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Revision 1.6 by elmex, Mon Apr 28 09:27:47 2008 UTC vs.
Revision 1.214 by root, Sun Jan 16 17:12:27 2011 UTC

1	package AnyEvent::Handle;
2
3	no warnings;
4	use strict;
5
6	use AnyEvent;
7	use IO::Handle;
8	use Errno qw/EAGAIN EINTR/;
9
10	=head1 NAME	1	=head1 NAME
11		2
12	AnyEvent::Handle - non-blocking I/O on filehandles via AnyEvent	3	AnyEvent::Handle - non-blocking I/O on streaming handles via AnyEvent
13
14	=head1 VERSION
15
16	Version 0.01
17
18	=cut
19
20	our $VERSION = '0.01';
21		4
22	=head1 SYNOPSIS	5	=head1 SYNOPSIS
23		6
24	use AnyEvent;	7	use AnyEvent;
25	use AnyEvent::Handle;	8	use AnyEvent::Handle;
26		9
27	my $cv = AnyEvent->condvar;	10	my $cv = AnyEvent->condvar;
28		11
29	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	12	my $hdl; $hdl = new AnyEvent::Handle
		13	fh => \*STDIN,
		14	on_error => sub {
		15	my ($hdl, $fatal, $msg) = @_;
		16	warn "got error $msg\n";
		17	$hdl->destroy;
		18	$cv->send;
		19	};
30		20
31	$ae_fh->on_eof (sub { $cv->broadcast });	21	# send some request line
		22	$hdl->push_write ("getinfo\015\012");
32		23
33	$ae_fh->readlines (sub {	24	# read the response line
		25	$hdl->push_read (line => sub {
34	my ($ae_fh, @lines) = @_;	26	my ($hdl, $line) = @_;
35	for (@lines) {	27	warn "got line <$line>\n";
		28	$cv->send;
		29	});
		30
		31	$cv->recv;
		32
		33	=head1 DESCRIPTION
		34
		35	This is a helper module to make it easier to do event-based I/O on
		36	stream-based filehandles (sockets, pipes, and other stream things).
		37
		38	The L<AnyEvent::Intro> tutorial contains some well-documented
		39	AnyEvent::Handle examples.
		40
		41	In the following, where the documentation refers to "bytes", it means
		42	characters. As sysread and syswrite are used for all I/O, their
		43	treatment of characters applies to this module as well.
		44
		45	At the very minimum, you should specify C<fh> or C<connect>, and the
		46	C<on_error> callback.
		47
		48	All callbacks will be invoked with the handle object as their first
		49	argument.
		50
		51	=cut
		52
		53	package AnyEvent::Handle;
		54
		55	use Scalar::Util ();
		56	use List::Util ();
		57	use Carp ();
		58	use Errno qw(EAGAIN EINTR);
		59
		60	use AnyEvent (); BEGIN { AnyEvent::common_sense }
		61	use AnyEvent::Util qw(WSAEWOULDBLOCK);
		62
		63	our $VERSION = $AnyEvent::VERSION;
		64
		65	sub _load_func($) {
		66	my $func = $_[0];
		67
		68	unless (defined &$func) {
		69	my $pkg = $func;
		70	do {
		71	$pkg =~ s/::[^:]+$//
		72	or return;
		73	eval "require $pkg";
		74	} until defined &$func;
		75	}
		76
		77	\&$func
		78	}
		79
		80	sub MAX_READ_SIZE() { 131072 }
		81
		82	=head1 METHODS
		83
		84	=over 4
		85
		86	=item $handle = B<new> AnyEvent::Handle fh => $filehandle, key => value...
		87
		88	The constructor supports these arguments (all as C<< key => value >> pairs).
		89
		90	=over 4
		91
		92	=item fh => $filehandle [C<fh> or C<connect> MANDATORY]
		93
		94	The filehandle this L<AnyEvent::Handle> object will operate on.
		95	NOTE: The filehandle will be set to non-blocking mode (using
		96	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		97	that mode.
		98
		99	=item connect => [$host, $service] [C<fh> or C<connect> MANDATORY]
		100
		101	Try to connect to the specified host and service (port), using
		102	C<AnyEvent::Socket::tcp_connect>. The C<$host> additionally becomes the
		103	default C<peername>.
		104
		105	You have to specify either this parameter, or C<fh>, above.
		106
		107	It is possible to push requests on the read and write queues, and modify
		108	properties of the stream, even while AnyEvent::Handle is connecting.
		109
		110	When this parameter is specified, then the C<on_prepare>,
		111	C<on_connect_error> and C<on_connect> callbacks will be called under the
		112	appropriate circumstances:
		113
		114	=over 4
		115
		116	=item on_prepare => $cb->($handle)
		117
		118	This (rarely used) callback is called before a new connection is
		119	attempted, but after the file handle has been created (you can access that
		120	file handle via C<< $handle->{fh} >>). It could be used to prepare the
		121	file handle with parameters required for the actual connect (as opposed to
		122	settings that can be changed when the connection is already established).
		123
		124	The return value of this callback should be the connect timeout value in
		125	seconds (or C<0>, or C<undef>, or the empty list, to indicate that the
		126	default timeout is to be used).
		127
		128	=item on_connect => $cb->($handle, $host, $port, $retry->())
		129
		130	This callback is called when a connection has been successfully established.
		131
		132	The peer's numeric host and port (the socket peername) are passed as
		133	parameters, together with a retry callback.
		134
		135	If, for some reason, the handle is not acceptable, calling C<$retry>
		136	will continue with the next connection target (in case of multi-homed
		137	hosts or SRV records there can be multiple connection endpoints). At the
		138	time it is called the read and write queues, eof status, tls status and
		139	similar properties of the handle will have been reset.
		140
		141	In most cases, you should ignore the C<$retry> parameter.
		142
		143	=item on_connect_error => $cb->($handle, $message)
		144
		145	This callback is called when the connection could not be
		146	established. C<$!> will contain the relevant error code, and C<$message> a
		147	message describing it (usually the same as C<"$!">).
		148
		149	If this callback isn't specified, then C<on_error> will be called with a
		150	fatal error instead.
		151
		152	=back
		153
		154	=item on_error => $cb->($handle, $fatal, $message)
		155
		156	This is the error callback, which is called when, well, some error
		157	occured, such as not being able to resolve the hostname, failure to
		158	connect, or a read error.
		159
		160	Some errors are fatal (which is indicated by C<$fatal> being true). On
		161	fatal errors the handle object will be destroyed (by a call to C<< ->
		162	destroy >>) after invoking the error callback (which means you are free to
		163	examine the handle object). Examples of fatal errors are an EOF condition
		164	with active (but unsatisfiable) read watchers (C<EPIPE>) or I/O errors. In
		165	cases where the other side can close the connection at will, it is
		166	often easiest to not report C<EPIPE> errors in this callback.
		167
		168	AnyEvent::Handle tries to find an appropriate error code for you to check
		169	against, but in some cases (TLS errors), this does not work well. It is
		170	recommended to always output the C<$message> argument in human-readable
		171	error messages (it's usually the same as C<"$!">).
		172
		173	Non-fatal errors can be retried by returning, but it is recommended
		174	to simply ignore this parameter and instead abondon the handle object
		175	when this callback is invoked. Examples of non-fatal errors are timeouts
		176	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
		177
		178	On entry to the callback, the value of C<$!> contains the operating
		179	system error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		180	C<EPROTO>).
		181
		182	While not mandatory, it is I<highly> recommended to set this callback, as
		183	you will not be notified of errors otherwise. The default just calls
		184	C<croak>.
		185
		186	=item on_read => $cb->($handle)
		187
		188	This sets the default read callback, which is called when data arrives
		189	and no read request is in the queue (unlike read queue callbacks, this
		190	callback will only be called when at least one octet of data is in the
		191	read buffer).
		192
		193	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
		194	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		195	must not enlarge or modify the read buffer, you can only remove data at
		196	the beginning from it.
		197
		198	You can also call C<< ->push_read (...) >> or any other function that
		199	modifies the read queue. Or do both. Or ...
		200
		201	When an EOF condition is detected, AnyEvent::Handle will first try to
		202	feed all the remaining data to the queued callbacks and C<on_read> before
		203	calling the C<on_eof> callback. If no progress can be made, then a fatal
		204	error will be raised (with C<$!> set to C<EPIPE>).
		205
		206	Note that, unlike requests in the read queue, an C<on_read> callback
		207	doesn't mean you I<require> some data: if there is an EOF and there
		208	are outstanding read requests then an error will be flagged. With an
		209	C<on_read> callback, the C<on_eof> callback will be invoked.
		210
		211	=item on_eof => $cb->($handle)
		212
		213	Set the callback to be called when an end-of-file condition is detected,
		214	i.e. in the case of a socket, when the other side has closed the
		215	connection cleanly, and there are no outstanding read requests in the
		216	queue (if there are read requests, then an EOF counts as an unexpected
		217	connection close and will be flagged as an error).
		218
		219	For sockets, this just means that the other side has stopped sending data,
		220	you can still try to write data, and, in fact, one can return from the EOF
		221	callback and continue writing data, as only the read part has been shut
		222	down.
		223
		224	If an EOF condition has been detected but no C<on_eof> callback has been
		225	set, then a fatal error will be raised with C<$!> set to <0>.
		226
		227	=item on_drain => $cb->($handle)
		228
		229	This sets the callback that is called when the write buffer becomes empty
		230	(or immediately if the buffer is empty already).
		231
		232	To append to the write buffer, use the C<< ->push_write >> method.
		233
		234	This callback is useful when you don't want to put all of your write data
		235	into the queue at once, for example, when you want to write the contents
		236	of some file to the socket you might not want to read the whole file into
		237	memory and push it into the queue, but instead only read more data from
		238	the file when the write queue becomes empty.
		239
		240	=item timeout => $fractional_seconds
		241
		242	=item rtimeout => $fractional_seconds
		243
		244	=item wtimeout => $fractional_seconds
		245
		246	If non-zero, then these enables an "inactivity" timeout: whenever this
		247	many seconds pass without a successful read or write on the underlying
		248	file handle (or a call to C<timeout_reset>), the C<on_timeout> callback
		249	will be invoked (and if that one is missing, a non-fatal C<ETIMEDOUT>
		250	error will be raised).
		251
		252	There are three variants of the timeouts that work independently
		253	of each other, for both read and write, just read, and just write:
		254	C<timeout>, C<rtimeout> and C<wtimeout>, with corresponding callbacks
		255	C<on_timeout>, C<on_rtimeout> and C<on_wtimeout>, and reset functions
		256	C<timeout_reset>, C<rtimeout_reset>, and C<wtimeout_reset>.
		257
		258	Note that timeout processing is active even when you do not have
		259	any outstanding read or write requests: If you plan to keep the connection
		260	idle then you should disable the timeout temporarily or ignore the timeout
		261	in the C<on_timeout> callback, in which case AnyEvent::Handle will simply
		262	restart the timeout.
		263
		264	Zero (the default) disables this timeout.
		265
		266	=item on_timeout => $cb->($handle)
		267
		268	Called whenever the inactivity timeout passes. If you return from this
		269	callback, then the timeout will be reset as if some activity had happened,
		270	so this condition is not fatal in any way.
		271
		272	=item rbuf_max => <bytes>
		273
		274	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		275	when the read buffer ever (strictly) exceeds this size. This is useful to
		276	avoid some forms of denial-of-service attacks.
		277
		278	For example, a server accepting connections from untrusted sources should
		279	be configured to accept only so-and-so much data that it cannot act on
		280	(for example, when expecting a line, an attacker could send an unlimited
		281	amount of data without a callback ever being called as long as the line
		282	isn't finished).
		283
		284	=item wbuf_max => <bytes>
		285
		286	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		287	when the write buffer ever (strictly) exceeds this size. This is useful to
		288	avoid some forms of denial-of-service attacks.
		289
		290	Although the units of this parameter is bytes, this is the I<raw> number
		291	of bytes not yet accepted by the kernel. This can make a difference when
		292	you e.g. use TLS, as TLS typically makes your write data larger (but it
		293	can also make it smaller due to compression).
		294
		295	As an example of when this limit is useful, take a chat server that sends
		296	chat messages to a client. If the client does not read those in a timely
		297	manner then the send buffer in the server would grow unbounded.
		298
		299	=item autocork => <boolean>
		300
		301	When disabled (the default), C<push_write> will try to immediately
		302	write the data to the handle if possible. This avoids having to register
		303	a write watcher and wait for the next event loop iteration, but can
		304	be inefficient if you write multiple small chunks (on the wire, this
		305	disadvantage is usually avoided by your kernel's nagle algorithm, see
		306	C<no_delay>, but this option can save costly syscalls).
		307
		308	When enabled, writes will always be queued till the next event loop
		309	iteration. This is efficient when you do many small writes per iteration,
		310	but less efficient when you do a single write only per iteration (or when
		311	the write buffer often is full). It also increases write latency.
		312
		313	=item no_delay => <boolean>
		314
		315	When doing small writes on sockets, your operating system kernel might
		316	wait a bit for more data before actually sending it out. This is called
		317	the Nagle algorithm, and usually it is beneficial.
		318
		319	In some situations you want as low a delay as possible, which can be
		320	accomplishd by setting this option to a true value.
		321
		322	The default is your operating system's default behaviour (most likely
		323	enabled). This option explicitly enables or disables it, if possible.
		324
		325	=item keepalive => <boolean>
		326
		327	Enables (default disable) the SO_KEEPALIVE option on the stream socket:
		328	normally, TCP connections have no time-out once established, so TCP
		329	connections, once established, can stay alive forever even when the other
		330	side has long gone. TCP keepalives are a cheap way to take down long-lived
		331	TCP connections when the other side becomes unreachable. While the default
		332	is OS-dependent, TCP keepalives usually kick in after around two hours,
		333	and, if the other side doesn't reply, take down the TCP connection some 10
		334	to 15 minutes later.
		335
		336	It is harmless to specify this option for file handles that do not support
		337	keepalives, and enabling it on connections that are potentially long-lived
		338	is usually a good idea.
		339
		340	=item oobinline => <boolean>
		341
		342	BSD majorly fucked up the implementation of TCP urgent data. The result
		343	is that almost no OS implements TCP according to the specs, and every OS
		344	implements it slightly differently.
		345
		346	If you want to handle TCP urgent data, then setting this flag (the default
		347	is enabled) gives you the most portable way of getting urgent data, by
		348	putting it into the stream.
		349
		350	Since BSD emulation of OOB data on top of TCP's urgent data can have
		351	security implications, AnyEvent::Handle sets this flag automatically
		352	unless explicitly specified. Note that setting this flag after
		353	establishing a connection I<may> be a bit too late (data loss could
		354	already have occured on BSD systems), but at least it will protect you
		355	from most attacks.
		356
		357	=item read_size => <bytes>
		358
		359	The initial read block size, the number of bytes this module will try to
		360	read during each loop iteration. Each handle object will consume at least
		361	this amount of memory for the read buffer as well, so when handling many
		362	connections requirements). See also C<max_read_size>. Default: C<2048>.
		363
		364	=item max_read_size => <bytes>
		365
		366	The maximum read buffer size used by the dynamic adjustment
		367	algorithm: Each time AnyEvent::Handle can read C<read_size> bytes in
		368	one go it will double C<read_size> up to the maximum given by this
		369	option. Default: C<131072> or C<read_size>, whichever is higher.
		370
		371	=item low_water_mark => <bytes>
		372
		373	Sets the number of bytes (default: C<0>) that make up an "empty" write
		374	buffer: If the buffer reaches this size or gets even samller it is
		375	considered empty.
		376
		377	Sometimes it can be beneficial (for performance reasons) to add data to
		378	the write buffer before it is fully drained, but this is a rare case, as
		379	the operating system kernel usually buffers data as well, so the default
		380	is good in almost all cases.
		381
		382	=item linger => <seconds>
		383
		384	If this is non-zero (default: C<3600>), the destructor of the
		385	AnyEvent::Handle object will check whether there is still outstanding
		386	write data and will install a watcher that will write this data to the
		387	socket. No errors will be reported (this mostly matches how the operating
		388	system treats outstanding data at socket close time).
		389
		390	This will not work for partial TLS data that could not be encoded
		391	yet. This data will be lost. Calling the C<stoptls> method in time might
		392	help.
		393
		394	=item peername => $string
		395
		396	A string used to identify the remote site - usually the DNS hostname
		397	(I<not> IDN!) used to create the connection, rarely the IP address.
		398
		399	Apart from being useful in error messages, this string is also used in TLS
		400	peername verification (see C<verify_peername> in L<AnyEvent::TLS>). This
		401	verification will be skipped when C<peername> is not specified or is
		402	C<undef>.
		403
		404	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		405
		406	When this parameter is given, it enables TLS (SSL) mode, that means
		407	AnyEvent will start a TLS handshake as soon as the connection has been
		408	established and will transparently encrypt/decrypt data afterwards.
		409
		410	All TLS protocol errors will be signalled as C<EPROTO>, with an
		411	appropriate error message.
		412
		413	TLS mode requires Net::SSLeay to be installed (it will be loaded
		414	automatically when you try to create a TLS handle): this module doesn't
		415	have a dependency on that module, so if your module requires it, you have
		416	to add the dependency yourself.
		417
		418	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		419	C<accept>, and for the TLS client side of a connection, use C<connect>
		420	mode.
		421
		422	You can also provide your own TLS connection object, but you have
		423	to make sure that you call either C<Net::SSLeay::set_connect_state>
		424	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		425	AnyEvent::Handle. Also, this module will take ownership of this connection
		426	object.
		427
		428	At some future point, AnyEvent::Handle might switch to another TLS
		429	implementation, then the option to use your own session object will go
		430	away.
		431
		432	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		433	passing in the wrong integer will lead to certain crash. This most often
		434	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		435	segmentation fault.
		436
		437	Use the C<< ->starttls >> method if you need to start TLS negotiation later.
		438
		439	=item tls_ctx => $anyevent_tls
		440
		441	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		442	(unless a connection object was specified directly). If this
		443	parameter is missing (or C<undef>), then AnyEvent::Handle will use
		444	C<AnyEvent::Handle::TLS_CTX>.
		445
		446	Instead of an object, you can also specify a hash reference with C<< key
		447	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		448	new TLS context object.
		449
		450	=item on_starttls => $cb->($handle, $success[, $error_message])
		451
		452	This callback will be invoked when the TLS/SSL handshake has finished. If
		453	C<$success> is true, then the TLS handshake succeeded, otherwise it failed
		454	(C<on_stoptls> will not be called in this case).
		455
		456	The session in C<< $handle->{tls} >> can still be examined in this
		457	callback, even when the handshake was not successful.
		458
		459	TLS handshake failures will not cause C<on_error> to be invoked when this
		460	callback is in effect, instead, the error message will be passed to C<on_starttls>.
		461
		462	Without this callback, handshake failures lead to C<on_error> being
		463	called as usual.
		464
		465	Note that you cannot just call C<starttls> again in this callback. If you
		466	need to do that, start an zero-second timer instead whose callback can
		467	then call C<< ->starttls >> again.
		468
		469	=item on_stoptls => $cb->($handle)
		470
		471	When a SSLv3/TLS shutdown/close notify/EOF is detected and this callback is
		472	set, then it will be invoked after freeing the TLS session. If it is not,
		473	then a TLS shutdown condition will be treated like a normal EOF condition
		474	on the handle.
		475
		476	The session in C<< $handle->{tls} >> can still be examined in this
		477	callback.
		478
		479	This callback will only be called on TLS shutdowns, not when the
		480	underlying handle signals EOF.
		481
		482	=item json => JSON or JSON::XS object
		483
		484	This is the json coder object used by the C<json> read and write types.
		485
		486	If you don't supply it, then AnyEvent::Handle will create and use a
		487	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		488	texts.
		489
		490	Note that you are responsible to depend on the JSON module if you want to
		491	use this functionality, as AnyEvent does not have a dependency itself.
		492
		493	=back
		494
		495	=cut
		496
		497	sub new {
		498	my $class = shift;
		499	my $self = bless { @_ }, $class;
		500
		501	if ($self->{fh}) {
		502	$self->_start;
		503	return unless $self->{fh}; # could be gone by now
		504
		505	} elsif ($self->{connect}) {
		506	require AnyEvent::Socket;
		507
		508	$self->{peername} = $self->{connect}[0]
		509	unless exists $self->{peername};
		510
		511	$self->{_skip_drain_rbuf} = 1;
		512
		513	{
		514	Scalar::Util::weaken (my $self = $self);
		515
		516	$self->{_connect} =
		517	AnyEvent::Socket::tcp_connect (
		518	$self->{connect}[0],
		519	$self->{connect}[1],
		520	sub {
		521	my ($fh, $host, $port, $retry) = @_;
		522
		523	delete $self->{_connect}; # no longer needed
		524
		525	if ($fh) {
		526	$self->{fh} = $fh;
		527
		528	delete $self->{_skip_drain_rbuf};
		529	$self->_start;
		530
		531	$self->{on_connect}
		532	and $self->{on_connect}($self, $host, $port, sub {
		533	delete @$self{qw(fh _tw _rtw _wtw _ww _rw _eof _queue rbuf _wbuf tls _tls_rbuf _tls_wbuf)};
		534	$self->{_skip_drain_rbuf} = 1;
		535	&$retry;
		536	});
		537
		538	} else {
		539	if ($self->{on_connect_error}) {
		540	$self->{on_connect_error}($self, "$!");
		541	$self->destroy;
		542	} else {
		543	$self->_error ($!, 1);
		544	}
		545	}
		546	},
		547	sub {
		548	local $self->{fh} = $_[0];
		549
		550	$self->{on_prepare}
		551	? $self->{on_prepare}->($self)
		552	: ()
		553	}
		554	);
		555	}
		556
		557	} else {
		558	Carp::croak "AnyEvent::Handle: either an existing fh or the connect parameter must be specified";
		559	}
		560
		561	$self
		562	}
		563
		564	sub _start {
		565	my ($self) = @_;
		566
		567	# too many clueless people try to use udp and similar sockets
		568	# with AnyEvent::Handle, do them a favour.
		569	my $type = getsockopt $self->{fh}, Socket::SOL_SOCKET (), Socket::SO_TYPE ();
		570	Carp::croak "AnyEvent::Handle: only stream sockets supported, anything else will NOT work!"
		571	if Socket::SOCK_STREAM () != (unpack "I", $type) && defined $type;
		572
		573	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
		574
		575	$self->{_activity} =
		576	$self->{_ractivity} =
		577	$self->{_wactivity} = AE::now;
		578
		579	$self->{read_size} ||= 2048;
		580	$self->{max_read_size} = $self->{read_size}
		581	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		582
		583	$self->timeout (delete $self->{timeout} ) if $self->{timeout};
		584	$self->rtimeout (delete $self->{rtimeout} ) if $self->{rtimeout};
		585	$self->wtimeout (delete $self->{wtimeout} ) if $self->{wtimeout};
		586
		587	$self->no_delay (delete $self->{no_delay} ) if exists $self->{no_delay} && $self->{no_delay};
		588	$self->keepalive (delete $self->{keepalive}) if exists $self->{keepalive} && $self->{keepalive};
		589
		590	$self->oobinline (exists $self->{oobinline} ? delete $self->{oobinline} : 1);
		591
		592	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		593	if $self->{tls};
		594
		595	$self->on_drain (delete $self->{on_drain} ) if $self->{on_drain};
		596
		597	$self->start_read
		598	if $self->{on_read} || @{ $self->{_queue} };
		599
		600	$self->_drain_wbuf;
		601	}
		602
		603	sub _error {
		604	my ($self, $errno, $fatal, $message) = @_;
		605
		606	$! = $errno;
		607	$message ||= "$!";
		608
		609	if ($self->{on_error}) {
		610	$self->{on_error}($self, $fatal, $message);
		611	$self->destroy if $fatal;
		612	} elsif ($self->{fh} || $self->{connect}) {
		613	$self->destroy;
		614	Carp::croak "AnyEvent::Handle uncaught error: $message";
		615	}
		616	}
		617
		618	=item $fh = $handle->fh
		619
		620	This method returns the file handle used to create the L<AnyEvent::Handle> object.
		621
		622	=cut
		623
		624	sub fh { $_[0]{fh} }
		625
		626	=item $handle->on_error ($cb)
		627
		628	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
		629
		630	=cut
		631
		632	sub on_error {
		633	$_[0]{on_error} = $_[1];
		634	}
		635
		636	=item $handle->on_eof ($cb)
		637
		638	Replace the current C<on_eof> callback (see the C<on_eof> constructor argument).
		639
		640	=cut
		641
		642	sub on_eof {
		643	$_[0]{on_eof} = $_[1];
		644	}
		645
		646	=item $handle->on_timeout ($cb)
		647
		648	=item $handle->on_rtimeout ($cb)
		649
		650	=item $handle->on_wtimeout ($cb)
		651
		652	Replace the current C<on_timeout>, C<on_rtimeout> or C<on_wtimeout>
		653	callback, or disables the callback (but not the timeout) if C<$cb> =
		654	C<undef>. See the C<timeout> constructor argument and method.
		655
		656	=cut
		657
		658	# see below
		659
		660	=item $handle->autocork ($boolean)
		661
		662	Enables or disables the current autocork behaviour (see C<autocork>
		663	constructor argument). Changes will only take effect on the next write.
		664
		665	=cut
		666
		667	sub autocork {
		668	$_[0]{autocork} = $_[1];
		669	}
		670
		671	=item $handle->no_delay ($boolean)
		672
		673	Enables or disables the C<no_delay> setting (see constructor argument of
		674	the same name for details).
		675
		676	=cut
		677
		678	sub no_delay {
		679	$_[0]{no_delay} = $_[1];
		680
		681	setsockopt $_[0]{fh}, Socket::IPPROTO_TCP (), Socket::TCP_NODELAY (), int $_[1]
		682	if $_[0]{fh};
		683	}
		684
		685	=item $handle->keepalive ($boolean)
		686
		687	Enables or disables the C<keepalive> setting (see constructor argument of
		688	the same name for details).
		689
		690	=cut
		691
		692	sub keepalive {
		693	$_[0]{keepalive} = $_[1];
		694
		695	eval {
		696	local $SIG{__DIE__};
		697	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		698	if $_[0]{fh};
		699	};
		700	}
		701
		702	=item $handle->oobinline ($boolean)
		703
		704	Enables or disables the C<oobinline> setting (see constructor argument of
		705	the same name for details).
		706
		707	=cut
		708
		709	sub oobinline {
		710	$_[0]{oobinline} = $_[1];
		711
		712	eval {
		713	local $SIG{__DIE__};
		714	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_OOBINLINE (), int $_[1]
		715	if $_[0]{fh};
		716	};
		717	}
		718
		719	=item $handle->keepalive ($boolean)
		720
		721	Enables or disables the C<keepalive> setting (see constructor argument of
		722	the same name for details).
		723
		724	=cut
		725
		726	sub keepalive {
		727	$_[0]{keepalive} = $_[1];
		728
		729	eval {
		730	local $SIG{__DIE__};
		731	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		732	if $_[0]{fh};
		733	};
		734	}
		735
		736	=item $handle->on_starttls ($cb)
		737
		738	Replace the current C<on_starttls> callback (see the C<on_starttls> constructor argument).
		739
		740	=cut
		741
		742	sub on_starttls {
		743	$_[0]{on_starttls} = $_[1];
		744	}
		745
		746	=item $handle->on_stoptls ($cb)
		747
		748	Replace the current C<on_stoptls> callback (see the C<on_stoptls> constructor argument).
		749
		750	=cut
		751
		752	sub on_stoptls {
		753	$_[0]{on_stoptls} = $_[1];
		754	}
		755
		756	=item $handle->rbuf_max ($max_octets)
		757
		758	Configures the C<rbuf_max> setting (C<undef> disables it).
		759
		760	=item $handle->wbuf_max ($max_octets)
		761
		762	Configures the C<wbuf_max> setting (C<undef> disables it).
		763
		764	=cut
		765
		766	sub rbuf_max {
		767	$_[0]{rbuf_max} = $_[1];
		768	}
		769
		770	sub rbuf_max {
		771	$_[0]{wbuf_max} = $_[1];
		772	}
		773
		774	#############################################################################
		775
		776	=item $handle->timeout ($seconds)
		777
		778	=item $handle->rtimeout ($seconds)
		779
		780	=item $handle->wtimeout ($seconds)
		781
		782	Configures (or disables) the inactivity timeout.
		783
		784	=item $handle->timeout_reset
		785
		786	=item $handle->rtimeout_reset
		787
		788	=item $handle->wtimeout_reset
		789
		790	Reset the activity timeout, as if data was received or sent.
		791
		792	These methods are cheap to call.
		793
		794	=cut
		795
		796	for my $dir ("", "r", "w") {
		797	my $timeout = "${dir}timeout";
		798	my $tw = "_${dir}tw";
		799	my $on_timeout = "on_${dir}timeout";
		800	my $activity = "_${dir}activity";
		801	my $cb;
		802
		803	*$on_timeout = sub {
		804	$_[0]{$on_timeout} = $_[1];
		805	};
		806
		807	*$timeout = sub {
		808	my ($self, $new_value) = @_;
		809
		810	$new_value >= 0
		811	or Carp::croak "AnyEvent::Handle->$timeout called with negative timeout ($new_value), caught";
		812
		813	$self->{$timeout} = $new_value;
		814	delete $self->{$tw}; &$cb;
		815	};
		816
		817	*{"${dir}timeout_reset"} = sub {
		818	$_[0]{$activity} = AE::now;
		819	};
		820
		821	# main workhorse:
		822	# reset the timeout watcher, as neccessary
		823	# also check for time-outs
		824	$cb = sub {
		825	my ($self) = @_;
		826
		827	if ($self->{$timeout} && $self->{fh}) {
		828	my $NOW = AE::now;
		829
		830	# when would the timeout trigger?
		831	my $after = $self->{$activity} + $self->{$timeout} - $NOW;
		832
		833	# now or in the past already?
		834	if ($after <= 0) {
		835	$self->{$activity} = $NOW;
		836
		837	if ($self->{$on_timeout}) {
		838	$self->{$on_timeout}($self);
		839	} else {
		840	$self->_error (Errno::ETIMEDOUT);
		841	}
		842
		843	# callback could have changed timeout value, optimise
		844	return unless $self->{$timeout};
		845
		846	# calculate new after
		847	$after = $self->{$timeout};
		848	}
		849
		850	Scalar::Util::weaken $self;
		851	return unless $self; # ->error could have destroyed $self
		852
		853	$self->{$tw} ||= AE::timer $after, 0, sub {
		854	delete $self->{$tw};
		855	$cb->($self);
36	chomp;	856	};
37	print "Line: $_";	857	} else {
		858	delete $self->{$tw};
		859	}
		860	}
		861	}
		862
		863	#############################################################################
		864
		865	=back
		866
		867	=head2 WRITE QUEUE
		868
		869	AnyEvent::Handle manages two queues per handle, one for writing and one
		870	for reading.
		871
		872	The write queue is very simple: you can add data to its end, and
		873	AnyEvent::Handle will automatically try to get rid of it for you.
		874
		875	When data could be written and the write buffer is shorter then the low
		876	water mark, the C<on_drain> callback will be invoked.
		877
		878	=over 4
		879
		880	=item $handle->on_drain ($cb)
		881
		882	Sets the C<on_drain> callback or clears it (see the description of
		883	C<on_drain> in the constructor).
		884
		885	This method may invoke callbacks (and therefore the handle might be
		886	destroyed after it returns).
		887
		888	=cut
		889
		890	sub on_drain {
		891	my ($self, $cb) = @_;
		892
		893	$self->{on_drain} = $cb;
		894
		895	$cb->($self)
		896	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
		897	}
		898
		899	=item $handle->push_write ($data)
		900
		901	Queues the given scalar to be written. You can push as much data as
		902	you want (only limited by the available memory and C<wbuf_max>), as
		903	C<AnyEvent::Handle> buffers it independently of the kernel.
		904
		905	This method may invoke callbacks (and therefore the handle might be
		906	destroyed after it returns).
		907
		908	=cut
		909
		910	sub _drain_wbuf {
		911	my ($self) = @_;
		912
		913	if (!$self->{_ww} && length $self->{wbuf}) {
		914
		915	Scalar::Util::weaken $self;
		916
		917	my $cb = sub {
		918	my $len = syswrite $self->{fh}, $self->{wbuf};
		919
		920	if (defined $len) {
		921	substr $self->{wbuf}, 0, $len, "";
		922
		923	$self->{_activity} = $self->{_wactivity} = AE::now;
		924
		925	$self->{on_drain}($self)
		926	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
		927	&& $self->{on_drain};
		928
		929	delete $self->{_ww} unless length $self->{wbuf};
		930	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		931	$self->_error ($!, 1);
		932	}
		933	};
		934
		935	# try to write data immediately
		936	$cb->() unless $self->{autocork};
		937
		938	# if still data left in wbuf, we need to poll
		939	$self->{_ww} = AE::io $self->{fh}, 1, $cb
		940	if length $self->{wbuf};
		941
		942	if (
		943	defined $self->{wbuf_max}
		944	&& $self->{wbuf_max} < length $self->{wbuf}
		945	) {
		946	$self->_error (Errno::ENOSPC, 1), return;
		947	}
		948	};
		949	}
		950
		951	our %WH;
		952
		953	# deprecated
		954	sub register_write_type($$) {
		955	$WH{$_[0]} = $_[1];
		956	}
		957
		958	sub push_write {
		959	my $self = shift;
		960
		961	if (@_ > 1) {
		962	my $type = shift;
		963
		964	@_ = ($WH{$type} ||= _load_func "$type\::anyevent_write_type"
		965	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_write")
		966	->($self, @_);
		967	}
		968
		969	# we downgrade here to avoid hard-to-track-down bugs,
		970	# and diagnose the problem earlier and better.
		971
		972	if ($self->{tls}) {
		973	utf8::downgrade $self->{_tls_wbuf} .= $_[0];
		974	&_dotls ($self) if $self->{fh};
		975	} else {
		976	utf8::downgrade $self->{wbuf} .= $_[0];
		977	$self->_drain_wbuf if $self->{fh};
		978	}
		979	}
		980
		981	=item $handle->push_write (type => @args)
		982
		983	Instead of formatting your data yourself, you can also let this module
		984	do the job by specifying a type and type-specific arguments. You
		985	can also specify the (fully qualified) name of a package, in which
		986	case AnyEvent tries to load the package and then expects to find the
		987	C<anyevent_write_type> function inside (see "custom write types", below).
		988
		989	Predefined types are (if you have ideas for additional types, feel free to
		990	drop by and tell us):
		991
		992	=over 4
		993
		994	=item netstring => $string
		995
		996	Formats the given value as netstring
		997	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		998
		999	=cut
		1000
		1001	register_write_type netstring => sub {
		1002	my ($self, $string) = @_;
		1003
		1004	(length $string) . ":$string,"
		1005	};
		1006
		1007	=item packstring => $format, $data
		1008
		1009	An octet string prefixed with an encoded length. The encoding C<$format>
		1010	uses the same format as a Perl C<pack> format, but must specify a single
		1011	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1012	optional C<!>, C<< < >> or C<< > >> modifier).
		1013
		1014	=cut
		1015
		1016	register_write_type packstring => sub {
		1017	my ($self, $format, $string) = @_;
		1018
		1019	pack "$format/a*", $string
		1020	};
		1021
		1022	=item json => $array_or_hashref
		1023
		1024	Encodes the given hash or array reference into a JSON object. Unless you
		1025	provide your own JSON object, this means it will be encoded to JSON text
		1026	in UTF-8.
		1027
		1028	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		1029	one end of a handle and read them at the other end without using any
		1030	additional framing.
		1031
		1032	The generated JSON text is guaranteed not to contain any newlines: While
		1033	this module doesn't need delimiters after or between JSON texts to be
		1034	able to read them, many other languages depend on that.
		1035
		1036	A simple RPC protocol that interoperates easily with others is to send
		1037	JSON arrays (or objects, although arrays are usually the better choice as
		1038	they mimic how function argument passing works) and a newline after each
		1039	JSON text:
		1040
		1041	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		1042	$handle->push_write ("\012");
		1043
		1044	An AnyEvent::Handle receiver would simply use the C<json> read type and
		1045	rely on the fact that the newline will be skipped as leading whitespace:
		1046
		1047	$handle->push_read (json => sub { my $array = $_[1]; ... });
		1048
		1049	Other languages could read single lines terminated by a newline and pass
		1050	this line into their JSON decoder of choice.
		1051
		1052	=cut
		1053
		1054	sub json_coder() {
		1055	eval { require JSON::XS; JSON::XS->new->utf8 }
		1056	|| do { require JSON; JSON->new->utf8 }
		1057	}
		1058
		1059	register_write_type json => sub {
		1060	my ($self, $ref) = @_;
		1061
		1062	my $json = $self->{json} ||= json_coder;
		1063
		1064	$json->encode ($ref)
		1065	};
		1066
		1067	=item storable => $reference
		1068
		1069	Freezes the given reference using L<Storable> and writes it to the
		1070	handle. Uses the C<nfreeze> format.
		1071
		1072	=cut
		1073
		1074	register_write_type storable => sub {
		1075	my ($self, $ref) = @_;
		1076
		1077	require Storable;
		1078
		1079	pack "w/a*", Storable::nfreeze ($ref)
		1080	};
		1081
		1082	=back
		1083
		1084	=item $handle->push_shutdown
		1085
		1086	Sometimes you know you want to close the socket after writing your data
		1087	before it was actually written. One way to do that is to replace your
		1088	C<on_drain> handler by a callback that shuts down the socket (and set
		1089	C<low_water_mark> to C<0>). This method is a shorthand for just that, and
		1090	replaces the C<on_drain> callback with:
		1091
		1092	sub { shutdown $_[0]{fh}, 1 }
		1093
		1094	This simply shuts down the write side and signals an EOF condition to the
		1095	the peer.
		1096
		1097	You can rely on the normal read queue and C<on_eof> handling
		1098	afterwards. This is the cleanest way to close a connection.
		1099
		1100	This method may invoke callbacks (and therefore the handle might be
		1101	destroyed after it returns).
		1102
		1103	=cut
		1104
		1105	sub push_shutdown {
		1106	my ($self) = @_;
		1107
		1108	delete $self->{low_water_mark};
		1109	$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
		1110	}
		1111
		1112	=item custom write types - Package::anyevent_write_type $handle, @args
		1113
		1114	Instead of one of the predefined types, you can also specify the name of
		1115	a package. AnyEvent will try to load the package and then expects to find
		1116	a function named C<anyevent_write_type> inside. If it isn't found, it
		1117	progressively tries to load the parent package until it either finds the
		1118	function (good) or runs out of packages (bad).
		1119
		1120	Whenever the given C<type> is used, C<push_write> will the function with
		1121	the handle object and the remaining arguments.
		1122
		1123	The function is supposed to return a single octet string that will be
		1124	appended to the write buffer, so you cna mentally treat this function as a
		1125	"arguments to on-the-wire-format" converter.
		1126
		1127	Example: implement a custom write type C<join> that joins the remaining
		1128	arguments using the first one.
		1129
		1130	$handle->push_write (My::Type => " ", 1,2,3);
		1131
		1132	# uses the following package, which can be defined in the "My::Type" or in
		1133	# the "My" modules to be auto-loaded, or just about anywhere when the
		1134	# My::Type::anyevent_write_type is defined before invoking it.
		1135
		1136	package My::Type;
		1137
		1138	sub anyevent_write_type {
		1139	my ($handle, $delim, @args) = @_;
		1140
		1141	join $delim, @args
		1142	}
		1143
		1144	=cut
		1145
		1146	#############################################################################
		1147
		1148	=back
		1149
		1150	=head2 READ QUEUE
		1151
		1152	AnyEvent::Handle manages two queues per handle, one for writing and one
		1153	for reading.
		1154
		1155	The read queue is more complex than the write queue. It can be used in two
		1156	ways, the "simple" way, using only C<on_read> and the "complex" way, using
		1157	a queue.
		1158
		1159	In the simple case, you just install an C<on_read> callback and whenever
		1160	new data arrives, it will be called. You can then remove some data (if
		1161	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you can
		1162	leave the data there if you want to accumulate more (e.g. when only a
		1163	partial message has been received so far), or change the read queue with
		1164	e.g. C<push_read>.
		1165
		1166	In the more complex case, you want to queue multiple callbacks. In this
		1167	case, AnyEvent::Handle will call the first queued callback each time new
		1168	data arrives (also the first time it is queued) and remove it when it has
		1169	done its job (see C<push_read>, below).
		1170
		1171	This way you can, for example, push three line-reads, followed by reading
		1172	a chunk of data, and AnyEvent::Handle will execute them in order.
		1173
		1174	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
		1175	the specified number of bytes which give an XML datagram.
		1176
		1177	# in the default state, expect some header bytes
		1178	$handle->on_read (sub {
		1179	# some data is here, now queue the length-header-read (4 octets)
		1180	shift->unshift_read (chunk => 4, sub {
		1181	# header arrived, decode
		1182	my $len = unpack "N", $_[1];
		1183
		1184	# now read the payload
		1185	shift->unshift_read (chunk => $len, sub {
		1186	my $xml = $_[1];
		1187	# handle xml
		1188	});
		1189	});
		1190	});
		1191
		1192	Example 2: Implement a client for a protocol that replies either with "OK"
		1193	and another line or "ERROR" for the first request that is sent, and 64
		1194	bytes for the second request. Due to the availability of a queue, we can
		1195	just pipeline sending both requests and manipulate the queue as necessary
		1196	in the callbacks.
		1197
		1198	When the first callback is called and sees an "OK" response, it will
		1199	C<unshift> another line-read. This line-read will be queued I<before> the
		1200	64-byte chunk callback.
		1201
		1202	# request one, returns either "OK + extra line" or "ERROR"
		1203	$handle->push_write ("request 1\015\012");
		1204
		1205	# we expect "ERROR" or "OK" as response, so push a line read
		1206	$handle->push_read (line => sub {
		1207	# if we got an "OK", we have to _prepend_ another line,
		1208	# so it will be read before the second request reads its 64 bytes
		1209	# which are already in the queue when this callback is called
		1210	# we don't do this in case we got an error
		1211	if ($_[1] eq "OK") {
		1212	$_[0]->unshift_read (line => sub {
		1213	my $response = $_[1];
		1214	...
		1215	});
38	}	1216	}
39	});	1217	});
40		1218
41	# or use the constructor to pass the callback:	1219	# request two, simply returns 64 octets
		1220	$handle->push_write ("request 2\015\012");
42		1221
43	my $ae_fh2 =	1222	# simply read 64 bytes, always
44	AnyEvent::Handle->new (	1223	$handle->push_read (chunk => 64, sub {
45	fh => \*STDIN,	1224	my $response = $_[1];
46	on_eof => sub {	1225	...
47	$cv->broadcast;	1226	});
48	},	1227
49	on_readline => sub {	1228	=over 4
50	my ($ae_fh, @lines) = @_;	1229
51	for (@lines) {	1230	=cut
52	chomp;	1231
53	print "Line: $_";	1232	sub _drain_rbuf {
		1233	my ($self) = @_;
		1234
		1235	# avoid recursion
		1236	return if $self->{_skip_drain_rbuf};
		1237	local $self->{_skip_drain_rbuf} = 1;
		1238
		1239	while () {
		1240	# we need to use a separate tls read buffer, as we must not receive data while
		1241	# we are draining the buffer, and this can only happen with TLS.
		1242	$self->{rbuf} .= delete $self->{_tls_rbuf}
		1243	if exists $self->{_tls_rbuf};
		1244
		1245	my $len = length $self->{rbuf};
		1246
		1247	if (my $cb = shift @{ $self->{_queue} }) {
		1248	unless ($cb->($self)) {
		1249	# no progress can be made
		1250	# (not enough data and no data forthcoming)
		1251	$self->_error (Errno::EPIPE, 1), return
		1252	if $self->{_eof};
		1253
		1254	unshift @{ $self->{_queue} }, $cb;
54	}	1255	last;
55	}	1256	}
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}) {	1257	} elsif ($self->{on_read}) {
121	$self->readlines ($self->{on_readline});	1258	last unless $len;
122		1259
		1260	$self->{on_read}($self);
		1261
		1262	if (
		1263	$len == length $self->{rbuf} # if no data has been consumed
		1264	&& !@{ $self->{_queue} } # and the queue is still empty
		1265	&& $self->{on_read} # but we still have on_read
		1266	) {
		1267	# no further data will arrive
		1268	# so no progress can be made
		1269	$self->_error (Errno::EPIPE, 1), return
		1270	if $self->{_eof};
		1271
		1272	last; # more data might arrive
		1273	}
		1274	} else {
		1275	# read side becomes idle
		1276	delete $self->{_rw} unless $self->{tls};
		1277	last;
		1278	}
		1279	}
		1280
123	} elsif ($self->{on_eof}) {	1281	if ($self->{_eof}) {
124	$self->on_eof ($self->{on_eof});	1282	$self->{on_eof}
		1283	? $self->{on_eof}($self)
		1284	: $self->_error (0, 1, "Unexpected end-of-file");
125		1285
126	} elsif ($self->{on_error}) {	1286	return;
127	$self->on_eof ($self->{on_error});
128	}	1287	}
129		1288
130	return $self	1289	if (
131	}	1290	defined $self->{rbuf_max}
		1291	&& $self->{rbuf_max} < length $self->{rbuf}
		1292	) {
		1293	$self->_error (Errno::ENOSPC, 1), return;
		1294	}
132		1295
133	=item B<fh>	1296	# may need to restart read watcher
		1297	unless ($self->{_rw}) {
		1298	$self->start_read
		1299	if $self->{on_read} || @{ $self->{_queue} };
		1300	}
		1301	}
134		1302
135	This method returns the filehandle of the L<AnyEvent::Handle> object.	1303	=item $handle->on_read ($cb)
136		1304
137	=cut	1305	This replaces the currently set C<on_read> callback, or clears it (when
		1306	the new callback is C<undef>). See the description of C<on_read> in the
		1307	constructor.
138		1308
139	sub fh { $_[0]->{fh} }	1309	This method may invoke callbacks (and therefore the handle might be
140		1310	destroyed after it returns).
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		1311
149	=cut	1312	=cut
150		1313
151	sub on_read {	1314	sub on_read {
152	my ($self, $cb) = @_;	1315	my ($self, $cb) = @_;
		1316
153	$self->{on_read} = $cb;	1317	$self->{on_read} = $cb;
		1318	$self->_drain_rbuf if $cb;
		1319	}
154		1320
155	unless (defined $self->{on_read}) {	1321	=item $handle->rbuf
156	delete $self->{on_read_w};	1322
		1323	Returns the read buffer (as a modifiable lvalue). You can also access the
		1324	read buffer directly as the C<< ->{rbuf} >> member, if you want (this is
		1325	much faster, and no less clean).
		1326
		1327	The only operation allowed on the read buffer (apart from looking at it)
		1328	is removing data from its beginning. Otherwise modifying or appending to
		1329	it is not allowed and will lead to hard-to-track-down bugs.
		1330
		1331	NOTE: The read buffer should only be used or modified in the C<on_read>
		1332	callback or when C<push_read> or C<unshift_read> are used with a single
		1333	callback (i.e. untyped). Typed C<push_read> and C<unshift_read> methods
		1334	will manage the read buffer on their own.
		1335
		1336	=cut
		1337
		1338	sub rbuf : lvalue {
		1339	$_[0]{rbuf}
		1340	}
		1341
		1342	=item $handle->push_read ($cb)
		1343
		1344	=item $handle->unshift_read ($cb)
		1345
		1346	Append the given callback to the end of the queue (C<push_read>) or
		1347	prepend it (C<unshift_read>).
		1348
		1349	The callback is called each time some additional read data arrives.
		1350
		1351	It must check whether enough data is in the read buffer already.
		1352
		1353	If not enough data is available, it must return the empty list or a false
		1354	value, in which case it will be called repeatedly until enough data is
		1355	available (or an error condition is detected).
		1356
		1357	If enough data was available, then the callback must remove all data it is
		1358	interested in (which can be none at all) and return a true value. After returning
		1359	true, it will be removed from the queue.
		1360
		1361	These methods may invoke callbacks (and therefore the handle might be
		1362	destroyed after it returns).
		1363
		1364	=cut
		1365
		1366	our %RH;
		1367
		1368	sub register_read_type($$) {
		1369	$RH{$_[0]} = $_[1];
		1370	}
		1371
		1372	sub push_read {
		1373	my $self = shift;
		1374	my $cb = pop;
		1375
		1376	if (@_) {
		1377	my $type = shift;
		1378
		1379	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1380	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_read")
		1381	->($self, $cb, @_);
		1382	}
		1383
		1384	push @{ $self->{_queue} }, $cb;
		1385	$self->_drain_rbuf;
		1386	}
		1387
		1388	sub unshift_read {
		1389	my $self = shift;
		1390	my $cb = pop;
		1391
		1392	if (@_) {
		1393	my $type = shift;
		1394
		1395	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1396	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::unshift_read")
		1397	->($self, $cb, @_);
		1398	}
		1399
		1400	unshift @{ $self->{_queue} }, $cb;
		1401	$self->_drain_rbuf;
		1402	}
		1403
		1404	=item $handle->push_read (type => @args, $cb)
		1405
		1406	=item $handle->unshift_read (type => @args, $cb)
		1407
		1408	Instead of providing a callback that parses the data itself you can chose
		1409	between a number of predefined parsing formats, for chunks of data, lines
		1410	etc. You can also specify the (fully qualified) name of a package, in
		1411	which case AnyEvent tries to load the package and then expects to find the
		1412	C<anyevent_read_type> function inside (see "custom read types", below).
		1413
		1414	Predefined types are (if you have ideas for additional types, feel free to
		1415	drop by and tell us):
		1416
		1417	=over 4
		1418
		1419	=item chunk => $octets, $cb->($handle, $data)
		1420
		1421	Invoke the callback only once C<$octets> bytes have been read. Pass the
		1422	data read to the callback. The callback will never be called with less
		1423	data.
		1424
		1425	Example: read 2 bytes.
		1426
		1427	$handle->push_read (chunk => 2, sub {
		1428	warn "yay ", unpack "H*", $_[1];
		1429	});
		1430
		1431	=cut
		1432
		1433	register_read_type chunk => sub {
		1434	my ($self, $cb, $len) = @_;
		1435
		1436	sub {
		1437	$len <= length $_[0]{rbuf} or return;
		1438	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
		1439	1
		1440	}
		1441	};
		1442
		1443	=item line => [$eol, ]$cb->($handle, $line, $eol)
		1444
		1445	The callback will be called only once a full line (including the end of
		1446	line marker, C<$eol>) has been read. This line (excluding the end of line
		1447	marker) will be passed to the callback as second argument (C<$line>), and
		1448	the end of line marker as the third argument (C<$eol>).
		1449
		1450	The end of line marker, C<$eol>, can be either a string, in which case it
		1451	will be interpreted as a fixed record end marker, or it can be a regex
		1452	object (e.g. created by C<qr>), in which case it is interpreted as a
		1453	regular expression.
		1454
		1455	The end of line marker argument C<$eol> is optional, if it is missing (NOT
		1456	undef), then C<qr|\015?\012|> is used (which is good for most internet
		1457	protocols).
		1458
		1459	Partial lines at the end of the stream will never be returned, as they are
		1460	not marked by the end of line marker.
		1461
		1462	=cut
		1463
		1464	register_read_type line => sub {
		1465	my ($self, $cb, $eol) = @_;
		1466
		1467	if (@_ < 3) {
		1468	# this is more than twice as fast as the generic code below
		1469	sub {
		1470	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		1471
		1472	$cb->($_[0], $1, $2);
		1473	1
		1474	}
		1475	} else {
		1476	$eol = quotemeta $eol unless ref $eol;
		1477	$eol = qr|^(.*?)($eol)|s;
		1478
		1479	sub {
		1480	$_[0]{rbuf} =~ s/$eol// or return;
		1481
		1482	$cb->($_[0], $1, $2);
		1483	1
		1484	}
		1485	}
		1486	};
		1487
		1488	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1489
		1490	Makes a regex match against the regex object C<$accept> and returns
		1491	everything up to and including the match.
		1492
		1493	Example: read a single line terminated by '\n'.
		1494
		1495	$handle->push_read (regex => qr<\n>, sub { ... });
		1496
		1497	If C<$reject> is given and not undef, then it determines when the data is
		1498	to be rejected: it is matched against the data when the C<$accept> regex
		1499	does not match and generates an C<EBADMSG> error when it matches. This is
		1500	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1501	receive buffer overflow).
		1502
		1503	Example: expect a single decimal number followed by whitespace, reject
		1504	anything else (not the use of an anchor).
		1505
		1506	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1507
		1508	If C<$skip> is given and not C<undef>, then it will be matched against
		1509	the receive buffer when neither C<$accept> nor C<$reject> match,
		1510	and everything preceding and including the match will be accepted
		1511	unconditionally. This is useful to skip large amounts of data that you
		1512	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1513	have to start matching from the beginning. This is purely an optimisation
		1514	and is usually worth it only when you expect more than a few kilobytes.
		1515
		1516	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1517	expect the header to be very large (it isn't in practice, but...), we use
		1518	a skip regex to skip initial portions. The skip regex is tricky in that
		1519	it only accepts something not ending in either \015 or \012, as these are
		1520	required for the accept regex.
		1521
		1522	$handle->push_read (regex =>
		1523	qr<\015\012\015\012>,
		1524	undef, # no reject
		1525	qr<^.*[^\015\012]>,
		1526	sub { ... });
		1527
		1528	=cut
		1529
		1530	register_read_type regex => sub {
		1531	my ($self, $cb, $accept, $reject, $skip) = @_;
		1532
		1533	my $data;
		1534	my $rbuf = \$self->{rbuf};
		1535
		1536	sub {
		1537	# accept
		1538	if ($$rbuf =~ $accept) {
		1539	$data .= substr $$rbuf, 0, $+[0], "";
		1540	$cb->($self, $data);
		1541	return 1;
		1542	}
		1543
		1544	# reject
		1545	if ($reject && $$rbuf =~ $reject) {
		1546	$self->_error (Errno::EBADMSG);
		1547	}
		1548
		1549	# skip
		1550	if ($skip && $$rbuf =~ $skip) {
		1551	$data .= substr $$rbuf, 0, $+[0], "";
		1552	}
		1553
		1554	()
		1555	}
		1556	};
		1557
		1558	=item netstring => $cb->($handle, $string)
		1559
		1560	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1561
		1562	Throws an error with C<$!> set to EBADMSG on format violations.
		1563
		1564	=cut
		1565
		1566	register_read_type netstring => sub {
		1567	my ($self, $cb) = @_;
		1568
		1569	sub {
		1570	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1571	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1572	$self->_error (Errno::EBADMSG);
		1573	}
157	return;	1574	return;
		1575	}
		1576
		1577	my $len = $1;
		1578
		1579	$self->unshift_read (chunk => $len, sub {
		1580	my $string = $_[1];
		1581	$_[0]->unshift_read (chunk => 1, sub {
		1582	if ($_[1] eq ",") {
		1583	$cb->($_[0], $string);
		1584	} else {
		1585	$self->_error (Errno::EBADMSG);
		1586	}
		1587	});
		1588	});
		1589
		1590	1
		1591	}
		1592	};
		1593
		1594	=item packstring => $format, $cb->($handle, $string)
		1595
		1596	An octet string prefixed with an encoded length. The encoding C<$format>
		1597	uses the same format as a Perl C<pack> format, but must specify a single
		1598	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1599	optional C<!>, C<< < >> or C<< > >> modifier).
		1600
		1601	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1602	EPP uses a prefix of C<N> (4 octtes).
		1603
		1604	Example: read a block of data prefixed by its length in BER-encoded
		1605	format (very efficient).
		1606
		1607	$handle->push_read (packstring => "w", sub {
		1608	my ($handle, $data) = @_;
158	}	1609	});
159		1610
160	$self->{on_read_w} =	1611	=cut
161	AnyEvent->io (poll => 'r', fh => $self->{fh}, cb => sub {	1612
162	#d# warn "READ:[$self->{read_size}] $self->{read_block_size} : ".length ($self->{rbuf})."\n";	1613	register_read_type packstring => sub {
		1614	my ($self, $cb, $format) = @_;
		1615
		1616	sub {
		1617	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1618	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1619	or return;
		1620
		1621	$format = length pack $format, $len;
		1622
		1623	# bypass unshift if we already have the remaining chunk
		1624	if ($format + $len <= length $_[0]{rbuf}) {
		1625	my $data = substr $_[0]{rbuf}, $format, $len;
		1626	substr $_[0]{rbuf}, 0, $format + $len, "";
		1627	$cb->($_[0], $data);
		1628	} else {
		1629	# remove prefix
		1630	substr $_[0]{rbuf}, 0, $format, "";
		1631
		1632	# read remaining chunk
		1633	$_[0]->unshift_read (chunk => $len, $cb);
		1634	}
		1635
		1636	1
		1637	}
		1638	};
		1639
		1640	=item json => $cb->($handle, $hash_or_arrayref)
		1641
		1642	Reads a JSON object or array, decodes it and passes it to the
		1643	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1644
		1645	If a C<json> object was passed to the constructor, then that will be used
		1646	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1647
		1648	This read type uses the incremental parser available with JSON version
		1649	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1650	dependency on your own: this module will load the JSON module, but
		1651	AnyEvent does not depend on it itself.
		1652
		1653	Since JSON texts are fully self-delimiting, the C<json> read and write
		1654	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1655	the C<json> write type description, above, for an actual example.
		1656
		1657	=cut
		1658
		1659	register_read_type json => sub {
		1660	my ($self, $cb) = @_;
		1661
		1662	my $json = $self->{json} ||= json_coder;
		1663
		1664	my $data;
163	my $rbuf_len = length $self->{rbuf};	1665	my $rbuf = \$self->{rbuf};
164	my $l;	1666
		1667	sub {
		1668	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1669
		1670	if ($ref) {
		1671	$self->{rbuf} = $json->incr_text;
		1672	$json->incr_text = "";
		1673	$cb->($self, $ref);
		1674
		1675	1
		1676	} elsif ($@) {
		1677	# error case
		1678	$json->incr_skip;
		1679
		1680	$self->{rbuf} = $json->incr_text;
		1681	$json->incr_text = "";
		1682
		1683	$self->_error (Errno::EBADMSG);
		1684
		1685	()
		1686	} else {
		1687	$self->{rbuf} = "";
		1688
		1689	()
		1690	}
		1691	}
		1692	};
		1693
		1694	=item storable => $cb->($handle, $ref)
		1695
		1696	Deserialises a L<Storable> frozen representation as written by the
		1697	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1698	data).
		1699
		1700	Raises C<EBADMSG> error if the data could not be decoded.
		1701
		1702	=cut
		1703
		1704	register_read_type storable => sub {
		1705	my ($self, $cb) = @_;
		1706
		1707	require Storable;
		1708
		1709	sub {
		1710	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1711	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1712	or return;
		1713
		1714	my $format = length pack "w", $len;
		1715
		1716	# bypass unshift if we already have the remaining chunk
		1717	if ($format + $len <= length $_[0]{rbuf}) {
		1718	my $data = substr $_[0]{rbuf}, $format, $len;
		1719	substr $_[0]{rbuf}, 0, $format + $len, "";
		1720	$cb->($_[0], Storable::thaw ($data));
		1721	} else {
		1722	# remove prefix
		1723	substr $_[0]{rbuf}, 0, $format, "";
		1724
		1725	# read remaining chunk
		1726	$_[0]->unshift_read (chunk => $len, sub {
		1727	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1728	$cb->($_[0], $ref);
		1729	} else {
		1730	$self->_error (Errno::EBADMSG);
		1731	}
		1732	});
		1733	}
		1734
		1735	1
		1736	}
		1737	};
		1738
		1739	=back
		1740
		1741	=item custom read types - Package::anyevent_read_type $handle, $cb, @args
		1742
		1743	Instead of one of the predefined types, you can also specify the name
		1744	of a package. AnyEvent will try to load the package and then expects to
		1745	find a function named C<anyevent_read_type> inside. If it isn't found, it
		1746	progressively tries to load the parent package until it either finds the
		1747	function (good) or runs out of packages (bad).
		1748
		1749	Whenever this type is used, C<push_read> will invoke the function with the
		1750	handle object, the original callback and the remaining arguments.
		1751
		1752	The function is supposed to return a callback (usually a closure) that
		1753	works as a plain read callback (see C<< ->push_read ($cb) >>), so you can
		1754	mentally treat the function as a "configurable read type to read callback"
		1755	converter.
		1756
		1757	It should invoke the original callback when it is done reading (remember
		1758	to pass C<$handle> as first argument as all other callbacks do that,
		1759	although there is no strict requirement on this).
		1760
		1761	For examples, see the source of this module (F<perldoc -m
		1762	AnyEvent::Handle>, search for C<register_read_type>)).
		1763
		1764	=item $handle->stop_read
		1765
		1766	=item $handle->start_read
		1767
		1768	In rare cases you actually do not want to read anything from the
		1769	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
		1770	any queued callbacks will be executed then. To start reading again, call
		1771	C<start_read>.
		1772
		1773	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1774	you change the C<on_read> callback or push/unshift a read callback, and it
		1775	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1776	there are any read requests in the queue.
		1777
		1778	In older versions of this module (<= 5.3), these methods had no effect,
		1779	as TLS does not support half-duplex connections. In current versions they
		1780	work as expected, as this behaviour is required to avoid certain resource
		1781	attacks, where the program would be forced to read (and buffer) arbitrary
		1782	amounts of data before being able to send some data. The drawback is that
		1783	some readings of the the SSL/TLS specifications basically require this
		1784	attack to be working, as SSL/TLS implementations might stall sending data
		1785	during a rehandshake.
		1786
		1787	As a guideline, during the initial handshake, you should not stop reading,
		1788	and as a client, it might cause problems, depending on your applciation.
		1789
		1790	=cut
		1791
		1792	sub stop_read {
		1793	my ($self) = @_;
		1794
		1795	delete $self->{_rw};
		1796	}
		1797
		1798	sub start_read {
		1799	my ($self) = @_;
		1800
		1801	unless ($self->{_rw} || $self->{_eof} || !$self->{fh}) {
		1802	Scalar::Util::weaken $self;
		1803
		1804	$self->{_rw} = AE::io $self->{fh}, 0, sub {
		1805	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
		1806	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size}, length $$rbuf;
		1807
		1808	if ($len > 0) {
		1809	$self->{_activity} = $self->{_ractivity} = AE::now;
		1810
		1811	if ($self->{tls}) {
		1812	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
		1813
		1814	&_dotls ($self);
		1815	} else {
		1816	$self->_drain_rbuf;
		1817	}
		1818
165	if (defined $self->{read_size}) {	1819	if ($len == $self->{read_size}) {
166	$l = sysread $self->{fh}, $self->{rbuf},	1820	$self->{read_size} *= 2;
167	($self->{read_size} - $rbuf_len), $rbuf_len;	1821	$self->{read_size} = $self->{max_read_size} || MAX_READ_SIZE
		1822	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		1823	}
		1824
		1825	} elsif (defined $len) {
		1826	delete $self->{_rw};
		1827	$self->{_eof} = 1;
		1828	$self->_drain_rbuf;
		1829
		1830	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		1831	return $self->_error ($!, 1);
		1832	}
		1833	};
		1834	}
		1835	}
		1836
		1837	our $ERROR_SYSCALL;
		1838	our $ERROR_WANT_READ;
		1839
		1840	sub _tls_error {
		1841	my ($self, $err) = @_;
		1842
		1843	return $self->_error ($!, 1)
		1844	if $err == Net::SSLeay::ERROR_SYSCALL ();
		1845
		1846	my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
		1847
		1848	# reduce error string to look less scary
		1849	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
		1850
		1851	if ($self->{_on_starttls}) {
		1852	(delete $self->{_on_starttls})->($self, undef, $err);
		1853	&_freetls;
		1854	} else {
		1855	&_freetls;
		1856	$self->_error (Errno::EPROTO, 1, $err);
		1857	}
		1858	}
		1859
		1860	# poll the write BIO and send the data if applicable
		1861	# also decode read data if possible
		1862	# this is basiclaly our TLS state machine
		1863	# more efficient implementations are possible with openssl,
		1864	# but not with the buggy and incomplete Net::SSLeay.
		1865	sub _dotls {
		1866	my ($self) = @_;
		1867
		1868	my $tmp;
		1869
		1870	if (length $self->{_tls_wbuf}) {
		1871	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1872	substr $self->{_tls_wbuf}, 0, $tmp, "";
		1873	}
		1874
		1875	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		1876	return $self->_tls_error ($tmp)
		1877	if $tmp != $ERROR_WANT_READ
		1878	&& ($tmp != $ERROR_SYSCALL || $!);
		1879	}
		1880
		1881	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		1882	unless (length $tmp) {
		1883	$self->{_on_starttls}
		1884	and (delete $self->{_on_starttls})->($self, undef, "EOF during handshake"); # ???
		1885	&_freetls;
		1886
		1887	if ($self->{on_stoptls}) {
		1888	$self->{on_stoptls}($self);
		1889	return;
168	} else {	1890	} else {
169	$l = sysread $self->{fh}, $self->{rbuf}, $self->{read_block_size}, $rbuf_len;	1891	# let's treat SSL-eof as we treat normal EOF
170	}
171	#d# warn "READL $l [$self->{rbuf}]\n";
172
173	if (not defined $l) {
174	return if $! == EAGAIN || $! == EINTR;
175	$self->{on_error}->($self) if $self->{on_error};
176	delete $self->{on_read_w};	1892	delete $self->{_rw};
177
178	} elsif ($l == 0) {
179	$self->{on_eof}->($self) if $self->{on_eof};
180	delete $self->{on_read_w};
181
182	} else {
183	$self->{on_read}->($self);
184	}
185	});
186	}
187
188	=item B<on_error ($callback)>
189
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 {
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) = @_;
240
241	$self->{read_cb} = $cb;
242	my $old_blk_size = $self->{read_block_size};
243	$self->{read_block_size} = $len;
244
245	$self->on_read (sub {
246	#d# warn "OFOFO $len || ".length($_[0]->{rbuf})."||\n";
247
248	if ($len == length $_[0]->{rbuf}) {
249	$_[0]->{read_block_size} = $old_blk_size;
250	$_[0]->on_read (undef);
251	$_[0]->{read_cb}->($_[0], (substr $self->{rbuf}, 0, $len, ''));
252	}
253	});
254	}
255
256	=item B<readlines ($callback)>
257
258	=item B<readlines ($sep, $callback)>
259
260	This method will read lines from the filehandle, seperated by C<$sep> or C<"\n">
261	if C<$sep> is not provided. C<$sep> will be used as "line" seperator.
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	}
293	$self->{on_readline}->($_[0], @lines);
294	});
295	}
296
297	=item B<write ($data)>
298
299	=item B<write ($callback)>
300
301	=item B<write ($data, $callback)>
302
303	This method will write C<$data> to the filehandle and call the C<$callback>
304	afterwards. If only C<$callback> is provided it will be called when the
305	write buffer becomes empty the next time (or immediately if it already is empty).
306
307	=cut
308
309	sub write {
310	my ($self, $data, $cb) = @_;
311	if (ref $data) { $cb = $data; undef $data }
312	push @{$self->{write_bufs}}, [$data, $cb];
313	$self->_check_writer;
314	}
315
316	sub _check_writer {
317	my ($self) = @_;
318
319	if ($self->{write_w}) {
320	unless ($self->{write_cb}) {
321	while (@{$self->{write_bufs}} && not defined $self->{write_bufs}->[0]->[1]) {
322	my $wba = shift @{$self->{write_bufs}};
323	$self->{wbuf} .= $wba->[0];	1893	$self->{_eof} = 1;
324	}	1894	}
325	}	1895	}
326	return;
327	}
328		1896
329	my $wba = shift @{$self->{write_bufs}}	1897	$self->{_tls_rbuf} .= $tmp;
330	or return;	1898	$self->_drain_rbuf;
331		1899	$self->{tls} or return; # tls session might have gone away in callback
332	unless (defined $wba->[0]) {
333	$wba->[1]->($self) if $wba->[1];
334	$self->_check_writer;
335	return;
336	}	1900	}
337		1901
338	$self->{wbuf} = $wba->[0];	1902	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
339	$self->{write_cb} = $wba->[1];	1903	return $self->_tls_error ($tmp)
		1904	if $tmp != $ERROR_WANT_READ
		1905	&& ($tmp != $ERROR_SYSCALL || $!);
340		1906
341	$self->{write_w} =	1907	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
342	AnyEvent->io (poll => 'w', fh => $self->{fh}, cb => sub {	1908	$self->{wbuf} .= $tmp;
343	my $l = syswrite $self->{fh}, $self->{wbuf}, length $self->{wbuf};	1909	$self->_drain_wbuf;
		1910	$self->{tls} or return; # tls session might have gone away in callback
		1911	}
344		1912
345	if (not defined $l) {	1913	$self->{_on_starttls}
346	return if $! == EAGAIN || $! == EINTR;	1914	and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
347	delete $self->{write_w};	1915	and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
348	$self->{on_error}->($self) if $self->{on_error};	1916	}
349		1917
		1918	=item $handle->starttls ($tls[, $tls_ctx])
		1919
		1920	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1921	object is created, you can also do that at a later time by calling
		1922	C<starttls>.
		1923
		1924	Starting TLS is currently an asynchronous operation - when you push some
		1925	write data and then call C<< ->starttls >> then TLS negotiation will start
		1926	immediately, after which the queued write data is then sent.
		1927
		1928	The first argument is the same as the C<tls> constructor argument (either
		1929	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1930
		1931	The second argument is the optional C<AnyEvent::TLS> object that is used
		1932	when AnyEvent::Handle has to create its own TLS connection object, or
		1933	a hash reference with C<< key => value >> pairs that will be used to
		1934	construct a new context.
		1935
		1936	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1937	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1938	changed to your liking. Note that the handshake might have already started
		1939	when this function returns.
		1940
		1941	Due to bugs in OpenSSL, it might or might not be possible to do multiple
		1942	handshakes on the same stream. It is best to not attempt to use the
		1943	stream after stopping TLS.
		1944
		1945	This method may invoke callbacks (and therefore the handle might be
		1946	destroyed after it returns).
		1947
		1948	=cut
		1949
		1950	our %TLS_CACHE; #TODO not yet documented, should we?
		1951
		1952	sub starttls {
		1953	my ($self, $tls, $ctx) = @_;
		1954
		1955	Carp::croak "It is an error to call starttls on an AnyEvent::Handle object while TLS is already active, caught"
		1956	if $self->{tls};
		1957
		1958	$self->{tls} = $tls;
		1959	$self->{tls_ctx} = $ctx if @_ > 2;
		1960
		1961	return unless $self->{fh};
		1962
		1963	require Net::SSLeay;
		1964
		1965	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		1966	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		1967
		1968	$tls = delete $self->{tls};
		1969	$ctx = $self->{tls_ctx};
		1970
		1971	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context or session
		1972
		1973	if ("HASH" eq ref $ctx) {
		1974	require AnyEvent::TLS;
		1975
		1976	if ($ctx->{cache}) {
		1977	my $key = $ctx+0;
		1978	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
350	} else {	1979	} else {
		1980	$ctx = new AnyEvent::TLS %$ctx;
		1981	}
		1982	}
		1983
		1984	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1985	$self->{tls} = $tls = $self->{tls_ctx}->_get_session ($tls, $self, $self->{peername});
		1986
		1987	# basically, this is deep magic (because SSL_read should have the same issues)
		1988	# but the openssl maintainers basically said: "trust us, it just works".
		1989	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1990	# and mismaintained ssleay-module doesn't even offer them).
		1991	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		1992	#
		1993	# in short: this is a mess.
		1994	#
		1995	# note that we do not try to keep the length constant between writes as we are required to do.
		1996	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		1997	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		1998	# have identity issues in that area.
		1999	# Net::SSLeay::CTX_set_mode ($ssl,
		2000	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		2001	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		2002	Net::SSLeay::CTX_set_mode ($tls, 1|2);
		2003
		2004	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2005	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2006
		2007	Net::SSLeay::BIO_write ($self->{_rbio}, delete $self->{rbuf});
		2008
		2009	Net::SSLeay::set_bio ($tls, $self->{_rbio}, $self->{_wbio});
		2010
		2011	$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
		2012	if $self->{on_starttls};
		2013
		2014	&_dotls; # need to trigger the initial handshake
		2015	$self->start_read; # make sure we actually do read
		2016	}
		2017
		2018	=item $handle->stoptls
		2019
		2020	Shuts down the SSL connection - this makes a proper EOF handshake by
		2021	sending a close notify to the other side, but since OpenSSL doesn't
		2022	support non-blocking shut downs, it is not guaranteed that you can re-use
		2023	the stream afterwards.
		2024
		2025	This method may invoke callbacks (and therefore the handle might be
		2026	destroyed after it returns).
		2027
		2028	=cut
		2029
		2030	sub stoptls {
		2031	my ($self) = @_;
		2032
		2033	if ($self->{tls} && $self->{fh}) {
		2034	Net::SSLeay::shutdown ($self->{tls});
		2035
		2036	&_dotls;
		2037
		2038	# # we don't give a shit. no, we do, but we can't. no...#d#
		2039	# # we, we... have to use openssl :/#d#
		2040	# &_freetls;#d#
		2041	}
		2042	}
		2043
		2044	sub _freetls {
		2045	my ($self) = @_;
		2046
		2047	return unless $self->{tls};
		2048
		2049	$self->{tls_ctx}->_put_session (delete $self->{tls})
		2050	if $self->{tls} > 0;
		2051
		2052	delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
		2053	}
		2054
		2055	sub DESTROY {
		2056	my ($self) = @_;
		2057
		2058	&_freetls;
		2059
		2060	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		2061
		2062	if ($linger && length $self->{wbuf} && $self->{fh}) {
		2063	my $fh = delete $self->{fh};
		2064	my $wbuf = delete $self->{wbuf};
		2065
		2066	my @linger;
		2067
		2068	push @linger, AE::io $fh, 1, sub {
		2069	my $len = syswrite $fh, $wbuf, length $wbuf;
		2070
		2071	if ($len > 0) {
351	substr $self->{wbuf}, 0, $l, '';	2072	substr $wbuf, 0, $len, "";
352		2073	} elsif (defined $len || ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK)) {
353	if (length ($self->{wbuf}) == 0) {	2074	@linger = (); # end
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	}	2075	}
		2076	};
		2077	push @linger, AE::timer $linger, 0, sub {
		2078	@linger = ();
		2079	};
		2080	}
		2081	}
		2082
		2083	=item $handle->destroy
		2084
		2085	Shuts down the handle object as much as possible - this call ensures that
		2086	no further callbacks will be invoked and as many resources as possible
		2087	will be freed. Any method you will call on the handle object after
		2088	destroying it in this way will be silently ignored (and it will return the
		2089	empty list).
		2090
		2091	Normally, you can just "forget" any references to an AnyEvent::Handle
		2092	object and it will simply shut down. This works in fatal error and EOF
		2093	callbacks, as well as code outside. It does I<NOT> work in a read or write
		2094	callback, so when you want to destroy the AnyEvent::Handle object from
		2095	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		2096	that case.
		2097
		2098	Destroying the handle object in this way has the advantage that callbacks
		2099	will be removed as well, so if those are the only reference holders (as
		2100	is common), then one doesn't need to do anything special to break any
		2101	reference cycles.
		2102
		2103	The handle might still linger in the background and write out remaining
		2104	data, as specified by the C<linger> option, however.
		2105
		2106	=cut
		2107
		2108	sub destroy {
		2109	my ($self) = @_;
		2110
		2111	$self->DESTROY;
		2112	%$self = ();
		2113	bless $self, "AnyEvent::Handle::destroyed";
		2114	}
		2115
		2116	sub AnyEvent::Handle::destroyed::AUTOLOAD {
		2117	#nop
		2118	}
		2119
		2120	=item $handle->destroyed
		2121
		2122	Returns false as long as the handle hasn't been destroyed by a call to C<<
		2123	->destroy >>, true otherwise.
		2124
		2125	Can be useful to decide whether the handle is still valid after some
		2126	callback possibly destroyed the handle. For example, C<< ->push_write >>,
		2127	C<< ->starttls >> and other methods can call user callbacks, which in turn
		2128	can destroy the handle, so work can be avoided by checking sometimes:
		2129
		2130	$hdl->starttls ("accept");
		2131	return if $hdl->destroyed;
		2132	$hdl->push_write (...
		2133
		2134	Note that the call to C<push_write> will silently be ignored if the handle
		2135	has been destroyed, so often you can just ignore the possibility of the
		2136	handle being destroyed.
		2137
		2138	=cut
		2139
		2140	sub destroyed { 0 }
		2141	sub AnyEvent::Handle::destroyed::destroyed { 1 }
		2142
		2143	=item AnyEvent::Handle::TLS_CTX
		2144
		2145	This function creates and returns the AnyEvent::TLS object used by default
		2146	for TLS mode.
		2147
		2148	The context is created by calling L<AnyEvent::TLS> without any arguments.
		2149
		2150	=cut
		2151
		2152	our $TLS_CTX;
		2153
		2154	sub TLS_CTX() {
		2155	$TLS_CTX ||= do {
		2156	require AnyEvent::TLS;
		2157
		2158	new AnyEvent::TLS
		2159	}
		2160	}
		2161
		2162	=back
		2163
		2164
		2165	=head1 NONFREQUENTLY ASKED QUESTIONS
		2166
		2167	=over 4
		2168
		2169	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		2170	still get further invocations!
		2171
		2172	That's because AnyEvent::Handle keeps a reference to itself when handling
		2173	read or write callbacks.
		2174
		2175	It is only safe to "forget" the reference inside EOF or error callbacks,
		2176	from within all other callbacks, you need to explicitly call the C<<
		2177	->destroy >> method.
		2178
		2179	=item Why is my C<on_eof> callback never called?
		2180
		2181	Probably because your C<on_error> callback is being called instead: When
		2182	you have outstanding requests in your read queue, then an EOF is
		2183	considered an error as you clearly expected some data.
		2184
		2185	To avoid this, make sure you have an empty read queue whenever your handle
		2186	is supposed to be "idle" (i.e. connection closes are O.K.). You cna set
		2187	an C<on_read> handler that simply pushes the first read requests in the
		2188	queue.
		2189
		2190	See also the next question, which explains this in a bit more detail.
		2191
		2192	=item How can I serve requests in a loop?
		2193
		2194	Most protocols consist of some setup phase (authentication for example)
		2195	followed by a request handling phase, where the server waits for requests
		2196	and handles them, in a loop.
		2197
		2198	There are two important variants: The first (traditional, better) variant
		2199	handles requests until the server gets some QUIT command, causing it to
		2200	close the connection first (highly desirable for a busy TCP server). A
		2201	client dropping the connection is an error, which means this variant can
		2202	detect an unexpected detection close.
		2203
		2204	To handle this case, always make sure you have a on-empty read queue, by
		2205	pushing the "read request start" handler on it:
		2206
		2207	# we assume a request starts with a single line
		2208	my @start_request; @start_request = (line => sub {
		2209	my ($hdl, $line) = @_;
		2210
		2211	... handle request
		2212
		2213	# push next request read, possibly from a nested callback
		2214	$hdl->push_read (@start_request);
		2215	});
		2216
		2217	# auth done, now go into request handling loop
		2218	# now push the first @start_request
		2219	$hdl->push_read (@start_request);
		2220
		2221	By always having an outstanding C<push_read>, the handle always expects
		2222	some data and raises the C<EPIPE> error when the connction is dropped
		2223	unexpectedly.
		2224
		2225	The second variant is a protocol where the client can drop the connection
		2226	at any time. For TCP, this means that the server machine may run out of
		2227	sockets easier, and in general, it means you cnanot distinguish a protocl
		2228	failure/client crash from a normal connection close. Nevertheless, these
		2229	kinds of protocols are common (and sometimes even the best solution to the
		2230	problem).
		2231
		2232	Having an outstanding read request at all times is possible if you ignore
		2233	C<EPIPE> errors, but this doesn't help with when the client drops the
		2234	connection during a request, which would still be an error.
		2235
		2236	A better solution is to push the initial request read in an C<on_read>
		2237	callback. This avoids an error, as when the server doesn't expect data
		2238	(i.e. is idly waiting for the next request, an EOF will not raise an
		2239	error, but simply result in an C<on_eof> callback. It is also a bit slower
		2240	and simpler:
		2241
		2242	# auth done, now go into request handling loop
		2243	$hdl->on_read (sub {
		2244	my ($hdl) = @_;
		2245
		2246	# called each time we receive data but the read queue is empty
		2247	# simply start read the request
		2248
		2249	$hdl->push_read (line => sub {
		2250	my ($hdl, $line) = @_;
		2251
		2252	... handle request
		2253
		2254	# do nothing special when the request has been handled, just
		2255	# let the request queue go empty.
363	});	2256	});
364	}	2257	});
		2258
		2259	=item I get different callback invocations in TLS mode/Why can't I pause
		2260	reading?
		2261
		2262	Unlike, say, TCP, TLS connections do not consist of two independent
		2263	communication channels, one for each direction. Or put differently, the
		2264	read and write directions are not independent of each other: you cannot
		2265	write data unless you are also prepared to read, and vice versa.
		2266
		2267	This means that, in TLS mode, you might get C<on_error> or C<on_eof>
		2268	callback invocations when you are not expecting any read data - the reason
		2269	is that AnyEvent::Handle always reads in TLS mode.
		2270
		2271	During the connection, you have to make sure that you always have a
		2272	non-empty read-queue, or an C<on_read> watcher. At the end of the
		2273	connection (or when you no longer want to use it) you can call the
		2274	C<destroy> method.
		2275
		2276	=item How do I read data until the other side closes the connection?
		2277
		2278	If you just want to read your data into a perl scalar, the easiest way
		2279	to achieve this is by setting an C<on_read> callback that does nothing,
		2280	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		2281	will be in C<$_[0]{rbuf}>:
		2282
		2283	$handle->on_read (sub { });
		2284	$handle->on_eof (undef);
		2285	$handle->on_error (sub {
		2286	my $data = delete $_[0]{rbuf};
		2287	});
		2288
		2289	The reason to use C<on_error> is that TCP connections, due to latencies
		2290	and packets loss, might get closed quite violently with an error, when in
		2291	fact all data has been received.
		2292
		2293	It is usually better to use acknowledgements when transferring data,
		2294	to make sure the other side hasn't just died and you got the data
		2295	intact. This is also one reason why so many internet protocols have an
		2296	explicit QUIT command.
		2297
		2298	=item I don't want to destroy the handle too early - how do I wait until
		2299	all data has been written?
		2300
		2301	After writing your last bits of data, set the C<on_drain> callback
		2302	and destroy the handle in there - with the default setting of
		2303	C<low_water_mark> this will be called precisely when all data has been
		2304	written to the socket:
		2305
		2306	$handle->push_write (...);
		2307	$handle->on_drain (sub {
		2308	warn "all data submitted to the kernel\n";
		2309	undef $handle;
		2310	});
		2311
		2312	If you just want to queue some data and then signal EOF to the other side,
		2313	consider using C<< ->push_shutdown >> instead.
		2314
		2315	=item I want to contact a TLS/SSL server, I don't care about security.
		2316
		2317	If your TLS server is a pure TLS server (e.g. HTTPS) that only speaks TLS,
		2318	connect to it and then create the AnyEvent::Handle with the C<tls>
		2319	parameter:
		2320
		2321	tcp_connect $host, $port, sub {
		2322	my ($fh) = @_;
		2323
		2324	my $handle = new AnyEvent::Handle
		2325	fh => $fh,
		2326	tls => "connect",
		2327	on_error => sub { ... };
		2328
		2329	$handle->push_write (...);
		2330	};
		2331
		2332	=item I want to contact a TLS/SSL server, I do care about security.
		2333
		2334	Then you should additionally enable certificate verification, including
		2335	peername verification, if the protocol you use supports it (see
		2336	L<AnyEvent::TLS>, C<verify_peername>).
		2337
		2338	E.g. for HTTPS:
		2339
		2340	tcp_connect $host, $port, sub {
		2341	my ($fh) = @_;
		2342
		2343	my $handle = new AnyEvent::Handle
		2344	fh => $fh,
		2345	peername => $host,
		2346	tls => "connect",
		2347	tls_ctx => { verify => 1, verify_peername => "https" },
		2348	...
		2349
		2350	Note that you must specify the hostname you connected to (or whatever
		2351	"peername" the protocol needs) as the C<peername> argument, otherwise no
		2352	peername verification will be done.
		2353
		2354	The above will use the system-dependent default set of trusted CA
		2355	certificates. If you want to check against a specific CA, add the
		2356	C<ca_file> (or C<ca_cert>) arguments to C<tls_ctx>:
		2357
		2358	tls_ctx => {
		2359	verify => 1,
		2360	verify_peername => "https",
		2361	ca_file => "my-ca-cert.pem",
		2362	},
		2363
		2364	=item I want to create a TLS/SSL server, how do I do that?
		2365
		2366	Well, you first need to get a server certificate and key. You have
		2367	three options: a) ask a CA (buy one, use cacert.org etc.) b) create a
		2368	self-signed certificate (cheap. check the search engine of your choice,
		2369	there are many tutorials on the net) or c) make your own CA (tinyca2 is a
		2370	nice program for that purpose).
		2371
		2372	Then create a file with your private key (in PEM format, see
		2373	L<AnyEvent::TLS>), followed by the certificate (also in PEM format). The
		2374	file should then look like this:
		2375
		2376	-----BEGIN RSA PRIVATE KEY-----
		2377	...header data
		2378	... lots of base64'y-stuff
		2379	-----END RSA PRIVATE KEY-----
		2380
		2381	-----BEGIN CERTIFICATE-----
		2382	... lots of base64'y-stuff
		2383	-----END CERTIFICATE-----
		2384
		2385	The important bits are the "PRIVATE KEY" and "CERTIFICATE" parts. Then
		2386	specify this file as C<cert_file>:
		2387
		2388	tcp_server undef, $port, sub {
		2389	my ($fh) = @_;
		2390
		2391	my $handle = new AnyEvent::Handle
		2392	fh => $fh,
		2393	tls => "accept",
		2394	tls_ctx => { cert_file => "my-server-keycert.pem" },
		2395	...
		2396
		2397	When you have intermediate CA certificates that your clients might not
		2398	know about, just append them to the C<cert_file>.
365		2399
366	=back	2400	=back
367		2401
		2402
		2403	=head1 SUBCLASSING AnyEvent::Handle
		2404
		2405	In many cases, you might want to subclass AnyEvent::Handle.
		2406
		2407	To make this easier, a given version of AnyEvent::Handle uses these
		2408	conventions:
		2409
		2410	=over 4
		2411
		2412	=item * all constructor arguments become object members.
		2413
		2414	At least initially, when you pass a C<tls>-argument to the constructor it
		2415	will end up in C<< $handle->{tls} >>. Those members might be changed or
		2416	mutated later on (for example C<tls> will hold the TLS connection object).
		2417
		2418	=item * other object member names are prefixed with an C<_>.
		2419
		2420	All object members not explicitly documented (internal use) are prefixed
		2421	with an underscore character, so the remaining non-C<_>-namespace is free
		2422	for use for subclasses.
		2423
		2424	=item * all members not documented here and not prefixed with an underscore
		2425	are free to use in subclasses.
		2426
		2427	Of course, new versions of AnyEvent::Handle may introduce more "public"
		2428	member variables, but that's just life. At least it is documented.
		2429
		2430	=back
		2431
368	=head1 AUTHOR	2432	=head1 AUTHOR
369		2433
370	Robin Redeker, C<< <elmex at ta-sa.org> >>	2434	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
371		2435
372	=cut	2436	=cut
373		2437
374	1; # End of AnyEvent::Handle	2438	1; # End of AnyEvent::Handle

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