AnyEvent
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=head1 NAME
AnyEvent::Handle - non-blocking I/O on streaming handles via AnyEvent
=head1 SYNOPSIS
use AnyEvent;
use AnyEvent::Handle;
my $cv = AnyEvent->condvar;
my $hdl; $hdl = new AnyEvent::Handle
fh => \*STDIN,
on_error => sub {
my ($hdl, $fatal, $msg) = @_;
AE::log error => $msg;
$hdl->destroy;
$cv->send;
};
# send some request line
$hdl->push_write ("getinfo\015\012");
# read the response line
$hdl->push_read (line => sub {
my ($hdl, $line) = @_;
say "got line <$line>";
$cv->send;
});
$cv->recv;
=head1 DESCRIPTION
This is a helper module to make it easier to do event-based I/O
on stream-based filehandles (sockets, pipes, and other stream
things). Specifically, it doesn't work as expected on files, packet-based
sockets or similar things.
The L<AnyEvent::Intro> tutorial contains some well-documented
AnyEvent::Handle examples.
In the following, where the documentation refers to "bytes", it means
characters. As sysread and syswrite are used for all I/O, their
treatment of characters applies to this module as well.
At the very minimum, you should specify C<fh> or C<connect>, and the
C<on_error> callback.
All callbacks will be invoked with the handle object as their first
argument.
=cut
package AnyEvent::Handle;
use Scalar::Util ();
use List::Util ();
use Carp ();
use Errno qw(EAGAIN EWOULDBLOCK EINTR);
use AnyEvent (); BEGIN { AnyEvent::common_sense }
use AnyEvent::Util qw(WSAEWOULDBLOCK);
our $VERSION = $AnyEvent::VERSION;
sub _load_func($) {
my $func = $_[0];
unless (defined &$func) {
my $pkg = $func;
do {
$pkg =~ s/::[^:]+$//
or return;
eval "require $pkg";
} until defined &$func;
}
\&$func
}
sub MAX_READ_SIZE() { 131072 }
=head1 METHODS
=over 4
=item $handle = B<new> AnyEvent::Handle fh => $filehandle, key => value...
The constructor supports these arguments (all as C<< key => value >> pairs).
=over 4
=item fh => $filehandle [C<fh> or C<connect> MANDATORY]
The filehandle this L<AnyEvent::Handle> object will operate on.
NOTE: The filehandle will be set to non-blocking mode (using
C<AnyEvent::fh_unblock>) by the constructor and needs to stay in
that mode.
=item connect => [$host, $service] [C<fh> or C<connect> MANDATORY]
Try to connect to the specified host and service (port), using
C<AnyEvent::Socket::tcp_connect>. The C<$host> additionally becomes the
default C<peername>.
You have to specify either this parameter, or C<fh>, above.
It is possible to push requests on the read and write queues, and modify
properties of the stream, even while AnyEvent::Handle is connecting.
When this parameter is specified, then the C<on_prepare>,
C<on_connect_error> and C<on_connect> callbacks will be called under the
appropriate circumstances:
=over 4
=item on_prepare => $cb->($handle)
This (rarely used) callback is called before a new connection is
attempted, but after the file handle has been created (you can access that
file handle via C<< $handle->{fh} >>). It could be used to prepare the
file handle with parameters required for the actual connect (as opposed to
settings that can be changed when the connection is already established).
The return value of this callback should be the connect timeout value in
seconds (or C<0>, or C<undef>, or the empty list, to indicate that the
default timeout is to be used).
=item on_connect => $cb->($handle, $host, $port, $retry->())
This callback is called when a connection has been successfully established.
The peer's numeric host and port (the socket peername) are passed as
parameters, together with a retry callback. At the time it is called the
read and write queues, EOF status, TLS status and similar properties of
the handle will have been reset.
If, for some reason, the handle is not acceptable, calling C<$retry> will
continue with the next connection target (in case of multi-homed hosts or
SRV records there can be multiple connection endpoints). The C<$retry>
callback can be invoked after the connect callback returns, i.e. one can
start a handshake and then decide to retry with the next host if the
handshake fails.
In most cases, you should ignore the C<$retry> parameter.
=item on_connect_error => $cb->($handle, $message)
This callback is called when the connection could not be
established. C<$!> will contain the relevant error code, and C<$message> a
message describing it (usually the same as C<"$!">).
If this callback isn't specified, then C<on_error> will be called with a
fatal error instead.
=back
=item on_error => $cb->($handle, $fatal, $message)
This is the error callback, which is called when, well, some error
occured, such as not being able to resolve the hostname, failure to
connect, or a read error.
Some errors are fatal (which is indicated by C<$fatal> being true). On
fatal errors the handle object will be destroyed (by a call to C<< ->
destroy >>) after invoking the error callback (which means you are free to
examine the handle object). Examples of fatal errors are an EOF condition
with active (but unsatisfiable) read watchers (C<EPIPE>) or I/O errors. In
cases where the other side can close the connection at will, it is
often easiest to not report C<EPIPE> errors in this callback.
AnyEvent::Handle tries to find an appropriate error code for you to check
against, but in some cases (TLS errors), this does not work well.
If you report the error to the user, it is recommended to always output
the C<$message> argument in human-readable error messages (you don't need
to report C<"$!"> if you report C<$message>).
If you want to react programmatically to the error, then looking at C<$!>
and comparing it against some of the documented C<Errno> values is usually
better than looking at the C<$message>.
Non-fatal errors can be retried by returning, but it is recommended
to simply ignore this parameter and instead abondon the handle object
when this callback is invoked. Examples of non-fatal errors are timeouts
C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
On entry to the callback, the value of C<$!> contains the operating
system error code (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT>, C<EBADMSG> or
C<EPROTO>).
While not mandatory, it is I<highly> recommended to set this callback, as
you will not be notified of errors otherwise. The default just calls
C<croak>.
=item on_read => $cb->($handle)
This sets the default read callback, which is called when data arrives
and no read request is in the queue (unlike read queue callbacks, this
callback will only be called when at least one octet of data is in the
read buffer).
To access (and remove data from) the read buffer, use the C<< ->rbuf >>
method or access the C<< $handle->{rbuf} >> member directly. Note that you
must not enlarge or modify the read buffer, you can only remove data at
the beginning from it.
You can also call C<< ->push_read (...) >> or any other function that
modifies the read queue. Or do both. Or ...
When an EOF condition is detected, AnyEvent::Handle will first try to
feed all the remaining data to the queued callbacks and C<on_read> before
calling the C<on_eof> callback. If no progress can be made, then a fatal
error will be raised (with C<$!> set to C<EPIPE>).
Note that, unlike requests in the read queue, an C<on_read> callback
doesn't mean you I<require> some data: if there is an EOF and there
are outstanding read requests then an error will be flagged. With an
C<on_read> callback, the C<on_eof> callback will be invoked.
=item on_eof => $cb->($handle)
Set the callback to be called when an end-of-file condition is detected,
i.e. in the case of a socket, when the other side has closed the
connection cleanly, and there are no outstanding read requests in the
queue (if there are read requests, then an EOF counts as an unexpected
connection close and will be flagged as an error).
For sockets, this just means that the other side has stopped sending data,
you can still try to write data, and, in fact, one can return from the EOF
callback and continue writing data, as only the read part has been shut
down.
If an EOF condition has been detected but no C<on_eof> callback has been
set, then a fatal error will be raised with C<$!> set to <0>.
=item on_drain => $cb->($handle)
This sets the callback that is called once when the write buffer becomes
empty (and immediately when the handle object is created).
To append to the write buffer, use the C<< ->push_write >> method.
This callback is useful when you don't want to put all of your write data
into the queue at once, for example, when you want to write the contents
of some file to the socket you might not want to read the whole file into
memory and push it into the queue, but instead only read more data from
the file when the write queue becomes empty.
=item timeout => $fractional_seconds
=item rtimeout => $fractional_seconds
=item wtimeout => $fractional_seconds
If non-zero, then these enables an "inactivity" timeout: whenever this
many seconds pass without a successful read or write on the underlying
file handle (or a call to C<timeout_reset>), the C<on_timeout> callback
will be invoked (and if that one is missing, a non-fatal C<ETIMEDOUT>
error will be raised).
There are three variants of the timeouts that work independently of each
other, for both read and write (triggered when nothing was read I<OR>
written), just read (triggered when nothing was read), and just write:
C<timeout>, C<rtimeout> and C<wtimeout>, with corresponding callbacks
C<on_timeout>, C<on_rtimeout> and C<on_wtimeout>, and reset functions
C<timeout_reset>, C<rtimeout_reset>, and C<wtimeout_reset>.
Note that timeout processing is active even when you do not have any
outstanding read or write requests: If you plan to keep the connection
idle then you should disable the timeout temporarily or ignore the
timeout in the corresponding C<on_timeout> callback, in which case
AnyEvent::Handle will simply restart the timeout.
Zero (the default) disables the corresponding timeout.
=item on_timeout => $cb->($handle)
=item on_rtimeout => $cb->($handle)
=item on_wtimeout => $cb->($handle)
Called whenever the inactivity timeout passes. If you return from this
callback, then the timeout will be reset as if some activity had happened,
so this condition is not fatal in any way.
=item rbuf_max => <bytes>
If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
when the read buffer ever (strictly) exceeds this size. This is useful to
avoid some forms of denial-of-service attacks.
For example, a server accepting connections from untrusted sources should
be configured to accept only so-and-so much data that it cannot act on
(for example, when expecting a line, an attacker could send an unlimited
amount of data without a callback ever being called as long as the line
isn't finished).
=item wbuf_max => <bytes>
If defined, then a fatal error will be raised (with C<$!> set to C<ENOSPC>)
when the write buffer ever (strictly) exceeds this size. This is useful to
avoid some forms of denial-of-service attacks.
Although the units of this parameter is bytes, this is the I<raw> number
of bytes not yet accepted by the kernel. This can make a difference when
you e.g. use TLS, as TLS typically makes your write data larger (but it
can also make it smaller due to compression).
As an example of when this limit is useful, take a chat server that sends
chat messages to a client. If the client does not read those in a timely
manner then the send buffer in the server would grow unbounded.
=item autocork => <boolean>
When disabled (the default), C<push_write> will try to immediately
write the data to the handle if possible. This avoids having to register
a write watcher and wait for the next event loop iteration, but can
be inefficient if you write multiple small chunks (on the wire, this
disadvantage is usually avoided by your kernel's nagle algorithm, see
C<no_delay>, but this option can save costly syscalls).
When enabled, writes will always be queued till the next event loop
iteration. This is efficient when you do many small writes per iteration,
but less efficient when you do a single write only per iteration (or when
lib/AnyEvent/Handle.pm view on Meta::CPAN
my ($self) = @_;
if ($self->{$timeout} && $self->{fh}) {
my $NOW = AE::now;
# when would the timeout trigger?
my $after = $self->{$activity} + $self->{$timeout} - $NOW;
# now or in the past already?
if ($after <= 0) {
$self->{$activity} = $NOW;
if ($self->{$on_timeout}) {
$self->{$on_timeout}($self);
} else {
$self->_error (Errno::ETIMEDOUT);
}
# callback could have changed timeout value, optimise
return unless $self->{$timeout};
# calculate new after
$after = $self->{$timeout};
}
Scalar::Util::weaken $self;
return unless $self; # ->error could have destroyed $self
$self->{$tw} ||= AE::timer $after, 0, sub {
delete $self->{$tw};
$cb->($self);
};
} else {
delete $self->{$tw};
}
}
}
#############################################################################
=back
=head2 WRITE QUEUE
AnyEvent::Handle manages two queues per handle, one for writing and one
for reading.
The write queue is very simple: you can add data to its end, and
AnyEvent::Handle will automatically try to get rid of it for you.
When data could be written and the write buffer is shorter then the low
water mark, the C<on_drain> callback will be invoked once.
=over 4
=item $handle->on_drain ($cb)
Sets the C<on_drain> callback or clears it (see the description of
C<on_drain> in the constructor).
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
sub on_drain {
my ($self, $cb) = @_;
$self->{on_drain} = $cb;
$cb->($self)
if $cb && $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf});
}
=item $handle->push_write ($data)
Queues the given scalar to be written. You can push as much data as
you want (only limited by the available memory and C<wbuf_max>), as
C<AnyEvent::Handle> buffers it independently of the kernel.
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
sub _drain_wbuf {
my ($self) = @_;
if (!$self->{_ww} && length $self->{wbuf}) {
Scalar::Util::weaken $self;
my $cb = sub {
my $len = syswrite $self->{fh}, $self->{wbuf};
if (defined $len) {
substr $self->{wbuf}, 0, $len, "";
$self->{_activity} = $self->{_wactivity} = AE::now;
$self->{on_drain}($self)
if $self->{low_water_mark} >= (length $self->{wbuf}) + (length $self->{_tls_wbuf})
&& $self->{on_drain};
delete $self->{_ww} unless length $self->{wbuf};
} elsif ($! != EAGAIN && $! != EINTR && $! != EWOULDBLOCK && $! != WSAEWOULDBLOCK) {
$self->_error ($!, 1);
}
};
# try to write data immediately
$cb->() unless $self->{autocork};
# if still data left in wbuf, we need to poll
$self->{_ww} = AE::io $self->{fh}, 1, $cb
if length $self->{wbuf};
if (
defined $self->{wbuf_max}
&& $self->{wbuf_max} < length $self->{wbuf}
) {
$self->_error (Errno::ENOSPC, 1), return;
}
};
}
our %WH;
# deprecated
sub register_write_type($$) {
$WH{$_[0]} = $_[1];
}
sub push_write {
my $self = shift;
if (@_ > 1) {
my $type = shift;
@_ = ($WH{$type} ||= _load_func "$type\::anyevent_write_type"
or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_write")
lib/AnyEvent/Handle.pm view on Meta::CPAN
=cut
sub json_coder() {
eval { require JSON::XS; JSON::XS->new->utf8 }
|| do { require JSON::PP; JSON::PP->new->utf8 }
}
register_write_type json => sub {
my ($self, $ref) = @_;
($self->{json} ||= json_coder)
->encode ($ref)
};
sub cbor_coder() {
require CBOR::XS;
CBOR::XS->new
}
register_write_type cbor => sub {
my ($self, $scalar) = @_;
($self->{cbor} ||= cbor_coder)
->encode ($scalar)
};
=item storable => $reference
Freezes the given reference using L<Storable> and writes it to the
handle. Uses the C<nfreeze> format.
=cut
register_write_type storable => sub {
my ($self, $ref) = @_;
require Storable unless $Storable::VERSION;
pack "w/a*", Storable::nfreeze ($ref)
};
=back
=item $handle->push_shutdown
Sometimes you know you want to close the socket after writing your data
before it was actually written. One way to do that is to replace your
C<on_drain> handler by a callback that shuts down the socket (and set
C<low_water_mark> to C<0>). This method is a shorthand for just that, and
replaces the C<on_drain> callback with:
sub { shutdown $_[0]{fh}, 1 }
This simply shuts down the write side and signals an EOF condition to the
the peer.
You can rely on the normal read queue and C<on_eof> handling
afterwards. This is the cleanest way to close a connection.
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
sub push_shutdown {
my ($self) = @_;
delete $self->{low_water_mark};
$self->on_drain (sub { shutdown $_[0]{fh}, 1 });
}
=item custom write types - Package::anyevent_write_type $handle, @args
Instead of one of the predefined types, you can also specify the name of
a package. AnyEvent will try to load the package and then expects to find
a function named C<anyevent_write_type> inside. If it isn't found, it
progressively tries to load the parent package until it either finds the
function (good) or runs out of packages (bad).
Whenever the given C<type> is used, C<push_write> will the function with
the handle object and the remaining arguments.
The function is supposed to return a single octet string that will be
appended to the write buffer, so you can mentally treat this function as a
"arguments to on-the-wire-format" converter.
Example: implement a custom write type C<join> that joins the remaining
arguments using the first one.
$handle->push_write (My::Type => " ", 1,2,3);
# uses the following package, which can be defined in the "My::Type" or in
# the "My" modules to be auto-loaded, or just about anywhere when the
# My::Type::anyevent_write_type is defined before invoking it.
package My::Type;
sub anyevent_write_type {
my ($handle, $delim, @args) = @_;
join $delim, @args
}
=cut
#############################################################################
=back
=head2 READ QUEUE
AnyEvent::Handle manages two queues per handle, one for writing and one
for reading.
The read queue is more complex than the write queue. It can be used in two
ways, the "simple" way, using only C<on_read> and the "complex" way, using
a queue.
In the simple case, you just install an C<on_read> callback and whenever
new data arrives, it will be called. You can then remove some data (if
enough is there) from the read buffer (C<< $handle->rbuf >>). Or you can
leave the data there if you want to accumulate more (e.g. when only a
partial message has been received so far), or change the read queue with
e.g. C<push_read>.
In the more complex case, you want to queue multiple callbacks. In this
case, AnyEvent::Handle will call the first queued callback each time new
data arrives (also the first time it is queued) and remove it when it has
done its job (see C<push_read>, below).
This way you can, for example, push three line-reads, followed by reading
a chunk of data, and AnyEvent::Handle will execute them in order.
Example 1: EPP protocol parser. EPP sends 4 byte length info, followed by
the specified number of bytes which give an XML datagram.
# in the default state, expect some header bytes
$handle->on_read (sub {
# some data is here, now queue the length-header-read (4 octets)
shift->unshift_read (chunk => 4, sub {
# header arrived, decode
my $len = unpack "N", $_[1];
# now read the payload
shift->unshift_read (chunk => $len, sub {
my $xml = $_[1];
# handle xml
});
});
});
Example 2: Implement a client for a protocol that replies either with "OK"
and another line or "ERROR" for the first request that is sent, and 64
bytes for the second request. Due to the availability of a queue, we can
just pipeline sending both requests and manipulate the queue as necessary
in the callbacks.
When the first callback is called and sees an "OK" response, it will
C<unshift> another line-read. This line-read will be queued I<before> the
64-byte chunk callback.
# request one, returns either "OK + extra line" or "ERROR"
$handle->push_write ("request 1\015\012");
# we expect "ERROR" or "OK" as response, so push a line read
$handle->push_read (line => sub {
# if we got an "OK", we have to _prepend_ another line,
# so it will be read before the second request reads its 64 bytes
# which are already in the queue when this callback is called
# we don't do this in case we got an error
if ($_[1] eq "OK") {
$_[0]->unshift_read (line => sub {
my $response = $_[1];
...
});
}
});
# request two, simply returns 64 octets
$handle->push_write ("request 2\015\012");
# simply read 64 bytes, always
$handle->push_read (chunk => 64, sub {
my $response = $_[1];
...
});
=over 4
=cut
sub _drain_rbuf {
my ($self) = @_;
# avoid recursion
return if $self->{_skip_drain_rbuf};
local $self->{_skip_drain_rbuf} = 1;
while () {
# we need to use a separate tls read buffer, as we must not receive data while
# we are draining the buffer, and this can only happen with TLS.
$self->{rbuf} .= delete $self->{_tls_rbuf}
if exists $self->{_tls_rbuf};
my $len = length $self->{rbuf};
if (my $cb = shift @{ $self->{_queue} }) {
unless ($cb->($self)) {
# no progress can be made
# (not enough data and no data forthcoming)
$self->_error (Errno::EPIPE, 1), return
if $self->{_eof};
unshift @{ $self->{_queue} }, $cb;
last;
}
} elsif ($self->{on_read}) {
last unless $len;
$self->{on_read}($self);
if (
$len == length $self->{rbuf} # if no data has been consumed
&& !@{ $self->{_queue} } # and the queue is still empty
&& $self->{on_read} # but we still have on_read
) {
# no further data will arrive
# so no progress can be made
$self->_error (Errno::EPIPE, 1), return
if $self->{_eof};
last; # more data might arrive
}
} else {
# read side becomes idle
delete $self->{_rw} unless $self->{tls};
last;
}
}
if ($self->{_eof}) {
$self->{on_eof}
? $self->{on_eof}($self)
: $self->_error (0, 1, "Unexpected end-of-file");
return;
}
if (
defined $self->{rbuf_max}
&& $self->{rbuf_max} < length $self->{rbuf}
) {
$self->_error (Errno::ENOSPC, 1), return;
}
# may need to restart read watcher
unless ($self->{_rw}) {
$self->start_read
if $self->{on_read} || @{ $self->{_queue} };
}
}
=item $handle->on_read ($cb)
This replaces the currently set C<on_read> callback, or clears it (when
the new callback is C<undef>). See the description of C<on_read> in the
constructor.
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
sub on_read {
my ($self, $cb) = @_;
$self->{on_read} = $cb;
$self->_drain_rbuf if $cb;
}
=item $handle->rbuf
Returns the read buffer (as a modifiable lvalue). You can also access the
read buffer directly as the C<< ->{rbuf} >> member, if you want (this is
much faster, and no less clean).
The only operation allowed on the read buffer (apart from looking at it)
is removing data from its beginning. Otherwise modifying or appending to
it is not allowed and will lead to hard-to-track-down bugs.
NOTE: The read buffer should only be used or modified in the C<on_read>
callback or when C<push_read> or C<unshift_read> are used with a single
callback (i.e. untyped). Typed C<push_read> and C<unshift_read> methods
will manage the read buffer on their own.
=cut
sub rbuf : lvalue {
$_[0]{rbuf}
}
=item $handle->push_read ($cb)
=item $handle->unshift_read ($cb)
Append the given callback to the end of the queue (C<push_read>) or
prepend it (C<unshift_read>).
The callback is called each time some additional read data arrives.
It must check whether enough data is in the read buffer already.
If not enough data is available, it must return the empty list or a false
value, in which case it will be called repeatedly until enough data is
available (or an error condition is detected).
If enough data was available, then the callback must remove all data it is
interested in (which can be none at all) and return a true value. After returning
true, it will be removed from the queue.
These methods may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
our %RH;
sub register_read_type($$) {
$RH{$_[0]} = $_[1];
}
sub push_read {
my $self = shift;
my $cb = pop;
if (@_) {
my $type = shift;
$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::push_read")
->($self, $cb, @_);
}
push @{ $self->{_queue} }, $cb;
$self->_drain_rbuf;
}
sub unshift_read {
my $self = shift;
my $cb = pop;
if (@_) {
my $type = shift;
$cb = ($RH{$type} ||= _load_func "$type\::anyevent_read_type"
or Carp::croak "unsupported/unloadable type '$type' passed to AnyEvent::Handle::unshift_read")
->($self, $cb, @_);
}
unshift @{ $self->{_queue} }, $cb;
$self->_drain_rbuf;
}
=item $handle->push_read (type => @args, $cb)
=item $handle->unshift_read (type => @args, $cb)
Instead of providing a callback that parses the data itself you can chose
between a number of predefined parsing formats, for chunks of data, lines
etc. You can also specify the (fully qualified) name of a package, in
which case AnyEvent tries to load the package and then expects to find the
C<anyevent_read_type> function inside (see "custom read types", below).
Predefined types are (if you have ideas for additional types, feel free to
drop by and tell us):
=over 4
=item chunk => $octets, $cb->($handle, $data)
Invoke the callback only once C<$octets> bytes have been read. Pass the
lib/AnyEvent/Handle.pm view on Meta::CPAN
$hdl->push_read (tls_autostart => "accept");
$hdl->push_read (line => sub {
print "received ", ($_[0]{tls} ? "encrypted" : "cleartext"), " <$_[1]>\n";
});
=cut
register_read_type tls_detect => sub {
my ($self, $cb) = @_;
sub {
# this regex matches a full or partial tls record
if (
# ssl3+: type(22=handshake) major(=3) minor(any) length_hi
$self->{rbuf} =~ /^(?:\z| \x16 (\z| [\x03\x04] (?:\z| . (?:\z| [\x00-\x40] ))))/xs
# ssl2 comapatible: len_hi len_lo type(1) major minor dummy(forlength)
or $self->{rbuf} =~ /^(?:\z| [\x80-\xff] (?:\z| . (?:\z| \x01 (\z| [\x03\x04] (?:\z| . (?:\z| . ))))))/xs
) {
return if 3 != length $1; # partial match, can't decide yet
# full match, valid TLS record
my ($major, $minor) = unpack "CC", $1;
$cb->($self, "accept", $major, $minor);
} else {
# mismatch == guaranteed not TLS
$cb->($self, undef);
}
1
}
};
register_read_type tls_autostart => sub {
my ($self, @tls) = @_;
$RH{tls_detect}($self, sub {
return unless $_[1];
$_[0]->starttls (@tls);
})
};
=back
=item custom read types - Package::anyevent_read_type $handle, $cb, @args
Instead of one of the predefined types, you can also specify the name
of a package. AnyEvent will try to load the package and then expects to
find a function named C<anyevent_read_type> inside. If it isn't found, it
progressively tries to load the parent package until it either finds the
function (good) or runs out of packages (bad).
Whenever this type is used, C<push_read> will invoke the function with the
handle object, the original callback and the remaining arguments.
The function is supposed to return a callback (usually a closure) that
works as a plain read callback (see C<< ->push_read ($cb) >>), so you can
mentally treat the function as a "configurable read type to read callback"
converter.
It should invoke the original callback when it is done reading (remember
to pass C<$handle> as first argument as all other callbacks do that,
although there is no strict requirement on this).
For examples, see the source of this module (F<perldoc -m
AnyEvent::Handle>, search for C<register_read_type>)).
=item $handle->stop_read
=item $handle->start_read
In rare cases you actually do not want to read anything from the
socket. In this case you can call C<stop_read>. Neither C<on_read> nor
any queued callbacks will be executed then. To start reading again, call
C<start_read>.
Note that AnyEvent::Handle will automatically C<start_read> for you when
you change the C<on_read> callback or push/unshift a read callback, and it
will automatically C<stop_read> for you when neither C<on_read> is set nor
there are any read requests in the queue.
In older versions of this module (<= 5.3), these methods had no effect,
as TLS does not support half-duplex connections. In current versions they
work as expected, as this behaviour is required to avoid certain resource
attacks, where the program would be forced to read (and buffer) arbitrary
amounts of data before being able to send some data. The drawback is that
some readings of the the SSL/TLS specifications basically require this
attack to be working, as SSL/TLS implementations might stall sending data
during a rehandshake.
As a guideline, during the initial handshake, you should not stop reading,
and as a client, it might cause problems, depending on your application.
=cut
sub stop_read {
my ($self) = @_;
delete $self->{_rw};
}
sub start_read {
my ($self) = @_;
unless ($self->{_rw} || $self->{_eof} || !$self->{fh}) {
Scalar::Util::weaken $self;
$self->{_rw} = AE::io $self->{fh}, 0, sub {
my $rbuf = \($self->{tls} ? my $buf : $self->{rbuf});
my $len = sysread $self->{fh}, $$rbuf, $self->{read_size}, length $$rbuf;
if ($len > 0) {
$self->{_activity} = $self->{_ractivity} = AE::now;
if ($self->{tls}) {
Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
&_dotls ($self);
} else {
$self->_drain_rbuf;
}
if ($len == $self->{read_size}) {
$self->{read_size} *= 2;
$self->{read_size} = $self->{max_read_size} || MAX_READ_SIZE
if $self->{read_size} > ($self->{max_read_size} || MAX_READ_SIZE);
}
} elsif (defined $len) {
delete $self->{_rw};
$self->{_eof} = 1;
$self->_drain_rbuf;
} elsif ($! != EAGAIN && $! != EINTR && $! != EWOULDBLOCK && $! != WSAEWOULDBLOCK) {
lib/AnyEvent/Handle.pm view on Meta::CPAN
if ($self->{on_stoptls}) {
$self->{on_stoptls}($self);
return;
} else {
# let's treat SSL-eof as we treat normal EOF
delete $self->{_rw};
$self->{_eof} = 1;
}
}
$self->{_tls_rbuf} .= $tmp;
$self->_drain_rbuf;
$self->{tls} or return; # tls session might have gone away in callback
}
$tmp = Net::SSLeay::get_error ($self->{tls}, -1); # -1 is not neccessarily correct, but Net::SSLeay doesn't tell us
return $self->_tls_error ($tmp)
if $tmp != $ERROR_WANT_READ
&& ($tmp != $ERROR_SYSCALL || $!);
while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
$self->{wbuf} .= $tmp;
$self->_drain_wbuf;
$self->{tls} or return; # tls session might have gone away in callback
}
$self->{_on_starttls}
and Net::SSLeay::state ($self->{tls}) == Net::SSLeay::ST_OK ()
and (delete $self->{_on_starttls})->($self, 1, "TLS/SSL connection established");
}
=item $handle->starttls ($tls[, $tls_ctx])
Instead of starting TLS negotiation immediately when the AnyEvent::Handle
object is created, you can also do that at a later time by calling
C<starttls>. See the C<tls> constructor argument for general info.
Starting TLS is currently an asynchronous operation - when you push some
write data and then call C<< ->starttls >> then TLS negotiation will start
immediately, after which the queued write data is then sent. This might
change in future versions, so best make sure you have no outstanding write
data when calling this method.
The first argument is the same as the C<tls> constructor argument (either
C<"connect">, C<"accept"> or an existing Net::SSLeay object).
The second argument is the optional C<AnyEvent::TLS> object that is used
when AnyEvent::Handle has to create its own TLS connection object, or
a hash reference with C<< key => value >> pairs that will be used to
construct a new context.
The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
context in C<< $handle->{tls_ctx} >> after this call and can be used or
changed to your liking. Note that the handshake might have already started
when this function returns.
Due to bugs in OpenSSL, it might or might not be possible to do multiple
handshakes on the same stream. It is best to not attempt to use the
stream after stopping TLS.
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
our %TLS_CACHE; #TODO not yet documented, should we?
sub starttls {
my ($self, $tls, $ctx) = @_;
Carp::croak "It is an error to call starttls on an AnyEvent::Handle object while TLS is already active, caught"
if $self->{tls};
unless (defined $AnyEvent::TLS::VERSION) {
eval {
require Net::SSLeay;
require AnyEvent::TLS;
1
} or return $self->_error (Errno::EPROTO, 1, "TLS support not available on this system");
}
$self->{tls} = $tls;
$self->{tls_ctx} = $ctx if @_ > 2;
return unless $self->{fh};
$ERROR_SYSCALL = Net::SSLeay::ERROR_SYSCALL ();
$ERROR_WANT_READ = Net::SSLeay::ERROR_WANT_READ ();
$tls = delete $self->{tls};
$ctx = $self->{tls_ctx};
local $Carp::CarpLevel = 1; # skip ourselves when creating a new context or session
if ("HASH" eq ref $ctx) {
if ($ctx->{cache}) {
my $key = $ctx+0;
$ctx = $TLS_CACHE{$key} ||= new AnyEvent::TLS %$ctx;
} else {
$ctx = new AnyEvent::TLS %$ctx;
}
}
$self->{tls_ctx} = $ctx || TLS_CTX ();
$self->{tls} = $tls = $self->{tls_ctx}->_get_session ($tls, $self, $self->{peername});
# basically, this is deep magic (because SSL_read should have the same issues)
# but the openssl maintainers basically said: "trust us, it just works".
# (unfortunately, we have to hardcode constants because the abysmally misdesigned
# and mismaintained ssleay-module didn't offer them for a decade or so).
# http://www.mail-archive.com/openssl-dev@openssl.org/msg22420.html
#
# in short: this is a mess.
#
# note that we do not try to keep the length constant between writes as we are required to do.
# we assume that most (but not all) of this insanity only applies to non-blocking cases,
# and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
# have identity issues in that area.
# Net::SSLeay::set_mode ($ssl,
# (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
# | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
Net::SSLeay::set_mode ($tls, 1|2);
$self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
$self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
Net::SSLeay::BIO_write ($self->{_rbio}, $self->{rbuf});
$self->{rbuf} = "";
Net::SSLeay::set_bio ($tls, $self->{_rbio}, $self->{_wbio});
$self->{_on_starttls} = sub { $_[0]{on_starttls}(@_) }
if $self->{on_starttls};
&_dotls; # need to trigger the initial handshake
$self->start_read; # make sure we actually do read
}
=item $handle->stoptls
Shuts down the SSL connection - this makes a proper EOF handshake by
sending a close notify to the other side, but since OpenSSL doesn't
support non-blocking shut downs, it is not guaranteed that you can re-use
the stream afterwards.
This method may invoke callbacks (and therefore the handle might be
destroyed after it returns).
=cut
sub stoptls {
my ($self) = @_;
if ($self->{tls} && $self->{fh}) {
Net::SSLeay::shutdown ($self->{tls});
&_dotls;
# # we don't give a shit. no, we do, but we can't. no...#d#
# # we, we... have to use openssl :/#d#
# &_freetls;#d#
}
}
sub _freetls {
my ($self) = @_;
return unless $self->{tls};
$self->{tls_ctx}->_put_session (delete $self->{tls})
if $self->{tls} > 0;
delete @$self{qw(_rbio _wbio _tls_wbuf _on_starttls)};
}
=item $handle->resettls
This rarely-used method simply resets and TLS state on the handle, usually
causing data loss.
One case where it may be useful is when you want to skip over the data in
the stream but you are not interested in interpreting it, so data loss is
no concern.
=cut
*resettls = \&_freetls;
sub DESTROY {
my ($self) = @_;
&_freetls;
my $linger = exists $self->{linger} ? $self->{linger} : 3600;
if ($linger && length $self->{wbuf} && $self->{fh}) {
my $fh = delete $self->{fh};
my $wbuf = delete $self->{wbuf};
my @linger;
push @linger, AE::io $fh, 1, sub {
my $len = syswrite $fh, $wbuf, length $wbuf;
if ($len > 0) {
substr $wbuf, 0, $len, "";
} elsif (defined $len || ($! != EAGAIN && $! != EINTR && $! != EWOULDBLOCK && $! != WSAEWOULDBLOCK)) {
@linger = (); # end
}
};
push @linger, AE::timer $linger, 0, sub {
@linger = ();
};
}
}
=item $handle->destroy
Shuts down the handle object as much as possible - this call ensures that
no further callbacks will be invoked and as many resources as possible
will be freed. Any method you will call on the handle object after
destroying it in this way will be silently ignored (and it will return the
empty list).
Normally, you can just "forget" any references to an AnyEvent::Handle
object and it will simply shut down. This works in fatal error and EOF
callbacks, as well as code outside. It does I<NOT> work in a read or write
callback, so when you want to destroy the AnyEvent::Handle object from
within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
that case.
Destroying the handle object in this way has the advantage that callbacks
will be removed as well, so if those are the only reference holders (as
is common), then one doesn't need to do anything special to break any
reference cycles.
The handle might still linger in the background and write out remaining
data, as specified by the C<linger> option, however.
=cut
sub destroy {
my ($self) = @_;
$self->DESTROY;
%$self = ();
bless $self, "AnyEvent::Handle::destroyed";
}
sub AnyEvent::Handle::destroyed::AUTOLOAD {
#nop
}
=item $handle->destroyed
Returns false as long as the handle hasn't been destroyed by a call to C<<
->destroy >>, true otherwise.
Can be useful to decide whether the handle is still valid after some
callback possibly destroyed the handle. For example, C<< ->push_write >>,
C<< ->starttls >> and other methods can call user callbacks, which in turn
can destroy the handle, so work can be avoided by checking sometimes:
$hdl->starttls ("accept");
return if $hdl->destroyed;
$hdl->push_write (...
Note that the call to C<push_write> will silently be ignored if the handle
has been destroyed, so often you can just ignore the possibility of the
handle being destroyed.
=cut
sub destroyed { 0 }
sub AnyEvent::Handle::destroyed::destroyed { 1 }
=item AnyEvent::Handle::TLS_CTX
This function creates and returns the AnyEvent::TLS object used by default
for TLS mode.
The context is created by calling L<AnyEvent::TLS> without any arguments.
=cut
our $TLS_CTX;
sub TLS_CTX() {
$TLS_CTX ||= do {
require AnyEvent::TLS;
new AnyEvent::TLS
}
}
=back
=head1 NONFREQUENTLY ASKED QUESTIONS
=over 4
=item I C<undef> the AnyEvent::Handle reference inside my callback and
still get further invocations!
That's because AnyEvent::Handle keeps a reference to itself when handling
read or write callbacks.
It is only safe to "forget" the reference inside EOF or error callbacks,
from within all other callbacks, you need to explicitly call the C<<
->destroy >> method.
=item Why is my C<on_eof> callback never called?
Probably because your C<on_error> callback is being called instead: When
you have outstanding requests in your read queue, then an EOF is
considered an error as you clearly expected some data.
To avoid this, make sure you have an empty read queue whenever your handle
is supposed to be "idle" (i.e. connection closes are O.K.). You can set
an C<on_read> handler that simply pushes the first read requests in the
queue.
See also the next question, which explains this in a bit more detail.
=item How can I serve requests in a loop?
Most protocols consist of some setup phase (authentication for example)
followed by a request handling phase, where the server waits for requests
and handles them, in a loop.
There are two important variants: The first (traditional, better) variant
handles requests until the server gets some QUIT command, causing it to
close the connection first (highly desirable for a busy TCP server). A
client dropping the connection is an error, which means this variant can
detect an unexpected detection close.
To handle this case, always make sure you have a non-empty read queue, by
pushing the "read request start" handler on it:
# we assume a request starts with a single line
my @start_request; @start_request = (line => sub {
my ($hdl, $line) = @_;
... handle request
# push next request read, possibly from a nested callback
$hdl->push_read (@start_request);
});
# auth done, now go into request handling loop
# now push the first @start_request
$hdl->push_read (@start_request);
By always having an outstanding C<push_read>, the handle always expects
some data and raises the C<EPIPE> error when the connction is dropped
unexpectedly.
The second variant is a protocol where the client can drop the connection
at any time. For TCP, this means that the server machine may run out of
sockets easier, and in general, it means you cannot distinguish a protocl
failure/client crash from a normal connection close. Nevertheless, these
kinds of protocols are common (and sometimes even the best solution to the
problem).
Having an outstanding read request at all times is possible if you ignore
C<EPIPE> errors, but this doesn't help with when the client drops the
connection during a request, which would still be an error.
A better solution is to push the initial request read in an C<on_read>
( run in 0.883 second using v1.01-cache-2.11-cpan-39bf76dae61 )