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Revision 1.5 by elmex, Mon Apr 28 08:01:05 2008 UTC vs.
Revision 1.141 by root, Mon Jul 6 01:03:09 2009 UTC

1	package AnyEvent::Handle;	1	package AnyEvent::Handle;
2		2
3	use warnings;	3	no warnings;
4	use strict;	4	use strict qw(subs vars);
5		5
6	use AnyEvent;	6	use AnyEvent ();
7	use IO::Handle;	7	use AnyEvent::Util qw(WSAEWOULDBLOCK);
		8	use Scalar::Util ();
		9	use Carp ();
		10	use Fcntl ();
8	use Errno qw/EAGAIN EINTR/;	11	use Errno qw(EAGAIN EINTR);
9		12
10	=head1 NAME	13	=head1 NAME
11		14
12	AnyEvent::Handle - non-blocking I/O on filehandles via AnyEvent	15	AnyEvent::Handle - non-blocking I/O on file handles via AnyEvent
13		16
14	=head1 VERSION
15
16	Version 0.01
17
18	=cut	17	=cut
19		18
20	our $VERSION = '0.01';	19	our $VERSION = 4.452;
21		20
22	=head1 SYNOPSIS	21	=head1 SYNOPSIS
23		22
24	use AnyEvent;	23	use AnyEvent;
25	use AnyEvent::Handle;	24	use AnyEvent::Handle;
26		25
27	my $cv = AnyEvent->condvar;	26	my $cv = AnyEvent->condvar;
28		27
29	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	28	my $handle =
30
31	$ae_fh->on_eof (sub { $cv->broadcast });
32
33	$ae_fh->readlines (sub {
34	my ($ae_fh, @lines) = @_;
35	for (@lines) {
36	chomp;
37	print "Line: $_";
38	}
39	});
40
41	# or use the constructor to pass the callback:
42
43	my $ae_fh2 =
44	AnyEvent::Handle->new (	29	AnyEvent::Handle->new (
45	fh => \*STDIN,	30	fh => \*STDIN,
46	on_eof => sub {	31	on_eof => sub {
47	$cv->broadcast;	32	$cv->send;
48	},	33	},
		34	);
		35
		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;
		47
		48	=head1 DESCRIPTION
		49
		50	This module is a helper module to make it easier to do event-based I/O on
		51	filehandles. For utility functions for doing non-blocking connects and accepts
		52	on sockets see L<AnyEvent::Util>.
		53
		54	The L<AnyEvent::Intro> tutorial contains some well-documented
		55	AnyEvent::Handle examples.
		56
		57	In the following, when the documentation refers to of "bytes" then this
		58	means characters. As sysread and syswrite are used for all I/O, their
		59	treatment of characters applies to this module as well.
		60
		61	All callbacks will be invoked with the handle object as their first
		62	argument.
		63
		64	=head1 METHODS
		65
		66	=over 4
		67
		68	=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
		69
		70	The constructor supports these arguments (all as C<< key => value >> pairs).
		71
		72	=over 4
		73
		74	=item fh => $filehandle [MANDATORY]
		75
		76	The filehandle this L<AnyEvent::Handle> object will operate on.
		77
		78	NOTE: The filehandle will be set to non-blocking mode (using
		79	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		80	that mode.
		81
		82	=item on_eof => $cb->($handle)
		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, $message)
		101
		102	This is the error callback, which is called when, well, some error
		103	occured, such as not being able to resolve the hostname, failure to
		104	connect or a read error.
		105
		106	Some errors are fatal (which is indicated by C<$fatal> being true). On
		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>).
		121
		122	On callback entrance, the value of C<$!> contains the operating system
		123	error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		124	C<EPROTO>).
		125
		126	While not mandatory, it is I<highly> recommended to set this callback, as
		127	you will not be notified of errors otherwise. The default simply calls
		128	C<croak>.
		129
		130	=item on_read => $cb->($handle)
		131
		132	This sets the default read callback, which is called when data arrives
		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).
		136
		137	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
		138	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		139	must not enlarge or modify the read buffer, you can only remove data at
		140	the beginning from it.
		141
		142	When an EOF condition is detected then AnyEvent::Handle will first try to
		143	feed all the remaining data to the queued callbacks and C<on_read> before
		144	calling the C<on_eof> callback. If no progress can be made, then a fatal
		145	error will be raised (with C<$!> set to C<EPIPE>).
		146
		147	=item on_drain => $cb->($handle)
		148
		149	This sets the callback that is called when the write buffer becomes empty
		150	(or when the callback is set and the buffer is empty already).
		151
		152	To append to the write buffer, use the C<< ->push_write >> method.
		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
		181	=item rbuf_max => <bytes>
		182
		183	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		184	when the read buffer ever (strictly) exceeds this size. This is useful to
		185	avoid some forms of denial-of-service attacks.
		186
		187	For example, a server accepting connections from untrusted sources should
		188	be configured to accept only so-and-so much data that it cannot act on
		189	(for example, when expecting a line, an attacker could send an unlimited
		190	amount of data without a callback ever being called as long as the line
		191	isn't finished).
		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
		219	=item read_size => <bytes>
		220
		221	The default read block size (the amount of bytes this module will
		222	try to read during each loop iteration, which affects memory
		223	requirements). Default: C<8192>.
		224
		225	=item low_water_mark => <bytes>
		226
		227	Sets the amount of bytes (default: C<0>) that make up an "empty" write
		228	buffer: If the write reaches this size or gets even samller it is
		229	considered empty.
		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>).
		255
		256	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		257
		258	When this parameter is given, it enables TLS (SSL) mode, that means
		259	AnyEvent will start a TLS handshake as soon as the conenction has been
		260	established and will transparently encrypt/decrypt data afterwards.
		261
		262	All TLS protocol errors will be signalled as C<EPROTO>, with an
		263	appropriate error message.
		264
		265	TLS mode requires Net::SSLeay to be installed (it will be loaded
		266	automatically when you try to create a TLS handle): this module doesn't
		267	have a dependency on that module, so if your module requires it, you have
		268	to add the dependency yourself.
		269
		270	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		271	C<accept>, and for the TLS client side of a connection, use C<connect>
		272	mode.
		273
		274	You can also provide your own TLS connection object, but you have
		275	to make sure that you call either C<Net::SSLeay::set_connect_state>
		276	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		277	AnyEvent::Handle. Also, this module will take ownership of this connection
		278	object.
		279
		280	At some future point, AnyEvent::Handle might switch to another TLS
		281	implementation, then the option to use your own session object will go
		282	away.
		283
		284	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		285	passing in the wrong integer will lead to certain crash. This most often
		286	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		287	segmentation fault.
		288
		289	See the C<< ->starttls >> method for when need to start TLS negotiation later.
		290
		291	=item tls_ctx => $anyevent_tls
		292
		293	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		294	(unless a connection object was specified directly). If this parameter is
		295	missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
		296
		297	Instead of an object, you can also specify a hash reference with C<< key
		298	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		299	new TLS context object.
		300
		301	=item json => JSON or JSON::XS object
		302
		303	This is the json coder object used by the C<json> read and write types.
		304
		305	If you don't supply it, then AnyEvent::Handle will create and use a
		306	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		307	texts.
		308
		309	Note that you are responsible to depend on the JSON module if you want to
		310	use this functionality, as AnyEvent does not have a dependency itself.
		311
		312	=back
		313
		314	=cut
		315
		316	sub new {
		317	my $class = shift;
		318	my $self = bless { @_ }, $class;
		319
		320	$self->{fh} or Carp::croak "mandatory argument fh is missing";
		321
		322	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
		323
		324	$self->{_activity} = AnyEvent->now;
		325	$self->_timeout;
		326
		327	$self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
		328
		329	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		330	if $self->{tls};
		331
		332	$self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
		333
		334	$self->start_read
		335	if $self->{on_read};
		336
		337	$self->{fh} && $self
		338	}
		339
		340	sub _shutdown {
		341	my ($self) = @_;
		342
		343	delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
		344	$self->{_eof} = 1; # tell starttls et. al to stop trying
		345
		346	&_freetls;
		347	}
		348
		349	sub _error {
		350	my ($self, $errno, $fatal, $message) = @_;
		351
		352	$self->_shutdown
		353	if $fatal;
		354
		355	$! = $errno;
		356	$message ||= "$!";
		357
		358	if ($self->{on_error}) {
		359	$self->{on_error}($self, $fatal, $message);
		360	} elsif ($self->{fh}) {
		361	Carp::croak "AnyEvent::Handle uncaught error: $message";
		362	}
		363	}
		364
		365	=item $fh = $handle->fh
		366
		367	This method returns the file handle used to create the L<AnyEvent::Handle> object.
		368
		369	=cut
		370
		371	sub fh { $_[0]{fh} }
		372
		373	=item $handle->on_error ($cb)
		374
		375	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
		376
		377	=cut
		378
		379	sub on_error {
		380	$_[0]{on_error} = $_[1];
		381	}
		382
		383	=item $handle->on_eof ($cb)
		384
		385	Replace the current C<on_eof> callback (see the C<on_eof> constructor argument).
		386
		387	=cut
		388
		389	sub on_eof {
		390	$_[0]{on_eof} = $_[1];
		391	}
		392
		393	=item $handle->on_timeout ($cb)
		394
		395	Replace the current C<on_timeout> callback, or disables the callback (but
		396	not the timeout) if C<$cb> = C<undef>. See the C<timeout> constructor
		397	argument and method.
		398
		399	=cut
		400
		401	sub on_timeout {
		402	$_[0]{on_timeout} = $_[1];
		403	}
		404
		405	=item $handle->autocork ($boolean)
		406
		407	Enables or disables the current autocork behaviour (see C<autocork>
		408	constructor argument). Changes will only take effect on the next write.
		409
		410	=cut
		411
		412	sub autocork {
		413	$_[0]{autocork} = $_[1];
		414	}
		415
		416	=item $handle->no_delay ($boolean)
		417
		418	Enables or disables the C<no_delay> setting (see constructor argument of
		419	the same name for details).
		420
		421	=cut
		422
		423	sub no_delay {
		424	$_[0]{no_delay} = $_[1];
		425
		426	eval {
		427	local $SIG{__DIE__};
		428	setsockopt $_[0]{fh}, &Socket::IPPROTO_TCP, &Socket::TCP_NODELAY, int $_[1];
		429	};
		430	}
		431
		432	#############################################################################
		433
		434	=item $handle->timeout ($seconds)
		435
		436	Configures (or disables) the inactivity timeout.
		437
		438	=cut
		439
		440	sub timeout {
		441	my ($self, $timeout) = @_;
		442
		443	$self->{timeout} = $timeout;
		444	$self->_timeout;
		445	}
		446
		447	# reset the timeout watcher, as neccessary
		448	# also check for time-outs
		449	sub _timeout {
		450	my ($self) = @_;
		451
		452	if ($self->{timeout}) {
		453	my $NOW = AnyEvent->now;
		454
		455	# when would the timeout trigger?
		456	my $after = $self->{_activity} + $self->{timeout} - $NOW;
		457
		458	# now or in the past already?
		459	if ($after <= 0) {
		460	$self->{_activity} = $NOW;
		461
		462	if ($self->{on_timeout}) {
		463	$self->{on_timeout}($self);
		464	} else {
		465	$self->_error (&Errno::ETIMEDOUT);
		466	}
		467
		468	# callback could have changed timeout value, optimise
		469	return unless $self->{timeout};
		470
		471	# calculate new after
		472	$after = $self->{timeout};
		473	}
		474
		475	Scalar::Util::weaken $self;
		476	return unless $self; # ->error could have destroyed $self
		477
		478	$self->{_tw} ||= AnyEvent->timer (after => $after, cb => sub {
		479	delete $self->{_tw};
		480	$self->_timeout;
		481	});
		482	} else {
		483	delete $self->{_tw};
		484	}
		485	}
		486
		487	#############################################################################
		488
		489	=back
		490
		491	=head2 WRITE QUEUE
		492
		493	AnyEvent::Handle manages two queues per handle, one for writing and one
		494	for reading.
		495
		496	The write queue is very simple: you can add data to its end, and
		497	AnyEvent::Handle will automatically try to get rid of it for you.
		498
		499	When data could be written and the write buffer is shorter then the low
		500	water mark, the C<on_drain> callback will be invoked.
		501
		502	=over 4
		503
		504	=item $handle->on_drain ($cb)
		505
		506	Sets the C<on_drain> callback or clears it (see the description of
		507	C<on_drain> in the constructor).
		508
		509	=cut
		510
		511	sub on_drain {
		512	my ($self, $cb) = @_;
		513
		514	$self->{on_drain} = $cb;
		515
		516	$cb->($self)
		517	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
		518	}
		519
		520	=item $handle->push_write ($data)
		521
		522	Queues the given scalar to be written. You can push as much data as you
		523	want (only limited by the available memory), as C<AnyEvent::Handle>
		524	buffers it independently of the kernel.
		525
		526	=cut
		527
		528	sub _drain_wbuf {
		529	my ($self) = @_;
		530
		531	if (!$self->{_ww} && length $self->{wbuf}) {
		532
		533	Scalar::Util::weaken $self;
		534
		535	my $cb = sub {
		536	my $len = syswrite $self->{fh}, $self->{wbuf};
		537
		538	if ($len >= 0) {
		539	substr $self->{wbuf}, 0, $len, "";
		540
		541	$self->{_activity} = AnyEvent->now;
		542
		543	$self->{on_drain}($self)
		544	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
		545	&& $self->{on_drain};
		546
		547	delete $self->{_ww} unless length $self->{wbuf};
		548	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		549	$self->_error ($!, 1);
		550	}
		551	};
		552
		553	# try to write data immediately
		554	$cb->() unless $self->{autocork};
		555
		556	# if still data left in wbuf, we need to poll
		557	$self->{_ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb)
		558	if length $self->{wbuf};
		559	};
		560	}
		561
		562	our %WH;
		563
		564	sub register_write_type($$) {
		565	$WH{$_[0]} = $_[1];
		566	}
		567
		568	sub push_write {
		569	my $self = shift;
		570
		571	if (@_ > 1) {
		572	my $type = shift;
		573
		574	@_ = ($WH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_write")
		575	->($self, @_);
		576	}
		577
		578	if ($self->{tls}) {
		579	$self->{_tls_wbuf} .= $_[0];
		580
		581	&_dotls ($self);
		582	} else {
		583	$self->{wbuf} .= $_[0];
		584	$self->_drain_wbuf;
		585	}
		586	}
		587
		588	=item $handle->push_write (type => @args)
		589
		590	Instead of formatting your data yourself, you can also let this module do
		591	the job by specifying a type and type-specific arguments.
		592
		593	Predefined types are (if you have ideas for additional types, feel free to
		594	drop by and tell us):
		595
		596	=over 4
		597
		598	=item netstring => $string
		599
		600	Formats the given value as netstring
		601	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		602
		603	=cut
		604
		605	register_write_type netstring => sub {
		606	my ($self, $string) = @_;
		607
		608	(length $string) . ":$string,"
		609	};
		610
		611	=item packstring => $format, $data
		612
		613	An octet string prefixed with an encoded length. The encoding C<$format>
		614	uses the same format as a Perl C<pack> format, but must specify a single
		615	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		616	optional C<!>, C<< < >> or C<< > >> modifier).
		617
		618	=cut
		619
		620	register_write_type packstring => sub {
		621	my ($self, $format, $string) = @_;
		622
		623	pack "$format/a*", $string
		624	};
		625
		626	=item json => $array_or_hashref
		627
		628	Encodes the given hash or array reference into a JSON object. Unless you
		629	provide your own JSON object, this means it will be encoded to JSON text
		630	in UTF-8.
		631
		632	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		633	one end of a handle and read them at the other end without using any
		634	additional framing.
		635
		636	The generated JSON text is guaranteed not to contain any newlines: While
		637	this module doesn't need delimiters after or between JSON texts to be
		638	able to read them, many other languages depend on that.
		639
		640	A simple RPC protocol that interoperates easily with others is to send
		641	JSON arrays (or objects, although arrays are usually the better choice as
		642	they mimic how function argument passing works) and a newline after each
		643	JSON text:
		644
		645	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		646	$handle->push_write ("\012");
		647
		648	An AnyEvent::Handle receiver would simply use the C<json> read type and
		649	rely on the fact that the newline will be skipped as leading whitespace:
		650
		651	$handle->push_read (json => sub { my $array = $_[1]; ... });
		652
		653	Other languages could read single lines terminated by a newline and pass
		654	this line into their JSON decoder of choice.
		655
		656	=cut
		657
		658	register_write_type json => sub {
		659	my ($self, $ref) = @_;
		660
		661	require JSON;
		662
		663	$self->{json} ? $self->{json}->encode ($ref)
		664	: JSON::encode_json ($ref)
		665	};
		666
		667	=item storable => $reference
		668
		669	Freezes the given reference using L<Storable> and writes it to the
		670	handle. Uses the C<nfreeze> format.
		671
		672	=cut
		673
		674	register_write_type storable => sub {
		675	my ($self, $ref) = @_;
		676
		677	require Storable;
		678
		679	pack "w/a*", Storable::nfreeze ($ref)
		680	};
		681
		682	=back
		683
		684	=item $handle->push_shutdown
		685
		686	Sometimes you know you want to close the socket after writing your data
		687	before it was actually written. One way to do that is to replace your
		688	C<on_drain> handler by a callback that shuts down the socket. This method
		689	is a shorthand for just that, and replaces the C<on_drain> callback with:
		690
		691	sub { shutdown $_[0]{fh}, 1 } # for push_shutdown
		692
		693	This simply shuts down the write side and signals an EOF condition to the
		694	the peer.
		695
		696	You can rely on the normal read queue and C<on_eof> handling
		697	afterwards. This is the cleanest way to close a connection.
		698
		699	=cut
		700
		701	sub push_shutdown {
		702	$_[0]->{on_drain} = sub { shutdown $_[0]{fh}, 1 };
		703	}
		704
		705	=item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
		706
		707	This function (not method) lets you add your own types to C<push_write>.
		708	Whenever the given C<type> is used, C<push_write> will invoke the code
		709	reference with the handle object and the remaining arguments.
		710
		711	The code reference is supposed to return a single octet string that will
		712	be appended to the write buffer.
		713
		714	Note that this is a function, and all types registered this way will be
		715	global, so try to use unique names.
		716
		717	=cut
		718
		719	#############################################################################
		720
		721	=back
		722
		723	=head2 READ QUEUE
		724
		725	AnyEvent::Handle manages two queues per handle, one for writing and one
		726	for reading.
		727
		728	The read queue is more complex than the write queue. It can be used in two
		729	ways, the "simple" way, using only C<on_read> and the "complex" way, using
		730	a queue.
		731
		732	In the simple case, you just install an C<on_read> callback and whenever
		733	new data arrives, it will be called. You can then remove some data (if
		734	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you cna
		735	leave the data there if you want to accumulate more (e.g. when only a
		736	partial message has been received so far).
		737
		738	In the more complex case, you want to queue multiple callbacks. In this
		739	case, AnyEvent::Handle will call the first queued callback each time new
		740	data arrives (also the first time it is queued) and removes it when it has
		741	done its job (see C<push_read>, below).
		742
		743	This way you can, for example, push three line-reads, followed by reading
		744	a chunk of data, and AnyEvent::Handle will execute them in order.
		745
		746	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
		747	the specified number of bytes which give an XML datagram.
		748
		749	# in the default state, expect some header bytes
		750	$handle->on_read (sub {
		751	# some data is here, now queue the length-header-read (4 octets)
		752	shift->unshift_read (chunk => 4, sub {
		753	# header arrived, decode
		754	my $len = unpack "N", $_[1];
		755
		756	# now read the payload
		757	shift->unshift_read (chunk => $len, sub {
		758	my $xml = $_[1];
		759	# handle xml
		760	});
		761	});
		762	});
		763
		764	Example 2: Implement a client for a protocol that replies either with "OK"
		765	and another line or "ERROR" for the first request that is sent, and 64
		766	bytes for the second request. Due to the availability of a queue, we can
		767	just pipeline sending both requests and manipulate the queue as necessary
		768	in the callbacks.
		769
		770	When the first callback is called and sees an "OK" response, it will
		771	C<unshift> another line-read. This line-read will be queued I<before> the
		772	64-byte chunk callback.
		773
		774	# request one, returns either "OK + extra line" or "ERROR"
		775	$handle->push_write ("request 1\015\012");
		776
		777	# we expect "ERROR" or "OK" as response, so push a line read
		778	$handle->push_read (line => sub {
		779	# if we got an "OK", we have to _prepend_ another line,
		780	# so it will be read before the second request reads its 64 bytes
		781	# which are already in the queue when this callback is called
		782	# we don't do this in case we got an error
		783	if ($_[1] eq "OK") {
49	on_readline => sub {	784	$_[0]->unshift_read (line => sub {
50	my ($ae_fh, @lines) = @_;	785	my $response = $_[1];
51	for (@lines) {	786	...
52	chomp;	787	});
53	print "Line: $_";	788	}
		789	});
		790
		791	# request two, simply returns 64 octets
		792	$handle->push_write ("request 2\015\012");
		793
		794	# simply read 64 bytes, always
		795	$handle->push_read (chunk => 64, sub {
		796	my $response = $_[1];
		797	...
		798	});
		799
		800	=over 4
		801
		802	=cut
		803
		804	sub _drain_rbuf {
		805	my ($self) = @_;
		806
		807	local $self->{_in_drain} = 1;
		808
		809	if (
		810	defined $self->{rbuf_max}
		811	&& $self->{rbuf_max} < length $self->{rbuf}
		812	) {
		813	$self->_error (&Errno::ENOSPC, 1), return;
		814	}
		815
		816	while () {
		817	# we need to use a separate tls read buffer, as we must not receive data while
		818	# we are draining the buffer, and this can only happen with TLS.
		819	$self->{rbuf} .= delete $self->{_tls_rbuf} if exists $self->{_tls_rbuf};
		820
		821	my $len = length $self->{rbuf};
		822
		823	if (my $cb = shift @{ $self->{_queue} }) {
		824	unless ($cb->($self)) {
		825	if ($self->{_eof}) {
		826	# no progress can be made (not enough data and no data forthcoming)
		827	$self->_error (&Errno::EPIPE, 1), return;
54	}	828	}
		829
		830	unshift @{ $self->{_queue} }, $cb;
		831	last;
55	}	832	}
56	);
57
58	$cv->wait;
59
60	=head1 DESCRIPTION
61
62	This module is a helper module to make it easier to do non-blocking I/O
63	on filehandles (and sockets, see L<AnyEvent::Socket>).
64
65	The event loop is provided by L<AnyEvent>.
66
67	=head1 METHODS
68
69	=over 4
70
71	=item B<new (%args)>
72
73	The constructor has these arguments:
74
75	=over 4
76
77	=item fh => $filehandle
78
79	The filehandle this L<AnyEvent::Handle> object will operate on.
80
81	NOTE: The filehandle will be set to non-blocking.
82
83	=item read_block_size => $size
84
85	The default read block size use for reads via the C<on_read>
86	method.
87
88	=item on_read => $cb
89
90	=item on_eof => $cb
91
92	=item on_error => $cb
93
94	These are shortcuts, that will call the corresponding method and set the callback to C<$cb>.
95
96	=item on_readline => $cb
97
98	The C<readlines> method is called with the default seperator and C<$cb> as callback
99	for you.
100
101	=back
102
103	=cut
104
105	sub new {
106	my $this = shift;
107	my $class = ref($this) || $this;
108	my $self = {
109	read_block_size => 4096,
110	rbuf => '',
111	@_
112	};
113	bless $self, $class;
114
115	$self->{fh}->blocking (0) if $self->{fh};
116
117	if ($self->{on_read}) {
118	$self->on_read ($self->{on_read});
119
120	} elsif ($self->{on_readline}) {	833	} elsif ($self->{on_read}) {
121	$self->readlines ($self->{on_readline});	834	last unless $len;
122		835
		836	$self->{on_read}($self);
		837
		838	if (
		839	$len == length $self->{rbuf} # if no data has been consumed
		840	&& !@{ $self->{_queue} } # and the queue is still empty
		841	&& $self->{on_read} # but we still have on_read
		842	) {
		843	# no further data will arrive
		844	# so no progress can be made
		845	$self->_error (&Errno::EPIPE, 1), return
		846	if $self->{_eof};
		847
		848	last; # more data might arrive
		849	}
		850	} else {
		851	# read side becomes idle
		852	delete $self->{_rw} unless $self->{tls};
		853	last;
		854	}
		855	}
		856
123	} elsif ($self->{on_eof}) {	857	if ($self->{_eof}) {
124	$self->on_eof ($self->{on_eof});
125
126	} elsif ($self->{on_error}) {	858	if ($self->{on_eof}) {
127	$self->on_eof ($self->{on_error});	859	$self->{on_eof}($self)
		860	} else {
		861	$self->_error (0, 1, "Unexpected end-of-file");
		862	}
128	}	863	}
129		864
130	return $self	865	# may need to restart read watcher
		866	unless ($self->{_rw}) {
		867	$self->start_read
		868	if $self->{on_read} || @{ $self->{_queue} };
		869	}
131	}	870	}
132		871
133	=item B<fh>	872	=item $handle->on_read ($cb)
134		873
135	This method returns the filehandle of the L<AnyEvent::Handle> object.	874	This replaces the currently set C<on_read> callback, or clears it (when
136		875	the new callback is C<undef>). See the description of C<on_read> in the
137	=cut	876	constructor.
138
139	sub fh { $_[0]->{fh} }
140
141	=item B<on_read ($callback)>
142
143	This method installs a C<$callback> that will be called
144	when new data arrived. You can access the read buffer via the C<rbuf>
145	method (see below).
146
147	The first argument of the C<$callback> will be the L<AnyEvent::Handle> object.
148		877
149	=cut	878	=cut
150		879
151	sub on_read {	880	sub on_read {
152	my ($self, $cb) = @_;	881	my ($self, $cb) = @_;
		882
153	$self->{on_read} = $cb;	883	$self->{on_read} = $cb;
		884	$self->_drain_rbuf if $cb && !$self->{_in_drain};
		885	}
154		886
155	unless (defined $self->{on_read}) {	887	=item $handle->rbuf
156	delete $self->{on_read_w};	888
		889	Returns the read buffer (as a modifiable lvalue).
		890
		891	You can access the read buffer directly as the C<< ->{rbuf} >>
		892	member, if you want. However, the only operation allowed on the
		893	read buffer (apart from looking at it) is removing data from its
		894	beginning. Otherwise modifying or appending to it is not allowed and will
		895	lead to hard-to-track-down bugs.
		896
		897	NOTE: The read buffer should only be used or modified if the C<on_read>,
		898	C<push_read> or C<unshift_read> methods are used. The other read methods
		899	automatically manage the read buffer.
		900
		901	=cut
		902
		903	sub rbuf : lvalue {
		904	$_[0]{rbuf}
		905	}
		906
		907	=item $handle->push_read ($cb)
		908
		909	=item $handle->unshift_read ($cb)
		910
		911	Append the given callback to the end of the queue (C<push_read>) or
		912	prepend it (C<unshift_read>).
		913
		914	The callback is called each time some additional read data arrives.
		915
		916	It must check whether enough data is in the read buffer already.
		917
		918	If not enough data is available, it must return the empty list or a false
		919	value, in which case it will be called repeatedly until enough data is
		920	available (or an error condition is detected).
		921
		922	If enough data was available, then the callback must remove all data it is
		923	interested in (which can be none at all) and return a true value. After returning
		924	true, it will be removed from the queue.
		925
		926	=cut
		927
		928	our %RH;
		929
		930	sub register_read_type($$) {
		931	$RH{$_[0]} = $_[1];
		932	}
		933
		934	sub push_read {
		935	my $self = shift;
		936	my $cb = pop;
		937
		938	if (@_) {
		939	my $type = shift;
		940
		941	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::push_read")
		942	->($self, $cb, @_);
		943	}
		944
		945	push @{ $self->{_queue} }, $cb;
		946	$self->_drain_rbuf unless $self->{_in_drain};
		947	}
		948
		949	sub unshift_read {
		950	my $self = shift;
		951	my $cb = pop;
		952
		953	if (@_) {
		954	my $type = shift;
		955
		956	$cb = ($RH{$type} or Carp::croak "unsupported type passed to AnyEvent::Handle::unshift_read")
		957	->($self, $cb, @_);
		958	}
		959
		960
		961	unshift @{ $self->{_queue} }, $cb;
		962	$self->_drain_rbuf unless $self->{_in_drain};
		963	}
		964
		965	=item $handle->push_read (type => @args, $cb)
		966
		967	=item $handle->unshift_read (type => @args, $cb)
		968
		969	Instead of providing a callback that parses the data itself you can chose
		970	between a number of predefined parsing formats, for chunks of data, lines
		971	etc.
		972
		973	Predefined types are (if you have ideas for additional types, feel free to
		974	drop by and tell us):
		975
		976	=over 4
		977
		978	=item chunk => $octets, $cb->($handle, $data)
		979
		980	Invoke the callback only once C<$octets> bytes have been read. Pass the
		981	data read to the callback. The callback will never be called with less
		982	data.
		983
		984	Example: read 2 bytes.
		985
		986	$handle->push_read (chunk => 2, sub {
		987	warn "yay ", unpack "H*", $_[1];
		988	});
		989
		990	=cut
		991
		992	register_read_type chunk => sub {
		993	my ($self, $cb, $len) = @_;
		994
		995	sub {
		996	$len <= length $_[0]{rbuf} or return;
		997	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
		998	1
		999	}
		1000	};
		1001
		1002	=item line => [$eol, ]$cb->($handle, $line, $eol)
		1003
		1004	The callback will be called only once a full line (including the end of
		1005	line marker, C<$eol>) has been read. This line (excluding the end of line
		1006	marker) will be passed to the callback as second argument (C<$line>), and
		1007	the end of line marker as the third argument (C<$eol>).
		1008
		1009	The end of line marker, C<$eol>, can be either a string, in which case it
		1010	will be interpreted as a fixed record end marker, or it can be a regex
		1011	object (e.g. created by C<qr>), in which case it is interpreted as a
		1012	regular expression.
		1013
		1014	The end of line marker argument C<$eol> is optional, if it is missing (NOT
		1015	undef), then C<qr|\015?\012|> is used (which is good for most internet
		1016	protocols).
		1017
		1018	Partial lines at the end of the stream will never be returned, as they are
		1019	not marked by the end of line marker.
		1020
		1021	=cut
		1022
		1023	register_read_type line => sub {
		1024	my ($self, $cb, $eol) = @_;
		1025
		1026	if (@_ < 3) {
		1027	# this is more than twice as fast as the generic code below
		1028	sub {
		1029	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		1030
		1031	$cb->($_[0], $1, $2);
		1032	1
		1033	}
		1034	} else {
		1035	$eol = quotemeta $eol unless ref $eol;
		1036	$eol = qr|^(.*?)($eol)|s;
		1037
		1038	sub {
		1039	$_[0]{rbuf} =~ s/$eol// or return;
		1040
		1041	$cb->($_[0], $1, $2);
		1042	1
		1043	}
		1044	}
		1045	};
		1046
		1047	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1048
		1049	Makes a regex match against the regex object C<$accept> and returns
		1050	everything up to and including the match.
		1051
		1052	Example: read a single line terminated by '\n'.
		1053
		1054	$handle->push_read (regex => qr<\n>, sub { ... });
		1055
		1056	If C<$reject> is given and not undef, then it determines when the data is
		1057	to be rejected: it is matched against the data when the C<$accept> regex
		1058	does not match and generates an C<EBADMSG> error when it matches. This is
		1059	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1060	receive buffer overflow).
		1061
		1062	Example: expect a single decimal number followed by whitespace, reject
		1063	anything else (not the use of an anchor).
		1064
		1065	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1066
		1067	If C<$skip> is given and not C<undef>, then it will be matched against
		1068	the receive buffer when neither C<$accept> nor C<$reject> match,
		1069	and everything preceding and including the match will be accepted
		1070	unconditionally. This is useful to skip large amounts of data that you
		1071	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1072	have to start matching from the beginning. This is purely an optimisation
		1073	and is usually worth only when you expect more than a few kilobytes.
		1074
		1075	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1076	expect the header to be very large (it isn't in practise, but...), we use
		1077	a skip regex to skip initial portions. The skip regex is tricky in that
		1078	it only accepts something not ending in either \015 or \012, as these are
		1079	required for the accept regex.
		1080
		1081	$handle->push_read (regex =>
		1082	qr<\015\012\015\012>,
		1083	undef, # no reject
		1084	qr<^.*[^\015\012]>,
		1085	sub { ... });
		1086
		1087	=cut
		1088
		1089	register_read_type regex => sub {
		1090	my ($self, $cb, $accept, $reject, $skip) = @_;
		1091
		1092	my $data;
		1093	my $rbuf = \$self->{rbuf};
		1094
		1095	sub {
		1096	# accept
		1097	if ($$rbuf =~ $accept) {
		1098	$data .= substr $$rbuf, 0, $+[0], "";
		1099	$cb->($self, $data);
157	return;	1100	return 1;
		1101	}
		1102
		1103	# reject
		1104	if ($reject && $$rbuf =~ $reject) {
		1105	$self->_error (&Errno::EBADMSG);
		1106	}
		1107
		1108	# skip
		1109	if ($skip && $$rbuf =~ $skip) {
		1110	$data .= substr $$rbuf, 0, $+[0], "";
		1111	}
		1112
		1113	()
158	}	1114	}
159		1115	};
160	$self->{on_read_w} =	1116
161	AnyEvent->io (poll => 'r', fh => $self->{fh}, cb => sub {	1117	=item netstring => $cb->($handle, $string)
162	#d# warn "READ:[$self->{read_size}] $self->{read_block_size} : ".length ($self->{rbuf})."\n";	1118
163	my $rbuf_len = length $self->{rbuf};	1119	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
164	my $l;	1120
165	if (defined $self->{read_size}) {	1121	Throws an error with C<$!> set to EBADMSG on format violations.
166	$l = sysread $self->{fh}, $self->{rbuf},	1122
167	($self->{read_size} - $rbuf_len), $rbuf_len;	1123	=cut
168	} else {	1124
169	$l = sysread $self->{fh}, $self->{rbuf}, $self->{read_block_size}, $rbuf_len;	1125	register_read_type netstring => sub {
		1126	my ($self, $cb) = @_;
		1127
		1128	sub {
		1129	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1130	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1131	$self->_error (&Errno::EBADMSG);
170	}	1132	}
171	#d# warn "READL $l [$self->{rbuf}]\n";	1133	return;
		1134	}
172		1135
173	if (not defined $l) {	1136	my $len = $1;
174	return if $! == EAGAIN || $! == EINTR;
175	$self->{on_error}->($self) if $self->{on_error};
176	delete $self->{on_read_w};
177		1137
178	} elsif ($l == 0) {	1138	$self->unshift_read (chunk => $len, sub {
179	$self->{on_eof}->($self) if $self->{on_eof};	1139	my $string = $_[1];
180	delete $self->{on_read_w};	1140	$_[0]->unshift_read (chunk => 1, sub {
181		1141	if ($_[1] eq ",") {
		1142	$cb->($_[0], $string);
182	} else {	1143	} else {
183	$self->{on_read}->($self);	1144	$self->_error (&Errno::EBADMSG);
		1145	}
		1146	});
		1147	});
		1148
		1149	1
		1150	}
		1151	};
		1152
		1153	=item packstring => $format, $cb->($handle, $string)
		1154
		1155	An octet string prefixed with an encoded length. The encoding C<$format>
		1156	uses the same format as a Perl C<pack> format, but must specify a single
		1157	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1158	optional C<!>, C<< < >> or C<< > >> modifier).
		1159
		1160	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1161	EPP uses a prefix of C<N> (4 octtes).
		1162
		1163	Example: read a block of data prefixed by its length in BER-encoded
		1164	format (very efficient).
		1165
		1166	$handle->push_read (packstring => "w", sub {
		1167	my ($handle, $data) = @_;
		1168	});
		1169
		1170	=cut
		1171
		1172	register_read_type packstring => sub {
		1173	my ($self, $cb, $format) = @_;
		1174
		1175	sub {
		1176	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1177	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1178	or return;
		1179
		1180	$format = length pack $format, $len;
		1181
		1182	# bypass unshift if we already have the remaining chunk
		1183	if ($format + $len <= length $_[0]{rbuf}) {
		1184	my $data = substr $_[0]{rbuf}, $format, $len;
		1185	substr $_[0]{rbuf}, 0, $format + $len, "";
		1186	$cb->($_[0], $data);
		1187	} else {
		1188	# remove prefix
		1189	substr $_[0]{rbuf}, 0, $format, "";
		1190
		1191	# read remaining chunk
		1192	$_[0]->unshift_read (chunk => $len, $cb);
		1193	}
		1194
		1195	1
		1196	}
		1197	};
		1198
		1199	=item json => $cb->($handle, $hash_or_arrayref)
		1200
		1201	Reads a JSON object or array, decodes it and passes it to the
		1202	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1203
		1204	If a C<json> object was passed to the constructor, then that will be used
		1205	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1206
		1207	This read type uses the incremental parser available with JSON version
		1208	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1209	dependency on your own: this module will load the JSON module, but
		1210	AnyEvent does not depend on it itself.
		1211
		1212	Since JSON texts are fully self-delimiting, the C<json> read and write
		1213	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1214	the C<json> write type description, above, for an actual example.
		1215
		1216	=cut
		1217
		1218	register_read_type json => sub {
		1219	my ($self, $cb) = @_;
		1220
		1221	my $json = $self->{json} ||=
		1222	eval { require JSON::XS; JSON::XS->new->utf8 }
		1223	|| do { require JSON; JSON->new->utf8 };
		1224
		1225	my $data;
		1226	my $rbuf = \$self->{rbuf};
		1227
		1228	sub {
		1229	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1230
		1231	if ($ref) {
		1232	$self->{rbuf} = $json->incr_text;
		1233	$json->incr_text = "";
		1234	$cb->($self, $ref);
		1235
		1236	1
		1237	} elsif ($@) {
		1238	# error case
		1239	$json->incr_skip;
		1240
		1241	$self->{rbuf} = $json->incr_text;
		1242	$json->incr_text = "";
		1243
		1244	$self->_error (&Errno::EBADMSG);
		1245
		1246	()
		1247	} else {
		1248	$self->{rbuf} = "";
		1249
		1250	()
		1251	}
		1252	}
		1253	};
		1254
		1255	=item storable => $cb->($handle, $ref)
		1256
		1257	Deserialises a L<Storable> frozen representation as written by the
		1258	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1259	data).
		1260
		1261	Raises C<EBADMSG> error if the data could not be decoded.
		1262
		1263	=cut
		1264
		1265	register_read_type storable => sub {
		1266	my ($self, $cb) = @_;
		1267
		1268	require Storable;
		1269
		1270	sub {
		1271	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1272	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1273	or return;
		1274
		1275	my $format = length pack "w", $len;
		1276
		1277	# bypass unshift if we already have the remaining chunk
		1278	if ($format + $len <= length $_[0]{rbuf}) {
		1279	my $data = substr $_[0]{rbuf}, $format, $len;
		1280	substr $_[0]{rbuf}, 0, $format + $len, "";
		1281	$cb->($_[0], Storable::thaw ($data));
		1282	} else {
		1283	# remove prefix
		1284	substr $_[0]{rbuf}, 0, $format, "";
		1285
		1286	# read remaining chunk
		1287	$_[0]->unshift_read (chunk => $len, sub {
		1288	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1289	$cb->($_[0], $ref);
		1290	} else {
		1291	$self->_error (&Errno::EBADMSG);
		1292	}
		1293	});
		1294	}
		1295
		1296	1
		1297	}
		1298	};
		1299
		1300	=back
		1301
		1302	=item AnyEvent::Handle::register_read_type type => $coderef->($handle, $cb, @args)
		1303
		1304	This function (not method) lets you add your own types to C<push_read>.
		1305
		1306	Whenever the given C<type> is used, C<push_read> will invoke the code
		1307	reference with the handle object, the callback and the remaining
		1308	arguments.
		1309
		1310	The code reference is supposed to return a callback (usually a closure)
		1311	that works as a plain read callback (see C<< ->push_read ($cb) >>).
		1312
		1313	It should invoke the passed callback when it is done reading (remember to
		1314	pass C<$handle> as first argument as all other callbacks do that).
		1315
		1316	Note that this is a function, and all types registered this way will be
		1317	global, so try to use unique names.
		1318
		1319	For examples, see the source of this module (F<perldoc -m AnyEvent::Handle>,
		1320	search for C<register_read_type>)).
		1321
		1322	=item $handle->stop_read
		1323
		1324	=item $handle->start_read
		1325
		1326	In rare cases you actually do not want to read anything from the
		1327	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
		1328	any queued callbacks will be executed then. To start reading again, call
		1329	C<start_read>.
		1330
		1331	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1332	you change the C<on_read> callback or push/unshift a read callback, and it
		1333	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1334	there are any read requests in the queue.
		1335
		1336	These methods will have no effect when in TLS mode (as TLS doesn't support
		1337	half-duplex connections).
		1338
		1339	=cut
		1340
		1341	sub stop_read {
		1342	my ($self) = @_;
		1343
		1344	delete $self->{_rw} unless $self->{tls};
		1345	}
		1346
		1347	sub start_read {
		1348	my ($self) = @_;
		1349
		1350	unless ($self->{_rw} || $self->{_eof}) {
		1351	Scalar::Util::weaken $self;
		1352
		1353	$self->{_rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {
		1354	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
		1355	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size} || 8192, length $$rbuf;
		1356
		1357	if ($len > 0) {
		1358	$self->{_activity} = AnyEvent->now;
		1359
		1360	if ($self->{tls}) {
		1361	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
		1362
		1363	&_dotls ($self);
		1364	} else {
		1365	$self->_drain_rbuf unless $self->{_in_drain};
		1366	}
		1367
		1368	} elsif (defined $len) {
		1369	delete $self->{_rw};
		1370	$self->{_eof} = 1;
		1371	$self->_drain_rbuf unless $self->{_in_drain};
		1372
		1373	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		1374	return $self->_error ($!, 1);
184	}	1375	}
185	});	1376	});
		1377	}
186	}	1378	}
187		1379
188	=item B<on_error ($callback)>	1380	our $ERROR_SYSCALL;
		1381	our $ERROR_WANT_READ;
		1382	our $ERROR_ZERO_RETURN;
189		1383
190	Whenever a read or write operation resulted in an error the C<$callback>
191	will be called.
192
193	The first argument of C<$callback> will be the L<AnyEvent::Handle> object itself.
194	The error is given as errno in C<$!>.
195
196	=cut
197
198	sub on_error {	1384	sub _tls_error {
199	$_[0]->{on_error} = $_[1];
200	}
201
202	=item B<on_eof ($callback)>
203
204	Installs the C<$callback> that will be called when the end of file is
205	encountered in a read operation this C<$callback> will be called. The first
206	argument will be the L<AnyEvent::Handle> object itself.
207
208	=cut
209
210	sub on_eof {
211	$_[0]->{on_eof} = $_[1];
212	}
213
214	=item B<rbuf>
215
216	Returns a reference to the read buffer.
217
218	NOTE: The read buffer should only be used or modified if the C<on_read>
219	method is used directly. The C<read> and C<readlines> methods will provide
220	the read data to their callbacks.
221
222	=cut
223
224	sub rbuf : lvalue {
225	$_[0]->{rbuf}
226	}
227
228	=item B<read ($len, $callback)>
229
230	Will read exactly C<$len> bytes from the filehandle and call the C<$callback>
231	if done so. The first argument to the C<$callback> will be the L<AnyEvent::Handle>
232	object itself and the second argument the read data.
233
234	NOTE: This method will override any callbacks installed via the C<on_read> method.
235
236	=cut
237
238	sub read {
239	my ($self, $len, $cb) = @_;	1385	my ($self, $err) = @_;
240		1386
241	$self->{read_cb} = $cb;	1387	return $self->_error ($!, 1)
242	my $old_blk_size = $self->{read_block_size};	1388	if $err == Net::SSLeay::ERROR_SYSCALL ();
243	$self->{read_block_size} = $len;
244		1389
245	$self->on_read (sub {	1390	my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
246	#d# warn "OFOFO $len || ".length($_[0]->{rbuf})."||\n";
247		1391
248	if ($len == length $_[0]->{rbuf}) {	1392	# reduce error string to look less scary
249	$_[0]->{read_block_size} = $old_blk_size;	1393	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
250	$_[0]->on_read (undef);	1394
251	$_[0]->{read_cb}->($_[0], (substr $self->{rbuf}, 0, $len, ''));	1395	$self->_error (&Errno::EPROTO, 1, $err);
		1396	}
		1397
		1398	# poll the write BIO and send the data if applicable
		1399	# also decode read data if possible
		1400	# this is basiclaly our TLS state machine
		1401	# more efficient implementations are possible with openssl,
		1402	# but not with the buggy and incomplete Net::SSLeay.
		1403	sub _dotls {
		1404	my ($self) = @_;
		1405
		1406	my $tmp;
		1407
		1408	if (length $self->{_tls_wbuf}) {
		1409	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1410	substr $self->{_tls_wbuf}, 0, $tmp, "";
252	}	1411	}
		1412
		1413	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		1414	return $self->_tls_error ($tmp)
		1415	if $tmp != $ERROR_WANT_READ
		1416	&& ($tmp != $ERROR_SYSCALL || $!)
		1417	&& $tmp != $ERROR_ZERO_RETURN;
253	});	1418	}
254	}
255		1419
256	=item B<readlines ($callback)>	1420	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
257		1421	unless (length $tmp) {
258	=item B<readlines ($sep, $callback)>	1422	# let's treat SSL-eof as we treat normal EOF
259		1423	delete $self->{_rw};
260	This method will read lines from the filehandle, seperated by C<$sep> or C<"\n">	1424	$self->{_eof} = 1;
261	if C<$sep> is not provided. C<$sep> will be used as "line" seperator.	1425	&_freetls;
262
263	The C<$callback> will be called when at least one
264	line could be read. The first argument to the C<$callback> will be the L<AnyEvent::Handle>
265	object itself and the rest of the arguments will be the read lines.
266
267	NOTE: This method will override any callbacks installed via the C<on_read> method.
268
269	=cut
270
271	sub readlines {
272	my ($self, $sep, $cb) = @_;
273
274	if (ref $sep) {
275	$cb = $sep;
276	$sep = "\n";
277
278	} elsif (not defined $sep) {
279	$sep = "\n";
280	}
281
282	my $sep_len = length $sep;
283
284	$self->{on_readline} = $cb;
285
286	$self->on_read (sub {
287	my @lines;
288	my $rb = \$_[0]->{rbuf};
289	my $pos;
290	while (($pos = index ($$rb, $sep)) >= 0) {
291	push @lines, substr $$rb, 0, $pos + $sep_len, '';
292	}	1426	}
293	$self->{on_readline}->($_[0], @lines);	1427
		1428	$self->{_tls_rbuf} .= $tmp;
		1429	$self->_drain_rbuf unless $self->{_in_drain};
		1430	$self->{tls} or return; # tls session might have gone away in callback
294	});	1431	}
295	}
296		1432
297	=item B<write ($data)>	1433	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
		1434	return $self->_tls_error ($tmp)
		1435	if $tmp != $ERROR_WANT_READ
		1436	&& ($tmp != $ERROR_SYSCALL || $!)
		1437	&& $tmp != $ERROR_ZERO_RETURN;
298		1438
299	=item B<write ($callback)>	1439	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
		1440	$self->{wbuf} .= $tmp;
		1441	$self->_drain_wbuf;
		1442	}
		1443	}
300		1444
301	=item B<write ($data, $callback)>	1445	=item $handle->starttls ($tls[, $tls_ctx])
302		1446
303	This method will write C<$data> to the filehandle and call the C<$callback>	1447	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
304	afterwards. If only C<$callback> is provided it will be called when the	1448	object is created, you can also do that at a later time by calling
305	write buffer becomes empty the next time (or immediately if it already is empty).	1449	C<starttls>.
306		1450
307	=cut	1451	The first argument is the same as the C<tls> constructor argument (either
		1452	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
308		1453
309	sub write {	1454	The second argument is the optional C<AnyEvent::TLS> object that is used
		1455	when AnyEvent::Handle has to create its own TLS connection object, or
		1456	a hash reference with C<< key => value >> pairs that will be used to
		1457	construct a new context.
		1458
		1459	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1460	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1461	changed to your liking. Note that the handshake might have already started
		1462	when this function returns.
		1463
		1464	If it an error to start a TLS handshake more than once per
		1465	AnyEvent::Handle object (this is due to bugs in OpenSSL).
		1466
		1467	=cut
		1468
		1469	our %TLS_CACHE; #TODO not yet documented, should we?
		1470
		1471	sub starttls {
310	my ($self, $data, $cb) = @_;	1472	my ($self, $ssl, $ctx) = @_;
311	if (ref $data) { $cb = $data; undef $data }
312	push @{$self->{write_bufs}}, [$data, $cb];
313	$self->_check_writer;
314	}
315		1473
316	sub _check_writer {	1474	require Net::SSLeay;
		1475
		1476	Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
		1477	if $self->{tls};
		1478
		1479	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		1480	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		1481	$ERROR_ZERO_RETURN = Net::SSLeay::ERROR_ZERO_RETURN ();
		1482
		1483	$ctx ||= $self->{tls_ctx};
		1484
		1485	if ("HASH" eq ref $ctx) {
		1486	require AnyEvent::TLS;
		1487
		1488	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
		1489
		1490	if ($ctx->{cache}) {
		1491	my $key = $ctx+0;
		1492	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
		1493	} else {
		1494	$ctx = new AnyEvent::TLS %$ctx;
		1495	}
		1496	}
		1497
		1498	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1499	$self->{tls} = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self, $self->{peername});
		1500
		1501	# basically, this is deep magic (because SSL_read should have the same issues)
		1502	# but the openssl maintainers basically said: "trust us, it just works".
		1503	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1504	# and mismaintained ssleay-module doesn't even offer them).
		1505	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1506	#
		1507	# in short: this is a mess.
		1508	#
		1509	# note that we do not try to keep the length constant between writes as we are required to do.
		1510	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1511	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1512	# have identity issues in that area.
		1513	# Net::SSLeay::CTX_set_mode ($ssl,
		1514	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		1515	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		1516	Net::SSLeay::CTX_set_mode ($ssl, 1|2);
		1517
		1518	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1519	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		1520
		1521	Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
		1522
		1523	&_dotls; # need to trigger the initial handshake
		1524	$self->start_read; # make sure we actually do read
		1525	}
		1526
		1527	=item $handle->stoptls
		1528
		1529	Shuts down the SSL connection - this makes a proper EOF handshake by
		1530	sending a close notify to the other side, but since OpenSSL doesn't
		1531	support non-blocking shut downs, it is not possible to re-use the stream
		1532	afterwards.
		1533
		1534	=cut
		1535
		1536	sub stoptls {
317	my ($self) = @_;	1537	my ($self) = @_;
318		1538
319	if ($self->{write_w}) {	1539	if ($self->{tls}) {
320	unless ($self->{write_cb}) {	1540	Net::SSLeay::shutdown ($self->{tls});
321	while (@{$self->{write_bufs}} && not defined $self->{write_bufs}->[0]->[1]) {	1541
322	my $wba = shift @{$self->{write_bufs}};	1542	&_dotls;
323	$self->{wbuf} .= $wba->[0];	1543
324	}	1544	# we don't give a shit. no, we do, but we can't. no...
325	}	1545	# we, we... have to use openssl :/
326	return;	1546	&_freetls;
		1547	}
		1548	}
		1549
		1550	sub _freetls {
		1551	my ($self) = @_;
		1552
		1553	return unless $self->{tls};
		1554
		1555	$self->{tls_ctx}->_put_session (delete $self->{tls});
327	}	1556
		1557	delete @$self{qw(_rbio _wbio _tls_wbuf)};
		1558	}
328		1559
329	my $wba = shift @{$self->{write_bufs}}	1560	sub DESTROY {
330	or return;	1561	my ($self) = @_;
331		1562
332	unless (defined $wba->[0]) {	1563	&_freetls;
333	$wba->[1]->($self) if $wba->[1];
334	$self->_check_writer;
335	return;
336	}
337		1564
338	$self->{wbuf} = $wba->[0];	1565	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
339	$self->{write_cb} = $wba->[1];
340		1566
341	$self->{write_w} =	1567	if ($linger && length $self->{wbuf}) {
342	AnyEvent->io (poll => 'w', fh => $self->{fh}, cb => sub {	1568	my $fh = delete $self->{fh};
		1569	my $wbuf = delete $self->{wbuf};
		1570
		1571	my @linger;
		1572
		1573	push @linger, AnyEvent->io (fh => $fh, poll => "w", cb => sub {
343	my $l = syswrite $self->{fh}, $self->{wbuf}, length $self->{wbuf};	1574	my $len = syswrite $fh, $wbuf, length $wbuf;
344		1575
345	if (not defined $l) {	1576	if ($len > 0) {
346	return if $! == EAGAIN || $! == EINTR;	1577	substr $wbuf, 0, $len, "";
347	delete $self->{write_w};
348	$self->{on_error}->($self) if $self->{on_error};
349
350	} else {	1578	} else {
351	substr $self->{wbuf}, 0, $l, '';	1579	@linger = (); # end
352
353	if (length ($self->{wbuf}) == 0) {
354	$self->{write_cb}->($self) if $self->{write_cb};
355
356	delete $self->{write_w};
357	delete $self->{wbuf};
358	delete $self->{write_cb};
359
360	$self->_check_writer;
361	}
362	}	1580	}
363	});	1581	});
		1582	push @linger, AnyEvent->timer (after => $linger, cb => sub {
		1583	@linger = ();
		1584	});
		1585	}
		1586	}
		1587
		1588	=item $handle->destroy
		1589
		1590	Shuts down the handle object as much as possible - this call ensures that
		1591	no further callbacks will be invoked and as many resources as possible
		1592	will be freed. You must not call any methods on the object afterwards.
		1593
		1594	Normally, you can just "forget" any references to an AnyEvent::Handle
		1595	object and it will simply shut down. This works in fatal error and EOF
		1596	callbacks, as well as code outside. It does I<NOT> work in a read or write
		1597	callback, so when you want to destroy the AnyEvent::Handle object from
		1598	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		1599	that case.
		1600
		1601	The handle might still linger in the background and write out remaining
		1602	data, as specified by the C<linger> option, however.
		1603
		1604	=cut
		1605
		1606	sub destroy {
		1607	my ($self) = @_;
		1608
		1609	$self->DESTROY;
		1610	%$self = ();
		1611	}
		1612
		1613	=item AnyEvent::Handle::TLS_CTX
		1614
		1615	This function creates and returns the AnyEvent::TLS object used by default
		1616	for TLS mode.
		1617
		1618	The context is created by calling L<AnyEvent::TLS> without any arguments.
		1619
		1620	=cut
		1621
		1622	our $TLS_CTX;
		1623
		1624	sub TLS_CTX() {
		1625	$TLS_CTX ||= do {
		1626	require AnyEvent::TLS;
		1627
		1628	new AnyEvent::TLS
		1629	}
364	}	1630	}
365		1631
366	=back	1632	=back
367		1633
		1634
		1635	=head1 NONFREQUENTLY ASKED QUESTIONS
		1636
		1637	=over 4
		1638
		1639	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		1640	still get further invocations!
		1641
		1642	That's because AnyEvent::Handle keeps a reference to itself when handling
		1643	read or write callbacks.
		1644
		1645	It is only safe to "forget" the reference inside EOF or error callbacks,
		1646	from within all other callbacks, you need to explicitly call the C<<
		1647	->destroy >> method.
		1648
		1649	=item I get different callback invocations in TLS mode/Why can't I pause
		1650	reading?
		1651
		1652	Unlike, say, TCP, TLS connections do not consist of two independent
		1653	communication channels, one for each direction. Or put differently. The
		1654	read and write directions are not independent of each other: you cannot
		1655	write data unless you are also prepared to read, and vice versa.
		1656
		1657	This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
		1658	callback invocations when you are not expecting any read data - the reason
		1659	is that AnyEvent::Handle always reads in TLS mode.
		1660
		1661	During the connection, you have to make sure that you always have a
		1662	non-empty read-queue, or an C<on_read> watcher. At the end of the
		1663	connection (or when you no longer want to use it) you can call the
		1664	C<destroy> method.
		1665
		1666	=item How do I read data until the other side closes the connection?
		1667
		1668	If you just want to read your data into a perl scalar, the easiest way
		1669	to achieve this is by setting an C<on_read> callback that does nothing,
		1670	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		1671	will be in C<$_[0]{rbuf}>:
		1672
		1673	$handle->on_read (sub { });
		1674	$handle->on_eof (undef);
		1675	$handle->on_error (sub {
		1676	my $data = delete $_[0]{rbuf};
		1677	undef $handle;
		1678	});
		1679
		1680	The reason to use C<on_error> is that TCP connections, due to latencies
		1681	and packets loss, might get closed quite violently with an error, when in
		1682	fact, all data has been received.
		1683
		1684	It is usually better to use acknowledgements when transferring data,
		1685	to make sure the other side hasn't just died and you got the data
		1686	intact. This is also one reason why so many internet protocols have an
		1687	explicit QUIT command.
		1688
		1689	=item I don't want to destroy the handle too early - how do I wait until
		1690	all data has been written?
		1691
		1692	After writing your last bits of data, set the C<on_drain> callback
		1693	and destroy the handle in there - with the default setting of
		1694	C<low_water_mark> this will be called precisely when all data has been
		1695	written to the socket:
		1696
		1697	$handle->push_write (...);
		1698	$handle->on_drain (sub {
		1699	warn "all data submitted to the kernel\n";
		1700	undef $handle;
		1701	});
		1702
		1703	=back
		1704
		1705
		1706	=head1 SUBCLASSING AnyEvent::Handle
		1707
		1708	In many cases, you might want to subclass AnyEvent::Handle.
		1709
		1710	To make this easier, a given version of AnyEvent::Handle uses these
		1711	conventions:
		1712
		1713	=over 4
		1714
		1715	=item * all constructor arguments become object members.
		1716
		1717	At least initially, when you pass a C<tls>-argument to the constructor it
		1718	will end up in C<< $handle->{tls} >>. Those members might be changed or
		1719	mutated later on (for example C<tls> will hold the TLS connection object).
		1720
		1721	=item * other object member names are prefixed with an C<_>.
		1722
		1723	All object members not explicitly documented (internal use) are prefixed
		1724	with an underscore character, so the remaining non-C<_>-namespace is free
		1725	for use for subclasses.
		1726
		1727	=item * all members not documented here and not prefixed with an underscore
		1728	are free to use in subclasses.
		1729
		1730	Of course, new versions of AnyEvent::Handle may introduce more "public"
		1731	member variables, but thats just life, at least it is documented.
		1732
		1733	=back
		1734
368	=head1 AUTHOR	1735	=head1 AUTHOR
369		1736
370	Robin Redeker, C<< <elmex at ta-sa.org> >>	1737	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
371		1738
372	=cut	1739	=cut
373		1740
374	1; # End of AnyEvent::Handle	1741	1; # End of AnyEvent::Handle

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