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Revision 1.10 by root, Sat May 3 12:17:35 2008 UTC vs.
Revision 1.149 by root, Thu Jul 16 03:48:33 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 = 4.82;
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 $hdl; $hdl = new AnyEvent::Handle
29
30	#TODO
31
32	# or use the constructor to pass the callback:
33
34	my $ae_fh2 =
35	AnyEvent::Handle->new (
36	fh => \*STDIN,	29	fh => \*STDIN,
37	on_eof => sub {	30	on_error => sub {
38	$cv->broadcast;	31	warn "got error $_[2]\n";
39	},	32	$cv->send;
40	#TODO
41	);	33	);
42		34
43	$cv->wait;	35	# send some request line
		36	$hdl->push_write ("getinfo\015\012");
		37
		38	# read the response line
		39	$hdl->push_read (line => sub {
		40	my ($hdl, $line) = @_;
		41	warn "got line <$line>\n";
		42	$cv->send;
		43	});
		44
		45	$cv->recv;
44		46
45	=head1 DESCRIPTION	47	=head1 DESCRIPTION
46		48
47	This module is a helper module to make it easier to do event-based I/O on	49	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	50	filehandles. For utility functions for doing non-blocking connects and accepts
49	non-blocking resolves and connects).	51	on sockets see L<AnyEvent::Util>.
		52
		53	The L<AnyEvent::Intro> tutorial contains some well-documented
		54	AnyEvent::Handle examples.
50		55
51	In the following, when the documentation refers to of "bytes" then this	56	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	57	means characters. As sysread and syswrite are used for all I/O, their
53	treatment of characters applies to this module as well.	58	treatment of characters applies to this module as well.
54		59
…		…
57		62
58	=head1 METHODS	63	=head1 METHODS
59		64
60	=over 4	65	=over 4
61		66
62	=item B<new (%args)>	67	=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
63		68
64	The constructor supports these arguments (all as key => value pairs).	69	The constructor supports these arguments (all as C<< key => value >> pairs).
65		70
66	=over 4	71	=over 4
67		72
68	=item fh => $filehandle [MANDATORY]	73	=item fh => $filehandle [MANDATORY]
69		74
70	The filehandle this L<AnyEvent::Handle> object will operate on.	75	The filehandle this L<AnyEvent::Handle> object will operate on.
71		76
72	NOTE: The filehandle will be set to non-blocking (using	77	NOTE: The filehandle will be set to non-blocking mode (using
73	AnyEvent::Util::fh_nonblocking).	78	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		79	that mode.
74		80
75	=item on_eof => $cb->($self) [MANDATORY]
76
77	Set the callback to be called on EOF.
78
79	=item on_error => $cb->($self)	81	=item on_eof => $cb->($handle)
80		82
		83	Set the callback to be called when an end-of-file condition is detected,
		84	i.e. in the case of a socket, when the other side has closed the
		85	connection cleanly.
		86
		87	For sockets, this just means that the other side has stopped sending data,
		88	you can still try to write data, and, in fact, one can return from the EOF
		89	callback and continue writing data, as only the read part has been shut
		90	down.
		91
		92	While not mandatory, it is I<highly> recommended to set an EOF callback,
		93	otherwise you might end up with a closed socket while you are still
		94	waiting for data.
		95
		96	If an EOF condition has been detected but no C<on_eof> callback has been
		97	set, then a fatal error will be raised with C<$!> set to <0>.
		98
		99	=item on_error => $cb->($handle, $fatal, $message)
		100
81	This is the fatal error callback, that is called when, well, a fatal error	101	This is the error callback, which is called when, well, some error
82	ocurs, such as not being able to resolve the hostname, failure to connect	102	occured, such as not being able to resolve the hostname, failure to
83	or a read error.	103	connect or a read error.
84		104
85	The object will not be in a usable state when this callback has been	105	Some errors are fatal (which is indicated by C<$fatal> being true). On
86	called.	106	fatal errors the handle object will be destroyed (by a call to C<< ->
		107	destroy >>) after invoking the error callback (which means you are free to
		108	examine the handle object). Examples of fatal errors are an EOF condition
		109	with active (but unsatisifable) read watchers (C<EPIPE>) or I/O errors.
		110
		111	AnyEvent::Handle tries to find an appropriate error code for you to check
		112	against, but in some cases (TLS errors), this does not work well. It is
		113	recommended to always output the C<$message> argument in human-readable
		114	error messages (it's usually the same as C<"$!">).
		115
		116	Non-fatal errors can be retried by simply returning, but it is recommended
		117	to simply ignore this parameter and instead abondon the handle object
		118	when this callback is invoked. Examples of non-fatal errors are timeouts
		119	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
87		120
88	On callback entrance, the value of C<$!> contains the operating system	121	On callback entrance, the value of C<$!> contains the operating system
89	error (or C<ENOSPC> or C<EPIPE>).	122	error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		123	C<EPROTO>).
90		124
91	While not mandatory, it is I<highly> recommended to set this callback, as	125	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	126	you will not be notified of errors otherwise. The default simply calls
93	die.	127	C<croak>.
94		128
95	=item on_read => $cb->($self)	129	=item on_read => $cb->($handle)
96		130
97	This sets the default read callback, which is called when data arrives	131	This sets the default read callback, which is called when data arrives
98	and no read request is in the queue.	132	and no read request is in the queue (unlike read queue callbacks, this
		133	callback will only be called when at least one octet of data is in the
		134	read buffer).
99		135
100	To access (and remove data from) the read buffer, use the C<< ->rbuf >>	136	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
101	method or acces sthe C<$self->{rbuf}> member directly.	137	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		138	must not enlarge or modify the read buffer, you can only remove data at
		139	the beginning from it.
102		140
103	When an EOF condition is detected then AnyEvent::Handle will first try to	141	When an EOF condition is detected then AnyEvent::Handle will first try to
104	feed all the remaining data to the queued callbacks and C<on_read> before	142	feed all the remaining data to the queued callbacks and C<on_read> before
105	calling the C<on_eof> callback. If no progress can be made, then a fatal	143	calling the C<on_eof> callback. If no progress can be made, then a fatal
106	error will be raised (with C<$!> set to C<EPIPE>).	144	error will be raised (with C<$!> set to C<EPIPE>).
107		145
108	=item on_drain => $cb->()	146	=item on_drain => $cb->($handle)
109		147
110	This sets the callback that is called when the write buffer becomes empty	148	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).	149	(or when the callback is set and the buffer is empty already).
112		150
113	To append to the write buffer, use the C<< ->push_write >> method.	151	To append to the write buffer, use the C<< ->push_write >> method.
114		152
		153	This callback is useful when you don't want to put all of your write data
		154	into the queue at once, for example, when you want to write the contents
		155	of some file to the socket you might not want to read the whole file into
		156	memory and push it into the queue, but instead only read more data from
		157	the file when the write queue becomes empty.
		158
		159	=item timeout => $fractional_seconds
		160
		161	If non-zero, then this enables an "inactivity" timeout: whenever this many
		162	seconds pass without a successful read or write on the underlying file
		163	handle, the C<on_timeout> callback will be invoked (and if that one is
		164	missing, a non-fatal C<ETIMEDOUT> error will be raised).
		165
		166	Note that timeout processing is also active when you currently do not have
		167	any outstanding read or write requests: If you plan to keep the connection
		168	idle then you should disable the timout temporarily or ignore the timeout
		169	in the C<on_timeout> callback, in which case AnyEvent::Handle will simply
		170	restart the timeout.
		171
		172	Zero (the default) disables this timeout.
		173
		174	=item on_timeout => $cb->($handle)
		175
		176	Called whenever the inactivity timeout passes. If you return from this
		177	callback, then the timeout will be reset as if some activity had happened,
		178	so this condition is not fatal in any way.
		179
115	=item rbuf_max => <bytes>	180	=item rbuf_max => <bytes>
116		181
117	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)	182	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
118	when the read buffer ever (strictly) exceeds this size. This is useful to	183	when the read buffer ever (strictly) exceeds this size. This is useful to
119	avoid denial-of-service attacks.	184	avoid some forms of denial-of-service attacks.
120		185
121	For example, a server accepting connections from untrusted sources should	186	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	187	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	188	(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	189	amount of data without a callback ever being called as long as the line
125	isn't finished).	190	isn't finished).
126		191
		192	=item autocork => <boolean>
		193
		194	When disabled (the default), then C<push_write> will try to immediately
		195	write the data to the handle, if possible. This avoids having to register
		196	a write watcher and wait for the next event loop iteration, but can
		197	be inefficient if you write multiple small chunks (on the wire, this
		198	disadvantage is usually avoided by your kernel's nagle algorithm, see
		199	C<no_delay>, but this option can save costly syscalls).
		200
		201	When enabled, then writes will always be queued till the next event loop
		202	iteration. This is efficient when you do many small writes per iteration,
		203	but less efficient when you do a single write only per iteration (or when
		204	the write buffer often is full). It also increases write latency.
		205
		206	=item no_delay => <boolean>
		207
		208	When doing small writes on sockets, your operating system kernel might
		209	wait a bit for more data before actually sending it out. This is called
		210	the Nagle algorithm, and usually it is beneficial.
		211
		212	In some situations you want as low a delay as possible, which can be
		213	accomplishd by setting this option to a true value.
		214
		215	The default is your opertaing system's default behaviour (most likely
		216	enabled), this option explicitly enables or disables it, if possible.
		217
127	=item read_size => <bytes>	218	=item read_size => <bytes>
128		219
129	The default read block size (the amount of bytes this module will try to read	220	The default read block size (the amount of bytes this module will
130	on each [loop iteration). Default: C<4096>.	221	try to read during each loop iteration, which affects memory
		222	requirements). Default: C<8192>.
131		223
132	=item low_water_mark => <bytes>	224	=item low_water_mark => <bytes>
133		225
134	Sets the amount of bytes (default: C<0>) that make up an "empty" write	226	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	227	buffer: If the write reaches this size or gets even samller it is
136	considered empty.	228	considered empty.
137		229
		230	Sometimes it can be beneficial (for performance reasons) to add data to
		231	the write buffer before it is fully drained, but this is a rare case, as
		232	the operating system kernel usually buffers data as well, so the default
		233	is good in almost all cases.
		234
		235	=item linger => <seconds>
		236
		237	If non-zero (default: C<3600>), then the destructor of the
		238	AnyEvent::Handle object will check whether there is still outstanding
		239	write data and will install a watcher that will write this data to the
		240	socket. No errors will be reported (this mostly matches how the operating
		241	system treats outstanding data at socket close time).
		242
		243	This will not work for partial TLS data that could not be encoded
		244	yet. This data will be lost. Calling the C<stoptls> method in time might
		245	help.
		246
		247	=item peername => $string
		248
		249	A string used to identify the remote site - usually the DNS hostname
		250	(I<not> IDN!) used to create the connection, rarely the IP address.
		251
		252	Apart from being useful in error messages, this string is also used in TLS
		253	peername verification (see C<verify_peername> in L<AnyEvent::TLS>). This
		254	verification will be skipped when C<peername> is not specified or
		255	C<undef>.
		256
		257	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		258
		259	When this parameter is given, it enables TLS (SSL) mode, that means
		260	AnyEvent will start a TLS handshake as soon as the conenction has been
		261	established and will transparently encrypt/decrypt data afterwards.
		262
		263	All TLS protocol errors will be signalled as C<EPROTO>, with an
		264	appropriate error message.
		265
		266	TLS mode requires Net::SSLeay to be installed (it will be loaded
		267	automatically when you try to create a TLS handle): this module doesn't
		268	have a dependency on that module, so if your module requires it, you have
		269	to add the dependency yourself.
		270
		271	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		272	C<accept>, and for the TLS client side of a connection, use C<connect>
		273	mode.
		274
		275	You can also provide your own TLS connection object, but you have
		276	to make sure that you call either C<Net::SSLeay::set_connect_state>
		277	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		278	AnyEvent::Handle. Also, this module will take ownership of this connection
		279	object.
		280
		281	At some future point, AnyEvent::Handle might switch to another TLS
		282	implementation, then the option to use your own session object will go
		283	away.
		284
		285	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		286	passing in the wrong integer will lead to certain crash. This most often
		287	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		288	segmentation fault.
		289
		290	See the C<< ->starttls >> method for when need to start TLS negotiation later.
		291
		292	=item tls_ctx => $anyevent_tls
		293
		294	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		295	(unless a connection object was specified directly). If this parameter is
		296	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
		297
		298	Instead of an object, you can also specify a hash reference with C<< key
		299	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		300	new TLS context object.
		301
		302	=item on_starttls => $cb->($handle, $success[, $error_message])
		303
		304	This callback will be invoked when the TLS/SSL handshake has finished. If
		305	C<$success> is true, then the TLS handshake succeeded, otherwise it failed
		306	(C<on_stoptls> will not be called in this case).
		307
		308	The session in C<< $handle->{tls} >> can still be examined in this
		309	callback, even when the handshake was not successful.
		310
		311	TLS handshake failures will not cause C<on_error> to be invoked when this
		312	callback is in effect, instead, the error message will be passed to C<on_starttls>.
		313
		314	Without this callback, handshake failures lead to C<on_error> being
		315	called, as normal.
		316
		317	Note that you cannot call C<starttls> right again in this callback. If you
		318	need to do that, start an zero-second timer instead whose callback can
		319	then call C<< ->starttls >> again.
		320
		321	=item on_stoptls => $cb->($handle)
		322
		323	When a SSLv3/TLS shutdown/close notify/EOF is detected and this callback is
		324	set, then it will be invoked after freeing the TLS session. If it is not,
		325	then a TLS shutdown condition will be treated like a normal EOF condition
		326	on the handle.
		327
		328	The session in C<< $handle->{tls} >> can still be examined in this
		329	callback.
		330
		331	This callback will only be called on TLS shutdowns, not when the
		332	underlying handle signals EOF.
		333
		334	=item json => JSON or JSON::XS object
		335
		336	This is the json coder object used by the C<json> read and write types.
		337
		338	If you don't supply it, then AnyEvent::Handle will create and use a
		339	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		340	texts.
		341
		342	Note that you are responsible to depend on the JSON module if you want to
		343	use this functionality, as AnyEvent does not have a dependency itself.
		344
138	=back	345	=back
139		346
140	=cut	347	=cut
141		348
142	sub new {	349	sub new {
143	my $class = shift;	350	my $class = shift;
144
145	my $self = bless { @_ }, $class;	351	my $self = bless { @_ }, $class;
146		352
147	$self->{fh} or Carp::croak "mandatory argument fh is missing";	353	$self->{fh} or Carp::croak "mandatory argument fh is missing";
148		354
149	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	355	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
150		356
151	$self->on_eof ((delete $self->{on_eof} ) or Carp::croak "mandatory argument on_eof is missing");	357	$self->{_activity} = AnyEvent->now;
		358	$self->_timeout;
152		359
153	$self->on_error (delete $self->{on_error}) if $self->{on_error};	360	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		361
		362	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		363	if $self->{tls};
		364
154	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	365	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};
155	$self->on_read (delete $self->{on_read} ) if $self->{on_read};
156		366
157	$self->start_read;	367	$self->start_read
		368	if $self->{on_read};
158		369
159	$self	370	$self->{fh} && $self
160	}	371	}
161		372
162	sub _shutdown {	373	#sub _shutdown {
163	my ($self) = @_;	374	# my ($self) = @_;
		375	#
		376	# delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
		377	# $self->{_eof} = 1; # tell starttls et. al to stop trying
		378	#
		379	# &_freetls;
		380	#}
164		381
165	delete $self->{rw};
166	delete $self->{ww};
167	delete $self->{fh};
168	}
169
170	sub error {	382	sub _error {
171	my ($self) = @_;	383	my ($self, $errno, $fatal, $message) = @_;
172		384
173	{	385	$! = $errno;
174	local $!;	386	$message ||= "$!";
175	$self->_shutdown;
176	}
177		387
178	if ($self->{on_error}) {	388	if ($self->{on_error}) {
179	$self->{on_error}($self);	389	$self->{on_error}($self, $fatal, $message);
180	} else {	390	$self->destroy;
		391	} elsif ($self->{fh}) {
		392	$self->destroy;
181	die "AnyEvent::Handle uncaught fatal error: $!";	393	Carp::croak "AnyEvent::Handle uncaught error: $message";
182	}	394	}
183	}	395	}
184		396
185	=item $fh = $handle->fh	397	=item $fh = $handle->fh
186		398
187	This method returns the filehandle of the L<AnyEvent::Handle> object.	399	This method returns the file handle used to create the L<AnyEvent::Handle> object.
188		400
189	=cut	401	=cut
190		402
191	sub fh { $_[0]->{fh} }	403	sub fh { $_[0]{fh} }
192		404
193	=item $handle->on_error ($cb)	405	=item $handle->on_error ($cb)
194		406
195	Replace the current C<on_error> callback (see the C<on_error> constructor argument).	407	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
196		408
…		…
208		420
209	sub on_eof {	421	sub on_eof {
210	$_[0]{on_eof} = $_[1];	422	$_[0]{on_eof} = $_[1];
211	}	423	}
212		424
		425	=item $handle->on_timeout ($cb)
		426
		427	Replace the current C<on_timeout> callback, or disables the callback (but
		428	not the timeout) if C<$cb> = C<undef>. See the C<timeout> constructor
		429	argument and method.
		430
		431	=cut
		432
		433	sub on_timeout {
		434	$_[0]{on_timeout} = $_[1];
		435	}
		436
		437	=item $handle->autocork ($boolean)
		438
		439	Enables or disables the current autocork behaviour (see C<autocork>
		440	constructor argument). Changes will only take effect on the next write.
		441
		442	=cut
		443
		444	sub autocork {
		445	$_[0]{autocork} = $_[1];
		446	}
		447
		448	=item $handle->no_delay ($boolean)
		449
		450	Enables or disables the C<no_delay> setting (see constructor argument of
		451	the same name for details).
		452
		453	=cut
		454
		455	sub no_delay {
		456	$_[0]{no_delay} = $_[1];
		457
		458	eval {
		459	local $SIG{__DIE__};
		460	setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
		461	};
		462	}
		463
		464	=item $handle->on_starttls ($cb)
		465
		466	Replace the current C<on_starttls> callback (see the C<on_starttls> constructor argument).
		467
		468	=cut
		469
		470	sub on_starttls {
		471	$_[0]{on_starttls} = $_[1];
		472	}
		473
		474	=item $handle->on_stoptls ($cb)
		475
		476	Replace the current C<on_stoptls> callback (see the C<on_stoptls> constructor argument).
		477
		478	=cut
		479
		480	sub on_starttls {
		481	$_[0]{on_stoptls} = $_[1];
		482	}
		483
		484	#############################################################################
		485
		486	=item $handle->timeout ($seconds)
		487
		488	Configures (or disables) the inactivity timeout.
		489
		490	=cut
		491
		492	sub timeout {
		493	my ($self, $timeout) = @_;
		494
		495	$self->{timeout} = $timeout;
		496	$self->_timeout;
		497	}
		498
		499	# reset the timeout watcher, as neccessary
		500	# also check for time-outs
		501	sub _timeout {
		502	my ($self) = @_;
		503
		504	if ($self->{timeout}) {
		505	my $NOW = AnyEvent->now;
		506
		507	# when would the timeout trigger?
		508	my $after = $self->{_activity} + $self->{timeout} - $NOW;
		509
		510	# now or in the past already?
		511	if ($after <= 0) {
		512	$self->{_activity} = $NOW;
		513
		514	if ($self->{on_timeout}) {
		515	$self->{on_timeout}($self);
		516	} else {
		517	$self->_error (&Errno::ETIMEDOUT);
		518	}
		519
		520	# callback could have changed timeout value, optimise
		521	return unless $self->{timeout};
		522
		523	# calculate new after
		524	$after = $self->{timeout};
		525	}
		526
		527	Scalar::Util::weaken $self;
		528	return unless $self; # ->error could have destroyed $self
		529
		530	$self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
		531	delete $self->{_tw};
		532	$self->_timeout;
		533	});
		534	} else {
		535	delete $self->{_tw};
		536	}
		537	}
		538
213	#############################################################################	539	#############################################################################
214		540
215	=back	541	=back
216		542
217	=head2 WRITE QUEUE	543	=head2 WRITE QUEUE
…		…
220	for reading.	546	for reading.
221		547
222	The write queue is very simple: you can add data to its end, and	548	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.	549	AnyEvent::Handle will automatically try to get rid of it for you.
224		550
225	When data could be writtena nd the write buffer is shorter then the low	551	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.	552	water mark, the C<on_drain> callback will be invoked.
227		553
228	=over 4	554	=over 4
229		555
230	=item $handle->on_drain ($cb)	556	=item $handle->on_drain ($cb)
…		…
238	my ($self, $cb) = @_;	564	my ($self, $cb) = @_;
239		565
240	$self->{on_drain} = $cb;	566	$self->{on_drain} = $cb;
241		567
242	$cb->($self)	568	$cb->($self)
243	if $cb && $self->{low_water_mark} >= length $self->{wbuf};	569	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
244	}	570	}
245		571
246	=item $handle->push_write ($data)	572	=item $handle->push_write ($data)
247		573
248	Queues the given scalar to be written. You can push as much data as you	574	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>	575	want (only limited by the available memory), as C<AnyEvent::Handle>
250	buffers it independently of the kernel.	576	buffers it independently of the kernel.
251		577
252	=cut	578	=cut
253		579
254	sub push_write {	580	sub _drain_wbuf {
255	my ($self, $data) = @_;	581	my ($self) = @_;
256		582
257	$self->{wbuf} .= $data;	583	if (!$self->{_ww} && length $self->{wbuf}) {
258		584
259	unless ($self->{ww}) {
260	Scalar::Util::weaken $self;	585	Scalar::Util::weaken $self;
		586
261	my $cb = sub {	587	my $cb = sub {
262	my $len = syswrite $self->{fh}, $self->{wbuf};	588	my $len = syswrite $self->{fh}, $self->{wbuf};
263		589
264	if ($len > 0) {	590	if (defined $len) {
265	substr $self->{wbuf}, 0, $len, "";	591	substr $self->{wbuf}, 0, $len, "";
266		592
		593	$self->{_activity} = AnyEvent->now;
267		594
268	$self->{on_drain}($self)	595	$self->{on_drain}($self)
269	if $self->{low_water_mark} >= length $self->{wbuf}	596	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
270	&& $self->{on_drain};	597	&& $self->{on_drain};
271		598
272	delete $self->{ww} unless length $self->{wbuf};	599	delete $self->{_ww} unless length $self->{wbuf};
273	} elsif ($! != EAGAIN && $! != EINTR) {	600	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
274	$self->error;	601	$self->_error ($!, 1);
275	}	602	}
276	};	603	};
277		604
		605	# try to write data immediately
		606	$cb->() unless $self->{autocork};
		607
		608	# if still data left in wbuf, we need to poll
278	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	609	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
279		610	if length $self->{wbuf};
280	$cb->($self);
281	};	611	};
282	}	612	}
		613
		614	our %WH;
		615
		616	sub register_write_type($$) {
		617	$WH{$_[0]} = $_[1];
		618	}
		619
		620	sub push_write {
		621	my $self = shift;
		622
		623	if (@_ > 1) {
		624	my $type = shift;
		625
		626	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
		627	->($self, @_);
		628	}
		629
		630	if ($self->{tls}) {
		631	$self->{_tls_wbuf} .= $_[0];
		632
		633	&_dotls ($self);
		634	} else {
		635	$self->{wbuf} .= $_[0];
		636	$self->_drain_wbuf;
		637	}
		638	}
		639
		640	=item $handle->push_write (type => @args)
		641
		642	Instead of formatting your data yourself, you can also let this module do
		643	the job by specifying a type and type-specific arguments.
		644
		645	Predefined types are (if you have ideas for additional types, feel free to
		646	drop by and tell us):
		647
		648	=over 4
		649
		650	=item netstring => $string
		651
		652	Formats the given value as netstring
		653	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		654
		655	=cut
		656
		657	register_write_type netstring => sub {
		658	my ($self, $string) = @_;
		659
		660	(length $string) . ":$string,"
		661	};
		662
		663	=item packstring => $format, $data
		664
		665	An octet string prefixed with an encoded length. The encoding C<$format>
		666	uses the same format as a Perl C<pack> format, but must specify a single
		667	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		668	optional C<!>, C<< < >> or C<< > >> modifier).
		669
		670	=cut
		671
		672	register_write_type packstring => sub {
		673	my ($self, $format, $string) = @_;
		674
		675	pack "$format/a*", $string
		676	};
		677
		678	=item json => $array_or_hashref
		679
		680	Encodes the given hash or array reference into a JSON object. Unless you
		681	provide your own JSON object, this means it will be encoded to JSON text
		682	in UTF-8.
		683
		684	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		685	one end of a handle and read them at the other end without using any
		686	additional framing.
		687
		688	The generated JSON text is guaranteed not to contain any newlines: While
		689	this module doesn't need delimiters after or between JSON texts to be
		690	able to read them, many other languages depend on that.
		691
		692	A simple RPC protocol that interoperates easily with others is to send
		693	JSON arrays (or objects, although arrays are usually the better choice as
		694	they mimic how function argument passing works) and a newline after each
		695	JSON text:
		696
		697	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		698	$handle->push_write ("\012");
		699
		700	An AnyEvent::Handle receiver would simply use the C<json> read type and
		701	rely on the fact that the newline will be skipped as leading whitespace:
		702
		703	$handle->push_read (json => sub { my $array = $_[1]; ... });
		704
		705	Other languages could read single lines terminated by a newline and pass
		706	this line into their JSON decoder of choice.
		707
		708	=cut
		709
		710	register_write_type json => sub {
		711	my ($self, $ref) = @_;
		712
		713	require JSON;
		714
		715	$self->{json} ? $self->{json}->encode ($ref)
		716	: JSON::encode_json ($ref)
		717	};
		718
		719	=item storable => $reference
		720
		721	Freezes the given reference using L<Storable> and writes it to the
		722	handle. Uses the C<nfreeze> format.
		723
		724	=cut
		725
		726	register_write_type storable => sub {
		727	my ($self, $ref) = @_;
		728
		729	require Storable;
		730
		731	pack "w/a*", Storable::nfreeze ($ref)
		732	};
		733
		734	=back
		735
		736	=item $handle->push_shutdown
		737
		738	Sometimes you know you want to close the socket after writing your data
		739	before it was actually written. One way to do that is to replace your
		740	C<on_drain> handler by a callback that shuts down the socket (and set
		741	C<low_water_mark> to C<0>). This method is a shorthand for just that, and
		742	replaces the C<on_drain> callback with:
		743
		744	sub { shutdown $_[0]{fh}, 1 } # for push_shutdown
		745
		746	This simply shuts down the write side and signals an EOF condition to the
		747	the peer.
		748
		749	You can rely on the normal read queue and C<on_eof> handling
		750	afterwards. This is the cleanest way to close a connection.
		751
		752	=cut
		753
		754	sub push_shutdown {
		755	my ($self) = @_;
		756
		757	delete $self->{low_water_mark};
		758	$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
		759	}
		760
		761	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
		762
		763	This function (not method) lets you add your own types to C<push_write>.
		764	Whenever the given C<type> is used, C<push_write> will invoke the code
		765	reference with the handle object and the remaining arguments.
		766
		767	The code reference is supposed to return a single octet string that will
		768	be appended to the write buffer.
		769
		770	Note that this is a function, and all types registered this way will be
		771	global, so try to use unique names.
		772
		773	=cut
283		774
284	#############################################################################	775	#############################################################################
285		776
286	=back	777	=back
287		778
…		…
294	ways, the "simple" way, using only C<on_read> and the "complex" way, using	785	ways, the "simple" way, using only C<on_read> and the "complex" way, using
295	a queue.	786	a queue.
296		787
297	In the simple case, you just install an C<on_read> callback and whenever	788	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	789	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	790	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
300	or not.	791	leave the data there if you want to accumulate more (e.g. when only a
		792	partial message has been received so far).
301		793
302	In the more complex case, you want to queue multiple callbacks. In this	794	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	795	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>,	796	data arrives (also the first time it is queued) and removes it when it has
305	below).	797	done its job (see C<push_read>, below).
306		798
307	This way you can, for example, push three line-reads, followed by reading	799	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.	800	a chunk of data, and AnyEvent::Handle will execute them in order.
309		801
310	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by	802	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
311	the specified number of bytes which give an XML datagram.	803	the specified number of bytes which give an XML datagram.
312		804
313	# in the default state, expect some header bytes	805	# in the default state, expect some header bytes
314	$handle->on_read (sub {	806	$handle->on_read (sub {
315	# some data is here, now queue the length-header-read (4 octets)	807	# some data is here, now queue the length-header-read (4 octets)
316	shift->unshift_read_chunk (4, sub {	808	shift->unshift_read (chunk => 4, sub {
317	# header arrived, decode	809	# header arrived, decode
318	my $len = unpack "N", $_[1];	810	my $len = unpack "N", $_[1];
319		811
320	# now read the payload	812	# now read the payload
321	shift->unshift_read_chunk ($len, sub {	813	shift->unshift_read (chunk => $len, sub {
322	my $xml = $_[1];	814	my $xml = $_[1];
323	# handle xml	815	# handle xml
324	});	816	});
325	});	817	});
326	});	818	});
327		819
328	Example 2: Implement a client for a protocol that replies either with	820	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	821	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	822	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	823	just pipeline sending both requests and manipulate the queue as necessary
332	the callbacks:	824	in the callbacks.
333		825
334	# request one	826	When the first callback is called and sees an "OK" response, it will
		827	C<unshift> another line-read. This line-read will be queued I<before> the
		828	64-byte chunk callback.
		829
		830	# request one, returns either "OK + extra line" or "ERROR"
335	$handle->push_write ("request 1\015\012");	831	$handle->push_write ("request 1\015\012");
336		832
337	# we expect "ERROR" or "OK" as response, so push a line read	833	# we expect "ERROR" or "OK" as response, so push a line read
338	$handle->push_read_line (sub {	834	$handle->push_read (line => sub {
339	# if we got an "OK", we have to _prepend_ another line,	835	# 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	836	# 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	837	# which are already in the queue when this callback is called
342	# we don't do this in case we got an error	838	# we don't do this in case we got an error
343	if ($_[1] eq "OK") {	839	if ($_[1] eq "OK") {
344	$_[0]->unshift_read_line (sub {	840	$_[0]->unshift_read (line => sub {
345	my $response = $_[1];	841	my $response = $_[1];
346	...	842	...
347	});	843	});
348	}	844	}
349	});	845	});
350		846
351	# request two	847	# request two, simply returns 64 octets
352	$handle->push_write ("request 2\015\012");	848	$handle->push_write ("request 2\015\012");
353		849
354	# simply read 64 bytes, always	850	# simply read 64 bytes, always
355	$handle->push_read_chunk (64, sub {	851	$handle->push_read (chunk => 64, sub {
356	my $response = $_[1];	852	my $response = $_[1];
357	...	853	...
358	});	854	});
359		855
360	=over 4	856	=over 4
…		…
362	=cut	858	=cut
363		859
364	sub _drain_rbuf {	860	sub _drain_rbuf {
365	my ($self) = @_;	861	my ($self) = @_;
366		862
367	return if exists $self->{in_drain};
368	local $self->{in_drain} = 1;	863	local $self->{_in_drain} = 1;
369		864
		865	if (
		866	defined $self->{rbuf_max}
		867	&& $self->{rbuf_max} < length $self->{rbuf}
		868	) {
		869	$self->_error (&Errno::ENOSPC, 1), return;
		870	}
		871
		872	while () {
		873	# we need to use a separate tls read buffer, as we must not receive data while
		874	# we are draining the buffer, and this can only happen with TLS.
		875	$self->{rbuf} .= delete $self->{_tls_rbuf} if exists $self->{_tls_rbuf};
		876
370	while (my $len = length $self->{rbuf}) {	877	my $len = length $self->{rbuf};
371	no strict 'refs';	878
372	if (my $cb = shift @{ $self->{queue} }) {	879	if (my $cb = shift @{ $self->{_queue} }) {
373	if (!$cb->($self)) {	880	unless ($cb->($self)) {
374	if ($self->{eof}) {	881	if ($self->{_eof}) {
375	# no progress can be made (not enough data and no data forthcoming)	882	# no progress can be made (not enough data and no data forthcoming)
376	$! = &Errno::EPIPE; return $self->error;	883	$self->_error (&Errno::EPIPE, 1), return;
377	}	884	}
378		885
379	unshift @{ $self->{queue} }, $cb;	886	unshift @{ $self->{_queue} }, $cb;
380	return;	887	last;
381	}	888	}
382	} elsif ($self->{on_read}) {	889	} elsif ($self->{on_read}) {
		890	last unless $len;
		891
383	$self->{on_read}($self);	892	$self->{on_read}($self);
384		893
385	if (	894	if (
386	$self->{eof} # if no further data will arrive
387	&& $len == length $self->{rbuf} # and no data has been consumed	895	$len == length $self->{rbuf} # if no data has been consumed
388	&& !@{ $self->{queue} } # and the queue is still empty	896	&& !@{ $self->{_queue} } # and the queue is still empty
389	&& $self->{on_read} # and we still want to read data	897	&& $self->{on_read} # but we still have on_read
390	) {	898	) {
		899	# no further data will arrive
391	# then no progress can be made	900	# so no progress can be made
392	$! = &Errno::EPIPE; return $self->error;	901	$self->_error (&Errno::EPIPE, 1), return
		902	if $self->{_eof};
		903
		904	last; # more data might arrive
393	}	905	}
394	} else {	906	} else {
395	# read side becomes idle	907	# read side becomes idle
396	delete $self->{rw};	908	delete $self->{_rw} unless $self->{tls};
397	return;	909	last;
398	}	910	}
399	}	911	}
400		912
401	if ($self->{eof}) {	913	if ($self->{_eof}) {
402	$self->_shutdown;	914	if ($self->{on_eof}) {
403	$self->{on_eof}($self);	915	$self->{on_eof}($self)
		916	} else {
		917	$self->_error (0, 1, "Unexpected end-of-file");
		918	}
		919	}
		920
		921	# may need to restart read watcher
		922	unless ($self->{_rw}) {
		923	$self->start_read
		924	if $self->{on_read} || @{ $self->{_queue} };
404	}	925	}
405	}	926	}
406		927
407	=item $handle->on_read ($cb)	928	=item $handle->on_read ($cb)
408		929
…		…
414		935
415	sub on_read {	936	sub on_read {
416	my ($self, $cb) = @_;	937	my ($self, $cb) = @_;
417		938
418	$self->{on_read} = $cb;	939	$self->{on_read} = $cb;
		940	$self->_drain_rbuf if $cb && !$self->{_in_drain};
419	}	941	}
420		942
421	=item $handle->rbuf	943	=item $handle->rbuf
422		944
423	Returns the read buffer (as a modifiable lvalue).	945	Returns the read buffer (as a modifiable lvalue).
424		946
425	You can access the read buffer directly as the C<< ->{rbuf} >> member, if	947	You can access the read buffer directly as the C<< ->{rbuf} >>
426	you want.	948	member, if you want. However, the only operation allowed on the
		949	read buffer (apart from looking at it) is removing data from its
		950	beginning. Otherwise modifying or appending to it is not allowed and will
		951	lead to hard-to-track-down bugs.
427		952
428	NOTE: The read buffer should only be used or modified if the C<on_read>,	953	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	954	C<push_read> or C<unshift_read> methods are used. The other read methods
430	automatically manage the read buffer.	955	automatically manage the read buffer.
431		956
…		…
442	Append the given callback to the end of the queue (C<push_read>) or	967	Append the given callback to the end of the queue (C<push_read>) or
443	prepend it (C<unshift_read>).	968	prepend it (C<unshift_read>).
444		969
445	The callback is called each time some additional read data arrives.	970	The callback is called each time some additional read data arrives.
446		971
447	It must check wether enough data is in the read buffer already.	972	It must check whether enough data is in the read buffer already.
448		973
449	If not enough data is available, it must return the empty list or a false	974	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	975	value, in which case it will be called repeatedly until enough data is
451	available (or an error condition is detected).	976	available (or an error condition is detected).
452		977
…		…
454	interested in (which can be none at all) and return a true value. After returning	979	interested in (which can be none at all) and return a true value. After returning
455	true, it will be removed from the queue.	980	true, it will be removed from the queue.
456		981
457	=cut	982	=cut
458		983
		984	our %RH;
		985
		986	sub register_read_type($$) {
		987	$RH{$_[0]} = $_[1];
		988	}
		989
459	sub push_read {	990	sub push_read {
460	my ($self, $cb) = @_;	991	my $self = shift;
		992	my $cb = pop;
461		993
		994	if (@_) {
		995	my $type = shift;
		996
		997	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
		998	->($self, $cb, @_);
		999	}
		1000
462	push @{ $self->{queue} }, $cb;	1001	push @{ $self->{_queue} }, $cb;
463	$self->_drain_rbuf;	1002	$self->_drain_rbuf unless $self->{_in_drain};
464	}	1003	}
465		1004
466	sub unshift_read {	1005	sub unshift_read {
467	my ($self, $cb) = @_;	1006	my $self = shift;
		1007	my $cb = pop;
468		1008
		1009	if (@_) {
		1010	my $type = shift;
		1011
		1012	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
		1013	->($self, $cb, @_);
		1014	}
		1015
		1016
469	push @{ $self->{queue} }, $cb;	1017	unshift @{ $self->{_queue} }, $cb;
470	$self->_drain_rbuf;	1018	$self->_drain_rbuf unless $self->{_in_drain};
471	}	1019	}
472		1020
473	=item $handle->push_read_chunk ($len, $cb->($self, $data))	1021	=item $handle->push_read (type => @args, $cb)
474		1022
475	=item $handle->unshift_read_chunk ($len, $cb->($self, $data))	1023	=item $handle->unshift_read (type => @args, $cb)
476		1024
477	Append the given callback to the end of the queue (C<push_read_chunk>) or	1025	Instead of providing a callback that parses the data itself you can chose
478	prepend it (C<unshift_read_chunk>).	1026	between a number of predefined parsing formats, for chunks of data, lines
		1027	etc.
479		1028
480	The callback will be called only once C<$len> bytes have been read, and	1029	Predefined types are (if you have ideas for additional types, feel free to
481	these C<$len> bytes will be passed to the callback.	1030	drop by and tell us):
482		1031
483	=cut	1032	=over 4
484		1033
485	sub _read_chunk($$) {	1034	=item chunk => $octets, $cb->($handle, $data)
		1035
		1036	Invoke the callback only once C<$octets> bytes have been read. Pass the
		1037	data read to the callback. The callback will never be called with less
		1038	data.
		1039
		1040	Example: read 2 bytes.
		1041
		1042	$handle->push_read (chunk => 2, sub {
		1043	warn "yay ", unpack "H*", $_[1];
		1044	});
		1045
		1046	=cut
		1047
		1048	register_read_type chunk => sub {
486	my ($self, $len, $cb) = @_;	1049	my ($self, $cb, $len) = @_;
487		1050
488	sub {	1051	sub {
489	$len <= length $_[0]{rbuf} or return;	1052	$len <= length $_[0]{rbuf} or return;
490	$cb->($self, $_[0], substr $_[0]{rbuf}, 0, $len, "");	1053	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
491	1	1054	1
492	}	1055	}
493	}	1056	};
494		1057
495	sub push_read_chunk {	1058	=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		1059
511	The callback will be called only once a full line (including the end of	1060	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	1061	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	1062	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>).	1063	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	1074	Partial lines at the end of the stream will never be returned, as they are
526	not marked by the end of line marker.	1075	not marked by the end of line marker.
527		1076
528	=cut	1077	=cut
529		1078
530	sub _read_line($$) {	1079	register_read_type line => sub {
531	my $self = shift;	1080	my ($self, $cb, $eol) = @_;
532	my $cb = pop;
533	my $eol = @_ ? shift : qr|(\015?\012)|;
534	my $pos;
535		1081
		1082	if (@_ < 3) {
		1083	# this is more than twice as fast as the generic code below
		1084	sub {
		1085	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		1086
		1087	$cb->($_[0], $1, $2);
		1088	1
		1089	}
		1090	} else {
536	$eol = qr|(\Q$eol\E)| unless ref $eol;	1091	$eol = quotemeta $eol unless ref $eol;
537	$eol = qr|^(.*?)($eol)|;	1092	$eol = qr|^(.*?)($eol)|s;
		1093
		1094	sub {
		1095	$_[0]{rbuf} =~ s/$eol// or return;
		1096
		1097	$cb->($_[0], $1, $2);
		1098	1
		1099	}
		1100	}
		1101	};
		1102
		1103	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1104
		1105	Makes a regex match against the regex object C<$accept> and returns
		1106	everything up to and including the match.
		1107
		1108	Example: read a single line terminated by '\n'.
		1109
		1110	$handle->push_read (regex => qr<\n>, sub { ... });
		1111
		1112	If C<$reject> is given and not undef, then it determines when the data is
		1113	to be rejected: it is matched against the data when the C<$accept> regex
		1114	does not match and generates an C<EBADMSG> error when it matches. This is
		1115	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1116	receive buffer overflow).
		1117
		1118	Example: expect a single decimal number followed by whitespace, reject
		1119	anything else (not the use of an anchor).
		1120
		1121	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1122
		1123	If C<$skip> is given and not C<undef>, then it will be matched against
		1124	the receive buffer when neither C<$accept> nor C<$reject> match,
		1125	and everything preceding and including the match will be accepted
		1126	unconditionally. This is useful to skip large amounts of data that you
		1127	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1128	have to start matching from the beginning. This is purely an optimisation
		1129	and is usually worth only when you expect more than a few kilobytes.
		1130
		1131	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1132	expect the header to be very large (it isn't in practise, but...), we use
		1133	a skip regex to skip initial portions. The skip regex is tricky in that
		1134	it only accepts something not ending in either \015 or \012, as these are
		1135	required for the accept regex.
		1136
		1137	$handle->push_read (regex =>
		1138	qr<\015\012\015\012>,
		1139	undef, # no reject
		1140	qr<^.*[^\015\012]>,
		1141	sub { ... });
		1142
		1143	=cut
		1144
		1145	register_read_type regex => sub {
		1146	my ($self, $cb, $accept, $reject, $skip) = @_;
		1147
		1148	my $data;
		1149	my $rbuf = \$self->{rbuf};
538		1150
539	sub {	1151	sub {
540	$_[0]{rbuf} =~ s/$eol// or return;	1152	# accept
541		1153	if ($$rbuf =~ $accept) {
		1154	$data .= substr $$rbuf, 0, $+[0], "";
542	$cb->($self, $1, $2);	1155	$cb->($self, $data);
		1156	return 1;
		1157	}
		1158
		1159	# reject
		1160	if ($reject && $$rbuf =~ $reject) {
		1161	$self->_error (&Errno::EBADMSG);
		1162	}
		1163
		1164	# skip
		1165	if ($skip && $$rbuf =~ $skip) {
		1166	$data .= substr $$rbuf, 0, $+[0], "";
		1167	}
		1168
		1169	()
		1170	}
		1171	};
		1172
		1173	=item netstring => $cb->($handle, $string)
		1174
		1175	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1176
		1177	Throws an error with C<$!> set to EBADMSG on format violations.
		1178
		1179	=cut
		1180
		1181	register_read_type netstring => sub {
		1182	my ($self, $cb) = @_;
		1183
		1184	sub {
		1185	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1186	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1187	$self->_error (&Errno::EBADMSG);
		1188	}
		1189	return;
		1190	}
		1191
		1192	my $len = $1;
		1193
		1194	$self->unshift_read (chunk => $len, sub {
		1195	my $string = $_[1];
		1196	$_[0]->unshift_read (chunk => 1, sub {
		1197	if ($_[1] eq ",") {
		1198	$cb->($_[0], $string);
		1199	} else {
		1200	$self->_error (&Errno::EBADMSG);
		1201	}
		1202	});
		1203	});
		1204
543	1	1205	1
544	}	1206	}
545	}	1207	};
546		1208
547	sub push_read_line {	1209	=item packstring => $format, $cb->($handle, $string)
548	$_[0]->push_read (&_read_line);
549	}
550		1210
551	sub unshift_read_line {	1211	An octet string prefixed with an encoded length. The encoding C<$format>
552	$_[0]->unshift_read (&_read_line);	1212	uses the same format as a Perl C<pack> format, but must specify a single
553	}	1213	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1214	optional C<!>, C<< < >> or C<< > >> modifier).
		1215
		1216	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1217	EPP uses a prefix of C<N> (4 octtes).
		1218
		1219	Example: read a block of data prefixed by its length in BER-encoded
		1220	format (very efficient).
		1221
		1222	$handle->push_read (packstring => "w", sub {
		1223	my ($handle, $data) = @_;
		1224	});
		1225
		1226	=cut
		1227
		1228	register_read_type packstring => sub {
		1229	my ($self, $cb, $format) = @_;
		1230
		1231	sub {
		1232	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1233	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1234	or return;
		1235
		1236	$format = length pack $format, $len;
		1237
		1238	# bypass unshift if we already have the remaining chunk
		1239	if ($format + $len <= length $_[0]{rbuf}) {
		1240	my $data = substr $_[0]{rbuf}, $format, $len;
		1241	substr $_[0]{rbuf}, 0, $format + $len, "";
		1242	$cb->($_[0], $data);
		1243	} else {
		1244	# remove prefix
		1245	substr $_[0]{rbuf}, 0, $format, "";
		1246
		1247	# read remaining chunk
		1248	$_[0]->unshift_read (chunk => $len, $cb);
		1249	}
		1250
		1251	1
		1252	}
		1253	};
		1254
		1255	=item json => $cb->($handle, $hash_or_arrayref)
		1256
		1257	Reads a JSON object or array, decodes it and passes it to the
		1258	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1259
		1260	If a C<json> object was passed to the constructor, then that will be used
		1261	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1262
		1263	This read type uses the incremental parser available with JSON version
		1264	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1265	dependency on your own: this module will load the JSON module, but
		1266	AnyEvent does not depend on it itself.
		1267
		1268	Since JSON texts are fully self-delimiting, the C<json> read and write
		1269	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1270	the C<json> write type description, above, for an actual example.
		1271
		1272	=cut
		1273
		1274	register_read_type json => sub {
		1275	my ($self, $cb) = @_;
		1276
		1277	my $json = $self->{json} ||=
		1278	eval { require JSON::XS; JSON::XS->new->utf8 }
		1279	|| do { require JSON; JSON->new->utf8 };
		1280
		1281	my $data;
		1282	my $rbuf = \$self->{rbuf};
		1283
		1284	sub {
		1285	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1286
		1287	if ($ref) {
		1288	$self->{rbuf} = $json->incr_text;
		1289	$json->incr_text = "";
		1290	$cb->($self, $ref);
		1291
		1292	1
		1293	} elsif ($@) {
		1294	# error case
		1295	$json->incr_skip;
		1296
		1297	$self->{rbuf} = $json->incr_text;
		1298	$json->incr_text = "";
		1299
		1300	$self->_error (&Errno::EBADMSG);
		1301
		1302	()
		1303	} else {
		1304	$self->{rbuf} = "";
		1305
		1306	()
		1307	}
		1308	}
		1309	};
		1310
		1311	=item storable => $cb->($handle, $ref)
		1312
		1313	Deserialises a L<Storable> frozen representation as written by the
		1314	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1315	data).
		1316
		1317	Raises C<EBADMSG> error if the data could not be decoded.
		1318
		1319	=cut
		1320
		1321	register_read_type storable => sub {
		1322	my ($self, $cb) = @_;
		1323
		1324	require Storable;
		1325
		1326	sub {
		1327	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1328	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1329	or return;
		1330
		1331	my $format = length pack "w", $len;
		1332
		1333	# bypass unshift if we already have the remaining chunk
		1334	if ($format + $len <= length $_[0]{rbuf}) {
		1335	my $data = substr $_[0]{rbuf}, $format, $len;
		1336	substr $_[0]{rbuf}, 0, $format + $len, "";
		1337	$cb->($_[0], Storable::thaw ($data));
		1338	} else {
		1339	# remove prefix
		1340	substr $_[0]{rbuf}, 0, $format, "";
		1341
		1342	# read remaining chunk
		1343	$_[0]->unshift_read (chunk => $len, sub {
		1344	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1345	$cb->($_[0], $ref);
		1346	} else {
		1347	$self->_error (&Errno::EBADMSG);
		1348	}
		1349	});
		1350	}
		1351
		1352	1
		1353	}
		1354	};
		1355
		1356	=back
		1357
		1358	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
		1359
		1360	This function (not method) lets you add your own types to C<push_read>.
		1361
		1362	Whenever the given C<type> is used, C<push_read> will invoke the code
		1363	reference with the handle object, the callback and the remaining
		1364	arguments.
		1365
		1366	The code reference is supposed to return a callback (usually a closure)
		1367	that works as a plain read callback (see C<< ->push_read ($cb) >>).
		1368
		1369	It should invoke the passed callback when it is done reading (remember to
		1370	pass C<$handle> as first argument as all other callbacks do that).
		1371
		1372	Note that this is a function, and all types registered this way will be
		1373	global, so try to use unique names.
		1374
		1375	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
		1376	search for C<register_read_type>)).
554		1377
555	=item $handle->stop_read	1378	=item $handle->stop_read
556		1379
557	=item $handle->start_read	1380	=item $handle->start_read
558		1381
559	In rare cases you actually do not want to read anything form the	1382	In rare cases you actually do not want to read anything from the
560	socket. In this case you can call C<stop_read>. Neither C<on_read> no	1383	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
561	any queued callbacks will be executed then. To start readign again, call	1384	any queued callbacks will be executed then. To start reading again, call
562	C<start_read>.	1385	C<start_read>.
		1386
		1387	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1388	you change the C<on_read> callback or push/unshift a read callback, and it
		1389	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1390	there are any read requests in the queue.
		1391
		1392	These methods will have no effect when in TLS mode (as TLS doesn't support
		1393	half-duplex connections).
563		1394
564	=cut	1395	=cut
565		1396
566	sub stop_read {	1397	sub stop_read {
567	my ($self) = @_;	1398	my ($self) = @_;
568		1399
569	delete $self->{rw};	1400	delete $self->{_rw} unless $self->{tls};
570	}	1401	}
571		1402
572	sub start_read {	1403	sub start_read {
573	my ($self) = @_;	1404	my ($self) = @_;
574		1405
575	unless ($self->{rw} || $self->{eof}) {	1406	unless ($self->{_rw} || $self->{_eof}) {
576	Scalar::Util::weaken $self;	1407	Scalar::Util::weaken $self;
577		1408
578	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {	1409	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
		1410	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
579	my $len = sysread $self->{fh}, $self->{rbuf}, $self->{read_size} || 8192, length $self->{rbuf};	1411	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
580		1412
581	if ($len > 0) {	1413	if ($len > 0) {
		1414	$self->{_activity} = AnyEvent->now;
		1415
582	if (exists $self->{rbuf_max}) {	1416	if ($self->{tls}) {
583	if ($self->{rbuf_max} < length $self->{rbuf}) {	1417	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
584	$! = &Errno::ENOSPC; return $self->error;	1418
585	}	1419	&_dotls ($self);
		1420	} else {
		1421	$self->_drain_rbuf unless $self->{_in_drain};
586	}	1422	}
587		1423
588	} elsif (defined $len) {	1424	} elsif (defined $len) {
589	$self->{eof} = 1;
590	delete $self->{rw};	1425	delete $self->{_rw};
		1426	$self->{_eof} = 1;
		1427	$self->_drain_rbuf unless $self->{_in_drain};
591		1428
592	} elsif ($! != EAGAIN && $! != EINTR) {	1429	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
593	return $self->error;	1430	return $self->_error ($!, 1);
594	}	1431	}
595
596	$self->_drain_rbuf;
597	});	1432	});
598	}	1433	}
599	}	1434	}
600		1435
		1436	our $ERROR_SYSCALL;
		1437	our $ERROR_WANT_READ;
		1438
		1439	sub _tls_error {
		1440	my ($self, $err) = @_;
		1441
		1442	return $self->_error ($!, 1)
		1443	if $err == Net::SSLeay::ERROR_SYSCALL ();
		1444
		1445	my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
		1446
		1447	# reduce error string to look less scary
		1448	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
		1449
		1450	if ($self->{_on_starttls}) {
		1451	(delete $self->{_on_starttls})->($self, undef, $err);
		1452	&_freetls;
		1453	} else {
		1454	&_freetls;
		1455	$self->_error (&Errno::EPROTO, 1, $err);
		1456	}
		1457	}
		1458
		1459	# poll the write BIO and send the data if applicable
		1460	# also decode read data if possible
		1461	# this is basiclaly our TLS state machine
		1462	# more efficient implementations are possible with openssl,
		1463	# but not with the buggy and incomplete Net::SSLeay.
		1464	sub _dotls {
		1465	my ($self) = @_;
		1466
		1467	my $tmp;
		1468
		1469	if (length $self->{_tls_wbuf}) {
		1470	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1471	substr $self->{_tls_wbuf}, 0, $tmp, "";
		1472	}
		1473
		1474	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		1475	return $self->_tls_error ($tmp)
		1476	if $tmp != $ERROR_WANT_READ
		1477	&& ($tmp != $ERROR_SYSCALL || $!);
		1478	}
		1479
		1480	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		1481	unless (length $tmp) {
		1482	$self->{_on_starttls}
		1483	and (delete $self->{_on_starttls})->($self, undef, "EOF during handshake"); # ???
		1484	&_freetls;
		1485
		1486	if ($self->{on_stoptls}) {
		1487	$self->{on_stoptls}($self);
		1488	return;
		1489	} else {
		1490	# let's treat SSL-eof as we treat normal EOF
		1491	delete $self->{_rw};
		1492	$self->{_eof} = 1;
		1493	}
		1494	}
		1495
		1496	$self->{_tls_rbuf} .= $tmp;
		1497	$self->_drain_rbuf unless $self->{_in_drain};
		1498	$self->{tls} or return; # tls session might have gone away in callback
		1499	}
		1500
		1501	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
		1502	return $self->_tls_error ($tmp)
		1503	if $tmp != $ERROR_WANT_READ
		1504	&& ($tmp != $ERROR_SYSCALL || $!);
		1505
		1506	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
		1507	$self->{wbuf} .= $tmp;
		1508	$self->_drain_wbuf;
		1509	}
		1510
		1511	$self->{_on_starttls}
		1512	and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
		1513	and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
		1514	}
		1515
		1516	=item $handle->starttls ($tls[, $tls_ctx])
		1517
		1518	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1519	object is created, you can also do that at a later time by calling
		1520	C<starttls>.
		1521
		1522	The first argument is the same as the C<tls> constructor argument (either
		1523	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1524
		1525	The second argument is the optional C<AnyEvent::TLS> object that is used
		1526	when AnyEvent::Handle has to create its own TLS connection object, or
		1527	a hash reference with C<< key => value >> pairs that will be used to
		1528	construct a new context.
		1529
		1530	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1531	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1532	changed to your liking. Note that the handshake might have already started
		1533	when this function returns.
		1534
		1535	If it an error to start a TLS handshake more than once per
		1536	AnyEvent::Handle object (this is due to bugs in OpenSSL).
		1537
		1538	=cut
		1539
		1540	our %TLS_CACHE; #TODO not yet documented, should we?
		1541
		1542	sub starttls {
		1543	my ($self, $ssl, $ctx) = @_;
		1544
		1545	require Net::SSLeay;
		1546
		1547	Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
		1548	if $self->{tls};
		1549
		1550	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		1551	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		1552
		1553	$ctx ||= $self->{tls_ctx};
		1554
		1555	if ("HASH" eq ref $ctx) {
		1556	require AnyEvent::TLS;
		1557
		1558	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
		1559
		1560	if ($ctx->{cache}) {
		1561	my $key = $ctx+0;
		1562	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
		1563	} else {
		1564	$ctx = new AnyEvent::TLS %$ctx;
		1565	}
		1566	}
		1567
		1568	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1569	$self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self, $self->{peername});
		1570
		1571	# basically, this is deep magic (because SSL_read should have the same issues)
		1572	# but the openssl maintainers basically said: "trust us, it just works".
		1573	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1574	# and mismaintained ssleay-module doesn't even offer them).
		1575	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1576	#
		1577	# in short: this is a mess.
		1578	#
		1579	# note that we do not try to keep the length constant between writes as we are required to do.
		1580	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1581	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1582	# have identity issues in that area.
		1583	# Net::SSLeay::CTX_set_mode ($ssl,
		1584	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		1585	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1586	Net::SSLeay::CTX_set_mode ($ssl, 1|2);
		1587
		1588	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1589	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1590
		1591	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
		1592
		1593	$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
		1594	if $self->{on_starttls};
		1595
		1596	&_dotls; # need to trigger the initial handshake
		1597	$self->start_read; # make sure we actually do read
		1598	}
		1599
		1600	=item $handle->stoptls
		1601
		1602	Shuts down the SSL connection - this makes a proper EOF handshake by
		1603	sending a close notify to the other side, but since OpenSSL doesn't
		1604	support non-blocking shut downs, it is not possible to re-use the stream
		1605	afterwards.
		1606
		1607	=cut
		1608
		1609	sub stoptls {
		1610	my ($self) = @_;
		1611
		1612	if ($self->{tls}) {
		1613	Net::SSLeay::shutdown ($self->{tls});
		1614
		1615	&_dotls;
		1616
		1617	# # we don't give a shit. no, we do, but we can't. no...#d#
		1618	# # we, we... have to use openssl :/#d#
		1619	# &_freetls;#d#
		1620	}
		1621	}
		1622
		1623	sub _freetls {
		1624	my ($self) = @_;
		1625
		1626	return unless $self->{tls};
		1627
		1628	$self->{tls_ctx}->_put_session (delete $self->{tls});
		1629
		1630	delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
		1631	}
		1632
		1633	sub DESTROY {
		1634	my ($self) = @_;
		1635
		1636	&_freetls;
		1637
		1638	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		1639
		1640	if ($linger && length $self->{wbuf}) {
		1641	my $fh = delete $self->{fh};
		1642	my $wbuf = delete $self->{wbuf};
		1643
		1644	my @linger;
		1645
		1646	push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
		1647	my $len = syswrite $fh, $wbuf, length $wbuf;
		1648
		1649	if ($len > 0) {
		1650	substr $wbuf, 0, $len, "";
		1651	} else {
		1652	@linger = (); # end
		1653	}
		1654	});
		1655	push @linger, AnyEvent->timer (after => $linger, cb => sub {
		1656	@linger = ();
		1657	});
		1658	}
		1659	}
		1660
		1661	=item $handle->destroy
		1662
		1663	Shuts down the handle object as much as possible - this call ensures that
		1664	no further callbacks will be invoked and as many resources as possible
		1665	will be freed. You must not call any methods on the object afterwards.
		1666
		1667	Normally, you can just "forget" any references to an AnyEvent::Handle
		1668	object and it will simply shut down. This works in fatal error and EOF
		1669	callbacks, as well as code outside. It does I<NOT> work in a read or write
		1670	callback, so when you want to destroy the AnyEvent::Handle object from
		1671	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		1672	that case.
		1673
		1674	Destroying the handle object in this way has the advantage that callbacks
		1675	will be removed as well, so if those are the only reference holders (as
		1676	is common), then one doesn't need to do anything special to break any
		1677	reference cycles.
		1678
		1679	The handle might still linger in the background and write out remaining
		1680	data, as specified by the C<linger> option, however.
		1681
		1682	=cut
		1683
		1684	sub destroy {
		1685	my ($self) = @_;
		1686
		1687	$self->DESTROY;
		1688	%$self = ();
		1689	}
		1690
		1691	=item AnyEvent::Handle::TLS_CTX
		1692
		1693	This function creates and returns the AnyEvent::TLS object used by default
		1694	for TLS mode.
		1695
		1696	The context is created by calling L<AnyEvent::TLS> without any arguments.
		1697
		1698	=cut
		1699
		1700	our $TLS_CTX;
		1701
		1702	sub TLS_CTX() {
		1703	$TLS_CTX ||= do {
		1704	require AnyEvent::TLS;
		1705
		1706	new AnyEvent::TLS
		1707	}
		1708	}
		1709
601	=back	1710	=back
602		1711
		1712
		1713	=head1 NONFREQUENTLY ASKED QUESTIONS
		1714
		1715	=over 4
		1716
		1717	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		1718	still get further invocations!
		1719
		1720	That's because AnyEvent::Handle keeps a reference to itself when handling
		1721	read or write callbacks.
		1722
		1723	It is only safe to "forget" the reference inside EOF or error callbacks,
		1724	from within all other callbacks, you need to explicitly call the C<<
		1725	->destroy >> method.
		1726
		1727	=item I get different callback invocations in TLS mode/Why can't I pause
		1728	reading?
		1729
		1730	Unlike, say, TCP, TLS connections do not consist of two independent
		1731	communication channels, one for each direction. Or put differently. The
		1732	read and write directions are not independent of each other: you cannot
		1733	write data unless you are also prepared to read, and vice versa.
		1734
		1735	This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
		1736	callback invocations when you are not expecting any read data - the reason
		1737	is that AnyEvent::Handle always reads in TLS mode.
		1738
		1739	During the connection, you have to make sure that you always have a
		1740	non-empty read-queue, or an C<on_read> watcher. At the end of the
		1741	connection (or when you no longer want to use it) you can call the
		1742	C<destroy> method.
		1743
		1744	=item How do I read data until the other side closes the connection?
		1745
		1746	If you just want to read your data into a perl scalar, the easiest way
		1747	to achieve this is by setting an C<on_read> callback that does nothing,
		1748	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		1749	will be in C<$_[0]{rbuf}>:
		1750
		1751	$handle->on_read (sub { });
		1752	$handle->on_eof (undef);
		1753	$handle->on_error (sub {
		1754	my $data = delete $_[0]{rbuf};
		1755	});
		1756
		1757	The reason to use C<on_error> is that TCP connections, due to latencies
		1758	and packets loss, might get closed quite violently with an error, when in
		1759	fact, all data has been received.
		1760
		1761	It is usually better to use acknowledgements when transferring data,
		1762	to make sure the other side hasn't just died and you got the data
		1763	intact. This is also one reason why so many internet protocols have an
		1764	explicit QUIT command.
		1765
		1766	=item I don't want to destroy the handle too early - how do I wait until
		1767	all data has been written?
		1768
		1769	After writing your last bits of data, set the C<on_drain> callback
		1770	and destroy the handle in there - with the default setting of
		1771	C<low_water_mark> this will be called precisely when all data has been
		1772	written to the socket:
		1773
		1774	$handle->push_write (...);
		1775	$handle->on_drain (sub {
		1776	warn "all data submitted to the kernel\n";
		1777	undef $handle;
		1778	});
		1779
		1780	If you just want to queue some data and then signal EOF to the other side,
		1781	consider using C<< ->push_shutdown >> instead.
		1782
		1783	=item I want to contact a TLS/SSL server, I don't care about security.
		1784
		1785	If your TLS server is a pure TLS server (e.g. HTTPS) that only speaks TLS,
		1786	simply connect to it and then create the AnyEvent::Handle with the C<tls>
		1787	parameter:
		1788
		1789	tcp_connect $host, $port, sub {
		1790	my ($fh) = @_;
		1791
		1792	my $handle = new AnyEvent::Handle
		1793	fh => $fh,
		1794	tls => "connect",
		1795	on_error => sub { ... };
		1796
		1797	$handle->push_write (...);
		1798	};
		1799
		1800	=item I want to contact a TLS/SSL server, I do care about security.
		1801
		1802	Then you should additionally enable certificate verification, including
		1803	peername verification, if the protocol you use supports it (see
		1804	L<AnyEvent::TLS>, C<verify_peername>).
		1805
		1806	E.g. for HTTPS:
		1807
		1808	tcp_connect $host, $port, sub {
		1809	my ($fh) = @_;
		1810
		1811	my $handle = new AnyEvent::Handle
		1812	fh => $fh,
		1813	peername => $host,
		1814	tls => "connect",
		1815	tls_ctx => { verify => 1, verify_peername => "https" },
		1816	...
		1817
		1818	Note that you must specify the hostname you connected to (or whatever
		1819	"peername" the protocol needs) as the C<peername> argument, otherwise no
		1820	peername verification will be done.
		1821
		1822	The above will use the system-dependent default set of trusted CA
		1823	certificates. If you want to check against a specific CA, add the
		1824	C<ca_file> (or C<ca_cert>) arguments to C<tls_ctx>:
		1825
		1826	tls_ctx => {
		1827	verify => 1,
		1828	verify_peername => "https",
		1829	ca_file => "my-ca-cert.pem",
		1830	},
		1831
		1832	=item I want to create a TLS/SSL server, how do I do that?
		1833
		1834	Well, you first need to get a server certificate and key. You have
		1835	three options: a) ask a CA (buy one, use cacert.org etc.) b) create a
		1836	self-signed certificate (cheap. check the search engine of your choice,
		1837	there are many tutorials on the net) or c) make your own CA (tinyca2 is a
		1838	nice program for that purpose).
		1839
		1840	Then create a file with your private key (in PEM format, see
		1841	L<AnyEvent::TLS>), followed by the certificate (also in PEM format). The
		1842	file should then look like this:
		1843
		1844	-----BEGIN RSA PRIVATE KEY-----
		1845	...header data
		1846	... lots of base64'y-stuff
		1847	-----END RSA PRIVATE KEY-----
		1848
		1849	-----BEGIN CERTIFICATE-----
		1850	... lots of base64'y-stuff
		1851	-----END CERTIFICATE-----
		1852
		1853	The important bits are the "PRIVATE KEY" and "CERTIFICATE" parts. Then
		1854	specify this file as C<cert_file>:
		1855
		1856	tcp_server undef, $port, sub {
		1857	my ($fh) = @_;
		1858
		1859	my $handle = new AnyEvent::Handle
		1860	fh => $fh,
		1861	tls => "accept",
		1862	tls_ctx => { cert_file => "my-server-keycert.pem" },
		1863	...
		1864
		1865	When you have intermediate CA certificates that your clients might not
		1866	know about, just append them to the C<cert_file>.
		1867
		1868	=back
		1869
		1870
		1871	=head1 SUBCLASSING AnyEvent::Handle
		1872
		1873	In many cases, you might want to subclass AnyEvent::Handle.
		1874
		1875	To make this easier, a given version of AnyEvent::Handle uses these
		1876	conventions:
		1877
		1878	=over 4
		1879
		1880	=item * all constructor arguments become object members.
		1881
		1882	At least initially, when you pass a C<tls>-argument to the constructor it
		1883	will end up in C<< $handle->{tls} >>. Those members might be changed or
		1884	mutated later on (for example C<tls> will hold the TLS connection object).
		1885
		1886	=item * other object member names are prefixed with an C<_>.
		1887
		1888	All object members not explicitly documented (internal use) are prefixed
		1889	with an underscore character, so the remaining non-C<_>-namespace is free
		1890	for use for subclasses.
		1891
		1892	=item * all members not documented here and not prefixed with an underscore
		1893	are free to use in subclasses.
		1894
		1895	Of course, new versions of AnyEvent::Handle may introduce more "public"
		1896	member variables, but thats just life, at least it is documented.
		1897
		1898	=back
		1899
603	=head1 AUTHOR	1900	=head1 AUTHOR
604		1901
605	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.	1902	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
606		1903
607	=cut	1904	=cut

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