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Revision 1.218 by root, Thu Feb 24 12:04:20 2011 UTC

1	package AnyEvent::Handle;
2
3	no warnings;
4	use strict;
5
6	use AnyEvent ();
7	use AnyEvent::Util ();
8	use Scalar::Util ();
9	use Carp ();
10	use Fcntl ();
11	use Errno qw/EAGAIN EINTR/;
12
13	=head1 NAME	1	=head1 NAME
14		2
15	AnyEvent::Handle - non-blocking I/O on filehandles via AnyEvent	3	AnyEvent::Handle - non-blocking I/O on streaming handles via AnyEvent
16
17	This module is experimental.
18
19	=cut
20
21	our $VERSION = '0.04';
22		4
23	=head1 SYNOPSIS	5	=head1 SYNOPSIS
24		6
25	use AnyEvent;	7	use AnyEvent;
26	use AnyEvent::Handle;	8	use AnyEvent::Handle;
27		9
28	my $cv = AnyEvent->condvar;	10	my $cv = AnyEvent->condvar;
29		11
30	my $ae_fh = AnyEvent::Handle->new (fh => \*STDIN);	12	my $hdl; $hdl = new AnyEvent::Handle
31
32	#TODO
33
34	# or use the constructor to pass the callback:
35
36	my $ae_fh2 =
37	AnyEvent::Handle->new (
38	fh => \*STDIN,	13	fh => \*STDIN,
39	on_eof => sub {	14	on_error => sub {
40	$cv->broadcast;	15	my ($hdl, $fatal, $msg) = @_;
41	},	16	warn "got error $msg\n";
42	#TODO	17	$hdl->destroy;
		18	$cv->send;
43	);	19	};
44		20
45	$cv->wait;	21	# send some request line
		22	$hdl->push_write ("getinfo\015\012");
		23
		24	# read the response line
		25	$hdl->push_read (line => sub {
		26	my ($hdl, $line) = @_;
		27	warn "got line <$line>\n";
		28	$cv->send;
		29	});
		30
		31	$cv->recv;
46		32
47	=head1 DESCRIPTION	33	=head1 DESCRIPTION
48		34
49	This module is a helper module to make it easier to do event-based I/O on	35	This is a helper module to make it easier to do event-based I/O on
50	filehandles. For utility functions for doing non-blocking connects and accepts	36	stream-based filehandles (sockets, pipes, and other stream things).
51	on sockets see L<AnyEvent::Util>.
52		37
		38	The L<AnyEvent::Intro> tutorial contains some well-documented
		39	AnyEvent::Handle examples.
		40
53	In the following, when the documentation refers to of "bytes" then this	41	In the following, where the documentation refers to "bytes", it means
54	means characters. As sysread and syswrite are used for all I/O, their	42	characters. As sysread and syswrite are used for all I/O, their
55	treatment of characters applies to this module as well.	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.
56		47
57	All callbacks will be invoked with the handle object as their first	48	All callbacks will be invoked with the handle object as their first
58	argument.	49	argument.
59		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
60	=head1 METHODS	82	=head1 METHODS
61		83
62	=over 4	84	=over 4
63		85
64	=item B<new (%args)>	86	=item $handle = B<new> AnyEvent::Handle fh => $filehandle, key => value...
65		87
66	The constructor supports these arguments (all as key => value pairs).	88	The constructor supports these arguments (all as C<< key => value >> pairs).
67		89
68	=over 4	90	=over 4
69		91
70	=item fh => $filehandle [MANDATORY]	92	=item fh => $filehandle [C<fh> or C<connect> MANDATORY]
71		93
72	The filehandle this L<AnyEvent::Handle> object will operate on.	94	The filehandle this L<AnyEvent::Handle> object will operate on.
73
74	NOTE: The filehandle will be set to non-blocking (using	95	NOTE: The filehandle will be set to non-blocking mode (using
75	AnyEvent::Util::fh_nonblocking).	96	C<AnyEvent::Util::fh_nonblocking>) by the constructor and needs to stay in
		97	that mode.
76		98
77	=item on_eof => $cb->($self)	99	=item connect => [$host, $service] [C<fh> or C<connect> MANDATORY]
78		100
79	Set the callback to be called on EOF.	101	Try to connect to the specified host and service (port), using
		102	C<AnyEvent::Socket::tcp_connect>. The C<$host> additionally becomes the
		103	default C<peername>.
80		104
81	While not mandatory, it is highly recommended to set an eof callback,	105	You have to specify either this parameter, or C<fh>, above.
82	otherwise you might end up with a closed socket while you are still
83	waiting for data.
84		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
85	=item on_error => $cb->($self)	116	=item on_prepare => $cb->($handle)
86		117
		118	This (rarely used) callback is called before a new connection is
		119	attempted, but after the file handle has been created (you can access that
		120	file handle via C<< $handle->{fh} >>). It could be used to prepare the
		121	file handle with parameters required for the actual connect (as opposed to
		122	settings that can be changed when the connection is already established).
		123
		124	The return value of this callback should be the connect timeout value in
		125	seconds (or C<0>, or C<undef>, or the empty list, to indicate that the
		126	default timeout is to be used).
		127
		128	=item on_connect => $cb->($handle, $host, $port, $retry->())
		129
		130	This callback is called when a connection has been successfully established.
		131
		132	The peer's numeric host and port (the socket peername) are passed as
		133	parameters, together with a retry callback.
		134
		135	If, for some reason, the handle is not acceptable, calling C<$retry>
		136	will continue with the next connection target (in case of multi-homed
		137	hosts or SRV records there can be multiple connection endpoints). At the
		138	time it is called the read and write queues, eof status, tls status and
		139	similar properties of the handle will have been reset.
		140
		141	In most cases, you should ignore the C<$retry> parameter.
		142
		143	=item on_connect_error => $cb->($handle, $message)
		144
		145	This callback is called when the connection could not be
		146	established. C<$!> will contain the relevant error code, and C<$message> a
		147	message describing it (usually the same as C<"$!">).
		148
		149	If this callback isn't specified, then C<on_error> will be called with a
		150	fatal error instead.
		151
		152	=back
		153
		154	=item on_error => $cb->($handle, $fatal, $message)
		155
87	This is the fatal error callback, that is called when, well, a fatal error	156	This is the error callback, which is called when, well, some error
88	ocurs, such as not being able to resolve the hostname, failure to connect	157	occured, such as not being able to resolve the hostname, failure to
89	or a read error.	158	connect, or a read error.
90		159
91	The object will not be in a usable state when this callback has been	160	Some errors are fatal (which is indicated by C<$fatal> being true). On
92	called.	161	fatal errors the handle object will be destroyed (by a call to C<< ->
		162	destroy >>) after invoking the error callback (which means you are free to
		163	examine the handle object). Examples of fatal errors are an EOF condition
		164	with active (but unsatisfiable) read watchers (C<EPIPE>) or I/O errors. In
		165	cases where the other side can close the connection at will, it is
		166	often easiest to not report C<EPIPE> errors in this callback.
93		167
		168	AnyEvent::Handle tries to find an appropriate error code for you to check
		169	against, but in some cases (TLS errors), this does not work well. It is
		170	recommended to always output the C<$message> argument in human-readable
		171	error messages (it's usually the same as C<"$!">).
		172
		173	Non-fatal errors can be retried by returning, but it is recommended
		174	to simply ignore this parameter and instead abondon the handle object
		175	when this callback is invoked. Examples of non-fatal errors are timeouts
		176	C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
		177
94	On callback entrance, the value of C<$!> contains the operating system	178	On entry to the callback, the value of C<$!> contains the operating
95	error (or C<ENOSPC> or C<EPIPE>).	179	system error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
		180	C<EPROTO>).
96		181
97	While not mandatory, it is I<highly> recommended to set this callback, as	182	While not mandatory, it is I<highly> recommended to set this callback, as
98	you will not be notified of errors otherwise. The default simply calls	183	you will not be notified of errors otherwise. The default just calls
99	die.	184	C<croak>.
100		185
101	=item on_read => $cb->($self)	186	=item on_read => $cb->($handle)
102		187
103	This sets the default read callback, which is called when data arrives	188	This sets the default read callback, which is called when data arrives
104	and no read request is in the queue.	189	and no read request is in the queue (unlike read queue callbacks, this
		190	callback will only be called when at least one octet of data is in the
		191	read buffer).
105		192
106	To access (and remove data from) the read buffer, use the C<< ->rbuf >>	193	To access (and remove data from) the read buffer, use the C<< ->rbuf >>
107	method or acces sthe C<$self->{rbuf}> member directly.	194	method or access the C<< $handle->{rbuf} >> member directly. Note that you
		195	must not enlarge or modify the read buffer, you can only remove data at
		196	the beginning from it.
108		197
		198	You can also call C<< ->push_read (...) >> or any other function that
		199	modifies the read queue. Or do both. Or ...
		200
109	When an EOF condition is detected then AnyEvent::Handle will first try to	201	When an EOF condition is detected, AnyEvent::Handle will first try to
110	feed all the remaining data to the queued callbacks and C<on_read> before	202	feed all the remaining data to the queued callbacks and C<on_read> before
111	calling the C<on_eof> callback. If no progress can be made, then a fatal	203	calling the C<on_eof> callback. If no progress can be made, then a fatal
112	error will be raised (with C<$!> set to C<EPIPE>).	204	error will be raised (with C<$!> set to C<EPIPE>).
113		205
		206	Note that, unlike requests in the read queue, an C<on_read> callback
		207	doesn't mean you I<require> some data: if there is an EOF and there
		208	are outstanding read requests then an error will be flagged. With an
		209	C<on_read> callback, the C<on_eof> callback will be invoked.
		210
		211	=item on_eof => $cb->($handle)
		212
		213	Set the callback to be called when an end-of-file condition is detected,
		214	i.e. in the case of a socket, when the other side has closed the
		215	connection cleanly, and there are no outstanding read requests in the
		216	queue (if there are read requests, then an EOF counts as an unexpected
		217	connection close and will be flagged as an error).
		218
		219	For sockets, this just means that the other side has stopped sending data,
		220	you can still try to write data, and, in fact, one can return from the EOF
		221	callback and continue writing data, as only the read part has been shut
		222	down.
		223
		224	If an EOF condition has been detected but no C<on_eof> callback has been
		225	set, then a fatal error will be raised with C<$!> set to <0>.
		226
114	=item on_drain => $cb->()	227	=item on_drain => $cb->($handle)
115		228
116	This sets the callback that is called when the write buffer becomes empty	229	This sets the callback that is called when the write buffer becomes empty
117	(or when the callback is set and the buffer is empty already).	230	(or immediately if the buffer is empty already).
118		231
119	To append to the write buffer, use the C<< ->push_write >> method.	232	To append to the write buffer, use the C<< ->push_write >> method.
		233
		234	This callback is useful when you don't want to put all of your write data
		235	into the queue at once, for example, when you want to write the contents
		236	of some file to the socket you might not want to read the whole file into
		237	memory and push it into the queue, but instead only read more data from
		238	the file when the write queue becomes empty.
		239
		240	=item timeout => $fractional_seconds
		241
		242	=item rtimeout => $fractional_seconds
		243
		244	=item wtimeout => $fractional_seconds
		245
		246	If non-zero, then these enables an "inactivity" timeout: whenever this
		247	many seconds pass without a successful read or write on the underlying
		248	file handle (or a call to C<timeout_reset>), the C<on_timeout> callback
		249	will be invoked (and if that one is missing, a non-fatal C<ETIMEDOUT>
		250	error will be raised).
		251
		252	There are three variants of the timeouts that work independently of each
		253	other, for both read and write (triggered when nothing was read I<OR>
		254	written), just read (triggered when nothing was read), and just write:
		255	C<timeout>, C<rtimeout> and C<wtimeout>, with corresponding callbacks
		256	C<on_timeout>, C<on_rtimeout> and C<on_wtimeout>, and reset functions
		257	C<timeout_reset>, C<rtimeout_reset>, and C<wtimeout_reset>.
		258
		259	Note that timeout processing is active even when you do not have any
		260	outstanding read or write requests: If you plan to keep the connection
		261	idle then you should disable the timeout temporarily or ignore the
		262	timeout in the corresponding C<on_timeout> callback, in which case
		263	AnyEvent::Handle will simply restart the timeout.
		264
		265	Zero (the default) disables the corresponding timeout.
		266
		267	=item on_timeout => $cb->($handle)
		268
		269	=item on_rtimeout => $cb->($handle)
		270
		271	=item on_wtimeout => $cb->($handle)
		272
		273	Called whenever the inactivity timeout passes. If you return from this
		274	callback, then the timeout will be reset as if some activity had happened,
		275	so this condition is not fatal in any way.
120		276
121	=item rbuf_max => <bytes>	277	=item rbuf_max => <bytes>
122		278
123	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)	279	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
124	when the read buffer ever (strictly) exceeds this size. This is useful to	280	when the read buffer ever (strictly) exceeds this size. This is useful to
125	avoid denial-of-service attacks.	281	avoid some forms of denial-of-service attacks.
126		282
127	For example, a server accepting connections from untrusted sources should	283	For example, a server accepting connections from untrusted sources should
128	be configured to accept only so-and-so much data that it cannot act on	284	be configured to accept only so-and-so much data that it cannot act on
129	(for example, when expecting a line, an attacker could send an unlimited	285	(for example, when expecting a line, an attacker could send an unlimited
130	amount of data without a callback ever being called as long as the line	286	amount of data without a callback ever being called as long as the line
131	isn't finished).	287	isn't finished).
132		288
		289	=item wbuf_max => <bytes>
		290
		291	If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
		292	when the write buffer ever (strictly) exceeds this size. This is useful to
		293	avoid some forms of denial-of-service attacks.
		294
		295	Although the units of this parameter is bytes, this is the I<raw> number
		296	of bytes not yet accepted by the kernel. This can make a difference when
		297	you e.g. use TLS, as TLS typically makes your write data larger (but it
		298	can also make it smaller due to compression).
		299
		300	As an example of when this limit is useful, take a chat server that sends
		301	chat messages to a client. If the client does not read those in a timely
		302	manner then the send buffer in the server would grow unbounded.
		303
		304	=item autocork => <boolean>
		305
		306	When disabled (the default), C<push_write> will try to immediately
		307	write the data to the handle if possible. This avoids having to register
		308	a write watcher and wait for the next event loop iteration, but can
		309	be inefficient if you write multiple small chunks (on the wire, this
		310	disadvantage is usually avoided by your kernel's nagle algorithm, see
		311	C<no_delay>, but this option can save costly syscalls).
		312
		313	When enabled, writes will always be queued till the next event loop
		314	iteration. This is efficient when you do many small writes per iteration,
		315	but less efficient when you do a single write only per iteration (or when
		316	the write buffer often is full). It also increases write latency.
		317
		318	=item no_delay => <boolean>
		319
		320	When doing small writes on sockets, your operating system kernel might
		321	wait a bit for more data before actually sending it out. This is called
		322	the Nagle algorithm, and usually it is beneficial.
		323
		324	In some situations you want as low a delay as possible, which can be
		325	accomplishd by setting this option to a true value.
		326
		327	The default is your operating system's default behaviour (most likely
		328	enabled). This option explicitly enables or disables it, if possible.
		329
		330	=item keepalive => <boolean>
		331
		332	Enables (default disable) the SO_KEEPALIVE option on the stream socket:
		333	normally, TCP connections have no time-out once established, so TCP
		334	connections, once established, can stay alive forever even when the other
		335	side has long gone. TCP keepalives are a cheap way to take down long-lived
		336	TCP connections when the other side becomes unreachable. While the default
		337	is OS-dependent, TCP keepalives usually kick in after around two hours,
		338	and, if the other side doesn't reply, take down the TCP connection some 10
		339	to 15 minutes later.
		340
		341	It is harmless to specify this option for file handles that do not support
		342	keepalives, and enabling it on connections that are potentially long-lived
		343	is usually a good idea.
		344
		345	=item oobinline => <boolean>
		346
		347	BSD majorly fucked up the implementation of TCP urgent data. The result
		348	is that almost no OS implements TCP according to the specs, and every OS
		349	implements it slightly differently.
		350
		351	If you want to handle TCP urgent data, then setting this flag (the default
		352	is enabled) gives you the most portable way of getting urgent data, by
		353	putting it into the stream.
		354
		355	Since BSD emulation of OOB data on top of TCP's urgent data can have
		356	security implications, AnyEvent::Handle sets this flag automatically
		357	unless explicitly specified. Note that setting this flag after
		358	establishing a connection I<may> be a bit too late (data loss could
		359	already have occured on BSD systems), but at least it will protect you
		360	from most attacks.
		361
133	=item read_size => <bytes>	362	=item read_size => <bytes>
134		363
135	The default read block size (the amount of bytes this module will try to read	364	The initial read block size, the number of bytes this module will try to
136	on each [loop iteration). Default: C<4096>.	365	read during each loop iteration. Each handle object will consume at least
		366	this amount of memory for the read buffer as well, so when handling many
		367	connections requirements). See also C<max_read_size>. Default: C<2048>.
		368
		369	=item max_read_size => <bytes>
		370
		371	The maximum read buffer size used by the dynamic adjustment
		372	algorithm: Each time AnyEvent::Handle can read C<read_size> bytes in
		373	one go it will double C<read_size> up to the maximum given by this
		374	option. Default: C<131072> or C<read_size>, whichever is higher.
137		375
138	=item low_water_mark => <bytes>	376	=item low_water_mark => <bytes>
139		377
140	Sets the amount of bytes (default: C<0>) that make up an "empty" write	378	Sets the number of bytes (default: C<0>) that make up an "empty" write
141	buffer: If the write reaches this size or gets even samller it is	379	buffer: If the buffer reaches this size or gets even samller it is
142	considered empty.	380	considered empty.
		381
		382	Sometimes it can be beneficial (for performance reasons) to add data to
		383	the write buffer before it is fully drained, but this is a rare case, as
		384	the operating system kernel usually buffers data as well, so the default
		385	is good in almost all cases.
		386
		387	=item linger => <seconds>
		388
		389	If this is non-zero (default: C<3600>), the destructor of the
		390	AnyEvent::Handle object will check whether there is still outstanding
		391	write data and will install a watcher that will write this data to the
		392	socket. No errors will be reported (this mostly matches how the operating
		393	system treats outstanding data at socket close time).
		394
		395	This will not work for partial TLS data that could not be encoded
		396	yet. This data will be lost. Calling the C<stoptls> method in time might
		397	help.
		398
		399	=item peername => $string
		400
		401	A string used to identify the remote site - usually the DNS hostname
		402	(I<not> IDN!) used to create the connection, rarely the IP address.
		403
		404	Apart from being useful in error messages, this string is also used in TLS
		405	peername verification (see C<verify_peername> in L<AnyEvent::TLS>). This
		406	verification will be skipped when C<peername> is not specified or is
		407	C<undef>.
		408
		409	=item tls => "accept" | "connect" | Net::SSLeay::SSL object
		410
		411	When this parameter is given, it enables TLS (SSL) mode, that means
		412	AnyEvent will start a TLS handshake as soon as the connection has been
		413	established and will transparently encrypt/decrypt data afterwards.
		414
		415	All TLS protocol errors will be signalled as C<EPROTO>, with an
		416	appropriate error message.
		417
		418	TLS mode requires Net::SSLeay to be installed (it will be loaded
		419	automatically when you try to create a TLS handle): this module doesn't
		420	have a dependency on that module, so if your module requires it, you have
		421	to add the dependency yourself.
		422
		423	Unlike TCP, TLS has a server and client side: for the TLS server side, use
		424	C<accept>, and for the TLS client side of a connection, use C<connect>
		425	mode.
		426
		427	You can also provide your own TLS connection object, but you have
		428	to make sure that you call either C<Net::SSLeay::set_connect_state>
		429	or C<Net::SSLeay::set_accept_state> on it before you pass it to
		430	AnyEvent::Handle. Also, this module will take ownership of this connection
		431	object.
		432
		433	At some future point, AnyEvent::Handle might switch to another TLS
		434	implementation, then the option to use your own session object will go
		435	away.
		436
		437	B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
		438	passing in the wrong integer will lead to certain crash. This most often
		439	happens when one uses a stylish C<< tls => 1 >> and is surprised about the
		440	segmentation fault.
		441
		442	Use the C<< ->starttls >> method if you need to start TLS negotiation later.
		443
		444	=item tls_ctx => $anyevent_tls
		445
		446	Use the given C<AnyEvent::TLS> object to create the new TLS connection
		447	(unless a connection object was specified directly). If this
		448	parameter is missing (or C<undef>), then AnyEvent::Handle will use
		449	C<AnyEvent::Handle::TLS_CTX>.
		450
		451	Instead of an object, you can also specify a hash reference with C<< key
		452	=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
		453	new TLS context object.
		454
		455	=item on_starttls => $cb->($handle, $success[, $error_message])
		456
		457	This callback will be invoked when the TLS/SSL handshake has finished. If
		458	C<$success> is true, then the TLS handshake succeeded, otherwise it failed
		459	(C<on_stoptls> will not be called in this case).
		460
		461	The session in C<< $handle->{tls} >> can still be examined in this
		462	callback, even when the handshake was not successful.
		463
		464	TLS handshake failures will not cause C<on_error> to be invoked when this
		465	callback is in effect, instead, the error message will be passed to C<on_starttls>.
		466
		467	Without this callback, handshake failures lead to C<on_error> being
		468	called as usual.
		469
		470	Note that you cannot just call C<starttls> again in this callback. If you
		471	need to do that, start an zero-second timer instead whose callback can
		472	then call C<< ->starttls >> again.
		473
		474	=item on_stoptls => $cb->($handle)
		475
		476	When a SSLv3/TLS shutdown/close notify/EOF is detected and this callback is
		477	set, then it will be invoked after freeing the TLS session. If it is not,
		478	then a TLS shutdown condition will be treated like a normal EOF condition
		479	on the handle.
		480
		481	The session in C<< $handle->{tls} >> can still be examined in this
		482	callback.
		483
		484	This callback will only be called on TLS shutdowns, not when the
		485	underlying handle signals EOF.
		486
		487	=item json => JSON or JSON::XS object
		488
		489	This is the json coder object used by the C<json> read and write types.
		490
		491	If you don't supply it, then AnyEvent::Handle will create and use a
		492	suitable one (on demand), which will write and expect UTF-8 encoded JSON
		493	texts.
		494
		495	Note that you are responsible to depend on the JSON module if you want to
		496	use this functionality, as AnyEvent does not have a dependency itself.
143		497
144	=back	498	=back
145		499
146	=cut	500	=cut
147		501
148	sub new {	502	sub new {
149	my $class = shift;	503	my $class = shift;
150
151	my $self = bless { @_ }, $class;	504	my $self = bless { @_ }, $class;
152		505
153	$self->{fh} or Carp::croak "mandatory argument fh is missing";	506	if ($self->{fh}) {
		507	$self->_start;
		508	return unless $self->{fh}; # could be gone by now
		509
		510	} elsif ($self->{connect}) {
		511	require AnyEvent::Socket;
		512
		513	$self->{peername} = $self->{connect}[0]
		514	unless exists $self->{peername};
		515
		516	$self->{_skip_drain_rbuf} = 1;
		517
		518	{
		519	Scalar::Util::weaken (my $self = $self);
		520
		521	$self->{_connect} =
		522	AnyEvent::Socket::tcp_connect (
		523	$self->{connect}[0],
		524	$self->{connect}[1],
		525	sub {
		526	my ($fh, $host, $port, $retry) = @_;
		527
		528	delete $self->{_connect}; # no longer needed
		529
		530	if ($fh) {
		531	$self->{fh} = $fh;
		532
		533	delete $self->{_skip_drain_rbuf};
		534	$self->_start;
		535
		536	$self->{on_connect}
		537	and $self->{on_connect}($self, $host, $port, sub {
		538	delete @$self{qw(fh _tw _rtw _wtw _ww _rw _eof _queue rbuf _wbuf tls _tls_rbuf _tls_wbuf)};
		539	$self->{_skip_drain_rbuf} = 1;
		540	&$retry;
		541	});
		542
		543	} else {
		544	if ($self->{on_connect_error}) {
		545	$self->{on_connect_error}($self, "$!");
		546	$self->destroy if $self;
		547	} else {
		548	$self->_error ($!, 1);
		549	}
		550	}
		551	},
		552	sub {
		553	local $self->{fh} = $_[0];
		554
		555	$self->{on_prepare}
		556	? $self->{on_prepare}->($self)
		557	: ()
		558	}
		559	);
		560	}
		561
		562	} else {
		563	Carp::croak "AnyEvent::Handle: either an existing fh or the connect parameter must be specified";
		564	}
		565
		566	$self
		567	}
		568
		569	sub _start {
		570	my ($self) = @_;
		571
		572	# too many clueless people try to use udp and similar sockets
		573	# with AnyEvent::Handle, do them a favour.
		574	my $type = getsockopt $self->{fh}, Socket::SOL_SOCKET (), Socket::SO_TYPE ();
		575	Carp::croak "AnyEvent::Handle: only stream sockets supported, anything else will NOT work!"
		576	if Socket::SOCK_STREAM () != (unpack "I", $type) && defined $type;
154		577
155	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;	578	AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
156		579
		580	$self->{_activity} =
		581	$self->{_ractivity} =
		582	$self->{_wactivity} = AE::now;
		583
		584	$self->{read_size} ||= 2048;
		585	$self->{max_read_size} = $self->{read_size}
		586	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		587
157	$self->on_eof (delete $self->{on_eof} ) if $self->{on_eof};	588	$self->timeout (delete $self->{timeout} ) if $self->{timeout};
158	$self->on_error (delete $self->{on_error}) if $self->{on_error};	589	$self->rtimeout (delete $self->{rtimeout} ) if $self->{rtimeout};
		590	$self->wtimeout (delete $self->{wtimeout} ) if $self->{wtimeout};
		591
		592	$self->no_delay (delete $self->{no_delay} ) if exists $self->{no_delay} && $self->{no_delay};
		593	$self->keepalive (delete $self->{keepalive}) if exists $self->{keepalive} && $self->{keepalive};
		594
		595	$self->oobinline (exists $self->{oobinline} ? delete $self->{oobinline} : 1);
		596
		597	$self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
		598	if $self->{tls};
		599
159	$self->on_drain (delete $self->{on_drain}) if $self->{on_drain};	600	$self->on_drain (delete $self->{on_drain} ) if $self->{on_drain};
160	$self->on_read (delete $self->{on_read} ) if $self->{on_read};
161		601
162	$self->start_read;	602	$self->start_read
		603	if $self->{on_read} || @{ $self->{_queue} };
163		604
164	$self	605	$self->_drain_wbuf;
165	}	606	}
166		607
167	sub _shutdown {
168	my ($self) = @_;
169
170	delete $self->{rw};
171	delete $self->{ww};
172	delete $self->{fh};
173	}
174
175	sub error {	608	sub _error {
176	my ($self) = @_;	609	my ($self, $errno, $fatal, $message) = @_;
177		610
178	{	611	$! = $errno;
179	local $!;	612	$message ||= "$!";
180	$self->_shutdown;
181	}
182		613
183	if ($self->{on_error}) {	614	if ($self->{on_error}) {
184	$self->{on_error}($self);	615	$self->{on_error}($self, $fatal, $message);
185	} else {	616	$self->destroy if $fatal;
		617	} elsif ($self->{fh} || $self->{connect}) {
		618	$self->destroy;
186	die "AnyEvent::Handle uncaught fatal error: $!";	619	Carp::croak "AnyEvent::Handle uncaught error: $message";
187	}	620	}
188	}	621	}
189		622
190	=item $fh = $handle->fh	623	=item $fh = $handle->fh
191		624
192	This method returns the filehandle of the L<AnyEvent::Handle> object.	625	This method returns the file handle used to create the L<AnyEvent::Handle> object.
193		626
194	=cut	627	=cut
195		628
196	sub fh { $_[0]->{fh} }	629	sub fh { $_[0]{fh} }
197		630
198	=item $handle->on_error ($cb)	631	=item $handle->on_error ($cb)
199		632
200	Replace the current C<on_error> callback (see the C<on_error> constructor argument).	633	Replace the current C<on_error> callback (see the C<on_error> constructor argument).
201		634
…		…
213		646
214	sub on_eof {	647	sub on_eof {
215	$_[0]{on_eof} = $_[1];	648	$_[0]{on_eof} = $_[1];
216	}	649	}
217		650
		651	=item $handle->on_timeout ($cb)
		652
		653	=item $handle->on_rtimeout ($cb)
		654
		655	=item $handle->on_wtimeout ($cb)
		656
		657	Replace the current C<on_timeout>, C<on_rtimeout> or C<on_wtimeout>
		658	callback, or disables the callback (but not the timeout) if C<$cb> =
		659	C<undef>. See the C<timeout> constructor argument and method.
		660
		661	=cut
		662
		663	# see below
		664
		665	=item $handle->autocork ($boolean)
		666
		667	Enables or disables the current autocork behaviour (see C<autocork>
		668	constructor argument). Changes will only take effect on the next write.
		669
		670	=cut
		671
		672	sub autocork {
		673	$_[0]{autocork} = $_[1];
		674	}
		675
		676	=item $handle->no_delay ($boolean)
		677
		678	Enables or disables the C<no_delay> setting (see constructor argument of
		679	the same name for details).
		680
		681	=cut
		682
		683	sub no_delay {
		684	$_[0]{no_delay} = $_[1];
		685
		686	setsockopt $_[0]{fh}, Socket::IPPROTO_TCP (), Socket::TCP_NODELAY (), int $_[1]
		687	if $_[0]{fh};
		688	}
		689
		690	=item $handle->keepalive ($boolean)
		691
		692	Enables or disables the C<keepalive> setting (see constructor argument of
		693	the same name for details).
		694
		695	=cut
		696
		697	sub keepalive {
		698	$_[0]{keepalive} = $_[1];
		699
		700	eval {
		701	local $SIG{__DIE__};
		702	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		703	if $_[0]{fh};
		704	};
		705	}
		706
		707	=item $handle->oobinline ($boolean)
		708
		709	Enables or disables the C<oobinline> setting (see constructor argument of
		710	the same name for details).
		711
		712	=cut
		713
		714	sub oobinline {
		715	$_[0]{oobinline} = $_[1];
		716
		717	eval {
		718	local $SIG{__DIE__};
		719	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_OOBINLINE (), int $_[1]
		720	if $_[0]{fh};
		721	};
		722	}
		723
		724	=item $handle->keepalive ($boolean)
		725
		726	Enables or disables the C<keepalive> setting (see constructor argument of
		727	the same name for details).
		728
		729	=cut
		730
		731	sub keepalive {
		732	$_[0]{keepalive} = $_[1];
		733
		734	eval {
		735	local $SIG{__DIE__};
		736	setsockopt $_[0]{fh}, Socket::SOL_SOCKET (), Socket::SO_KEEPALIVE (), int $_[1]
		737	if $_[0]{fh};
		738	};
		739	}
		740
		741	=item $handle->on_starttls ($cb)
		742
		743	Replace the current C<on_starttls> callback (see the C<on_starttls> constructor argument).
		744
		745	=cut
		746
		747	sub on_starttls {
		748	$_[0]{on_starttls} = $_[1];
		749	}
		750
		751	=item $handle->on_stoptls ($cb)
		752
		753	Replace the current C<on_stoptls> callback (see the C<on_stoptls> constructor argument).
		754
		755	=cut
		756
		757	sub on_stoptls {
		758	$_[0]{on_stoptls} = $_[1];
		759	}
		760
		761	=item $handle->rbuf_max ($max_octets)
		762
		763	Configures the C<rbuf_max> setting (C<undef> disables it).
		764
		765	=item $handle->wbuf_max ($max_octets)
		766
		767	Configures the C<wbuf_max> setting (C<undef> disables it).
		768
		769	=cut
		770
		771	sub rbuf_max {
		772	$_[0]{rbuf_max} = $_[1];
		773	}
		774
		775	sub wbuf_max {
		776	$_[0]{wbuf_max} = $_[1];
		777	}
		778
		779	#############################################################################
		780
		781	=item $handle->timeout ($seconds)
		782
		783	=item $handle->rtimeout ($seconds)
		784
		785	=item $handle->wtimeout ($seconds)
		786
		787	Configures (or disables) the inactivity timeout.
		788
		789	The timeout will be checked instantly, so this method might destroy the
		790	handle before it returns.
		791
		792	=item $handle->timeout_reset
		793
		794	=item $handle->rtimeout_reset
		795
		796	=item $handle->wtimeout_reset
		797
		798	Reset the activity timeout, as if data was received or sent.
		799
		800	These methods are cheap to call.
		801
		802	=cut
		803
		804	for my $dir ("", "r", "w") {
		805	my $timeout = "${dir}timeout";
		806	my $tw = "_${dir}tw";
		807	my $on_timeout = "on_${dir}timeout";
		808	my $activity = "_${dir}activity";
		809	my $cb;
		810
		811	*$on_timeout = sub {
		812	$_[0]{$on_timeout} = $_[1];
		813	};
		814
		815	*$timeout = sub {
		816	my ($self, $new_value) = @_;
		817
		818	$new_value >= 0
		819	or Carp::croak "AnyEvent::Handle->$timeout called with negative timeout ($new_value), caught";
		820
		821	$self->{$timeout} = $new_value;
		822	delete $self->{$tw}; &$cb;
		823	};
		824
		825	*{"${dir}timeout_reset"} = sub {
		826	$_[0]{$activity} = AE::now;
		827	};
		828
		829	# main workhorse:
		830	# reset the timeout watcher, as neccessary
		831	# also check for time-outs
		832	$cb = sub {
		833	my ($self) = @_;
		834
		835	if ($self->{$timeout} && $self->{fh}) {
		836	my $NOW = AE::now;
		837
		838	# when would the timeout trigger?
		839	my $after = $self->{$activity} + $self->{$timeout} - $NOW;
		840
		841	# now or in the past already?
		842	if ($after <= 0) {
		843	$self->{$activity} = $NOW;
		844
		845	if ($self->{$on_timeout}) {
		846	$self->{$on_timeout}($self);
		847	} else {
		848	$self->_error (Errno::ETIMEDOUT);
		849	}
		850
		851	# callback could have changed timeout value, optimise
		852	return unless $self->{$timeout};
		853
		854	# calculate new after
		855	$after = $self->{$timeout};
		856	}
		857
		858	Scalar::Util::weaken $self;
		859	return unless $self; # ->error could have destroyed $self
		860
		861	$self->{$tw} ||= AE::timer $after, 0, sub {
		862	delete $self->{$tw};
		863	$cb->($self);
		864	};
		865	} else {
		866	delete $self->{$tw};
		867	}
		868	}
		869	}
		870
218	#############################################################################	871	#############################################################################
219		872
220	=back	873	=back
221		874
222	=head2 WRITE QUEUE	875	=head2 WRITE QUEUE
…		…
225	for reading.	878	for reading.
226		879
227	The write queue is very simple: you can add data to its end, and	880	The write queue is very simple: you can add data to its end, and
228	AnyEvent::Handle will automatically try to get rid of it for you.	881	AnyEvent::Handle will automatically try to get rid of it for you.
229		882
230	When data could be writtena nd the write buffer is shorter then the low	883	When data could be written and the write buffer is shorter then the low
231	water mark, the C<on_drain> callback will be invoked.	884	water mark, the C<on_drain> callback will be invoked.
232		885
233	=over 4	886	=over 4
234		887
235	=item $handle->on_drain ($cb)	888	=item $handle->on_drain ($cb)
236		889
237	Sets the C<on_drain> callback or clears it (see the description of	890	Sets the C<on_drain> callback or clears it (see the description of
238	C<on_drain> in the constructor).	891	C<on_drain> in the constructor).
239		892
		893	This method may invoke callbacks (and therefore the handle might be
		894	destroyed after it returns).
		895
240	=cut	896	=cut
241		897
242	sub on_drain {	898	sub on_drain {
243	my ($self, $cb) = @_;	899	my ($self, $cb) = @_;
244		900
245	$self->{on_drain} = $cb;	901	$self->{on_drain} = $cb;
246		902
247	$cb->($self)	903	$cb->($self)
248	if $cb && $self->{low_water_mark} >= length $self->{wbuf};	904	if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
249	}	905	}
250		906
251	=item $handle->push_write ($data)	907	=item $handle->push_write ($data)
252		908
253	Queues the given scalar to be written. You can push as much data as you	909	Queues the given scalar to be written. You can push as much data as
254	want (only limited by the available memory), as C<AnyEvent::Handle>	910	you want (only limited by the available memory and C<wbuf_max>), as
255	buffers it independently of the kernel.	911	C<AnyEvent::Handle> buffers it independently of the kernel.
256		912
257	=cut	913	This method may invoke callbacks (and therefore the handle might be
		914	destroyed after it returns).
258		915
259	sub push_write {	916	=cut
		917
		918	sub _drain_wbuf {
260	my ($self, $data) = @_;	919	my ($self) = @_;
261		920
262	$self->{wbuf} .= $data;	921	if (!$self->{_ww} && length $self->{wbuf}) {
263		922
264	unless ($self->{ww}) {
265	Scalar::Util::weaken $self;	923	Scalar::Util::weaken $self;
		924
266	my $cb = sub {	925	my $cb = sub {
267	my $len = syswrite $self->{fh}, $self->{wbuf};	926	my $len = syswrite $self->{fh}, $self->{wbuf};
268		927
269	if ($len > 0) {	928	if (defined $len) {
270	substr $self->{wbuf}, 0, $len, "";	929	substr $self->{wbuf}, 0, $len, "";
271		930
		931	$self->{_activity} = $self->{_wactivity} = AE::now;
272		932
273	$self->{on_drain}($self)	933	$self->{on_drain}($self)
274	if $self->{low_water_mark} >= length $self->{wbuf}	934	if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
275	&& $self->{on_drain};	935	&& $self->{on_drain};
276		936
277	delete $self->{ww} unless length $self->{wbuf};	937	delete $self->{_ww} unless length $self->{wbuf};
278	} elsif ($! != EAGAIN && $! != EINTR) {	938	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
279	$self->error;	939	$self->_error ($!, 1);
280	}	940	}
281	};	941	};
282		942
283	$self->{ww} = AnyEvent->io (fh => $self->{fh}, poll => "w", cb => $cb);	943	# try to write data immediately
		944	$cb->() unless $self->{autocork};
284		945
285	$cb->($self);	946	# if still data left in wbuf, we need to poll
		947	$self->{_ww} = AE::io $self->{fh}, 1, $cb
		948	if length $self->{wbuf};
		949
		950	if (
		951	defined $self->{wbuf_max}
		952	&& $self->{wbuf_max} < length $self->{wbuf}
		953	) {
		954	$self->_error (Errno::ENOSPC, 1), return;
		955	}
286	};	956	};
287	}	957	}
		958
		959	our %WH;
		960
		961	# deprecated
		962	sub register_write_type($$) {
		963	$WH{$_[0]} = $_[1];
		964	}
		965
		966	sub push_write {
		967	my $self = shift;
		968
		969	if (@_ > 1) {
		970	my $type = shift;
		971
		972	@_ = ($WH{$type} ||= _load_func "$type\::anyevent_write_type"
		973	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_write")
		974	->($self, @_);
		975	}
		976
		977	# we downgrade here to avoid hard-to-track-down bugs,
		978	# and diagnose the problem earlier and better.
		979
		980	if ($self->{tls}) {
		981	utf8::downgrade $self->{_tls_wbuf} .= $_[0];
		982	&_dotls ($self) if $self->{fh};
		983	} else {
		984	utf8::downgrade $self->{wbuf} .= $_[0];
		985	$self->_drain_wbuf if $self->{fh};
		986	}
		987	}
		988
		989	=item $handle->push_write (type => @args)
		990
		991	Instead of formatting your data yourself, you can also let this module
		992	do the job by specifying a type and type-specific arguments. You
		993	can also specify the (fully qualified) name of a package, in which
		994	case AnyEvent tries to load the package and then expects to find the
		995	C<anyevent_write_type> function inside (see "custom write types", below).
		996
		997	Predefined types are (if you have ideas for additional types, feel free to
		998	drop by and tell us):
		999
		1000	=over 4
		1001
		1002	=item netstring => $string
		1003
		1004	Formats the given value as netstring
		1005	(http://cr.yp.to/proto/netstrings.txt, this is not a recommendation to use them).
		1006
		1007	=cut
		1008
		1009	register_write_type netstring => sub {
		1010	my ($self, $string) = @_;
		1011
		1012	(length $string) . ":$string,"
		1013	};
		1014
		1015	=item packstring => $format, $data
		1016
		1017	An octet string prefixed with an encoded length. The encoding C<$format>
		1018	uses the same format as a Perl C<pack> format, but must specify a single
		1019	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1020	optional C<!>, C<< < >> or C<< > >> modifier).
		1021
		1022	=cut
		1023
		1024	register_write_type packstring => sub {
		1025	my ($self, $format, $string) = @_;
		1026
		1027	pack "$format/a*", $string
		1028	};
		1029
		1030	=item json => $array_or_hashref
		1031
		1032	Encodes the given hash or array reference into a JSON object. Unless you
		1033	provide your own JSON object, this means it will be encoded to JSON text
		1034	in UTF-8.
		1035
		1036	JSON objects (and arrays) are self-delimiting, so you can write JSON at
		1037	one end of a handle and read them at the other end without using any
		1038	additional framing.
		1039
		1040	The generated JSON text is guaranteed not to contain any newlines: While
		1041	this module doesn't need delimiters after or between JSON texts to be
		1042	able to read them, many other languages depend on that.
		1043
		1044	A simple RPC protocol that interoperates easily with others is to send
		1045	JSON arrays (or objects, although arrays are usually the better choice as
		1046	they mimic how function argument passing works) and a newline after each
		1047	JSON text:
		1048
		1049	$handle->push_write (json => ["method", "arg1", "arg2"]); # whatever
		1050	$handle->push_write ("\012");
		1051
		1052	An AnyEvent::Handle receiver would simply use the C<json> read type and
		1053	rely on the fact that the newline will be skipped as leading whitespace:
		1054
		1055	$handle->push_read (json => sub { my $array = $_[1]; ... });
		1056
		1057	Other languages could read single lines terminated by a newline and pass
		1058	this line into their JSON decoder of choice.
		1059
		1060	=cut
		1061
		1062	sub json_coder() {
		1063	eval { require JSON::XS; JSON::XS->new->utf8 }
		1064	|| do { require JSON; JSON->new->utf8 }
		1065	}
		1066
		1067	register_write_type json => sub {
		1068	my ($self, $ref) = @_;
		1069
		1070	my $json = $self->{json} ||= json_coder;
		1071
		1072	$json->encode ($ref)
		1073	};
		1074
		1075	=item storable => $reference
		1076
		1077	Freezes the given reference using L<Storable> and writes it to the
		1078	handle. Uses the C<nfreeze> format.
		1079
		1080	=cut
		1081
		1082	register_write_type storable => sub {
		1083	my ($self, $ref) = @_;
		1084
		1085	require Storable;
		1086
		1087	pack "w/a*", Storable::nfreeze ($ref)
		1088	};
		1089
		1090	=back
		1091
		1092	=item $handle->push_shutdown
		1093
		1094	Sometimes you know you want to close the socket after writing your data
		1095	before it was actually written. One way to do that is to replace your
		1096	C<on_drain> handler by a callback that shuts down the socket (and set
		1097	C<low_water_mark> to C<0>). This method is a shorthand for just that, and
		1098	replaces the C<on_drain> callback with:
		1099
		1100	sub { shutdown $_[0]{fh}, 1 }
		1101
		1102	This simply shuts down the write side and signals an EOF condition to the
		1103	the peer.
		1104
		1105	You can rely on the normal read queue and C<on_eof> handling
		1106	afterwards. This is the cleanest way to close a connection.
		1107
		1108	This method may invoke callbacks (and therefore the handle might be
		1109	destroyed after it returns).
		1110
		1111	=cut
		1112
		1113	sub push_shutdown {
		1114	my ($self) = @_;
		1115
		1116	delete $self->{low_water_mark};
		1117	$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
		1118	}
		1119
		1120	=item custom write types - Package::anyevent_write_type $handle, @args
		1121
		1122	Instead of one of the predefined types, you can also specify the name of
		1123	a package. AnyEvent will try to load the package and then expects to find
		1124	a function named C<anyevent_write_type> inside. If it isn't found, it
		1125	progressively tries to load the parent package until it either finds the
		1126	function (good) or runs out of packages (bad).
		1127
		1128	Whenever the given C<type> is used, C<push_write> will the function with
		1129	the handle object and the remaining arguments.
		1130
		1131	The function is supposed to return a single octet string that will be
		1132	appended to the write buffer, so you cna mentally treat this function as a
		1133	"arguments to on-the-wire-format" converter.
		1134
		1135	Example: implement a custom write type C<join> that joins the remaining
		1136	arguments using the first one.
		1137
		1138	$handle->push_write (My::Type => " ", 1,2,3);
		1139
		1140	# uses the following package, which can be defined in the "My::Type" or in
		1141	# the "My" modules to be auto-loaded, or just about anywhere when the
		1142	# My::Type::anyevent_write_type is defined before invoking it.
		1143
		1144	package My::Type;
		1145
		1146	sub anyevent_write_type {
		1147	my ($handle, $delim, @args) = @_;
		1148
		1149	join $delim, @args
		1150	}
		1151
		1152	=cut
288		1153
289	#############################################################################	1154	#############################################################################
290		1155
291	=back	1156	=back
292		1157
…		…
299	ways, the "simple" way, using only C<on_read> and the "complex" way, using	1164	ways, the "simple" way, using only C<on_read> and the "complex" way, using
300	a queue.	1165	a queue.
301		1166
302	In the simple case, you just install an C<on_read> callback and whenever	1167	In the simple case, you just install an C<on_read> callback and whenever
303	new data arrives, it will be called. You can then remove some data (if	1168	new data arrives, it will be called. You can then remove some data (if
304	enough is there) from the read buffer (C<< $handle->rbuf >>) if you want	1169	enough is there) from the read buffer (C<< $handle->rbuf >>). Or you can
305	or not.	1170	leave the data there if you want to accumulate more (e.g. when only a
		1171	partial message has been received so far), or change the read queue with
		1172	e.g. C<push_read>.
306		1173
307	In the more complex case, you want to queue multiple callbacks. In this	1174	In the more complex case, you want to queue multiple callbacks. In this
308	case, AnyEvent::Handle will call the first queued callback each time new	1175	case, AnyEvent::Handle will call the first queued callback each time new
309	data arrives and removes it when it has done its job (see C<push_read>,	1176	data arrives (also the first time it is queued) and remove it when it has
310	below).	1177	done its job (see C<push_read>, below).
311		1178
312	This way you can, for example, push three line-reads, followed by reading	1179	This way you can, for example, push three line-reads, followed by reading
313	a chunk of data, and AnyEvent::Handle will execute them in order.	1180	a chunk of data, and AnyEvent::Handle will execute them in order.
314		1181
315	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by	1182	Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
316	the specified number of bytes which give an XML datagram.	1183	the specified number of bytes which give an XML datagram.
317		1184
318	# in the default state, expect some header bytes	1185	# in the default state, expect some header bytes
319	$handle->on_read (sub {	1186	$handle->on_read (sub {
320	# some data is here, now queue the length-header-read (4 octets)	1187	# some data is here, now queue the length-header-read (4 octets)
321	shift->unshift_read_chunk (4, sub {	1188	shift->unshift_read (chunk => 4, sub {
322	# header arrived, decode	1189	# header arrived, decode
323	my $len = unpack "N", $_[1];	1190	my $len = unpack "N", $_[1];
324		1191
325	# now read the payload	1192	# now read the payload
326	shift->unshift_read_chunk ($len, sub {	1193	shift->unshift_read (chunk => $len, sub {
327	my $xml = $_[1];	1194	my $xml = $_[1];
328	# handle xml	1195	# handle xml
329	});	1196	});
330	});	1197	});
331	});	1198	});
332		1199
333	Example 2: Implement a client for a protocol that replies either with	1200	Example 2: Implement a client for a protocol that replies either with "OK"
334	"OK" and another line or "ERROR" for one request, and 64 bytes for the	1201	and another line or "ERROR" for the first request that is sent, and 64
335	second request. Due tot he availability of a full queue, we can just	1202	bytes for the second request. Due to the availability of a queue, we can
336	pipeline sending both requests and manipulate the queue as necessary in	1203	just pipeline sending both requests and manipulate the queue as necessary
337	the callbacks:	1204	in the callbacks.
338		1205
339	# request one	1206	When the first callback is called and sees an "OK" response, it will
		1207	C<unshift> another line-read. This line-read will be queued I<before> the
		1208	64-byte chunk callback.
		1209
		1210	# request one, returns either "OK + extra line" or "ERROR"
340	$handle->push_write ("request 1\015\012");	1211	$handle->push_write ("request 1\015\012");
341		1212
342	# we expect "ERROR" or "OK" as response, so push a line read	1213	# we expect "ERROR" or "OK" as response, so push a line read
343	$handle->push_read_line (sub {	1214	$handle->push_read (line => sub {
344	# if we got an "OK", we have to _prepend_ another line,	1215	# if we got an "OK", we have to _prepend_ another line,
345	# so it will be read before the second request reads its 64 bytes	1216	# so it will be read before the second request reads its 64 bytes
346	# which are already in the queue when this callback is called	1217	# which are already in the queue when this callback is called
347	# we don't do this in case we got an error	1218	# we don't do this in case we got an error
348	if ($_[1] eq "OK") {	1219	if ($_[1] eq "OK") {
349	$_[0]->unshift_read_line (sub {	1220	$_[0]->unshift_read (line => sub {
350	my $response = $_[1];	1221	my $response = $_[1];
351	...	1222	...
352	});	1223	});
353	}	1224	}
354	});	1225	});
355		1226
356	# request two	1227	# request two, simply returns 64 octets
357	$handle->push_write ("request 2\015\012");	1228	$handle->push_write ("request 2\015\012");
358		1229
359	# simply read 64 bytes, always	1230	# simply read 64 bytes, always
360	$handle->push_read_chunk (64, sub {	1231	$handle->push_read (chunk => 64, sub {
361	my $response = $_[1];	1232	my $response = $_[1];
362	...	1233	...
363	});	1234	});
364		1235
365	=over 4	1236	=over 4
…		…
367	=cut	1238	=cut
368		1239
369	sub _drain_rbuf {	1240	sub _drain_rbuf {
370	my ($self) = @_;	1241	my ($self) = @_;
371		1242
		1243	# avoid recursion
372	return if $self->{in_drain};	1244	return if $self->{_skip_drain_rbuf};
373	local $self->{in_drain} = 1;	1245	local $self->{_skip_drain_rbuf} = 1;
374		1246
		1247	while () {
		1248	# we need to use a separate tls read buffer, as we must not receive data while
		1249	# we are draining the buffer, and this can only happen with TLS.
		1250	$self->{rbuf} .= delete $self->{_tls_rbuf}
		1251	if exists $self->{_tls_rbuf};
		1252
375	while (my $len = length $self->{rbuf}) {	1253	my $len = length $self->{rbuf};
376	no strict 'refs';	1254
377	if (my $cb = shift @{ $self->{queue} }) {	1255	if (my $cb = shift @{ $self->{_queue} }) {
378	if (!$cb->($self)) {	1256	unless ($cb->($self)) {
		1257	# no progress can be made
		1258	# (not enough data and no data forthcoming)
		1259	$self->_error (Errno::EPIPE, 1), return
379	if ($self->{eof}) {	1260	if $self->{_eof};
380	# no progress can be made (not enough data and no data forthcoming)
381	$! = &Errno::EPIPE; return $self->error;
382	}
383		1261
384	unshift @{ $self->{queue} }, $cb;	1262	unshift @{ $self->{_queue} }, $cb;
385	return;	1263	last;
386	}	1264	}
387	} elsif ($self->{on_read}) {	1265	} elsif ($self->{on_read}) {
		1266	last unless $len;
		1267
388	$self->{on_read}($self);	1268	$self->{on_read}($self);
389		1269
390	if (	1270	if (
391	$self->{eof} # if no further data will arrive
392	&& $len == length $self->{rbuf} # and no data has been consumed	1271	$len == length $self->{rbuf} # if no data has been consumed
393	&& !@{ $self->{queue} } # and the queue is still empty	1272	&& !@{ $self->{_queue} } # and the queue is still empty
394	&& $self->{on_read} # and we still want to read data	1273	&& $self->{on_read} # but we still have on_read
395	) {	1274	) {
		1275	# no further data will arrive
396	# then no progress can be made	1276	# so no progress can be made
397	$! = &Errno::EPIPE; return $self->error;	1277	$self->_error (Errno::EPIPE, 1), return
		1278	if $self->{_eof};
		1279
		1280	last; # more data might arrive
398	}	1281	}
399	} else {	1282	} else {
400	# read side becomes idle	1283	# read side becomes idle
401	delete $self->{rw};	1284	delete $self->{_rw} unless $self->{tls};
402	return;	1285	last;
403	}	1286	}
404	}	1287	}
405		1288
406	if ($self->{eof}) {	1289	if ($self->{_eof}) {
407	$self->_shutdown;	1290	$self->{on_eof}
408	$self->{on_eof}($self)	1291	? $self->{on_eof}($self)
409	if $self->{on_eof};	1292	: $self->_error (0, 1, "Unexpected end-of-file");
		1293
		1294	return;
		1295	}
		1296
		1297	if (
		1298	defined $self->{rbuf_max}
		1299	&& $self->{rbuf_max} < length $self->{rbuf}
		1300	) {
		1301	$self->_error (Errno::ENOSPC, 1), return;
		1302	}
		1303
		1304	# may need to restart read watcher
		1305	unless ($self->{_rw}) {
		1306	$self->start_read
		1307	if $self->{on_read} || @{ $self->{_queue} };
410	}	1308	}
411	}	1309	}
412		1310
413	=item $handle->on_read ($cb)	1311	=item $handle->on_read ($cb)
414		1312
415	This replaces the currently set C<on_read> callback, or clears it (when	1313	This replaces the currently set C<on_read> callback, or clears it (when
416	the new callback is C<undef>). See the description of C<on_read> in the	1314	the new callback is C<undef>). See the description of C<on_read> in the
417	constructor.	1315	constructor.
418		1316
		1317	This method may invoke callbacks (and therefore the handle might be
		1318	destroyed after it returns).
		1319
419	=cut	1320	=cut
420		1321
421	sub on_read {	1322	sub on_read {
422	my ($self, $cb) = @_;	1323	my ($self, $cb) = @_;
423		1324
424	$self->{on_read} = $cb;	1325	$self->{on_read} = $cb;
		1326	$self->_drain_rbuf if $cb;
425	}	1327	}
426		1328
427	=item $handle->rbuf	1329	=item $handle->rbuf
428		1330
429	Returns the read buffer (as a modifiable lvalue).	1331	Returns the read buffer (as a modifiable lvalue). You can also access the
		1332	read buffer directly as the C<< ->{rbuf} >> member, if you want (this is
		1333	much faster, and no less clean).
430		1334
431	You can access the read buffer directly as the C<< ->{rbuf} >> member, if	1335	The only operation allowed on the read buffer (apart from looking at it)
432	you want.	1336	is removing data from its beginning. Otherwise modifying or appending to
		1337	it is not allowed and will lead to hard-to-track-down bugs.
433		1338
434	NOTE: The read buffer should only be used or modified if the C<on_read>,	1339	NOTE: The read buffer should only be used or modified in the C<on_read>
435	C<push_read> or C<unshift_read> methods are used. The other read methods	1340	callback or when C<push_read> or C<unshift_read> are used with a single
436	automatically manage the read buffer.	1341	callback (i.e. untyped). Typed C<push_read> and C<unshift_read> methods
		1342	will manage the read buffer on their own.
437		1343
438	=cut	1344	=cut
439		1345
440	sub rbuf : lvalue {	1346	sub rbuf : lvalue {
441	$_[0]{rbuf}	1347	$_[0]{rbuf}
…		…
448	Append the given callback to the end of the queue (C<push_read>) or	1354	Append the given callback to the end of the queue (C<push_read>) or
449	prepend it (C<unshift_read>).	1355	prepend it (C<unshift_read>).
450		1356
451	The callback is called each time some additional read data arrives.	1357	The callback is called each time some additional read data arrives.
452		1358
453	It must check wether enough data is in the read buffer already.	1359	It must check whether enough data is in the read buffer already.
454		1360
455	If not enough data is available, it must return the empty list or a false	1361	If not enough data is available, it must return the empty list or a false
456	value, in which case it will be called repeatedly until enough data is	1362	value, in which case it will be called repeatedly until enough data is
457	available (or an error condition is detected).	1363	available (or an error condition is detected).
458		1364
459	If enough data was available, then the callback must remove all data it is	1365	If enough data was available, then the callback must remove all data it is
460	interested in (which can be none at all) and return a true value. After returning	1366	interested in (which can be none at all) and return a true value. After returning
461	true, it will be removed from the queue.	1367	true, it will be removed from the queue.
462		1368
		1369	These methods may invoke callbacks (and therefore the handle might be
		1370	destroyed after it returns).
		1371
463	=cut	1372	=cut
		1373
		1374	our %RH;
		1375
		1376	sub register_read_type($$) {
		1377	$RH{$_[0]} = $_[1];
		1378	}
464		1379
465	sub push_read {	1380	sub push_read {
466	my ($self, $cb) = @_;	1381	my $self = shift;
		1382	my $cb = pop;
467		1383
		1384	if (@_) {
		1385	my $type = shift;
		1386
		1387	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1388	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_read")
		1389	->($self, $cb, @_);
		1390	}
		1391
468	push @{ $self->{queue} }, $cb;	1392	push @{ $self->{_queue} }, $cb;
469	$self->_drain_rbuf;	1393	$self->_drain_rbuf;
470	}	1394	}
471		1395
472	sub unshift_read {	1396	sub unshift_read {
473	my ($self, $cb) = @_;	1397	my $self = shift;
		1398	my $cb = pop;
474		1399
		1400	if (@_) {
		1401	my $type = shift;
		1402
		1403	$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
		1404	or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::unshift_read")
		1405	->($self, $cb, @_);
		1406	}
		1407
475	push @{ $self->{queue} }, $cb;	1408	unshift @{ $self->{_queue} }, $cb;
476	$self->_drain_rbuf;	1409	$self->_drain_rbuf;
477	}	1410	}
478		1411
479	=item $handle->push_read_chunk ($len, $cb->($self, $data))	1412	=item $handle->push_read (type => @args, $cb)
480		1413
481	=item $handle->unshift_read_chunk ($len, $cb->($self, $data))	1414	=item $handle->unshift_read (type => @args, $cb)
482		1415
483	Append the given callback to the end of the queue (C<push_read_chunk>) or	1416	Instead of providing a callback that parses the data itself you can chose
484	prepend it (C<unshift_read_chunk>).	1417	between a number of predefined parsing formats, for chunks of data, lines
		1418	etc. You can also specify the (fully qualified) name of a package, in
		1419	which case AnyEvent tries to load the package and then expects to find the
		1420	C<anyevent_read_type> function inside (see "custom read types", below).
485		1421
486	The callback will be called only once C<$len> bytes have been read, and	1422	Predefined types are (if you have ideas for additional types, feel free to
487	these C<$len> bytes will be passed to the callback.	1423	drop by and tell us):
488		1424
489	=cut	1425	=over 4
490		1426
491	sub _read_chunk($$) {	1427	=item chunk => $octets, $cb->($handle, $data)
		1428
		1429	Invoke the callback only once C<$octets> bytes have been read. Pass the
		1430	data read to the callback. The callback will never be called with less
		1431	data.
		1432
		1433	Example: read 2 bytes.
		1434
		1435	$handle->push_read (chunk => 2, sub {
		1436	warn "yay ", unpack "H*", $_[1];
		1437	});
		1438
		1439	=cut
		1440
		1441	register_read_type chunk => sub {
492	my ($self, $len, $cb) = @_;	1442	my ($self, $cb, $len) = @_;
493		1443
494	sub {	1444	sub {
495	$len <= length $_[0]{rbuf} or return;	1445	$len <= length $_[0]{rbuf} or return;
496	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");	1446	$cb->($_[0], substr $_[0]{rbuf}, 0, $len, "");
497	1	1447	1
498	}	1448	}
499	}	1449	};
500		1450
501	sub push_read_chunk {	1451	=item line => [$eol, ]$cb->($handle, $line, $eol)
502	$_[0]->push_read (&_read_chunk);
503	}
504
505
506	sub unshift_read_chunk {
507	$_[0]->unshift_read (&_read_chunk);
508	}
509
510	=item $handle->push_read_line ([$eol, ]$cb->($self, $line, $eol))
511
512	=item $handle->unshift_read_line ([$eol, ]$cb->($self, $line, $eol))
513
514	Append the given callback to the end of the queue (C<push_read_line>) or
515	prepend it (C<unshift_read_line>).
516		1452
517	The callback will be called only once a full line (including the end of	1453	The callback will be called only once a full line (including the end of
518	line marker, C<$eol>) has been read. This line (excluding the end of line	1454	line marker, C<$eol>) has been read. This line (excluding the end of line
519	marker) will be passed to the callback as second argument (C<$line>), and	1455	marker) will be passed to the callback as second argument (C<$line>), and
520	the end of line marker as the third argument (C<$eol>).	1456	the end of line marker as the third argument (C<$eol>).
…		…
531	Partial lines at the end of the stream will never be returned, as they are	1467	Partial lines at the end of the stream will never be returned, as they are
532	not marked by the end of line marker.	1468	not marked by the end of line marker.
533		1469
534	=cut	1470	=cut
535		1471
536	sub _read_line($$) {	1472	register_read_type line => sub {
537	my $self = shift;	1473	my ($self, $cb, $eol) = @_;
538	my $cb = pop;
539	my $eol = @_ ? shift : qr|(\015?\012)|;
540	my $pos;
541		1474
		1475	if (@_ < 3) {
		1476	# this is more than twice as fast as the generic code below
		1477	sub {
		1478	$_[0]{rbuf} =~ s/^([^\015\012]*)(\015?\012)// or return;
		1479
		1480	$cb->($_[0], $1, $2);
		1481	1
		1482	}
		1483	} else {
542	$eol = quotemeta $eol unless ref $eol;	1484	$eol = quotemeta $eol unless ref $eol;
543	$eol = qr|^(.*?)($eol)|s;	1485	$eol = qr|^(.*?)($eol)|s;
		1486
		1487	sub {
		1488	$_[0]{rbuf} =~ s/$eol// or return;
		1489
		1490	$cb->($_[0], $1, $2);
		1491	1
		1492	}
		1493	}
		1494	};
		1495
		1496	=item regex => $accept[, $reject[, $skip], $cb->($handle, $data)
		1497
		1498	Makes a regex match against the regex object C<$accept> and returns
		1499	everything up to and including the match.
		1500
		1501	Example: read a single line terminated by '\n'.
		1502
		1503	$handle->push_read (regex => qr<\n>, sub { ... });
		1504
		1505	If C<$reject> is given and not undef, then it determines when the data is
		1506	to be rejected: it is matched against the data when the C<$accept> regex
		1507	does not match and generates an C<EBADMSG> error when it matches. This is
		1508	useful to quickly reject wrong data (to avoid waiting for a timeout or a
		1509	receive buffer overflow).
		1510
		1511	Example: expect a single decimal number followed by whitespace, reject
		1512	anything else (not the use of an anchor).
		1513
		1514	$handle->push_read (regex => qr<^[0-9]+\s>, qr<[^0-9]>, sub { ... });
		1515
		1516	If C<$skip> is given and not C<undef>, then it will be matched against
		1517	the receive buffer when neither C<$accept> nor C<$reject> match,
		1518	and everything preceding and including the match will be accepted
		1519	unconditionally. This is useful to skip large amounts of data that you
		1520	know cannot be matched, so that the C<$accept> or C<$reject> regex do not
		1521	have to start matching from the beginning. This is purely an optimisation
		1522	and is usually worth it only when you expect more than a few kilobytes.
		1523
		1524	Example: expect a http header, which ends at C<\015\012\015\012>. Since we
		1525	expect the header to be very large (it isn't in practice, but...), we use
		1526	a skip regex to skip initial portions. The skip regex is tricky in that
		1527	it only accepts something not ending in either \015 or \012, as these are
		1528	required for the accept regex.
		1529
		1530	$handle->push_read (regex =>
		1531	qr<\015\012\015\012>,
		1532	undef, # no reject
		1533	qr<^.*[^\015\012]>,
		1534	sub { ... });
		1535
		1536	=cut
		1537
		1538	register_read_type regex => sub {
		1539	my ($self, $cb, $accept, $reject, $skip) = @_;
		1540
		1541	my $data;
		1542	my $rbuf = \$self->{rbuf};
544		1543
545	sub {	1544	sub {
546	$_[0]{rbuf} =~ s/$eol// or return;	1545	# accept
		1546	if ($$rbuf =~ $accept) {
		1547	$data .= substr $$rbuf, 0, $+[0], "";
		1548	$cb->($self, $data);
		1549	return 1;
		1550	}
		1551
		1552	# reject
		1553	if ($reject && $$rbuf =~ $reject) {
		1554	$self->_error (Errno::EBADMSG);
		1555	}
547		1556
548	$cb->($_[0], $1, $2);	1557	# skip
		1558	if ($skip && $$rbuf =~ $skip) {
		1559	$data .= substr $$rbuf, 0, $+[0], "";
		1560	}
		1561
		1562	()
		1563	}
		1564	};
		1565
		1566	=item netstring => $cb->($handle, $string)
		1567
		1568	A netstring (http://cr.yp.to/proto/netstrings.txt, this is not an endorsement).
		1569
		1570	Throws an error with C<$!> set to EBADMSG on format violations.
		1571
		1572	=cut
		1573
		1574	register_read_type netstring => sub {
		1575	my ($self, $cb) = @_;
		1576
		1577	sub {
		1578	unless ($_[0]{rbuf} =~ s/^(0|[1-9][0-9]*)://) {
		1579	if ($_[0]{rbuf} =~ /[^0-9]/) {
		1580	$self->_error (Errno::EBADMSG);
		1581	}
		1582	return;
		1583	}
		1584
		1585	my $len = $1;
		1586
		1587	$self->unshift_read (chunk => $len, sub {
		1588	my $string = $_[1];
		1589	$_[0]->unshift_read (chunk => 1, sub {
		1590	if ($_[1] eq ",") {
		1591	$cb->($_[0], $string);
		1592	} else {
		1593	$self->_error (Errno::EBADMSG);
		1594	}
		1595	});
		1596	});
		1597
549	1	1598	1
550	}	1599	}
551	}	1600	};
552		1601
553	sub push_read_line {	1602	=item packstring => $format, $cb->($handle, $string)
554	$_[0]->push_read (&_read_line);
555	}
556		1603
557	sub unshift_read_line {	1604	An octet string prefixed with an encoded length. The encoding C<$format>
558	$_[0]->unshift_read (&_read_line);	1605	uses the same format as a Perl C<pack> format, but must specify a single
559	}	1606	integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
		1607	optional C<!>, C<< < >> or C<< > >> modifier).
		1608
		1609	For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
		1610	EPP uses a prefix of C<N> (4 octtes).
		1611
		1612	Example: read a block of data prefixed by its length in BER-encoded
		1613	format (very efficient).
		1614
		1615	$handle->push_read (packstring => "w", sub {
		1616	my ($handle, $data) = @_;
		1617	});
		1618
		1619	=cut
		1620
		1621	register_read_type packstring => sub {
		1622	my ($self, $cb, $format) = @_;
		1623
		1624	sub {
		1625	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1626	defined (my $len = eval { unpack $format, $_[0]{rbuf} })
		1627	or return;
		1628
		1629	$format = length pack $format, $len;
		1630
		1631	# bypass unshift if we already have the remaining chunk
		1632	if ($format + $len <= length $_[0]{rbuf}) {
		1633	my $data = substr $_[0]{rbuf}, $format, $len;
		1634	substr $_[0]{rbuf}, 0, $format + $len, "";
		1635	$cb->($_[0], $data);
		1636	} else {
		1637	# remove prefix
		1638	substr $_[0]{rbuf}, 0, $format, "";
		1639
		1640	# read remaining chunk
		1641	$_[0]->unshift_read (chunk => $len, $cb);
		1642	}
		1643
		1644	1
		1645	}
		1646	};
		1647
		1648	=item json => $cb->($handle, $hash_or_arrayref)
		1649
		1650	Reads a JSON object or array, decodes it and passes it to the
		1651	callback. When a parse error occurs, an C<EBADMSG> error will be raised.
		1652
		1653	If a C<json> object was passed to the constructor, then that will be used
		1654	for the final decode, otherwise it will create a JSON coder expecting UTF-8.
		1655
		1656	This read type uses the incremental parser available with JSON version
		1657	2.09 (and JSON::XS version 2.2) and above. You have to provide a
		1658	dependency on your own: this module will load the JSON module, but
		1659	AnyEvent does not depend on it itself.
		1660
		1661	Since JSON texts are fully self-delimiting, the C<json> read and write
		1662	types are an ideal simple RPC protocol: just exchange JSON datagrams. See
		1663	the C<json> write type description, above, for an actual example.
		1664
		1665	=cut
		1666
		1667	register_read_type json => sub {
		1668	my ($self, $cb) = @_;
		1669
		1670	my $json = $self->{json} ||= json_coder;
		1671
		1672	my $data;
		1673	my $rbuf = \$self->{rbuf};
		1674
		1675	sub {
		1676	my $ref = eval { $json->incr_parse ($self->{rbuf}) };
		1677
		1678	if ($ref) {
		1679	$self->{rbuf} = $json->incr_text;
		1680	$json->incr_text = "";
		1681	$cb->($self, $ref);
		1682
		1683	1
		1684	} elsif ($@) {
		1685	# error case
		1686	$json->incr_skip;
		1687
		1688	$self->{rbuf} = $json->incr_text;
		1689	$json->incr_text = "";
		1690
		1691	$self->_error (Errno::EBADMSG);
		1692
		1693	()
		1694	} else {
		1695	$self->{rbuf} = "";
		1696
		1697	()
		1698	}
		1699	}
		1700	};
		1701
		1702	=item storable => $cb->($handle, $ref)
		1703
		1704	Deserialises a L<Storable> frozen representation as written by the
		1705	C<storable> write type (BER-encoded length prefix followed by nfreeze'd
		1706	data).
		1707
		1708	Raises C<EBADMSG> error if the data could not be decoded.
		1709
		1710	=cut
		1711
		1712	register_read_type storable => sub {
		1713	my ($self, $cb) = @_;
		1714
		1715	require Storable;
		1716
		1717	sub {
		1718	# when we can use 5.10 we can use ".", but for 5.8 we use the re-pack method
		1719	defined (my $len = eval { unpack "w", $_[0]{rbuf} })
		1720	or return;
		1721
		1722	my $format = length pack "w", $len;
		1723
		1724	# bypass unshift if we already have the remaining chunk
		1725	if ($format + $len <= length $_[0]{rbuf}) {
		1726	my $data = substr $_[0]{rbuf}, $format, $len;
		1727	substr $_[0]{rbuf}, 0, $format + $len, "";
		1728	$cb->($_[0], Storable::thaw ($data));
		1729	} else {
		1730	# remove prefix
		1731	substr $_[0]{rbuf}, 0, $format, "";
		1732
		1733	# read remaining chunk
		1734	$_[0]->unshift_read (chunk => $len, sub {
		1735	if (my $ref = eval { Storable::thaw ($_[1]) }) {
		1736	$cb->($_[0], $ref);
		1737	} else {
		1738	$self->_error (Errno::EBADMSG);
		1739	}
		1740	});
		1741	}
		1742
		1743	1
		1744	}
		1745	};
		1746
		1747	=back
		1748
		1749	=item custom read types - Package::anyevent_read_type $handle, $cb, @args
		1750
		1751	Instead of one of the predefined types, you can also specify the name
		1752	of a package. AnyEvent will try to load the package and then expects to
		1753	find a function named C<anyevent_read_type> inside. If it isn't found, it
		1754	progressively tries to load the parent package until it either finds the
		1755	function (good) or runs out of packages (bad).
		1756
		1757	Whenever this type is used, C<push_read> will invoke the function with the
		1758	handle object, the original callback and the remaining arguments.
		1759
		1760	The function is supposed to return a callback (usually a closure) that
		1761	works as a plain read callback (see C<< ->push_read ($cb) >>), so you can
		1762	mentally treat the function as a "configurable read type to read callback"
		1763	converter.
		1764
		1765	It should invoke the original callback when it is done reading (remember
		1766	to pass C<$handle> as first argument as all other callbacks do that,
		1767	although there is no strict requirement on this).
		1768
		1769	For examples, see the source of this module (F<perldoc -m
		1770	AnyEvent::Handle>, search for C<register_read_type>)).
560		1771
561	=item $handle->stop_read	1772	=item $handle->stop_read
562		1773
563	=item $handle->start_read	1774	=item $handle->start_read
564		1775
565	In rare cases you actually do not want to read anything form the	1776	In rare cases you actually do not want to read anything from the
566	socket. In this case you can call C<stop_read>. Neither C<on_read> no	1777	socket. In this case you can call C<stop_read>. Neither C<on_read> nor
567	any queued callbacks will be executed then. To start readign again, call	1778	any queued callbacks will be executed then. To start reading again, call
568	C<start_read>.	1779	C<start_read>.
		1780
		1781	Note that AnyEvent::Handle will automatically C<start_read> for you when
		1782	you change the C<on_read> callback or push/unshift a read callback, and it
		1783	will automatically C<stop_read> for you when neither C<on_read> is set nor
		1784	there are any read requests in the queue.
		1785
		1786	In older versions of this module (<= 5.3), these methods had no effect,
		1787	as TLS does not support half-duplex connections. In current versions they
		1788	work as expected, as this behaviour is required to avoid certain resource
		1789	attacks, where the program would be forced to read (and buffer) arbitrary
		1790	amounts of data before being able to send some data. The drawback is that
		1791	some readings of the the SSL/TLS specifications basically require this
		1792	attack to be working, as SSL/TLS implementations might stall sending data
		1793	during a rehandshake.
		1794
		1795	As a guideline, during the initial handshake, you should not stop reading,
		1796	and as a client, it might cause problems, depending on your applciation.
569		1797
570	=cut	1798	=cut
571		1799
572	sub stop_read {	1800	sub stop_read {
573	my ($self) = @_;	1801	my ($self) = @_;
574		1802
575	delete $self->{rw};	1803	delete $self->{_rw};
576	}	1804	}
577		1805
578	sub start_read {	1806	sub start_read {
579	my ($self) = @_;	1807	my ($self) = @_;
580		1808
581	unless ($self->{rw} || $self->{eof}) {	1809	unless ($self->{_rw} || $self->{_eof} || !$self->{fh}) {
582	Scalar::Util::weaken $self;	1810	Scalar::Util::weaken $self;
583		1811
584	$self->{rw} = AnyEvent->io (fh => $self->{fh}, poll => "r", cb => sub {	1812	$self->{_rw} = AE::io $self->{fh}, 0, sub {
		1813	my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
585	my $len = sysread $self->{fh}, $self->{rbuf}, $self->{read_size} || 8192, length $self->{rbuf};	1814	my $len = sysread $self->{fh}, $$rbuf, $self->{read_size}, length $$rbuf;
586		1815
587	if ($len > 0) {	1816	if ($len > 0) {
588	if (defined $self->{rbuf_max}) {	1817	$self->{_activity} = $self->{_ractivity} = AE::now;
589	if ($self->{rbuf_max} < length $self->{rbuf}) {	1818
590	$! = &Errno::ENOSPC; return $self->error;	1819	if ($self->{tls}) {
591	}	1820	Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
		1821
		1822	&_dotls ($self);
		1823	} else {
		1824	$self->_drain_rbuf;
592	}	1825	}
593		1826
		1827	if ($len == $self->{read_size}) {
		1828	$self->{read_size} *= 2;
		1829	$self->{read_size} = $self->{max_read_size} || MAX_READ_SIZE
		1830	if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
		1831	}
		1832
594	} elsif (defined $len) {	1833	} elsif (defined $len) {
595	$self->{eof} = 1;
596	delete $self->{rw};	1834	delete $self->{_rw};
		1835	$self->{_eof} = 1;
		1836	$self->_drain_rbuf;
597		1837
598	} elsif ($! != EAGAIN && $! != EINTR) {	1838	} elsif ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK) {
599	return $self->error;	1839	return $self->_error ($!, 1);
600	}	1840	}
		1841	};
		1842	}
		1843	}
601		1844
		1845	our $ERROR_SYSCALL;
		1846	our $ERROR_WANT_READ;
		1847
		1848	sub _tls_error {
		1849	my ($self, $err) = @_;
		1850
		1851	return $self->_error ($!, 1)
		1852	if $err == Net::SSLeay::ERROR_SYSCALL ();
		1853
		1854	my $err =Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ());
		1855
		1856	# reduce error string to look less scary
		1857	$err =~ s/^error:[0-9a-fA-F]{8}:[^:]+:([^:]+):/\L$1: /;
		1858
		1859	if ($self->{_on_starttls}) {
		1860	(delete $self->{_on_starttls})->($self, undef, $err);
		1861	&_freetls;
		1862	} else {
		1863	&_freetls;
		1864	$self->_error (Errno::EPROTO, 1, $err);
		1865	}
		1866	}
		1867
		1868	# poll the write BIO and send the data if applicable
		1869	# also decode read data if possible
		1870	# this is basiclaly our TLS state machine
		1871	# more efficient implementations are possible with openssl,
		1872	# but not with the buggy and incomplete Net::SSLeay.
		1873	sub _dotls {
		1874	my ($self) = @_;
		1875
		1876	my $tmp;
		1877
		1878	if (length $self->{_tls_wbuf}) {
		1879	while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
		1880	substr $self->{_tls_wbuf}, 0, $tmp, "";
		1881	}
		1882
		1883	$tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
		1884	return $self->_tls_error ($tmp)
		1885	if $tmp != $ERROR_WANT_READ
		1886	&& ($tmp != $ERROR_SYSCALL || $!);
		1887	}
		1888
		1889	while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
		1890	unless (length $tmp) {
		1891	$self->{_on_starttls}
		1892	and (delete $self->{_on_starttls})->($self, undef, "EOF during handshake"); # ???
		1893	&_freetls;
		1894
		1895	if ($self->{on_stoptls}) {
		1896	$self->{on_stoptls}($self);
		1897	return;
		1898	} else {
		1899	# let's treat SSL-eof as we treat normal EOF
		1900	delete $self->{_rw};
		1901	$self->{_eof} = 1;
		1902	}
		1903	}
		1904
		1905	$self->{_tls_rbuf} .= $tmp;
602	$self->_drain_rbuf;	1906	$self->_drain_rbuf;
		1907	$self->{tls} or return; # tls session might have gone away in callback
		1908	}
		1909
		1910	$tmp = Net::SSLeay::get_error ($self->{tls}, -1);
		1911	return $self->_tls_error ($tmp)
		1912	if $tmp != $ERROR_WANT_READ
		1913	&& ($tmp != $ERROR_SYSCALL || $!);
		1914
		1915	while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
		1916	$self->{wbuf} .= $tmp;
		1917	$self->_drain_wbuf;
		1918	$self->{tls} or return; # tls session might have gone away in callback
		1919	}
		1920
		1921	$self->{_on_starttls}
		1922	and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
		1923	and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
		1924	}
		1925
		1926	=item $handle->starttls ($tls[, $tls_ctx])
		1927
		1928	Instead of starting TLS negotiation immediately when the AnyEvent::Handle
		1929	object is created, you can also do that at a later time by calling
		1930	C<starttls>.
		1931
		1932	Starting TLS is currently an asynchronous operation - when you push some
		1933	write data and then call C<< ->starttls >> then TLS negotiation will start
		1934	immediately, after which the queued write data is then sent.
		1935
		1936	The first argument is the same as the C<tls> constructor argument (either
		1937	C<"connect">, C<"accept"> or an existing Net::SSLeay object).
		1938
		1939	The second argument is the optional C<AnyEvent::TLS> object that is used
		1940	when AnyEvent::Handle has to create its own TLS connection object, or
		1941	a hash reference with C<< key => value >> pairs that will be used to
		1942	construct a new context.
		1943
		1944	The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
		1945	context in C<< $handle->{tls_ctx} >> after this call and can be used or
		1946	changed to your liking. Note that the handshake might have already started
		1947	when this function returns.
		1948
		1949	Due to bugs in OpenSSL, it might or might not be possible to do multiple
		1950	handshakes on the same stream. It is best to not attempt to use the
		1951	stream after stopping TLS.
		1952
		1953	This method may invoke callbacks (and therefore the handle might be
		1954	destroyed after it returns).
		1955
		1956	=cut
		1957
		1958	our %TLS_CACHE; #TODO not yet documented, should we?
		1959
		1960	sub starttls {
		1961	my ($self, $tls, $ctx) = @_;
		1962
		1963	Carp::croak "It is an error to call starttls on an AnyEvent::Handle object while TLS is already active, caught"
		1964	if $self->{tls};
		1965
		1966	$self->{tls} = $tls;
		1967	$self->{tls_ctx} = $ctx if @_ > 2;
		1968
		1969	return unless $self->{fh};
		1970
		1971	require Net::SSLeay;
		1972
		1973	$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
		1974	$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
		1975
		1976	$tls = delete $self->{tls};
		1977	$ctx = $self->{tls_ctx};
		1978
		1979	local $Carp::CarpLevel = 1; # skip ourselves when creating a new context or session
		1980
		1981	if ("HASH" eq ref $ctx) {
		1982	require AnyEvent::TLS;
		1983
		1984	if ($ctx->{cache}) {
		1985	my $key = $ctx+0;
		1986	$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
		1987	} else {
		1988	$ctx = new AnyEvent::TLS %$ctx;
		1989	}
		1990	}
		1991
		1992	$self->{tls_ctx} = $ctx || TLS_CTX ();
		1993	$self->{tls} = $tls = $self->{tls_ctx}->_get_session ($tls, $self, $self->{peername});
		1994
		1995	# basically, this is deep magic (because SSL_read should have the same issues)
		1996	# but the openssl maintainers basically said: "trust us, it just works".
		1997	# (unfortunately, we have to hardcode constants because the abysmally misdesigned
		1998	# and mismaintained ssleay-module doesn't even offer them).
		1999	# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
		2000	#
		2001	# in short: this is a mess.
		2002	#
		2003	# note that we do not try to keep the length constant between writes as we are required to do.
		2004	# we assume that most (but not all) of this insanity only applies to non-blocking cases,
		2005	# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
		2006	# have identity issues in that area.
		2007	# Net::SSLeay::CTX_set_mode ($ssl,
		2008	# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
		2009	# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
		2010	Net::SSLeay::CTX_set_mode ($tls, 1|2);
		2011
		2012	$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2013	$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
		2014
		2015	Net::SSLeay::BIO_write ($self->{_rbio}, delete $self->{rbuf});
		2016
		2017	Net::SSLeay::set_bio ($tls, $self->{_rbio}, $self->{_wbio});
		2018
		2019	$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
		2020	if $self->{on_starttls};
		2021
		2022	&_dotls; # need to trigger the initial handshake
		2023	$self->start_read; # make sure we actually do read
		2024	}
		2025
		2026	=item $handle->stoptls
		2027
		2028	Shuts down the SSL connection - this makes a proper EOF handshake by
		2029	sending a close notify to the other side, but since OpenSSL doesn't
		2030	support non-blocking shut downs, it is not guaranteed that you can re-use
		2031	the stream afterwards.
		2032
		2033	This method may invoke callbacks (and therefore the handle might be
		2034	destroyed after it returns).
		2035
		2036	=cut
		2037
		2038	sub stoptls {
		2039	my ($self) = @_;
		2040
		2041	if ($self->{tls} && $self->{fh}) {
		2042	Net::SSLeay::shutdown ($self->{tls});
		2043
		2044	&_dotls;
		2045
		2046	# # we don't give a shit. no, we do, but we can't. no...#d#
		2047	# # we, we... have to use openssl :/#d#
		2048	# &_freetls;#d#
		2049	}
		2050	}
		2051
		2052	sub _freetls {
		2053	my ($self) = @_;
		2054
		2055	return unless $self->{tls};
		2056
		2057	$self->{tls_ctx}->_put_session (delete $self->{tls})
		2058	if $self->{tls} > 0;
		2059
		2060	delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
		2061	}
		2062
		2063	=item $handle->resettls
		2064
		2065	This rarely-used method simply resets and TLS state on the handle, usually
		2066	causing data loss.
		2067
		2068	One case where it may be useful is when you want to skip over the data in
		2069	the stream but you are not interested in interpreting it, so data loss is
		2070	no concern.
		2071
		2072	=cut
		2073
		2074	*resettls = \&_freetls;
		2075
		2076	sub DESTROY {
		2077	my ($self) = @_;
		2078
		2079	&_freetls;
		2080
		2081	my $linger = exists $self->{linger} ? $self->{linger} : 3600;
		2082
		2083	if ($linger && length $self->{wbuf} && $self->{fh}) {
		2084	my $fh = delete $self->{fh};
		2085	my $wbuf = delete $self->{wbuf};
		2086
		2087	my @linger;
		2088
		2089	push @linger, AE::io $fh, 1, sub {
		2090	my $len = syswrite $fh, $wbuf, length $wbuf;
		2091
		2092	if ($len > 0) {
		2093	substr $wbuf, 0, $len, "";
		2094	} elsif (defined $len || ($! != EAGAIN && $! != EINTR && $! != WSAEWOULDBLOCK)) {
		2095	@linger = (); # end
		2096	}
		2097	};
		2098	push @linger, AE::timer $linger, 0, sub {
		2099	@linger = ();
		2100	};
		2101	}
		2102	}
		2103
		2104	=item $handle->destroy
		2105
		2106	Shuts down the handle object as much as possible - this call ensures that
		2107	no further callbacks will be invoked and as many resources as possible
		2108	will be freed. Any method you will call on the handle object after
		2109	destroying it in this way will be silently ignored (and it will return the
		2110	empty list).
		2111
		2112	Normally, you can just "forget" any references to an AnyEvent::Handle
		2113	object and it will simply shut down. This works in fatal error and EOF
		2114	callbacks, as well as code outside. It does I<NOT> work in a read or write
		2115	callback, so when you want to destroy the AnyEvent::Handle object from
		2116	within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
		2117	that case.
		2118
		2119	Destroying the handle object in this way has the advantage that callbacks
		2120	will be removed as well, so if those are the only reference holders (as
		2121	is common), then one doesn't need to do anything special to break any
		2122	reference cycles.
		2123
		2124	The handle might still linger in the background and write out remaining
		2125	data, as specified by the C<linger> option, however.
		2126
		2127	=cut
		2128
		2129	sub destroy {
		2130	my ($self) = @_;
		2131
		2132	$self->DESTROY;
		2133	%$self = ();
		2134	bless $self, "AnyEvent::Handle::destroyed";
		2135	}
		2136
		2137	sub AnyEvent::Handle::destroyed::AUTOLOAD {
		2138	#nop
		2139	}
		2140
		2141	=item $handle->destroyed
		2142
		2143	Returns false as long as the handle hasn't been destroyed by a call to C<<
		2144	->destroy >>, true otherwise.
		2145
		2146	Can be useful to decide whether the handle is still valid after some
		2147	callback possibly destroyed the handle. For example, C<< ->push_write >>,
		2148	C<< ->starttls >> and other methods can call user callbacks, which in turn
		2149	can destroy the handle, so work can be avoided by checking sometimes:
		2150
		2151	$hdl->starttls ("accept");
		2152	return if $hdl->destroyed;
		2153	$hdl->push_write (...
		2154
		2155	Note that the call to C<push_write> will silently be ignored if the handle
		2156	has been destroyed, so often you can just ignore the possibility of the
		2157	handle being destroyed.
		2158
		2159	=cut
		2160
		2161	sub destroyed { 0 }
		2162	sub AnyEvent::Handle::destroyed::destroyed { 1 }
		2163
		2164	=item AnyEvent::Handle::TLS_CTX
		2165
		2166	This function creates and returns the AnyEvent::TLS object used by default
		2167	for TLS mode.
		2168
		2169	The context is created by calling L<AnyEvent::TLS> without any arguments.
		2170
		2171	=cut
		2172
		2173	our $TLS_CTX;
		2174
		2175	sub TLS_CTX() {
		2176	$TLS_CTX ||= do {
		2177	require AnyEvent::TLS;
		2178
		2179	new AnyEvent::TLS
		2180	}
		2181	}
		2182
		2183	=back
		2184
		2185
		2186	=head1 NONFREQUENTLY ASKED QUESTIONS
		2187
		2188	=over 4
		2189
		2190	=item I C<undef> the AnyEvent::Handle reference inside my callback and
		2191	still get further invocations!
		2192
		2193	That's because AnyEvent::Handle keeps a reference to itself when handling
		2194	read or write callbacks.
		2195
		2196	It is only safe to "forget" the reference inside EOF or error callbacks,
		2197	from within all other callbacks, you need to explicitly call the C<<
		2198	->destroy >> method.
		2199
		2200	=item Why is my C<on_eof> callback never called?
		2201
		2202	Probably because your C<on_error> callback is being called instead: When
		2203	you have outstanding requests in your read queue, then an EOF is
		2204	considered an error as you clearly expected some data.
		2205
		2206	To avoid this, make sure you have an empty read queue whenever your handle
		2207	is supposed to be "idle" (i.e. connection closes are O.K.). You cna set
		2208	an C<on_read> handler that simply pushes the first read requests in the
		2209	queue.
		2210
		2211	See also the next question, which explains this in a bit more detail.
		2212
		2213	=item How can I serve requests in a loop?
		2214
		2215	Most protocols consist of some setup phase (authentication for example)
		2216	followed by a request handling phase, where the server waits for requests
		2217	and handles them, in a loop.
		2218
		2219	There are two important variants: The first (traditional, better) variant
		2220	handles requests until the server gets some QUIT command, causing it to
		2221	close the connection first (highly desirable for a busy TCP server). A
		2222	client dropping the connection is an error, which means this variant can
		2223	detect an unexpected detection close.
		2224
		2225	To handle this case, always make sure you have a on-empty read queue, by
		2226	pushing the "read request start" handler on it:
		2227
		2228	# we assume a request starts with a single line
		2229	my @start_request; @start_request = (line => sub {
		2230	my ($hdl, $line) = @_;
		2231
		2232	... handle request
		2233
		2234	# push next request read, possibly from a nested callback
		2235	$hdl->push_read (@start_request);
		2236	});
		2237
		2238	# auth done, now go into request handling loop
		2239	# now push the first @start_request
		2240	$hdl->push_read (@start_request);
		2241
		2242	By always having an outstanding C<push_read>, the handle always expects
		2243	some data and raises the C<EPIPE> error when the connction is dropped
		2244	unexpectedly.
		2245
		2246	The second variant is a protocol where the client can drop the connection
		2247	at any time. For TCP, this means that the server machine may run out of
		2248	sockets easier, and in general, it means you cnanot distinguish a protocl
		2249	failure/client crash from a normal connection close. Nevertheless, these
		2250	kinds of protocols are common (and sometimes even the best solution to the
		2251	problem).
		2252
		2253	Having an outstanding read request at all times is possible if you ignore
		2254	C<EPIPE> errors, but this doesn't help with when the client drops the
		2255	connection during a request, which would still be an error.
		2256
		2257	A better solution is to push the initial request read in an C<on_read>
		2258	callback. This avoids an error, as when the server doesn't expect data
		2259	(i.e. is idly waiting for the next request, an EOF will not raise an
		2260	error, but simply result in an C<on_eof> callback. It is also a bit slower
		2261	and simpler:
		2262
		2263	# auth done, now go into request handling loop
		2264	$hdl->on_read (sub {
		2265	my ($hdl) = @_;
		2266
		2267	# called each time we receive data but the read queue is empty
		2268	# simply start read the request
		2269
		2270	$hdl->push_read (line => sub {
		2271	my ($hdl, $line) = @_;
		2272
		2273	... handle request
		2274
		2275	# do nothing special when the request has been handled, just
		2276	# let the request queue go empty.
603	});	2277	});
		2278	});
		2279
		2280	=item I get different callback invocations in TLS mode/Why can't I pause
		2281	reading?
		2282
		2283	Unlike, say, TCP, TLS connections do not consist of two independent
		2284	communication channels, one for each direction. Or put differently, the
		2285	read and write directions are not independent of each other: you cannot
		2286	write data unless you are also prepared to read, and vice versa.
		2287
		2288	This means that, in TLS mode, you might get C<on_error> or C<on_eof>
		2289	callback invocations when you are not expecting any read data - the reason
		2290	is that AnyEvent::Handle always reads in TLS mode.
		2291
		2292	During the connection, you have to make sure that you always have a
		2293	non-empty read-queue, or an C<on_read> watcher. At the end of the
		2294	connection (or when you no longer want to use it) you can call the
		2295	C<destroy> method.
		2296
		2297	=item How do I read data until the other side closes the connection?
		2298
		2299	If you just want to read your data into a perl scalar, the easiest way
		2300	to achieve this is by setting an C<on_read> callback that does nothing,
		2301	clearing the C<on_eof> callback and in the C<on_error> callback, the data
		2302	will be in C<$_[0]{rbuf}>:
		2303
		2304	$handle->on_read (sub { });
		2305	$handle->on_eof (undef);
		2306	$handle->on_error (sub {
		2307	my $data = delete $_[0]{rbuf};
		2308	});
		2309
		2310	The reason to use C<on_error> is that TCP connections, due to latencies
		2311	and packets loss, might get closed quite violently with an error, when in
		2312	fact all data has been received.
		2313
		2314	It is usually better to use acknowledgements when transferring data,
		2315	to make sure the other side hasn't just died and you got the data
		2316	intact. This is also one reason why so many internet protocols have an
		2317	explicit QUIT command.
		2318
		2319	=item I don't want to destroy the handle too early - how do I wait until
		2320	all data has been written?
		2321
		2322	After writing your last bits of data, set the C<on_drain> callback
		2323	and destroy the handle in there - with the default setting of
		2324	C<low_water_mark> this will be called precisely when all data has been
		2325	written to the socket:
		2326
		2327	$handle->push_write (...);
		2328	$handle->on_drain (sub {
		2329	warn "all data submitted to the kernel\n";
		2330	undef $handle;
		2331	});
		2332
		2333	If you just want to queue some data and then signal EOF to the other side,
		2334	consider using C<< ->push_shutdown >> instead.
		2335
		2336	=item I want to contact a TLS/SSL server, I don't care about security.
		2337
		2338	If your TLS server is a pure TLS server (e.g. HTTPS) that only speaks TLS,
		2339	connect to it and then create the AnyEvent::Handle with the C<tls>
		2340	parameter:
		2341
		2342	tcp_connect $host, $port, sub {
		2343	my ($fh) = @_;
		2344
		2345	my $handle = new AnyEvent::Handle
		2346	fh => $fh,
		2347	tls => "connect",
		2348	on_error => sub { ... };
		2349
		2350	$handle->push_write (...);
604	}	2351	};
605	}	2352
		2353	=item I want to contact a TLS/SSL server, I do care about security.
		2354
		2355	Then you should additionally enable certificate verification, including
		2356	peername verification, if the protocol you use supports it (see
		2357	L<AnyEvent::TLS>, C<verify_peername>).
		2358
		2359	E.g. for HTTPS:
		2360
		2361	tcp_connect $host, $port, sub {
		2362	my ($fh) = @_;
		2363
		2364	my $handle = new AnyEvent::Handle
		2365	fh => $fh,
		2366	peername => $host,
		2367	tls => "connect",
		2368	tls_ctx => { verify => 1, verify_peername => "https" },
		2369	...
		2370
		2371	Note that you must specify the hostname you connected to (or whatever
		2372	"peername" the protocol needs) as the C<peername> argument, otherwise no
		2373	peername verification will be done.
		2374
		2375	The above will use the system-dependent default set of trusted CA
		2376	certificates. If you want to check against a specific CA, add the
		2377	C<ca_file> (or C<ca_cert>) arguments to C<tls_ctx>:
		2378
		2379	tls_ctx => {
		2380	verify => 1,
		2381	verify_peername => "https",
		2382	ca_file => "my-ca-cert.pem",
		2383	},
		2384
		2385	=item I want to create a TLS/SSL server, how do I do that?
		2386
		2387	Well, you first need to get a server certificate and key. You have
		2388	three options: a) ask a CA (buy one, use cacert.org etc.) b) create a
		2389	self-signed certificate (cheap. check the search engine of your choice,
		2390	there are many tutorials on the net) or c) make your own CA (tinyca2 is a
		2391	nice program for that purpose).
		2392
		2393	Then create a file with your private key (in PEM format, see
		2394	L<AnyEvent::TLS>), followed by the certificate (also in PEM format). The
		2395	file should then look like this:
		2396
		2397	-----BEGIN RSA PRIVATE KEY-----
		2398	...header data
		2399	... lots of base64'y-stuff
		2400	-----END RSA PRIVATE KEY-----
		2401
		2402	-----BEGIN CERTIFICATE-----
		2403	... lots of base64'y-stuff
		2404	-----END CERTIFICATE-----
		2405
		2406	The important bits are the "PRIVATE KEY" and "CERTIFICATE" parts. Then
		2407	specify this file as C<cert_file>:
		2408
		2409	tcp_server undef, $port, sub {
		2410	my ($fh) = @_;
		2411
		2412	my $handle = new AnyEvent::Handle
		2413	fh => $fh,
		2414	tls => "accept",
		2415	tls_ctx => { cert_file => "my-server-keycert.pem" },
		2416	...
		2417
		2418	When you have intermediate CA certificates that your clients might not
		2419	know about, just append them to the C<cert_file>.
606		2420
607	=back	2421	=back
608		2422
		2423
		2424	=head1 SUBCLASSING AnyEvent::Handle
		2425
		2426	In many cases, you might want to subclass AnyEvent::Handle.
		2427
		2428	To make this easier, a given version of AnyEvent::Handle uses these
		2429	conventions:
		2430
		2431	=over 4
		2432
		2433	=item * all constructor arguments become object members.
		2434
		2435	At least initially, when you pass a C<tls>-argument to the constructor it
		2436	will end up in C<< $handle->{tls} >>. Those members might be changed or
		2437	mutated later on (for example C<tls> will hold the TLS connection object).
		2438
		2439	=item * other object member names are prefixed with an C<_>.
		2440
		2441	All object members not explicitly documented (internal use) are prefixed
		2442	with an underscore character, so the remaining non-C<_>-namespace is free
		2443	for use for subclasses.
		2444
		2445	=item * all members not documented here and not prefixed with an underscore
		2446	are free to use in subclasses.
		2447
		2448	Of course, new versions of AnyEvent::Handle may introduce more "public"
		2449	member variables, but that's just life. At least it is documented.
		2450
		2451	=back
		2452
609	=head1 AUTHOR	2453	=head1 AUTHOR
610		2454
611	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.	2455	Robin Redeker C<< <elmex at ta-sa.org> >>, Marc Lehmann <schmorp@schmorp.de>.
612		2456
613	=cut	2457	=cut

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