are many tutorials on the net) or c) make your own CA (tinyca2 is a
		1836	nice program for that purpose).
		1837
		1838	Then create a file with your private key (in PEM format, see
		1839	L<AnyEvent::TLS>), followed by the certificate (also in PEM format). The
		1840	file should then look like this:
		1841
		1842	-----BEGIN RSA PRIVATE KEY-----
		1843	...header data
		1844	... lots of base64'y-stuff
		1845	-----END RSA PRIVATE KEY-----
		1846
		1847	-----BEGIN CERTIFICATE-----
		1848	... lots of base64'y-stuff
		1849	-----END CERTIFICATE-----
		1850
		1851	The important bits are the "PRIVATE KEY" and "CERTIFICATE" parts. Then
		1852	specify this file as C<cert_file>:
		1853
		1854	tcp_server undef, $port, sub {
		1855	my ($fh) = @_;
		1856
		1857	my $handle = new AnyEvent::Handle
		1858	fh => $fh,
		1859	tls => "accept",
		1860	tls_ctx => { cert_file => "my-server-keycert.pem" },
		1861	...
		1862
		1863	When you have intermediate CA certificates that your clients might not
		1864	know about, just append them to the C<cert_file>.
		1865
		1866	=back
		1867
		1868
		1869	=head1 SUBCLASSING AnyEvent::Handle
		1870
		1871	In many cases, you might want to subclass AnyEvent::Handle.
		1872
		1873	To make this easier, a given version of AnyEvent::Handle uses these
		1874	conventions:
		1875
		1876	=over 4
		1877
		1878	=item * all constructor arguments become object members.
		1879
		1880	At least initially, when you pass a C<tls>-argument to the constructor it
		1881	will end up in C<< $handle->{tls} >>. Those members might be changed or
		1882	mutated later on (for example C<tls> will hold the TLS connection object).
		1883
		1884	=item * other object member names are prefixed with an C<_>.
		1885
		1886	All object members not explicitly documented (internal use) are prefixed
		1887	with an underscore character, so the remaining non-C<_>-namespace is free
		1888	for use for subclasses.
		1889
		1890	=item * all members not documented here and not prefixed with an underscore
		1891	are free to use in subclasses.
		1892
		1893	Of course, new versions of AnyEvent::Handle may introduce more "public"
		1894	member variables, but thats just life, at least it is documented.
		1895
		1896	=back
		1897
603	=head1 AUTHOR	1898	=head1 AUTHOR
604		1899
605	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.	1900	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
606		1901
607	=cut	1902	=cut

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