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Revision 1.4 by elmex, Sun Apr 27 20:20:20 2008 UTC vs.
Revision 1.238 by root, Tue Dec 10 15:54:51 2013 UTC

1	package AnyEvent::Handle;
2
3	use 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	AE::log error => $msg;
		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, $line) = @_;
35	for (@lines) {	27	say "got line <$line>";
		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, $retry->())
		129
		130	This callback is called when a connection has been successfully established.
		131
		132	The peer's numeric host and port (the socket peername) are passed as
		133	parameters, together with a retry callback. At the time it is called the
		134	read and write queues, EOF status, TLS status and similar properties of
		135	the handle will have been reset.
		136
		137	It is not allowed to use the read or write queues while the handle object
		138	is connecting.
		139
		140	If, for some reason, the handle is not acceptable, calling C<$retry> will
		141	continue with the next connection target (in case of multi-homed hosts or
		142	SRV records there can be multiple connection endpoints). The C<$retry>
		143	callback can be invoked after the connect callback returns, i.e. one can
		144	start a handshake and then decide to retry with the next host if the
		145	handshake fails.
		146
		147	In most cases, you should ignore the C<$retry> parameter.
		148
		149	=item on_connect_error => $cb->($handle, $message)
		150
		151	This callback is called when the connection could not be
		152	established. C<$!> will contain the relevant error code, and C<$message> a
		153	message describing it (usually the same as C<"$!">).
		154
		155	If this callback isn't specified, then C<on_error> will be called with a
		156	fatal error instead.
		157
		158	=back
		159
		160	=item on_error => $cb->($handle, $fatal, $message)
		161
		162	This is the error callback, which is called when, well, some error
		163	occured, such as not being able to resolve the hostname, failure to
		164	connect, or a read error.
		165
		166	Some errors are fatal (which is indicated by C<$fatal> being true). On
		167	fatal errors the handle object will be destroyed (by a call to C<< ->
		168	destroy >>) after invoking the error callback (which means you are free to
		169	examine the handle object). Examples of fatal errors are an EOF condition
		170	with active (but unsatisfiable) read watchers (C<EPIPE>) or I/O errors. In
		171	cases where the other side can close the connection at will, it is
		172	often easiest to not report C<EPIPE> errors in this callback.
		173
		174	AnyEvent::Handle tries to find an appropriate error code for you to check
		175	against, but in some cases (TLS errors), this does not work well.
		176
		177	If you report the error to the user, it is recommended to always output
		178	the C<$message> argument in human-readable error messages (you don't need
		179	to report C<"$!"> if you report C<$message>).
		180
		181	If you want to react programmatically to the error, then looking at C<$!>
		182	and comparing it against some of the documented C<Errno> values is usually
		183	better than looking at the C<$message>.
		184
		185	Non-fatal errors can be retried by returning, but it is recommended
		186	to simply ignore this parameter and instead abondon the handle object
		187	when this callback is invoked. Examples of non-fatal errors are timeouts
		188	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
		189
		190	On entry to the callback, the value of C<$!> contains the operating
		191	system error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		192	C<EPROTO>).
		193
		194	While not mandatory, it is I<highly> recommended to set this callback, as
		195	you will not be notified of errors otherwise. The default just calls
		196	C<croak>.
		197
		198	=item on_read => $cb->($handle)
		199
		200	This sets the default read callback, which is called when data arrives
		201	and no read request is in the queue (unlike read queue callbacks, this
		202	callback will only be called when at least one octet of data is in the
		203	read buffer).
		204
		205	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
		206	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		207	must not enlarge or modify the read buffer, you can only remove data at
		208	the beginning from it.
		209
		210	You can also call C<< ->push_read (...) >> or any other function that
		211	modifies the read queue. Or do both. Or ...
		212
		213	When an EOF condition is detected, AnyEvent::Handle will first try to
		214	feed all the remaining data to the queued callbacks and C<on_read> before
		215	calling the C<on_eof> callback. If no progress can be made, then a fatal
		216	error will be raised (with C<$!> set to C<EPIPE>).
		217
		218	Note that, unlike requests in the read queue, an C<on_read> callback
		219	doesn't mean you I<require> some data: if there is an EOF and there
		220	are outstanding read requests then an error will be flagged. With an
		221	C<on_read> callback, the C<on_eof> callback will be invoked.
		222
		223	=item on_eof => $cb->($handle)
		224
		225	Set the callback to be called when an end-of-file condition is detected,
		226	i.e. in the case of a socket, when the other side has closed the
		227	connection cleanly, and there are no outstanding read requests in the
		228	queue (if there are read requests, then an EOF counts as an unexpected
		229	connection close and will be flagged as an error).
		230
		231	For sockets, this just means that the other side has stopped sending data,
		232	you can still try to write data, and, in fact, one can return from the EOF
		233	callback and continue writing data, as only the read part has been shut
		234	down.
		235
		236	If an EOF condition has been detected but no C<on_eof> callback has been
		237	set, then a fatal error will be raised with C<$!> set to <0>.
		238
		239	=item on_drain => $cb->($handle)
		240
		241	This sets the callback that is called once when the write buffer becomes
		242	empty (and immediately when the handle object is created).
		243
		244	To append to the write buffer, use the C<< ->push_write >> method.
		245
		246	This callback is useful when you don't want to put all of your write data
		247	into the queue at once, for example, when you want to write the contents
		248	of some file to the socket you might not want to read the whole file into
		249	memory and push it into the queue, but instead only read more data from
		250	the file when the write queue becomes empty.
		251
		252	=item timeout => $fractional_seconds
		253
		254	=item rtimeout => $fractional_seconds
		255
		256	=item wtimeout => $fractional_seconds
		257
		258	If non-zero, then these enables an "inactivity" timeout: whenever this
		259	many seconds pass without a successful read or write on the underlying
		260	file handle (or a call to C<timeout_reset>), the C<on_timeout> callback
		261	will be invoked (and if that one is missing, a non-fatal C<ETIMEDOUT>
		262	error will be raised).
		263
		264	There are three variants of the timeouts that work independently of each
		265	other, for both read and write (triggered when nothing was read I<OR>
		266	written), just read (triggered when nothing was read), and just write:
		267	C<timeout>, C<rtimeout> and C<wtimeout>, with corresponding callbacks
		268	C<on_timeout>, C<on_rtimeout> and C<on_wtimeout>, and reset functions
		269	C<timeout_reset>, C<rtimeout_reset>, and C<wtimeout_reset>.
		270
		271	Note that timeout processing is active even when you do not have any
		272	outstanding read or write requests: If you plan to keep the connection
		273	idle then you should disable the timeout temporarily or ignore the
		274	timeout in the corresponding C<on_timeout> callback, in which case
		275	AnyEvent::Handle will simply restart the timeout.
		276
		277	Zero (the default) disables the corresponding timeout.
		278
		279	=item on_timeout => $cb->($handle)
		280
		281	=item on_rtimeout => $cb->($handle)
		282
		283	=item on_wtimeout => $cb->($handle)
		284
		285	Called whenever the inactivity timeout passes. If you return from this
		286	callback, then the timeout will be reset as if some activity had happened,
		287	so this condition is not fatal in any way.
		288
		289	=item rbuf_max => <bytes>
		290
		291	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		292	when the read buffer ever (strictly) exceeds this size. This is useful to
		293	avoid some forms of denial-of-service attacks.
		294
		295	For example, a server accepting connections from untrusted sources should
		296	be configured to accept only so-and-so much data that it cannot act on
		297	(for example, when expecting a line, an attacker could send an unlimited
		298	amount of data without a callback ever being called as long as the line
		299	isn't finished).
		300
		301	=item wbuf_max => <bytes>
		302
		303	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		304	when the write buffer ever (strictly) exceeds this size. This is useful to
		305	avoid some forms of denial-of-service attacks.
		306
		307	Although the units of this parameter is bytes, this is the I<raw> number
		308	of bytes not yet accepted by the kernel. This can make a difference when
		309	you e.g. use TLS, as TLS typically makes your write data larger (but it
		310	can also make it smaller due to compression).
		311
		312	As an example of when this limit is useful, take a chat server that sends
		313	chat messages to a client. If the client does not read those in a timely
		314	manner then the send buffer in the server would grow unbounded.
		315
		316	=item autocork => <boolean>
		317
		318	When disabled (the default), C<push_write> will try to immediately
		319	write the data to the handle if possible. This avoids having to register
		320	a write watcher and wait for the next event loop iteration, but can
		321	be inefficient if you write multiple small chunks (on the wire, this
		322	disadvantage is usually avoided by your kernel's nagle algorithm, see
		323	C<no_delay>, but this option can save costly syscalls).
		324
		325	When enabled, writes will always be queued till the next event loop
		326	iteration. This is efficient when you do many small writes per iteration,
		327	but less efficient when you do a single write only per iteration (or when
		328	the write buffer often is full). It also increases write latency.
		329
		330	=item no_delay => <boolean>
		331
		332	When doing small writes on sockets, your operating system kernel might
		333	wait a bit for more data before actually sending it out. This is called
		334	the Nagle algorithm, and usually it is beneficial.
		335
		336	In some situations you want as low a delay as possible, which can be
		337	accomplishd by setting this option to a true value.
		338
		339	The default is your operating system's default behaviour (most likely
		340	enabled). This option explicitly enables or disables it, if possible.
		341
		342	=item keepalive => <boolean>
		343
		344	Enables (default disable) the SO_KEEPALIVE option on the stream socket:
		345	normally, TCP connections have no time-out once established, so TCP
		346	connections, once established, can stay alive forever even when the other
		347	side has long gone. TCP keepalives are a cheap way to take down long-lived
		348	TCP connections when the other side becomes unreachable. While the default
		349	is OS-dependent, TCP keepalives usually kick in after around two hours,
		350	and, if the other side doesn't reply, take down the TCP connection some 10
		351	to 15 minutes later.
		352
		353	It is harmless to specify this option for file handles that do not support
		354	keepalives, and enabling it on connections that are potentially long-lived
		355	is usually a good idea.
		356
		357	=item oobinline => <boolean>
		358
		359	BSD majorly fucked up the implementation of TCP urgent data. The result
		360	is that almost no OS implements TCP according to the specs, and every OS
		361	implements it slightly differently.
		362
		363	If you want to handle TCP urgent data, then setting this flag (the default
		364	is enabled) gives you the most portable way of getting urgent data, by
		365	putting it into the stream.
		366
		367	Since BSD emulation of OOB data on top of TCP's urgent data can have
		368	security implications, AnyEvent::Handle sets this flag automatically
		369	unless explicitly specified. Note that setting this flag after
		370	establishing a connection I<may> be a bit too late (data loss could
		371	already have occured on BSD systems), but at least it will protect you
		372	from most attacks.
		373
		374	=item read_size => <bytes>
		375
		376	The initial read block size, the number of bytes this module will try
		377	to read during each loop iteration. Each handle object will consume
		378	at least this amount of memory for the read buffer as well, so when
		379	handling many connections watch out for memory requirements). See also
		380	C<max_read_size>. Default: C<2048>.
		381
		382	=item max_read_size => <bytes>
		383
		384	The maximum read buffer size used by the dynamic adjustment
		385	algorithm: Each time AnyEvent::Handle can read C<read_size> bytes in
		386	one go it will double C<read_size> up to the maximum given by this
		387	option. Default: C<131072> or C<read_size>, whichever is higher.
		388
		389	=item low_water_mark => <bytes>
		390
		391	Sets the number of bytes (default: C<0>) that make up an "empty" write
		392	buffer: If the buffer reaches this size or gets even samller it is
		393	considered empty.
		394
		395	Sometimes it can be beneficial (for performance reasons) to add data to
		396	the write buffer before it is fully drained, but this is a rare case, as
		397	the operating system kernel usually buffers data as well, so the default
		398	is good in almost all cases.
		399
		400	=item linger => <seconds>
		401
		402	If this is non-zero (default: C<3600>), the destructor of the
		403	AnyEvent::Handle object will check whether there is still outstanding
		404	write data and will install a watcher that will write this data to the
		405	socket. No errors will be reported (this mostly matches how the operating
		406	system treats outstanding data at socket close time).
		407
		408	This will not work for partial TLS data that could not be encoded
		409	yet. This data will be lost. Calling the C<stoptls> method in time might
		410	help.
		411
		412	=item peername => $string
		413
		414	A string used to identify the remote site - usually the DNS hostname
		415	(I<not> IDN!) used to create the connection, rarely the IP address.
		416
		417	Apart from being useful in error messages, this string is also used in TLS
		418	peername verification (see C<verify_peername> in L<AnyEvent::TLS>). This
		419	verification will be skipped when C<peername> is not specified or is
		420	C<undef>.
		421
		422	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		423
		424	When this parameter is given, it enables TLS (SSL) mode, that means
		425	AnyEvent will start a TLS handshake as soon as the connection has been
		426	established and will transparently encrypt/decrypt data afterwards.
		427
		428	All TLS protocol errors will be signalled as C<EPROTO>, with an
		429	appropriate error message.
		430
		431	TLS mode requires Net::SSLeay to be installed (it will be loaded
		432	automatically when you try to create a TLS handle): this module doesn't
		433	have a dependency on that module, so if your module requires it, you have
		434	to add the dependency yourself. If Net::SSLeay cannot be loaded or is too
		435	old, you get an C<EPROTO> error.
		436
		437	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		438	C<accept>, and for the TLS client side of a connection, use C<connect>
		439	mode.
		440
		441	You can also provide your own TLS connection object, but you have
		442	to make sure that you call either C<Net::SSLeay::set_connect_state>
		443	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		444	AnyEvent::Handle. Also, this module will take ownership of this connection
		445	object.
		446
		447	At some future point, AnyEvent::Handle might switch to another TLS
		448	implementation, then the option to use your own session object will go
		449	away.
		450
		451	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		452	passing in the wrong integer will lead to certain crash. This most often
		453	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		454	segmentation fault.
		455
		456	Use the C<< ->starttls >> method if you need to start TLS negotiation later.
		457
		458	=item tls_ctx => $anyevent_tls
		459
		460	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		461	(unless a connection object was specified directly). If this
		462	parameter is missing (or C<undef>), then AnyEvent::Handle will use
		463	C<AnyEvent::Handle::TLS_CTX>.
		464
		465	Instead of an object, you can also specify a hash reference with C<< key
		466	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		467	new TLS context object.
		468
		469	=item on_starttls => $cb->($handle, $success[, $error_message])
		470
		471	This callback will be invoked when the TLS/SSL handshake has finished. If
		472	C<$success> is true, then the TLS handshake succeeded, otherwise it failed
		473	(C<on_stoptls> will not be called in this case).
		474
		475	The session in C<< $handle->{tls} >> can still be examined in this
		476	callback, even when the handshake was not successful.
		477
		478	TLS handshake failures will not cause C<on_error> to be invoked when this
		479	callback is in effect, instead, the error message will be passed to C<on_starttls>.
		480
		481	Without this callback, handshake failures lead to C<on_error> being
		482	called as usual.
		483
		484	Note that you cannot just call C<starttls> again in this callback. If you
		485	need to do that, start an zero-second timer instead whose callback can
		486	then call C<< ->starttls >> again.
		487
		488	=item on_stoptls => $cb->($handle)
		489
		490	When a SSLv3/TLS shutdown/close notify/EOF is detected and this callback is
		491	set, then it will be invoked after freeing the TLS session. If it is not,
		492	then a TLS shutdown condition will be treated like a normal EOF condition
		493	on the handle.
		494
		495	The session in C<< $handle->{tls} >> can still be examined in this
		496	callback.
		497
		498	This callback will only be called on TLS shutdowns, not when the
		499	underlying handle signals EOF.
		500
		501	=item json => L<JSON> or L<JSON::XS> object
		502
		503	This is the json coder object used by the C<json> read and write types.
		504
		505	If you don't supply it, then AnyEvent::Handle will create and use a
		506	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		507	texts.
		508
		509	Note that you are responsible to depend on the L<JSON> module if you want
		510	to use this functionality, as AnyEvent does not have a dependency on it
		511	itself.
		512
		513	=item cbor => L<CBOR::XS> object
		514
		515	This is the cbor coder object used by the C<cbor> read and write types.
		516
		517	If you don't supply it, then AnyEvent::Handle will create and use a
		518	suitable one (on demand), which will write CBOR without using extensions,
		519	if possible. texts.
		520
		521	Note that you are responsible to depend on the L<CBOR::XS> module if you
		522	want to use this functionality, as AnyEvent does not have a dependency on
		523	it itself.
		524
		525	=back
		526
		527	=cut
		528
		529	sub new {
		530	my $class = shift;
		531	my $self = bless { @_ }, $class;
		532
		533	if ($self->{fh}) {
		534	$self->_start;
		535	return unless $self->{fh}; # could be gone by now
		536
		537	} elsif ($self->{connect}) {
		538	require AnyEvent::Socket;
		539
		540	$self->{peername} = $self->{connect}[0]
		541	unless exists $self->{peername};
		542
		543	$self->{_skip_drain_rbuf} = 1;
		544
		545	{
		546	Scalar::Util::weaken (my $self = $self);
		547
		548	$self->{_connect} =
		549	AnyEvent::Socket::tcp_connect (
		550	$self->{connect}[0],
		551	$self->{connect}[1],
		552	sub {
		553	my ($fh, $host, $port, $retry) = @_;
		554
		555	delete $self->{_connect}; # no longer needed
		556
		557	if ($fh) {
		558	$self->{fh} = $fh;
		559
		560	delete $self->{_skip_drain_rbuf};
		561	$self->_start;
		562
		563	$self->{on_connect}
		564	and $self->{on_connect}($self, $host, $port, sub {
		565	delete @$self{qw(fh _tw _rtw _wtw _ww _rw _eof _queue rbuf _wbuf tls _tls_rbuf _tls_wbuf)};
		566	$self->{_skip_drain_rbuf} = 1;
		567	&$retry;
		568	});
		569
		570	} else {
		571	if ($self->{on_connect_error}) {
		572	$self->{on_connect_error}($self, "$!");
		573	$self->destroy if $self;
		574	} else {
		575	$self->_error ($!, 1);
		576	}
		577	}
		578	},
		579	sub {
		580	local $self->{fh} = $_[0];
		581
		582	$self->{on_prepare}
		583	? $self->{on_prepare}->($self)
		584	: ()
		585	}
		586	);
		587	}
		588
		589	} else {
		590	Carp::croak "AnyEvent::Handle: either an existing fh or the connect parameter must be specified";
		591	}
		592
		593	$self
		594	}
		595
		596	sub _start {
		597	my ($self) = @_;
		598
		599	# too many clueless people try to use udp and similar sockets
		600	# with AnyEvent::Handle, do them a favour.
		601	my $type = getsockopt $self->{fh}, Socket::SOL_SOCKET (), Socket::SO_TYPE ();
		602	Carp::croak "AnyEvent::Handle: only stream sockets supported, anything else will NOT work!"
		603	if Socket::SOCK_STREAM () != (unpack "I", $type) && defined $type;
		604
		605	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
		606
		607	$self->{_activity} =
		608	$self->{_ractivity} =
		609	$self->{_wactivity} = AE::now;
		610
		611	$self->{read_size} ||= 2048;
		612	$self->{max_read_size} = $self->{read_size}
		613	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		614
		615	$self->timeout (delete $self->{timeout} ) if $self->{timeout};
		616	$self->rtimeout (delete $self->{rtimeout} ) if $self->{rtimeout};
		617	$self->wtimeout (delete $self->{wtimeout} ) if $self->{wtimeout};
		618
		619	$self->no_delay (delete $self->{no_delay} ) if exists $self->{no_delay} && $self->{no_delay};
		620	$self->keepalive (delete $self->{keepalive}) if exists $self->{keepalive} && $self->{keepalive};
		621
		622	$self->oobinline (exists $self->{oobinline} ? delete $self->{oobinline} : 1);
		623
		624	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		625	if $self->{tls};
		626
		627	$self->on_drain (delete $self->{on_drain} ) if $self->{on_drain};
		628
		629	$self->start_read
		630	if $self->{on_read} || @{ $self->{_queue} };
		631
		632	$self->_drain_wbuf;
		633	}
		634
		635	sub _error {
		636	my ($self, $errno, $fatal, $message) = @_;
		637
		638	$! = $errno;
		639	$message ||= "$!";
		640
		641	if ($self->{on_error}) {
		642	$self->{on_error}($self, $fatal, $message);
		643	$self->destroy if $fatal;
		644	} elsif ($self->{fh} || $self->{connect}) {
		645	$self->destroy;
		646	Carp::croak "AnyEvent::Handle uncaught error: $message";
		647	}
		648	}
		649
		650	=item $fh = $handle->fh
		651
		652	This method returns the file handle used to create the L<AnyEvent::Handle> object.
		653
		654	=cut
		655
		656	sub fh { $_[0]{fh} }
		657
		658	=item $handle->on_error ($cb)
		659
		660	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
		661
		662	=cut
		663
		664	sub on_error {
		665	$_[0]{on_error} = $_[1];
		666	}
		667
		668	=item $handle->on_eof ($cb)
		669
		670	Replace the current C<on_eof> callback (see the C<on_eof> constructor argument).
		671
		672	=cut
		673
		674	sub on_eof {
		675	$_[0]{on_eof} = $_[1];
		676	}
		677
		678	=item $handle->on_timeout ($cb)
		679
		680	=item $handle->on_rtimeout ($cb)
		681
		682	=item $handle->on_wtimeout ($cb)
		683
		684	Replace the current C<on_timeout>, C<on_rtimeout> or C<on_wtimeout>
		685	callback, or disables the callback (but not the timeout) if C<$cb> =
		686	C<undef>. See the C<timeout> constructor argument and method.
		687
		688	=cut
		689
		690	# see below
		691
		692	=item $handle->autocork ($boolean)
		693
		694	Enables or disables the current autocork behaviour (see C<autocork>
		695	constructor argument). Changes will only take effect on the next write.
		696
		697	=cut
		698
		699	sub autocork {
		700	$_[0]{autocork} = $_[1];
		701	}
		702
		703	=item $handle->no_delay ($boolean)
		704
		705	Enables or disables the C<no_delay> setting (see constructor argument of
		706	the same name for details).
		707
		708	=cut
		709
		710	sub no_delay {
		711	$_[0]{no_delay} = $_[1];
		712
		713	setsockopt $_[0]{fh}, Socket::IPPROTO_TCP (), Socket::TCP_NODELAY (), int $_[1]
		714	if $_[0]{fh};
		715	}
		716
		717	=item $handle->keepalive ($boolean)
		718
		719	Enables or disables the C<keepalive> setting (see constructor argument of
		720	the same name for details).
		721
		722	=cut
		723
		724	sub keepalive {
		725	$_[0]{keepalive} = $_[1];
		726
		727	eval {
		728	local $SIG{__DIE__};
		729	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		730	if $_[0]{fh};
		731	};
		732	}
		733
		734	=item $handle->oobinline ($boolean)
		735
		736	Enables or disables the C<oobinline> setting (see constructor argument of
		737	the same name for details).
		738
		739	=cut
		740
		741	sub oobinline {
		742	$_[0]{oobinline} = $_[1];
		743
		744	eval {
		745	local $SIG{__DIE__};
		746	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_OOBINLINE (), int $_[1]
		747	if $_[0]{fh};
		748	};
		749	}
		750
		751	=item $handle->keepalive ($boolean)
		752
		753	Enables or disables the C<keepalive> setting (see constructor argument of
		754	the same name for details).
		755
		756	=cut
		757
		758	sub keepalive {
		759	$_[0]{keepalive} = $_[1];
		760
		761	eval {
		762	local $SIG{__DIE__};
		763	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		764	if $_[0]{fh};
		765	};
		766	}
		767
		768	=item $handle->on_starttls ($cb)
		769
		770	Replace the current C<on_starttls> callback (see the C<on_starttls> constructor argument).
		771
		772	=cut
		773
		774	sub on_starttls {
		775	$_[0]{on_starttls} = $_[1];
		776	}
		777
		778	=item $handle->on_stoptls ($cb)
		779
		780	Replace the current C<on_stoptls> callback (see the C<on_stoptls> constructor argument).
		781
		782	=cut
		783
		784	sub on_stoptls {
		785	$_[0]{on_stoptls} = $_[1];
		786	}
		787
		788	=item $handle->rbuf_max ($max_octets)
		789
		790	Configures the C<rbuf_max> setting (C<undef> disables it).
		791
		792	=item $handle->wbuf_max ($max_octets)
		793
		794	Configures the C<wbuf_max> setting (C<undef> disables it).
		795
		796	=cut
		797
		798	sub rbuf_max {
		799	$_[0]{rbuf_max} = $_[1];
		800	}
		801
		802	sub wbuf_max {
		803	$_[0]{wbuf_max} = $_[1];
		804	}
		805
		806	#############################################################################
		807
		808	=item $handle->timeout ($seconds)
		809
		810	=item $handle->rtimeout ($seconds)
		811
		812	=item $handle->wtimeout ($seconds)
		813
		814	Configures (or disables) the inactivity timeout.
		815
		816	The timeout will be checked instantly, so this method might destroy the
		817	handle before it returns.
		818
		819	=item $handle->timeout_reset
		820
		821	=item $handle->rtimeout_reset
		822
		823	=item $handle->wtimeout_reset
		824
		825	Reset the activity timeout, as if data was received or sent.
		826
		827	These methods are cheap to call.
		828
		829	=cut
		830
		831	for my $dir ("", "r", "w") {
		832	my $timeout = "${dir}timeout";
		833	my $tw = "_${dir}tw";
		834	my $on_timeout = "on_${dir}timeout";
		835	my $activity = "_${dir}activity";
		836	my $cb;
		837
		838	*$on_timeout = sub {
		839	$_[0]{$on_timeout} = $_[1];
		840	};
		841
		842	*$timeout = sub {
		843	my ($self, $new_value) = @_;
		844
		845	$new_value >= 0
		846	or Carp::croak "AnyEvent::Handle->$timeout called with negative timeout ($new_value), caught";
		847
		848	$self->{$timeout} = $new_value;
		849	delete $self->{$tw}; &$cb;
		850	};
		851
		852	*{"${dir}timeout_reset"} = sub {
		853	$_[0]{$activity} = AE::now;
		854	};
		855
		856	# main workhorse:
		857	# reset the timeout watcher, as neccessary
		858	# also check for time-outs
		859	$cb = sub {
		860	my ($self) = @_;
		861
		862	if ($self->{$timeout} && $self->{fh}) {
		863	my $NOW = AE::now;
		864
		865	# when would the timeout trigger?
		866	my $after = $self->{$activity} + $self->{$timeout} - $NOW;
		867
		868	# now or in the past already?
		869	if ($after <= 0) {
		870	$self->{$activity} = $NOW;
		871
		872	if ($self->{$on_timeout}) {
		873	$self->{$on_timeout}($self);
		874	} else {
		875	$self->_error (Errno::ETIMEDOUT);
		876	}
		877
		878	# callback could have changed timeout value, optimise
		879	return unless $self->{$timeout};
		880
		881	# calculate new after
		882	$after = $self->{$timeout};
		883	}
		884
		885	Scalar::Util::weaken $self;
		886	return unless $self; # ->error could have destroyed $self
		887
		888	$self->{$tw} ||= AE::timer $after, 0, sub {
		889	delete $self->{$tw};
		890	$cb->($self);
36	chomp;	891	};
37	print "Line: $_";	892	} else {
		893	delete $self->{$tw};
		894	}
		895	}
		896	}
		897
		898	#############################################################################
		899
		900	=back
		901
		902	=head2 WRITE QUEUE
		903
		904	AnyEvent::Handle manages two queues per handle, one for writing and one
		905	for reading.
		906
		907	The write queue is very simple: you can add data to its end, and
		908	AnyEvent::Handle will automatically try to get rid of it for you.
		909
		910	When data could be written and the write buffer is shorter then the low
		911	water mark, the C<on_drain> callback will be invoked once.
		912
		913	=over 4
		914
		915	=item $handle->on_drain ($cb)
		916
		917	Sets the C<on_drain> callback or clears it (see the description of
		918	C<on_drain> in the constructor).
		919
		920	This method may invoke callbacks (and therefore the handle might be
		921	destroyed after it returns).
		922
		923	=cut
		924
		925	sub on_drain {
		926	my ($self, $cb) = @_;
		927
		928	$self->{on_drain} = $cb;
		929
		930	$cb->($self)
		931	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
		932	}
		933
		934	=item $handle->push_write ($data)
		935
		936	Queues the given scalar to be written. You can push as much data as
		937	you want (only limited by the available memory and C<wbuf_max>), as
		938	C<AnyEvent::Handle> buffers it independently of the kernel.
		939
		940	This method may invoke callbacks (and therefore the handle might be
		941	destroyed after it returns).
		942
		943	=cut
		944
		945	sub _drain_wbuf {
		946	my ($self) = @_;
		947
		948	if (!$self->{_ww} && length $self->{wbuf}) {
		949
		950	Scalar::Util::weaken $self;
		951
		952	my $cb = sub {
		953	my $len = syswrite $self->{fh}, $self->{wbuf};
		954
		955	if (defined $len) {
		956	substr $self->{wbuf}, 0, $len, "";
		957
		958	$self->{_activity} = $self->{_wactivity} = AE::now;
		959
		960	$self->{on_drain}($self)
		961	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
		962	&& $self->{on_drain};
		963
		964	delete $self->{_ww} unless length $self->{wbuf};
		965	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		966	$self->_error ($!, 1);
		967	}
		968	};
		969
		970	# try to write data immediately
		971	$cb->() unless $self->{autocork};
		972
		973	# if still data left in wbuf, we need to poll
		974	$self->{_ww} = AE::io $self->{fh}, 1, $cb
		975	if length $self->{wbuf};
		976
		977	if (
		978	defined $self->{wbuf_max}
		979	&& $self->{wbuf_max} < length $self->{wbuf}
		980	) {
		981	$self->_error (Errno::ENOSPC, 1), return;
		982	}
		983	};
		984	}
		985
		986	our %WH;
		987
		988	# deprecated
		989	sub register_write_type($$) {
		990	$WH{$_[0]} = $_[1];
		991	}
		992
		993	sub push_write {
		994	my $self = shift;
		995
		996	if (@_ > 1) {
		997	my $type = shift;
		998
		999	@_ = ($WH{$type} ||= _load_func "$type\::anyevent_write_type"
		1000	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_write")
		1001	->($self, @_);
		1002	}
		1003
		1004	# we downgrade here to avoid hard-to-track-down bugs,
		1005	# and diagnose the problem earlier and better.
		1006
		1007	if ($self->{tls}) {
		1008	utf8::downgrade $self->{_tls_wbuf} .= $_[0];
		1009	&_dotls ($self) if $self->{fh};
		1010	} else {
		1011	utf8::downgrade $self->{wbuf} .= $_[0];
		1012	$self->_drain_wbuf if $self->{fh};
		1013	}
		1014	}
		1015
		1016	=item $handle->push_write (type => @args)
		1017
		1018	Instead of formatting your data yourself, you can also let this module
		1019	do the job by specifying a type and type-specific arguments. You
		1020	can also specify the (fully qualified) name of a package, in which
		1021	case AnyEvent tries to load the package and then expects to find the
		1022	C<anyevent_write_type> function inside (see "custom write types", below).
		1023
		1024	Predefined types are (if you have ideas for additional types, feel free to
		1025	drop by and tell us):
		1026
		1027	=over 4
		1028
		1029	=item netstring => $string
		1030
		1031	Formats the given value as netstring
		1032	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		1033
		1034	=cut
		1035
		1036	register_write_type netstring => sub {
		1037	my ($self, $string) = @_;
		1038
		1039	(length $string) . ":$string,"
		1040	};
		1041
		1042	=item packstring => $format, $data
		1043
		1044	An octet string prefixed with an encoded length. The encoding C<$format>
		1045	uses the same format as a Perl C<pack> format, but must specify a single
		1046	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1047	optional C<!>, C<< < >> or C<< > >> modifier).
		1048
		1049	=cut
		1050
		1051	register_write_type packstring => sub {
		1052	my ($self, $format, $string) = @_;
		1053
		1054	pack "$format/a*", $string
		1055	};
		1056
		1057	=item json => $array_or_hashref
		1058
		1059	Encodes the given hash or array reference into a JSON object. Unless you
		1060	provide your own JSON object, this means it will be encoded to JSON text
		1061	in UTF-8.
		1062
		1063	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		1064	one end of a handle and read them at the other end without using any
		1065	additional framing.
		1066
		1067	The generated JSON text is guaranteed not to contain any newlines: While
		1068	this module doesn't need delimiters after or between JSON texts to be
		1069	able to read them, many other languages depend on that.
		1070
		1071	A simple RPC protocol that interoperates easily with other languages is
		1072	to send JSON arrays (or objects, although arrays are usually the better
		1073	choice as they mimic how function argument passing works) and a newline
		1074	after each JSON text:
		1075
		1076	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		1077	$handle->push_write ("\012");
		1078
		1079	An AnyEvent::Handle receiver would simply use the C<json> read type and
		1080	rely on the fact that the newline will be skipped as leading whitespace:
		1081
		1082	$handle->push_read (json => sub { my $array = $_[1]; ... });
		1083
		1084	Other languages could read single lines terminated by a newline and pass
		1085	this line into their JSON decoder of choice.
		1086
		1087	=item cbor => $perl_scalar
		1088
		1089	Encodes the given scalar into a CBOR value. Unless you provide your own
		1090	L<CBOR::XS> object, this means it will be encoded to a CBOR string not
		1091	using any extensions, if possible.
		1092
		1093	CBOR values are self-delimiting, so you can write CBOR at one end of
		1094	a handle and read them at the other end without using any additional
		1095	framing.
		1096
		1097	A simple nd very very fast RPC protocol that interoperates with
		1098	other languages is to send CBOR and receive CBOR values (arrays are
		1099	recommended):
		1100
		1101	$handle->push_write (cbor => ["method", "arg1", "arg2"]); # whatever
		1102
		1103	An AnyEvent::Handle receiver would simply use the C<cbor> read type:
		1104
		1105	$handle->push_read (cbor => sub { my $array = $_[1]; ... });
		1106
		1107	=cut
		1108
		1109	sub json_coder() {
		1110	eval { require JSON::XS; JSON::XS->new->utf8 }
		1111	|| do { require JSON; JSON->new->utf8 }
		1112	}
		1113
		1114	register_write_type json => sub {
		1115	my ($self, $ref) = @_;
		1116
		1117	($self->{json} ||= json_coder)
		1118	->encode ($ref)
		1119	};
		1120
		1121	sub cbor_coder() {
		1122	require CBOR::XS;
		1123	CBOR::XS->new
		1124	}
		1125
		1126	register_write_type cbor => sub {
		1127	my ($self, $scalar) = @_;
		1128
		1129	($self->{cbor} ||= cbor_coder)
		1130	->encode ($scalar)
		1131	};
		1132
		1133	=item storable => $reference
		1134
		1135	Freezes the given reference using L<Storable> and writes it to the
		1136	handle. Uses the C<nfreeze> format.
		1137
		1138	=cut
		1139
		1140	register_write_type storable => sub {
		1141	my ($self, $ref) = @_;
		1142
		1143	require Storable unless $Storable::VERSION;
		1144
		1145	pack "w/a*", Storable::nfreeze ($ref)
		1146	};
		1147
		1148	=back
		1149
		1150	=item $handle->push_shutdown
		1151
		1152	Sometimes you know you want to close the socket after writing your data
		1153	before it was actually written. One way to do that is to replace your
		1154	C<on_drain> handler by a callback that shuts down the socket (and set
		1155	C<low_water_mark> to C<0>). This method is a shorthand for just that, and
		1156	replaces the C<on_drain> callback with:
		1157
		1158	sub { shutdown $_[0]{fh}, 1 }
		1159
		1160	This simply shuts down the write side and signals an EOF condition to the
		1161	the peer.
		1162
		1163	You can rely on the normal read queue and C<on_eof> handling
		1164	afterwards. This is the cleanest way to close a connection.
		1165
		1166	This method may invoke callbacks (and therefore the handle might be
		1167	destroyed after it returns).
		1168
		1169	=cut
		1170
		1171	sub push_shutdown {
		1172	my ($self) = @_;
		1173
		1174	delete $self->{low_water_mark};
		1175	$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
		1176	}
		1177
		1178	=item custom write types - Package::anyevent_write_type $handle, @args
		1179
		1180	Instead of one of the predefined types, you can also specify the name of
		1181	a package. AnyEvent will try to load the package and then expects to find
		1182	a function named C<anyevent_write_type> inside. If it isn't found, it
		1183	progressively tries to load the parent package until it either finds the
		1184	function (good) or runs out of packages (bad).
		1185
		1186	Whenever the given C<type> is used, C<push_write> will the function with
		1187	the handle object and the remaining arguments.
		1188
		1189	The function is supposed to return a single octet string that will be
		1190	appended to the write buffer, so you can mentally treat this function as a
		1191	"arguments to on-the-wire-format" converter.
		1192
		1193	Example: implement a custom write type C<join> that joins the remaining
		1194	arguments using the first one.
		1195
		1196	$handle->push_write (My::Type => " ", 1,2,3);
		1197
		1198	# uses the following package, which can be defined in the "My::Type" or in
		1199	# the "My" modules to be auto-loaded, or just about anywhere when the
		1200	# My::Type::anyevent_write_type is defined before invoking it.
		1201
		1202	package My::Type;
		1203
		1204	sub anyevent_write_type {
		1205	my ($handle, $delim, @args) = @_;
		1206
		1207	join $delim, @args
		1208	}
		1209
		1210	=cut
		1211
		1212	#############################################################################
		1213
		1214	=back
		1215
		1216	=head2 READ QUEUE
		1217
		1218	AnyEvent::Handle manages two queues per handle, one for writing and one
		1219	for reading.
		1220
		1221	The read queue is more complex than the write queue. It can be used in two
		1222	ways, the "simple" way, using only C<on_read> and the "complex" way, using
		1223	a queue.
		1224
		1225	In the simple case, you just install an C<on_read> callback and whenever
		1226	new data arrives, it will be called. You can then remove some data (if
		1227	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you can
		1228	leave the data there if you want to accumulate more (e.g. when only a
		1229	partial message has been received so far), or change the read queue with
		1230	e.g. C<push_read>.
		1231
		1232	In the more complex case, you want to queue multiple callbacks. In this
		1233	case, AnyEvent::Handle will call the first queued callback each time new
		1234	data arrives (also the first time it is queued) and remove it when it has
		1235	done its job (see C<push_read>, below).
		1236
		1237	This way you can, for example, push three line-reads, followed by reading
		1238	a chunk of data, and AnyEvent::Handle will execute them in order.
		1239
		1240	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
		1241	the specified number of bytes which give an XML datagram.
		1242
		1243	# in the default state, expect some header bytes
		1244	$handle->on_read (sub {
		1245	# some data is here, now queue the length-header-read (4 octets)
		1246	shift->unshift_read (chunk => 4, sub {
		1247	# header arrived, decode
		1248	my $len = unpack "N", $_[1];
		1249
		1250	# now read the payload
		1251	shift->unshift_read (chunk => $len, sub {
		1252	my $xml = $_[1];
		1253	# handle xml
		1254	});
		1255	});
		1256	});
		1257
		1258	Example 2: Implement a client for a protocol that replies either with "OK"
		1259	and another line or "ERROR" for the first request that is sent, and 64
		1260	bytes for the second request. Due to the availability of a queue, we can
		1261	just pipeline sending both requests and manipulate the queue as necessary
		1262	in the callbacks.
		1263
		1264	When the first callback is called and sees an "OK" response, it will
		1265	C<unshift> another line-read. This line-read will be queued I<before> the
		1266	64-byte chunk callback.
		1267
		1268	# request one, returns either "OK + extra line" or "ERROR"
		1269	$handle->push_write ("request 1\015\012");
		1270
		1271	# we expect "ERROR" or "OK" as response, so push a line read
		1272	$handle->push_read (line => sub {
		1273	# if we got an "OK", we have to _prepend_ another line,
		1274	# so it will be read before the second request reads its 64 bytes
		1275	# which are already in the queue when this callback is called
		1276	# we don't do this in case we got an error
		1277	if ($_[1] eq "OK") {
		1278	$_[0]->unshift_read (line => sub {
		1279	my $response = $_[1];
		1280	...
		1281	});
38	}	1282	}
39	});	1283	});
40		1284
41	# or use the constructor to pass the callback:	1285	# request two, simply returns 64 octets
		1286	$handle->push_write ("request 2\015\012");
42		1287
43	my $ae_fh2 =	1288	# simply read 64 bytes, always
44	AnyEvent::Handle->new (	1289	$handle->push_read (chunk => 64, sub {
45	fh => \*STDIN,	1290	my $response = $_[1];
46	on_eof => sub {	1291	...
47	$cv->broadcast;	1292	});
48	},	1293
49	on_readline => sub {	1294	=over 4
50	my ($ae_fh, @lines) = @_;	1295
51	for (@lines) {	1296	=cut
52	chomp;	1297
53	print "Line: $_";	1298	sub _drain_rbuf {
		1299	my ($self) = @_;
		1300
		1301	# avoid recursion
		1302	return if $self->{_skip_drain_rbuf};
		1303	local $self->{_skip_drain_rbuf} = 1;
		1304
		1305	while () {
		1306	# we need to use a separate tls read buffer, as we must not receive data while
		1307	# we are draining the buffer, and this can only happen with TLS.
		1308	$self->{rbuf} .= delete $self->{_tls_rbuf}
		1309	if exists $self->{_tls_rbuf};
		1310
		1311	my $len = length $self->{rbuf};
		1312
		1313	if (my $cb = shift @{ $self->{_queue} }) {
		1314	unless ($cb->($self)) {
		1315	# no progress can be made
		1316	# (not enough data and no data forthcoming)
		1317	$self->_error (Errno::EPIPE, 1), return
		1318	if $self->{_eof};
		1319
		1320	unshift @{ $self->{_queue} }, $cb;
54	}	1321	last;
55	}	1322	}
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}) {	1323	} elsif ($self->{on_read}) {
121	$self->readlines ($self->{on_readline});	1324	last unless $len;
122		1325
		1326	$self->{on_read}($self);
		1327
		1328	if (
		1329	$len == length $self->{rbuf} # if no data has been consumed
		1330	&& !@{ $self->{_queue} } # and the queue is still empty
		1331	&& $self->{on_read} # but we still have on_read
		1332	) {
		1333	# no further data will arrive
		1334	# so no progress can be made
		1335	$self->_error (Errno::EPIPE, 1), return
		1336	if $self->{_eof};
		1337
		1338	last; # more data might arrive
		1339	}
		1340	} else {
		1341	# read side becomes idle
		1342	delete $self->{_rw} unless $self->{tls};
		1343	last;
		1344	}
		1345	}
		1346
123	} elsif ($self->{on_eof}) {	1347	if ($self->{_eof}) {
124	$self->on_eof ($self->{on_eof});	1348	$self->{on_eof}
		1349	? $self->{on_eof}($self)
		1350	: $self->_error (0, 1, "Unexpected end-of-file");
125		1351
126	} elsif ($self->{on_error}) {	1352	return;
127	$self->on_eof ($self->{on_error});
128	}	1353	}
129		1354
130	return $self	1355	if (
131	}	1356	defined $self->{rbuf_max}
		1357	&& $self->{rbuf_max} < length $self->{rbuf}
		1358	) {
		1359	$self->_error (Errno::ENOSPC, 1), return;
		1360	}
132		1361
133	=item B<fh>	1362	# may need to restart read watcher
		1363	unless ($self->{_rw}) {
		1364	$self->start_read
		1365	if $self->{on_read} || @{ $self->{_queue} };
		1366	}
		1367	}
134		1368
135	This method returns the filehandle of the L<AnyEvent::Handle> object.	1369	=item $handle->on_read ($cb)
136		1370
137	=cut	1371	This replaces the currently set C<on_read> callback, or clears it (when
		1372	the new callback is C<undef>). See the description of C<on_read> in the
		1373	constructor.
138		1374
139	sub fh { $_[0]->{fh} }	1375	This method may invoke callbacks (and therefore the handle might be
140		1376	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		1377
149	=cut	1378	=cut
150		1379
151	sub on_read {	1380	sub on_read {
152	my ($self, $cb) = @_;	1381	my ($self, $cb) = @_;
		1382
153	$self->{on_read} = $cb;	1383	$self->{on_read} = $cb;
		1384	$self->_drain_rbuf if $cb;
		1385	}
154		1386
155	unless (defined $self->{on_read}) {	1387	=item $handle->rbuf
156	delete $self->{on_read_w};	1388
		1389	Returns the read buffer (as a modifiable lvalue). You can also access the
		1390	read buffer directly as the C<< ->{rbuf} >> member, if you want (this is
		1391	much faster, and no less clean).
		1392
		1393	The only operation allowed on the read buffer (apart from looking at it)
		1394	is removing data from its beginning. Otherwise modifying or appending to
		1395	it is not allowed and will lead to hard-to-track-down bugs.
		1396
		1397	NOTE: The read buffer should only be used or modified in the C<on_read>
		1398	callback or when C<push_read> or C<unshift_read> are used with a single
		1399	callback (i.e. untyped). Typed C<push_read> and C<unshift_read> methods
		1400	will manage the read buffer on their own.
		1401
		1402	=cut
		1403
		1404	sub rbuf : lvalue {
		1405	$_[0]{rbuf}
		1406	}
		1407
		1408	=item $handle->push_read ($cb)
		1409
		1410	=item $handle->unshift_read ($cb)
		1411
		1412	Append the given callback to the end of the queue (C<push_read>) or
		1413	prepend it (C<unshift_read>).
		1414
		1415	The callback is called each time some additional read data arrives.
		1416
		1417	It must check whether enough data is in the read buffer already.
		1418
		1419	If not enough data is available, it must return the empty list or a false
		1420	value, in which case it will be called repeatedly until enough data is
		1421	available (or an error condition is detected).
		1422
		1423	If enough data was available, then the callback must remove all data it is
		1424	interested in (which can be none at all) and return a true value. After returning
		1425	true, it will be removed from the queue.
		1426
		1427	These methods may invoke callbacks (and therefore the handle might be
		1428	destroyed after it returns).
		1429
		1430	=cut
		1431
		1432	our %RH;
		1433
		1434	sub register_read_type($$) {
		1435	$RH{$_[0]} = $_[1];
		1436	}
		1437
		1438	sub push_read {
		1439	my $self = shift;
		1440	my $cb = pop;
		1441
		1442	if (@_) {
		1443	my $type = shift;
		1444
		1445	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1446	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_read")
		1447	->($self, $cb, @_);
		1448	}
		1449
		1450	push @{ $self->{_queue} }, $cb;
		1451	$self->_drain_rbuf;
		1452	}
		1453
		1454	sub unshift_read {
		1455	my $self = shift;
		1456	my $cb = pop;
		1457
		1458	if (@_) {
		1459	my $type = shift;
		1460
		1461	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1462	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::unshift_read")
		1463	->($self, $cb, @_);
		1464	}
		1465
		1466	unshift @{ $self->{_queue} }, $cb;
		1467	$self->_drain_rbuf;
		1468	}
		1469
		1470	=item $handle->push_read (type => @args, $cb)
		1471
		1472	=item $handle->unshift_read (type => @args, $cb)
		1473
		1474	Instead of providing a callback that parses the data itself you can chose
		1475	between a number of predefined parsing formats, for chunks of data, lines
		1476	etc. You can also specify the (fully qualified) name of a package, in
		1477	which case AnyEvent tries to load the package and then expects to find the
		1478	C<anyevent_read_type> function inside (see "custom read types", below).
		1479
		1480	Predefined types are (if you have ideas for additional types, feel free to
		1481	drop by and tell us):
		1482
		1483	=over 4
		1484
		1485	=item chunk => $octets, $cb->($handle, $data)
		1486
		1487	Invoke the callback only once C<$octets> bytes have been read. Pass the
		1488	data read to the callback. The callback will never be called with less
		1489	data.
		1490
		1491	Example: read 2 bytes.
		1492
		1493	$handle->push_read (chunk => 2, sub {
		1494	say "yay " . unpack "H*", $_[1];
		1495	});
		1496
		1497	=cut
		1498
		1499	register_read_type chunk => sub {
		1500	my ($self, $cb, $len) = @_;
		1501
		1502	sub {
		1503	$len <= length $_[0]{rbuf} or return;
		1504	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
		1505	1
		1506	}
		1507	};
		1508
		1509	=item line => [$eol, ]$cb->($handle, $line, $eol)
		1510
		1511	The callback will be called only once a full line (including the end of
		1512	line marker, C<$eol>) has been read. This line (excluding the end of line
		1513	marker) will be passed to the callback as second argument (C<$line>), and
		1514	the end of line marker as the third argument (C<$eol>).
		1515
		1516	The end of line marker, C<$eol>, can be either a string, in which case it
		1517	will be interpreted as a fixed record end marker, or it can be a regex
		1518	object (e.g. created by C<qr>), in which case it is interpreted as a
		1519	regular expression.
		1520
		1521	The end of line marker argument C<$eol> is optional, if it is missing (NOT
		1522	undef), then C<qr|\015?\012|> is used (which is good for most internet
		1523	protocols).
		1524
		1525	Partial lines at the end of the stream will never be returned, as they are
		1526	not marked by the end of line marker.
		1527
		1528	=cut
		1529
		1530	register_read_type line => sub {
		1531	my ($self, $cb, $eol) = @_;
		1532
		1533	if (@_ < 3) {
		1534	# this is faster then the generic code below
		1535	sub {
		1536	(my $pos = index $_[0]{rbuf}, "\012") >= 0
		1537	or return;
		1538
		1539	(my $str = substr $_[0]{rbuf}, 0, $pos + 1, "") =~ s/(\015?\012)\Z// or die;
		1540	$cb->($_[0], $str, "$1");
		1541	1
		1542	}
		1543	} else {
		1544	$eol = quotemeta $eol unless ref $eol;
		1545	$eol = qr|^(.*?)($eol)|s;
		1546
		1547	sub {
		1548	$_[0]{rbuf} =~ s/$eol// or return;
		1549
		1550	$cb->($_[0], "$1", "$2");
		1551	1
		1552	}
		1553	}
		1554	};
		1555
		1556	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1557
		1558	Makes a regex match against the regex object C<$accept> and returns
		1559	everything up to and including the match.
		1560
		1561	Example: read a single line terminated by '\n'.
		1562
		1563	$handle->push_read (regex => qr<\n>, sub { ... });
		1564
		1565	If C<$reject> is given and not undef, then it determines when the data is
		1566	to be rejected: it is matched against the data when the C<$accept> regex
		1567	does not match and generates an C<EBADMSG> error when it matches. This is
		1568	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1569	receive buffer overflow).
		1570
		1571	Example: expect a single decimal number followed by whitespace, reject
		1572	anything else (not the use of an anchor).
		1573
		1574	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1575
		1576	If C<$skip> is given and not C<undef>, then it will be matched against
		1577	the receive buffer when neither C<$accept> nor C<$reject> match,
		1578	and everything preceding and including the match will be accepted
		1579	unconditionally. This is useful to skip large amounts of data that you
		1580	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1581	have to start matching from the beginning. This is purely an optimisation
		1582	and is usually worth it only when you expect more than a few kilobytes.
		1583
		1584	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1585	expect the header to be very large (it isn't in practice, but...), we use
		1586	a skip regex to skip initial portions. The skip regex is tricky in that
		1587	it only accepts something not ending in either \015 or \012, as these are
		1588	required for the accept regex.
		1589
		1590	$handle->push_read (regex =>
		1591	qr<\015\012\015\012>,
		1592	undef, # no reject
		1593	qr<^.*[^\015\012]>,
		1594	sub { ... });
		1595
		1596	=cut
		1597
		1598	register_read_type regex => sub {
		1599	my ($self, $cb, $accept, $reject, $skip) = @_;
		1600
		1601	my $data;
		1602	my $rbuf = \$self->{rbuf};
		1603
		1604	sub {
		1605	# accept
		1606	if ($$rbuf =~ $accept) {
		1607	$data .= substr $$rbuf, 0, $+[0], "";
		1608	$cb->($_[0], $data);
		1609	return 1;
		1610	}
		1611
		1612	# reject
		1613	if ($reject && $$rbuf =~ $reject) {
		1614	$_[0]->_error (Errno::EBADMSG);
		1615	}
		1616
		1617	# skip
		1618	if ($skip && $$rbuf =~ $skip) {
		1619	$data .= substr $$rbuf, 0, $+[0], "";
		1620	}
		1621
		1622	()
		1623	}
		1624	};
		1625
		1626	=item netstring => $cb->($handle, $string)
		1627
		1628	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1629
		1630	Throws an error with C<$!> set to EBADMSG on format violations.
		1631
		1632	=cut
		1633
		1634	register_read_type netstring => sub {
		1635	my ($self, $cb) = @_;
		1636
		1637	sub {
		1638	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1639	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1640	$_[0]->_error (Errno::EBADMSG);
		1641	}
157	return;	1642	return;
		1643	}
		1644
		1645	my $len = $1;
		1646
		1647	$_[0]->unshift_read (chunk => $len, sub {
		1648	my $string = $_[1];
		1649	$_[0]->unshift_read (chunk => 1, sub {
		1650	if ($_[1] eq ",") {
		1651	$cb->($_[0], $string);
		1652	} else {
		1653	$_[0]->_error (Errno::EBADMSG);
		1654	}
		1655	});
		1656	});
		1657
		1658	1
		1659	}
		1660	};
		1661
		1662	=item packstring => $format, $cb->($handle, $string)
		1663
		1664	An octet string prefixed with an encoded length. The encoding C<$format>
		1665	uses the same format as a Perl C<pack> format, but must specify a single
		1666	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1667	optional C<!>, C<< < >> or C<< > >> modifier).
		1668
		1669	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1670	EPP uses a prefix of C<N> (4 octtes).
		1671
		1672	Example: read a block of data prefixed by its length in BER-encoded
		1673	format (very efficient).
		1674
		1675	$handle->push_read (packstring => "w", sub {
		1676	my ($handle, $data) = @_;
		1677	});
		1678
		1679	=cut
		1680
		1681	register_read_type packstring => sub {
		1682	my ($self, $cb, $format) = @_;
		1683
		1684	sub {
		1685	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1686	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1687	or return;
		1688
		1689	$format = length pack $format, $len;
		1690
		1691	# bypass unshift if we already have the remaining chunk
		1692	if ($format + $len <= length $_[0]{rbuf}) {
		1693	my $data = substr $_[0]{rbuf}, $format, $len;
		1694	substr $_[0]{rbuf}, 0, $format + $len, "";
		1695	$cb->($_[0], $data);
		1696	} else {
		1697	# remove prefix
		1698	substr $_[0]{rbuf}, 0, $format, "";
		1699
		1700	# read remaining chunk
		1701	$_[0]->unshift_read (chunk => $len, $cb);
		1702	}
		1703
		1704	1
		1705	}
		1706	};
		1707
		1708	=item json => $cb->($handle, $hash_or_arrayref)
		1709
		1710	Reads a JSON object or array, decodes it and passes it to the
		1711	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1712
		1713	If a C<json> object was passed to the constructor, then that will be used
		1714	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1715
		1716	This read type uses the incremental parser available with JSON version
		1717	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1718	dependency on your own: this module will load the JSON module, but
		1719	AnyEvent does not depend on it itself.
		1720
		1721	Since JSON texts are fully self-delimiting, the C<json> read and write
		1722	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1723	the C<json> write type description, above, for an actual example.
		1724
		1725	=cut
		1726
		1727	register_read_type json => sub {
		1728	my ($self, $cb) = @_;
		1729
		1730	my $json = $self->{json} ||= json_coder;
		1731
		1732	my $data;
		1733
		1734	sub {
		1735	my $ref = eval { $json->incr_parse ($_[0]{rbuf}) };
		1736
		1737	if ($ref) {
		1738	$_[0]{rbuf} = $json->incr_text;
		1739	$json->incr_text = "";
		1740	$cb->($_[0], $ref);
		1741
		1742	1
		1743	} elsif ($@) {
		1744	# error case
		1745	$json->incr_skip;
		1746
		1747	$_[0]{rbuf} = $json->incr_text;
		1748	$json->incr_text = "";
		1749
		1750	$_[0]->_error (Errno::EBADMSG);
		1751
		1752	()
		1753	} else {
		1754	$_[0]{rbuf} = "";
		1755
		1756	()
		1757	}
		1758	}
		1759	};
		1760
		1761	=item cbor => $cb->($handle, $scalar)
		1762
		1763	Reads a CBOR value, decodes it and passes it to the callback. When a parse
		1764	error occurs, an C<EBADMSG> error will be raised.
		1765
		1766	If a L<CBOR::XS> object was passed to the constructor, then that will be
		1767	used for the final decode, otherwise it will create a CBOR coder without
		1768	enabling any options.
		1769
		1770	You have to provide a dependency to L<CBOR::XS> on your own: this module
		1771	will load the L<CBOR::XS> module, but AnyEvent does not depend on it
		1772	itself.
		1773
		1774	Since CBOR values are fully self-delimiting, the C<cbor> read and write
		1775	types are an ideal simple RPC protocol: just exchange CBOR datagrams. See
		1776	the C<cbor> write type description, above, for an actual example.
		1777
		1778	=cut
		1779
		1780	register_read_type cbor => sub {
		1781	my ($self, $cb) = @_;
		1782
		1783	my $cbor = $self->{cbor} ||= cbor_coder;
		1784
		1785	my $data;
		1786
		1787	sub {
		1788	my (@value) = eval { $cbor->incr_parse ($_[0]{rbuf}) };
		1789
		1790	if (@value) {
		1791	$cb->($_[0], @value);
		1792
		1793	1
		1794	} elsif ($@) {
		1795	# error case
		1796	$cbor->incr_reset;
		1797
		1798	$_[0]->_error (Errno::EBADMSG);
		1799
		1800	()
		1801	} else {
		1802	()
		1803	}
		1804	}
		1805	};
		1806
		1807	=item storable => $cb->($handle, $ref)
		1808
		1809	Deserialises a L<Storable> frozen representation as written by the
		1810	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1811	data).
		1812
		1813	Raises C<EBADMSG> error if the data could not be decoded.
		1814
		1815	=cut
		1816
		1817	register_read_type storable => sub {
		1818	my ($self, $cb) = @_;
		1819
		1820	require Storable unless $Storable::VERSION;
		1821
		1822	sub {
		1823	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1824	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1825	or return;
		1826
		1827	my $format = length pack "w", $len;
		1828
		1829	# bypass unshift if we already have the remaining chunk
		1830	if ($format + $len <= length $_[0]{rbuf}) {
		1831	my $data = substr $_[0]{rbuf}, $format, $len;
		1832	substr $_[0]{rbuf}, 0, $format + $len, "";
		1833
		1834	eval { $cb->($_[0], Storable::thaw ($data)); 1 }
		1835	or return $_[0]->_error (Errno::EBADMSG);
		1836	} else {
		1837	# remove prefix
		1838	substr $_[0]{rbuf}, 0, $format, "";
		1839
		1840	# read remaining chunk
		1841	$_[0]->unshift_read (chunk => $len, sub {
		1842	eval { $cb->($_[0], Storable::thaw ($_[1])); 1 }
		1843	or $_[0]->_error (Errno::EBADMSG);
		1844	});
		1845	}
		1846
		1847	1
		1848	}
		1849	};
		1850
		1851	=item tls_detect => $cb->($handle, $detect, $major, $minor)
		1852
		1853	Checks the input stream for a valid SSL or TLS handshake TLSPaintext
		1854	record without consuming anything. Only SSL version 3 or higher
		1855	is handled, up to the fictituous protocol 4.x (but both SSL3+ and
		1856	SSL2-compatible framing is supported).
		1857
		1858	If it detects that the input data is likely TLS, it calls the callback
		1859	with a true value for C<$detect> and the (on-wire) TLS version as second
		1860	and third argument (C<$major> is C<3>, and C<$minor> is 0..3 for SSL
		1861	3.0, TLS 1.0, 1.1 and 1.2, respectively). If it detects the input to
		1862	be definitely not TLS, it calls the callback with a false value for
		1863	C<$detect>.
		1864
		1865	The callback could use this information to decide whether or not to start
		1866	TLS negotiation.
		1867
		1868	In all cases the data read so far is passed to the following read
		1869	handlers.
		1870
		1871	Usually you want to use the C<tls_autostart> read type instead.
		1872
		1873	If you want to design a protocol that works in the presence of TLS
		1874	dtection, make sure that any non-TLS data doesn't start with the octet 22
		1875	(ASCII SYN, 16 hex) or 128-255 (i.e. highest bit set). The checks this
		1876	read type does are a bit more strict, but might losen in the future to
		1877	accomodate protocol changes.
		1878
		1879	This read type does not rely on L<AnyEvent::TLS> (and thus, not on
		1880	L<Net::SSLeay>).
		1881
		1882	=item tls_autostart => $tls[, $tls_ctx]
		1883
		1884	Tries to detect a valid SSL or TLS handshake. If one is detected, it tries
		1885	to start tls by calling C<starttls> with the given arguments.
		1886
		1887	In practise, C<$tls> must be C<accept>, or a Net::SSLeay context that has
		1888	been configured to accept, as servers do not normally send a handshake on
		1889	their own and ths cannot be detected in this way.
		1890
		1891	See C<tls_detect> above for more details.
		1892
		1893	Example: give the client a chance to start TLS before accepting a text
		1894	line.
		1895
		1896	$hdl->push_read (tls_detect => "accept");
		1897	$hdl->push_read (line => sub {
		1898	print "received ", ($_[0]{tls} ? "encrypted" : "cleartext"), " <$_[1]>\n";
		1899	});
		1900
		1901	=cut
		1902
		1903	register_read_type tls_detect => sub {
		1904	my ($self, $cb) = @_;
		1905
		1906	sub {
		1907	# this regex matches a full or partial tls record
		1908	if (
		1909	# ssl3+: type(22=handshake) major(=3) minor(any) length_hi
		1910	$self->{rbuf} =~ /^(?:\z| \x16 (\z| [\x03\x04] (?:\z| . (?:\z| [\x00-\x40] ))))/xs
		1911	# ssl2 comapatible: len_hi len_lo type(1) major minor dummy(forlength)
		1912	or $self->{rbuf} =~ /^(?:\z| [\x80-\xff] (?:\z| . (?:\z| \x01 (\z| [\x03\x04] (?:\z| . (?:\z| . ))))))/xs
		1913	) {
		1914	return if 3 != length $1; # partial match, can't decide yet
		1915
		1916	# full match, valid TLS record
		1917	my ($major, $minor) = unpack "CC", $1;
		1918	$cb->($self, "accept", $major + $minor * 0.1);
		1919	} else {
		1920	# mismatch == guaranteed not TLS
		1921	$cb->($self, undef);
		1922	}
		1923
		1924	1
		1925	}
		1926	};
		1927
		1928	register_read_type tls_autostart => sub {
		1929	my ($self, @tls) = @_;
		1930
		1931	$RH{tls_detect}($self, sub {
		1932	return unless $_[1];
		1933	$_[0]->starttls (@tls);
158	}	1934	})
159		1935	};
160	$self->{on_read_w} =	1936
161	AnyEvent->io (poll => 'r', fh => $self->{fh}, cb => sub {	1937	=back
162	#d# warn "READ:[$self->{read_size}] $self->{read_block_size} : ".length ($self->{rbuf})."\n";	1938
163	my $rbuf_len = length $self->{rbuf};	1939	=item custom read types - Package::anyevent_read_type $handle, $cb, @args
164	my $l;	1940
		1941	Instead of one of the predefined types, you can also specify the name
		1942	of a package. AnyEvent will try to load the package and then expects to
		1943	find a function named C<anyevent_read_type> inside. If it isn't found, it
		1944	progressively tries to load the parent package until it either finds the
		1945	function (good) or runs out of packages (bad).
		1946
		1947	Whenever this type is used, C<push_read> will invoke the function with the
		1948	handle object, the original callback and the remaining arguments.
		1949
		1950	The function is supposed to return a callback (usually a closure) that
		1951	works as a plain read callback (see C<< ->push_read ($cb) >>), so you can
		1952	mentally treat the function as a "configurable read type to read callback"
		1953	converter.
		1954
		1955	It should invoke the original callback when it is done reading (remember
		1956	to pass C<$handle> as first argument as all other callbacks do that,
		1957	although there is no strict requirement on this).
		1958
		1959	For examples, see the source of this module (F<perldoc -m
		1960	AnyEvent::Handle>, search for C<register_read_type>)).
		1961
		1962	=item $handle->stop_read
		1963
		1964	=item $handle->start_read
		1965
		1966	In rare cases you actually do not want to read anything from the
		1967	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
		1968	any queued callbacks will be executed then. To start reading again, call
		1969	C<start_read>.
		1970
		1971	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1972	you change the C<on_read> callback or push/unshift a read callback, and it
		1973	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1974	there are any read requests in the queue.
		1975
		1976	In older versions of this module (<= 5.3), these methods had no effect,
		1977	as TLS does not support half-duplex connections. In current versions they
		1978	work as expected, as this behaviour is required to avoid certain resource
		1979	attacks, where the program would be forced to read (and buffer) arbitrary
		1980	amounts of data before being able to send some data. The drawback is that
		1981	some readings of the the SSL/TLS specifications basically require this
		1982	attack to be working, as SSL/TLS implementations might stall sending data
		1983	during a rehandshake.
		1984
		1985	As a guideline, during the initial handshake, you should not stop reading,
		1986	and as a client, it might cause problems, depending on your application.
		1987
		1988	=cut
		1989
		1990	sub stop_read {
		1991	my ($self) = @_;
		1992
		1993	delete $self->{_rw};
		1994	}
		1995
		1996	sub start_read {
		1997	my ($self) = @_;
		1998
		1999	unless ($self->{_rw} || $self->{_eof} || !$self->{fh}) {
		2000	Scalar::Util::weaken $self;
		2001
		2002	$self->{_rw} = AE::io $self->{fh}, 0, sub {
		2003	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
		2004	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size}, length $$rbuf;
		2005
		2006	if ($len > 0) {
		2007	$self->{_activity} = $self->{_ractivity} = AE::now;
		2008
		2009	if ($self->{tls}) {
		2010	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
		2011
		2012	&_dotls ($self);
		2013	} else {
		2014	$self->_drain_rbuf;
		2015	}
		2016
165	if (defined $self->{read_size}) {	2017	if ($len == $self->{read_size}) {
166	$l = sysread $self->{fh}, $self->{rbuf},	2018	$self->{read_size} *= 2;
167	($self->{read_size} - $rbuf_len), $rbuf_len;	2019	$self->{read_size} = $self->{max_read_size} || MAX_READ_SIZE
		2020	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		2021	}
		2022
		2023	} elsif (defined $len) {
		2024	delete $self->{_rw};
		2025	$self->{_eof} = 1;
		2026	$self->_drain_rbuf;
		2027
		2028	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
		2029	return $self->_error ($!, 1);
		2030	}
		2031	};
		2032	}
		2033	}
		2034
		2035	our $ERROR_SYSCALL;
		2036	our $ERROR_WANT_READ;
		2037
		2038	sub _tls_error {
		2039	my ($self, $err) = @_;
		2040
		2041	return $self->_error ($!, 1)
		2042	if $err == Net::SSLeay::ERROR_SYSCALL ();
		2043
		2044	my $err = Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
		2045
		2046	# reduce error string to look less scary
		2047	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
		2048
		2049	if ($self->{_on_starttls}) {
		2050	(delete $self->{_on_starttls})->($self, undef, $err);
		2051	&_freetls;
		2052	} else {
		2053	&_freetls;
		2054	$self->_error (Errno::EPROTO, 1, $err);
		2055	}
		2056	}
		2057
		2058	# poll the write BIO and send the data if applicable
		2059	# also decode read data if possible
		2060	# this is basiclaly our TLS state machine
		2061	# more efficient implementations are possible with openssl,
		2062	# but not with the buggy and incomplete Net::SSLeay.
		2063	sub _dotls {
		2064	my ($self) = @_;
		2065
		2066	my $tmp;
		2067
		2068	if (length $self->{_tls_wbuf}) {
		2069	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		2070	substr $self->{_tls_wbuf}, 0, $tmp, "";
		2071	}
		2072
		2073	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		2074	return $self->_tls_error ($tmp)
		2075	if $tmp != $ERROR_WANT_READ
		2076	&& ($tmp != $ERROR_SYSCALL || $!);
		2077	}
		2078
		2079	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		2080	unless (length $tmp) {
		2081	$self->{_on_starttls}
		2082	and (delete $self->{_on_starttls})->($self, undef, "EOF during handshake"); # ???
		2083	&_freetls;
		2084
		2085	if ($self->{on_stoptls}) {
		2086	$self->{on_stoptls}($self);
		2087	return;
168	} else {	2088	} else {
169	$l = sysread $self->{fh}, $self->{rbuf}, $self->{read_block_size}, $rbuf_len;	2089	# 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};	2090	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 part of a regex, so it can be
262	a regex itself and won't be quoted!
263
264	The C<$callback> will be called when at least one
265	line could be read. The first argument to the C<$callback> will be the L<AnyEvent::Handle>
266	object itself and the rest of the arguments will be the read lines.
267
268	NOTE: This method will override any callbacks installed via the C<on_read> method.
269
270	=cut
271
272	sub readlines {
273	my ($self, $NL, $cb) = @_;
274
275	if (ref $NL) {
276	$cb = $NL;
277	$NL = "\n";
278	}
279
280	$self->{on_readline} = $cb;
281
282	$self->on_read (sub {
283	my @lines;
284	push @lines, $1 while $_[0]->{rbuf} =~ s/(.*)$NL//;
285	$self->{on_readline}->($_[0], @lines);
286	});
287	}
288
289	=item B<write ($data)>
290
291	=item B<write ($callback)>
292
293	=item B<write ($data, $callback)>
294
295	This method will write C<$data> to the filehandle and call the C<$callback>
296	afterwards. If only C<$callback> is provided it will be called when the
297	write buffer becomes empty the next time (or immediately if it already is empty).
298
299	=cut
300
301	sub write {
302	my ($self, $data, $cb) = @_;
303	if (ref $data) { $cb = $data; undef $data }
304	push @{$self->{write_bufs}}, [$data, $cb];
305	$self->_check_writer;
306	}
307
308	sub _check_writer {
309	my ($self) = @_;
310
311	if ($self->{write_w}) {
312	unless ($self->{write_cb}) {
313	while (@{$self->{write_bufs}} && not defined $self->{write_bufs}->[0]->[1]) {
314	my $wba = shift @{$self->{write_bufs}};
315	$self->{wbuf} .= $wba->[0];	2091	$self->{_eof} = 1;
316	}	2092	}
317	}	2093	}
318	return;
319	}
320		2094
321	my $wba = shift @{$self->{write_bufs}}	2095	$self->{_tls_rbuf} .= $tmp;
322	or return;	2096	$self->_drain_rbuf;
323		2097	$self->{tls} or return; # tls session might have gone away in callback
324	unless (defined $wba->[0]) {
325	$wba->[1]->($self) if $wba->[1];
326	$self->_check_writer;
327	return;
328	}	2098	}
329		2099
330	$self->{wbuf} = $wba->[0];	2100	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
331	$self->{write_cb} = $wba->[1];	2101	return $self->_tls_error ($tmp)
		2102	if $tmp != $ERROR_WANT_READ
		2103	&& ($tmp != $ERROR_SYSCALL || $!);
332		2104
333	$self->{write_w} =	2105	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
334	AnyEvent->io (poll => 'w', fh => $self->{fh}, cb => sub {	2106	$self->{wbuf} .= $tmp;
335	my $l = syswrite $self->{fh}, $self->{wbuf}, length $self->{wbuf};	2107	$self->_drain_wbuf;
		2108	$self->{tls} or return; # tls session might have gone away in callback
		2109	}
336		2110
337	if (not defined $l) {	2111	$self->{_on_starttls}
338	return if $! == EAGAIN || $! == EINTR;	2112	and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
339	delete $self->{write_w};	2113	and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
340	$self->{on_error}->($self) if $self->{on_error};	2114	}
341		2115
		2116	=item $handle->starttls ($tls[, $tls_ctx])
		2117
		2118	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		2119	object is created, you can also do that at a later time by calling
		2120	C<starttls>. See the C<tls> constructor argument for general info.
		2121
		2122	Starting TLS is currently an asynchronous operation - when you push some
		2123	write data and then call C<< ->starttls >> then TLS negotiation will start
		2124	immediately, after which the queued write data is then sent. This might
		2125	change in future versions, so best make sure you have no outstanding write
		2126	data when calling this method.
		2127
		2128	The first argument is the same as the C<tls> constructor argument (either
		2129	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		2130
		2131	The second argument is the optional C<AnyEvent::TLS> object that is used
		2132	when AnyEvent::Handle has to create its own TLS connection object, or
		2133	a hash reference with C<< key => value >> pairs that will be used to
		2134	construct a new context.
		2135
		2136	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		2137	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		2138	changed to your liking. Note that the handshake might have already started
		2139	when this function returns.
		2140
		2141	Due to bugs in OpenSSL, it might or might not be possible to do multiple
		2142	handshakes on the same stream. It is best to not attempt to use the
		2143	stream after stopping TLS.
		2144
		2145	This method may invoke callbacks (and therefore the handle might be
		2146	destroyed after it returns).
		2147
		2148	=cut
		2149
		2150	our %TLS_CACHE; #TODO not yet documented, should we?
		2151
		2152	sub starttls {
		2153	my ($self, $tls, $ctx) = @_;
		2154
		2155	Carp::croak "It is an error to call starttls on an AnyEvent::Handle object while TLS is already active, caught"
		2156	if $self->{tls};
		2157
		2158	unless (defined $AnyEvent::TLS::VERSION) {
		2159	eval {
		2160	require Net::SSLeay;
		2161	require AnyEvent::TLS;
		2162	1
		2163	} or return $self->_error (Errno::EPROTO, 1, "TLS support not available on this system");
		2164	}
		2165
		2166	$self->{tls} = $tls;
		2167	$self->{tls_ctx} = $ctx if @_ > 2;
		2168
		2169	return unless $self->{fh};
		2170
		2171	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		2172	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		2173
		2174	$tls = delete $self->{tls};
		2175	$ctx = $self->{tls_ctx};
		2176
		2177	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context or session
		2178
		2179	if ("HASH" eq ref $ctx) {
		2180	if ($ctx->{cache}) {
		2181	my $key = $ctx+0;
		2182	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
342	} else {	2183	} else {
		2184	$ctx = new AnyEvent::TLS %$ctx;
		2185	}
		2186	}
		2187
		2188	$self->{tls_ctx} = $ctx || TLS_CTX ();
		2189	$self->{tls} = $tls = $self->{tls_ctx}->_get_session ($tls, $self, $self->{peername});
		2190
		2191	# basically, this is deep magic (because SSL_read should have the same issues)
		2192	# but the openssl maintainers basically said: "trust us, it just works".
		2193	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		2194	# and mismaintained ssleay-module doesn't even offer them).
		2195	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		2196	#
		2197	# in short: this is a mess.
		2198	#
		2199	# note that we do not try to keep the length constant between writes as we are required to do.
		2200	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		2201	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		2202	# have identity issues in that area.
		2203	# Net::SSLeay::CTX_set_mode ($ssl,
		2204	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		2205	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		2206	Net::SSLeay::CTX_set_mode ($tls, 1|2);
		2207
		2208	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2209	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2210
		2211	Net::SSLeay::BIO_write ($self->{_rbio}, $self->{rbuf});
		2212	$self->{rbuf} = "";
		2213
		2214	Net::SSLeay::set_bio ($tls, $self->{_rbio}, $self->{_wbio});
		2215
		2216	$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
		2217	if $self->{on_starttls};
		2218
		2219	&_dotls; # need to trigger the initial handshake
		2220	$self->start_read; # make sure we actually do read
		2221	}
		2222
		2223	=item $handle->stoptls
		2224
		2225	Shuts down the SSL connection - this makes a proper EOF handshake by
		2226	sending a close notify to the other side, but since OpenSSL doesn't
		2227	support non-blocking shut downs, it is not guaranteed that you can re-use
		2228	the stream afterwards.
		2229
		2230	This method may invoke callbacks (and therefore the handle might be
		2231	destroyed after it returns).
		2232
		2233	=cut
		2234
		2235	sub stoptls {
		2236	my ($self) = @_;
		2237
		2238	if ($self->{tls} && $self->{fh}) {
		2239	Net::SSLeay::shutdown ($self->{tls});
		2240
		2241	&_dotls;
		2242
		2243	# # we don't give a shit. no, we do, but we can't. no...#d#
		2244	# # we, we... have to use openssl :/#d#
		2245	# &_freetls;#d#
		2246	}
		2247	}
		2248
		2249	sub _freetls {
		2250	my ($self) = @_;
		2251
		2252	return unless $self->{tls};
		2253
		2254	$self->{tls_ctx}->_put_session (delete $self->{tls})
		2255	if $self->{tls} > 0;
		2256
		2257	delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
		2258	}
		2259
		2260	=item $handle->resettls
		2261
		2262	This rarely-used method simply resets and TLS state on the handle, usually
		2263	causing data loss.
		2264
		2265	One case where it may be useful is when you want to skip over the data in
		2266	the stream but you are not interested in interpreting it, so data loss is
		2267	no concern.
		2268
		2269	=cut
		2270
		2271	*resettls = \&_freetls;
		2272
		2273	sub DESTROY {
		2274	my ($self) = @_;
		2275
		2276	&_freetls;
		2277
		2278	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		2279
		2280	if ($linger && length $self->{wbuf} && $self->{fh}) {
		2281	my $fh = delete $self->{fh};
		2282	my $wbuf = delete $self->{wbuf};
		2283
		2284	my @linger;
		2285
		2286	push @linger, AE::io $fh, 1, sub {
		2287	my $len = syswrite $fh, $wbuf, length $wbuf;
		2288
		2289	if ($len > 0) {
343	substr $self->{wbuf}, 0, $l, '';	2290	substr $wbuf, 0, $len, "";
344		2291	} elsif (defined $len || ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK)) {
345	if (length ($self->{wbuf}) == 0) {	2292	@linger = (); # end
346	$self->{write_cb}->($self) if $self->{write_cb};
347
348	delete $self->{write_w};
349	delete $self->{wbuf};
350	delete $self->{write_cb};
351
352	$self->_check_writer;
353	}
354	}	2293	}
		2294	};
		2295	push @linger, AE::timer $linger, 0, sub {
		2296	@linger = ();
		2297	};
		2298	}
		2299	}
		2300
		2301	=item $handle->destroy
		2302
		2303	Shuts down the handle object as much as possible - this call ensures that
		2304	no further callbacks will be invoked and as many resources as possible
		2305	will be freed. Any method you will call on the handle object after
		2306	destroying it in this way will be silently ignored (and it will return the
		2307	empty list).
		2308
		2309	Normally, you can just "forget" any references to an AnyEvent::Handle
		2310	object and it will simply shut down. This works in fatal error and EOF
		2311	callbacks, as well as code outside. It does I<NOT> work in a read or write
		2312	callback, so when you want to destroy the AnyEvent::Handle object from
		2313	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		2314	that case.
		2315
		2316	Destroying the handle object in this way has the advantage that callbacks
		2317	will be removed as well, so if those are the only reference holders (as
		2318	is common), then one doesn't need to do anything special to break any
		2319	reference cycles.
		2320
		2321	The handle might still linger in the background and write out remaining
		2322	data, as specified by the C<linger> option, however.
		2323
		2324	=cut
		2325
		2326	sub destroy {
		2327	my ($self) = @_;
		2328
		2329	$self->DESTROY;
		2330	%$self = ();
		2331	bless $self, "AnyEvent::Handle::destroyed";
		2332	}
		2333
		2334	sub AnyEvent::Handle::destroyed::AUTOLOAD {
		2335	#nop
		2336	}
		2337
		2338	=item $handle->destroyed
		2339
		2340	Returns false as long as the handle hasn't been destroyed by a call to C<<
		2341	->destroy >>, true otherwise.
		2342
		2343	Can be useful to decide whether the handle is still valid after some
		2344	callback possibly destroyed the handle. For example, C<< ->push_write >>,
		2345	C<< ->starttls >> and other methods can call user callbacks, which in turn
		2346	can destroy the handle, so work can be avoided by checking sometimes:
		2347
		2348	$hdl->starttls ("accept");
		2349	return if $hdl->destroyed;
		2350	$hdl->push_write (...
		2351
		2352	Note that the call to C<push_write> will silently be ignored if the handle
		2353	has been destroyed, so often you can just ignore the possibility of the
		2354	handle being destroyed.
		2355
		2356	=cut
		2357
		2358	sub destroyed { 0 }
		2359	sub AnyEvent::Handle::destroyed::destroyed { 1 }
		2360
		2361	=item AnyEvent::Handle::TLS_CTX
		2362
		2363	This function creates and returns the AnyEvent::TLS object used by default
		2364	for TLS mode.
		2365
		2366	The context is created by calling L<AnyEvent::TLS> without any arguments.
		2367
		2368	=cut
		2369
		2370	our $TLS_CTX;
		2371
		2372	sub TLS_CTX() {
		2373	$TLS_CTX ||= do {
		2374	require AnyEvent::TLS;
		2375
		2376	new AnyEvent::TLS
		2377	}
		2378	}
		2379
		2380	=back
		2381
		2382
		2383	=head1 NONFREQUENTLY ASKED QUESTIONS
		2384
		2385	=over 4
		2386
		2387	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		2388	still get further invocations!
		2389
		2390	That's because AnyEvent::Handle keeps a reference to itself when handling
		2391	read or write callbacks.
		2392
		2393	It is only safe to "forget" the reference inside EOF or error callbacks,
		2394	from within all other callbacks, you need to explicitly call the C<<
		2395	->destroy >> method.
		2396
		2397	=item Why is my C<on_eof> callback never called?
		2398
		2399	Probably because your C<on_error> callback is being called instead: When
		2400	you have outstanding requests in your read queue, then an EOF is
		2401	considered an error as you clearly expected some data.
		2402
		2403	To avoid this, make sure you have an empty read queue whenever your handle
		2404	is supposed to be "idle" (i.e. connection closes are O.K.). You can set
		2405	an C<on_read> handler that simply pushes the first read requests in the
		2406	queue.
		2407
		2408	See also the next question, which explains this in a bit more detail.
		2409
		2410	=item How can I serve requests in a loop?
		2411
		2412	Most protocols consist of some setup phase (authentication for example)
		2413	followed by a request handling phase, where the server waits for requests
		2414	and handles them, in a loop.
		2415
		2416	There are two important variants: The first (traditional, better) variant
		2417	handles requests until the server gets some QUIT command, causing it to
		2418	close the connection first (highly desirable for a busy TCP server). A
		2419	client dropping the connection is an error, which means this variant can
		2420	detect an unexpected detection close.
		2421
		2422	To handle this case, always make sure you have a non-empty read queue, by
		2423	pushing the "read request start" handler on it:
		2424
		2425	# we assume a request starts with a single line
		2426	my @start_request; @start_request = (line => sub {
		2427	my ($hdl, $line) = @_;
		2428
		2429	... handle request
		2430
		2431	# push next request read, possibly from a nested callback
		2432	$hdl->push_read (@start_request);
		2433	});
		2434
		2435	# auth done, now go into request handling loop
		2436	# now push the first @start_request
		2437	$hdl->push_read (@start_request);
		2438
		2439	By always having an outstanding C<push_read>, the handle always expects
		2440	some data and raises the C<EPIPE> error when the connction is dropped
		2441	unexpectedly.
		2442
		2443	The second variant is a protocol where the client can drop the connection
		2444	at any time. For TCP, this means that the server machine may run out of
		2445	sockets easier, and in general, it means you cannot distinguish a protocl
		2446	failure/client crash from a normal connection close. Nevertheless, these
		2447	kinds of protocols are common (and sometimes even the best solution to the
		2448	problem).
		2449
		2450	Having an outstanding read request at all times is possible if you ignore
		2451	C<EPIPE> errors, but this doesn't help with when the client drops the
		2452	connection during a request, which would still be an error.
		2453
		2454	A better solution is to push the initial request read in an C<on_read>
		2455	callback. This avoids an error, as when the server doesn't expect data
		2456	(i.e. is idly waiting for the next request, an EOF will not raise an
		2457	error, but simply result in an C<on_eof> callback. It is also a bit slower
		2458	and simpler:
		2459
		2460	# auth done, now go into request handling loop
		2461	$hdl->on_read (sub {
		2462	my ($hdl) = @_;
		2463
		2464	# called each time we receive data but the read queue is empty
		2465	# simply start read the request
		2466
		2467	$hdl->push_read (line => sub {
		2468	my ($hdl, $line) = @_;
		2469
		2470	... handle request
		2471
		2472	# do nothing special when the request has been handled, just
		2473	# let the request queue go empty.
355	});	2474	});
356	}	2475	});
		2476
		2477	=item I get different callback invocations in TLS mode/Why can't I pause
		2478	reading?
		2479
		2480	Unlike, say, TCP, TLS connections do not consist of two independent
		2481	communication channels, one for each direction. Or put differently, the
		2482	read and write directions are not independent of each other: you cannot
		2483	write data unless you are also prepared to read, and vice versa.
		2484
		2485	This means that, in TLS mode, you might get C<on_error> or C<on_eof>
		2486	callback invocations when you are not expecting any read data - the reason
		2487	is that AnyEvent::Handle always reads in TLS mode.
		2488
		2489	During the connection, you have to make sure that you always have a
		2490	non-empty read-queue, or an C<on_read> watcher. At the end of the
		2491	connection (or when you no longer want to use it) you can call the
		2492	C<destroy> method.
		2493
		2494	=item How do I read data until the other side closes the connection?
		2495
		2496	If you just want to read your data into a perl scalar, the easiest way
		2497	to achieve this is by setting an C<on_read> callback that does nothing,
		2498	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		2499	will be in C<$_[0]{rbuf}>:
		2500
		2501	$handle->on_read (sub { });
		2502	$handle->on_eof (undef);
		2503	$handle->on_error (sub {
		2504	my $data = delete $_[0]{rbuf};
		2505	});
		2506
		2507	Note that this example removes the C<rbuf> member from the handle object,
		2508	which is not normally allowed by the API. It is expressly permitted in
		2509	this case only, as the handle object needs to be destroyed afterwards.
		2510
		2511	The reason to use C<on_error> is that TCP connections, due to latencies
		2512	and packets loss, might get closed quite violently with an error, when in
		2513	fact all data has been received.
		2514
		2515	It is usually better to use acknowledgements when transferring data,
		2516	to make sure the other side hasn't just died and you got the data
		2517	intact. This is also one reason why so many internet protocols have an
		2518	explicit QUIT command.
		2519
		2520	=item I don't want to destroy the handle too early - how do I wait until
		2521	all data has been written?
		2522
		2523	After writing your last bits of data, set the C<on_drain> callback
		2524	and destroy the handle in there - with the default setting of
		2525	C<low_water_mark> this will be called precisely when all data has been
		2526	written to the socket:
		2527
		2528	$handle->push_write (...);
		2529	$handle->on_drain (sub {
		2530	AE::log debug => "All data submitted to the kernel.";
		2531	undef $handle;
		2532	});
		2533
		2534	If you just want to queue some data and then signal EOF to the other side,
		2535	consider using C<< ->push_shutdown >> instead.
		2536
		2537	=item I want to contact a TLS/SSL server, I don't care about security.
		2538
		2539	If your TLS server is a pure TLS server (e.g. HTTPS) that only speaks TLS,
		2540	connect to it and then create the AnyEvent::Handle with the C<tls>
		2541	parameter:
		2542
		2543	tcp_connect $host, $port, sub {
		2544	my ($fh) = @_;
		2545
		2546	my $handle = new AnyEvent::Handle
		2547	fh => $fh,
		2548	tls => "connect",
		2549	on_error => sub { ... };
		2550
		2551	$handle->push_write (...);
		2552	};
		2553
		2554	=item I want to contact a TLS/SSL server, I do care about security.
		2555
		2556	Then you should additionally enable certificate verification, including
		2557	peername verification, if the protocol you use supports it (see
		2558	L<AnyEvent::TLS>, C<verify_peername>).
		2559
		2560	E.g. for HTTPS:
		2561
		2562	tcp_connect $host, $port, sub {
		2563	my ($fh) = @_;
		2564
		2565	my $handle = new AnyEvent::Handle
		2566	fh => $fh,
		2567	peername => $host,
		2568	tls => "connect",
		2569	tls_ctx => { verify => 1, verify_peername => "https" },
		2570	...
		2571
		2572	Note that you must specify the hostname you connected to (or whatever
		2573	"peername" the protocol needs) as the C<peername> argument, otherwise no
		2574	peername verification will be done.
		2575
		2576	The above will use the system-dependent default set of trusted CA
		2577	certificates. If you want to check against a specific CA, add the
		2578	C<ca_file> (or C<ca_cert>) arguments to C<tls_ctx>:
		2579
		2580	tls_ctx => {
		2581	verify => 1,
		2582	verify_peername => "https",
		2583	ca_file => "my-ca-cert.pem",
		2584	},
		2585
		2586	=item I want to create a TLS/SSL server, how do I do that?
		2587
		2588	Well, you first need to get a server certificate and key. You have
		2589	three options: a) ask a CA (buy one, use cacert.org etc.) b) create a
		2590	self-signed certificate (cheap. check the search engine of your choice,
		2591	there are many tutorials on the net) or c) make your own CA (tinyca2 is a
		2592	nice program for that purpose).
		2593
		2594	Then create a file with your private key (in PEM format, see
		2595	L<AnyEvent::TLS>), followed by the certificate (also in PEM format). The
		2596	file should then look like this:
		2597
		2598	-----BEGIN RSA PRIVATE KEY-----
		2599	...header data
		2600	... lots of base64'y-stuff
		2601	-----END RSA PRIVATE KEY-----
		2602
		2603	-----BEGIN CERTIFICATE-----
		2604	... lots of base64'y-stuff
		2605	-----END CERTIFICATE-----
		2606
		2607	The important bits are the "PRIVATE KEY" and "CERTIFICATE" parts. Then
		2608	specify this file as C<cert_file>:
		2609
		2610	tcp_server undef, $port, sub {
		2611	my ($fh) = @_;
		2612
		2613	my $handle = new AnyEvent::Handle
		2614	fh => $fh,
		2615	tls => "accept",
		2616	tls_ctx => { cert_file => "my-server-keycert.pem" },
		2617	...
		2618
		2619	When you have intermediate CA certificates that your clients might not
		2620	know about, just append them to the C<cert_file>.
357		2621
358	=back	2622	=back
359		2623
		2624	=head1 SUBCLASSING AnyEvent::Handle
		2625
		2626	In many cases, you might want to subclass AnyEvent::Handle.
		2627
		2628	To make this easier, a given version of AnyEvent::Handle uses these
		2629	conventions:
		2630
		2631	=over 4
		2632
		2633	=item * all constructor arguments become object members.
		2634
		2635	At least initially, when you pass a C<tls>-argument to the constructor it
		2636	will end up in C<< $handle->{tls} >>. Those members might be changed or
		2637	mutated later on (for example C<tls> will hold the TLS connection object).
		2638
		2639	=item * other object member names are prefixed with an C<_>.
		2640
		2641	All object members not explicitly documented (internal use) are prefixed
		2642	with an underscore character, so the remaining non-C<_>-namespace is free
		2643	for use for subclasses.
		2644
		2645	=item * all members not documented here and not prefixed with an underscore
		2646	are free to use in subclasses.
		2647
		2648	Of course, new versions of AnyEvent::Handle may introduce more "public"
		2649	member variables, but that's just life. At least it is documented.
		2650
		2651	=back
		2652
360	=head1 AUTHOR	2653	=head1 AUTHOR
361		2654
362	Robin Redeker, C<< <elmex at ta-sa.org> >>	2655	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
363		2656
364	=cut	2657	=cut
365		2658
366	1; # End of AnyEvent::Handle	2659	1
		2660

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