[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent/Handle.pm

Comparing AnyEvent/lib/AnyEvent/Handle.pm (file contents):
Revision 1.94 by root, Wed Oct 1 15:50:33 2008 UTC vs.
Revision 1.134 by root, Fri Jul 3 00:09:04 2009 UTC

 AnyEvent::Handle - non-blocking I/O on file handles via AnyEvent
 =cut
-our $VERSION = 4.3;
+our $VERSION = 4.45;
 =head1 SYNOPSIS
    use AnyEvent;
    use AnyEvent::Handle;
    my $handle =
       AnyEvent::Handle->new (
          fh => \*STDIN,
          on_eof => sub {
-            $cv->broadcast;
+            $cv->send;
          },
       );
    # send some request line
    $handle->push_write ("getinfo\015\012");
 treatment of characters applies to this module as well.
 All callbacks will be invoked with the handle object as their first
 argument.
-=head2 SIGPIPE is not handled by this module
-SIGPIPE is not handled by this module, so one of the practical
-requirements of using it is to ignore SIGPIPE (C<$SIG{PIPE} =
-'IGNORE'>). At least, this is highly recommend in a networked program: If
-you use AnyEvent::Handle in a filter program (like sort), exiting on
-SIGPIPE is probably the right thing to do.
 =head1 METHODS
 =over 4
-=item B<new (%args)>
+=item $handle = B<new> AnyEvent::TLS fh => $filehandle, key => value...
-The constructor supports these arguments (all as key => value pairs).
+The constructor supports these arguments (all as C<< key => value >> pairs).
 =over 4
 =item fh => $filehandle [MANDATORY]
 Set the callback to be called when an end-of-file condition is detected,
 i.e. in the case of a socket, when the other side has closed the
 connection cleanly.
 For sockets, this just means that the other side has stopped sending data,
-you can still try to write data, and, in fact, one can return from the eof
+you can still try to write data, and, in fact, one can return from the EOF
 callback and continue writing data, as only the read part has been shut
 down.
-While not mandatory, it is I<highly> recommended to set an eof callback,
+While not mandatory, it is I<highly> recommended to set an EOF callback,
 otherwise you might end up with a closed socket while you are still
 waiting for data.
 If an EOF condition has been detected but no C<on_eof> callback has been
 set, then a fatal error will be raised with C<$!> set to <0>.
-=item on_error => $cb->($handle, $fatal)
+=item on_error => $cb->($handle, $fatal, $message)
 This is the error callback, which is called when, well, some error
 occured, such as not being able to resolve the hostname, failure to
 connect or a read error.
 fatal errors the handle object will be shut down and will not be usable
 (but you are free to look at the current C<< ->rbuf >>). Examples of fatal
 errors are an EOF condition with active (but unsatisifable) read watchers
 (C<EPIPE>) or I/O errors.
+AnyEvent::Handle tries to find an appropriate error code for you to check
+against, but in some cases (TLS errors), this does not work well. It is
+recommended to always output the C<$message> argument in human-readable
+error messages (it's usually the same as C<"$!">).
 Non-fatal errors can be retried by simply returning, but it is recommended
 to simply ignore this parameter and instead abondon the handle object
 when this callback is invoked. Examples of non-fatal errors are timeouts
 C<ETIMEDOUT>) or badly-formatted data (C<EBADMSG>).
 On callback entrance, the value of C<$!> contains the operating system
-error (or C<ENOSPC>, C<EPIPE>, C<ETIMEDOUT> or C<EBADMSG>).
+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 simply calls
 C<croak>.
 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<$handle->{rbuf}> member directly.
+method or access the C<$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.
 When an EOF condition is detected then 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>).
 This will not work for partial TLS data that could not be encoded
 yet. This data will be lost. Calling the C<stoptls> method in time might
 help.
+=item peername => $string
+A string used to identify the remote site - usually the DNS hostname
+(I<not> IDN!) used to create the connection, rarely the IP address.
+Apart from being useful in error messages, this string is also used in TLS
+common name verification (see C<verify_cn> in L<AnyEvent::TLS>).
 =item tls => "accept" | "connect" | Net::SSLeay::SSL object
 When this parameter is given, it enables TLS (SSL) mode, that means
 AnyEvent will start a TLS handshake as soon as the conenction has been
 established and will transparently encrypt/decrypt data afterwards.
+All TLS protocol errors will be signalled as C<EPROTO>, with an
+appropriate error message.
 TLS mode requires Net::SSLeay to be installed (it will be loaded
 automatically when you try to create a TLS handle): this module doesn't
 have a dependency on that module, so if your module requires it, you have
 to add the dependency yourself.
 mode.
 You can also provide your own TLS connection object, but you have
 to make sure that you call either C<Net::SSLeay::set_connect_state>
 or C<Net::SSLeay::set_accept_state> on it before you pass it to
-AnyEvent::Handle.
+AnyEvent::Handle. Also, this module will take ownership of this connection
+object.
+At some future point, AnyEvent::Handle might switch to another TLS
+implementation, then the option to use your own session object will go
+away.
+B<IMPORTANT:> since Net::SSLeay "objects" are really only integers,
+passing in the wrong integer will lead to certain crash. This most often
+happens when one uses a stylish C<< tls => 1 >> and is surprised about the
+segmentation fault.
 See the C<< ->starttls >> method for when need to start TLS negotiation later.
-=item tls_ctx => $ssl_ctx
+=item tls_ctx => $anyevent_tls
-Use the given C<Net::SSLeay::CTX> object to create the new TLS connection
+Use the given C<AnyEvent::TLS> object to create the new TLS connection
 (unless a connection object was specified directly). If this parameter is
 missing, then AnyEvent::Handle will use C<AnyEvent::Handle::TLS_CTX>.
+Instead of an object, you can also specify a hash reference with C<< key
+=> value >> pairs. Those will be passed to L<AnyEvent::TLS> to create a
+new TLS context object.
 =item json => JSON or JSON::XS object
 This is the json coder object used by the C<json> read and write types.
 =cut
 sub new {
    my $class = shift;
    my $self = bless { @_ }, $class;
    $self->{fh} or Carp::croak "mandatory argument fh is missing";
    AnyEvent::Util::fh_nonblocking $self->{fh}, 1;
+   $self->{_activity} = AnyEvent->now;
+   $self->_timeout;
+   $self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
    $self->starttls (delete $self->{tls}, delete $self->{tls_ctx})
       if $self->{tls};
-   $self->{_activity} = AnyEvent->now;
-   $self->_timeout;
    $self->on_drain (delete $self->{on_drain}) if exists $self->{on_drain};
-   $self->no_delay (delete $self->{no_delay}) if exists $self->{no_delay};
    $self->start_read
       if $self->{on_read};
-   $self
+   $self->{fh} && $self
 }
 sub _shutdown {
    my ($self) = @_;
-   delete $self->{_tw};
+   delete @$self{qw(_tw _rw _ww fh wbuf on_read _queue)};
-   delete $self->{_rw};
+   $self->{_eof} = 1; # tell starttls et. al to stop trying
-   delete $self->{_ww};
-   delete $self->{fh};
    &_freetls;
-   delete $self->{on_read};
-   delete $self->{_queue};
 }
 sub _error {
-   my ($self, $errno, $fatal) = @_;
+   my ($self, $errno, $fatal, $message) = @_;
    $self->_shutdown
       if $fatal;
    $! = $errno;
+   $message ||= "$!";
    if ($self->{on_error}) {
-      $self->{on_error}($self, $fatal);
+      $self->{on_error}($self, $fatal, $message);
-   } else {
+   } elsif ($self->{fh}) {
-      Carp::croak "AnyEvent::Handle uncaught error: $!";
+      Carp::croak "AnyEvent::Handle uncaught error: $message";
    }
 }
 =item $fh = $handle->fh
 }
 =item $handle->autocork ($boolean)
 Enables or disables the current autocork behaviour (see C<autocork>
-constructor argument).
+constructor argument). Changes will only take effect on the next write.
 =cut
+sub autocork {
+   $_[0]{autocork} = $_[1];
+}
 =item $handle->no_delay ($boolean)
 Enables or disables the C<no_delay> setting (see constructor argument of
 the same name for details).
            ->($self, @_);
    }
    if ($self->{tls}) {
       $self->{_tls_wbuf} .= $_[0];
       &_dotls ($self);
    } else {
       $self->{wbuf} .= $_[0];
       $self->_drain_wbuf;
    }
 =cut
 register_write_type netstring => sub {
    my ($self, $string) = @_;
-   sprintf "%d:%s,", (length $string), $string
+   (length $string) . ":$string,"
 };
 =item packstring => $format, $data
 An octet string prefixed with an encoded length. The encoding C<$format>
    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. This method
+is a shorthand for just that, and replaces the C<on_drain> callback with:
+   sub { shutdown $_[0]{fh}, 1 }    # for push_shutdown
+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.
+=cut
+sub push_shutdown {
+   $_[0]->{on_drain} = sub { shutdown $_[0]{fh}, 1 };
+}
 =item AnyEvent::Handle::register_write_type type => $coderef->($handle, @args)
 This function (not method) lets you add your own types to C<push_write>.
 Whenever the given C<type> is used, C<push_write> will invoke the code
    ) {
       $self->_error (&Errno::ENOSPC, 1), return;
    }
    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->($self)) {
             if ($self->{_eof}) {
 =item $handle->rbuf
 Returns the read buffer (as a modifiable lvalue).
-You can access the read buffer directly as the C<< ->{rbuf} >> member, if
+You can access the read buffer directly as the C<< ->{rbuf} >>
-you want.
+member, if you want. However, the only operation allowed on the
+read buffer (apart from looking at it) is removing data from its
+beginning. Otherwise modifying or appending to it is not allowed and will
+lead to hard-to-track-down bugs.
 NOTE: The read buffer should only be used or modified if the C<on_read>,
 C<push_read> or C<unshift_read> methods are used. The other read methods
 automatically manage the read buffer.
 An octet string prefixed with an encoded length. The encoding C<$format>
 uses the same format as a Perl C<pack> format, but must specify a single
 integer only (only one of C<cCsSlLqQiInNvVjJw> is allowed, plus an
 optional C<!>, C<< < >> or C<< > >> modifier).
-DNS over TCP uses a prefix of C<n>, EPP uses a prefix of C<N>.
+For example, DNS over TCP uses a prefix of C<n> (2 octet network order),
+EPP uses a prefix of C<N> (4 octtes).
 Example: read a block of data prefixed by its length in BER-encoded
 format (very efficient).
    $handle->push_read (packstring => "w", sub {
    }
 };
 =item json => $cb->($handle, $hash_or_arrayref)
-Reads a JSON object or array, decodes it and passes it to the callback.
+Reads a JSON object or array, decodes it and passes it to the
+callback. When a parse error occurs, an C<EBADMSG> error will be raised.
 If a C<json> object was passed to the constructor, then that will be used
 for the final decode, otherwise it will create a JSON coder expecting UTF-8.
 This read type uses the incremental parser available with JSON version
    my $rbuf = \$self->{rbuf};
    my $json = $self->{json} ||= JSON->new->utf8;
    sub {
-      my $ref = $json->incr_parse ($self->{rbuf});
+      my $ref = eval { $json->incr_parse ($self->{rbuf}) };
       if ($ref) {
          $self->{rbuf} = $json->incr_text;
          $json->incr_text = "";
          $cb->($self, $ref);
          1
+      } elsif ($@) {
+         # error case
+         $json->incr_skip;
+         $self->{rbuf} = $json->incr_text;
+         $json->incr_text = "";
+         $self->_error (&Errno::EBADMSG);
+         ()
       } else {
          $self->{rbuf} = "";
          ()
       }
    }
 };
          if ($len > 0) {
             $self->{_activity} = AnyEvent->now;
             if ($self->{tls}) {
                Net::SSLeay::BIO_write ($self->{_rbio}, $$rbuf);
                &_dotls ($self);
             } else {
                $self->_drain_rbuf unless $self->{_in_drain};
             }
          }
       });
    }
 }
+our $ERROR_SYSCALL;
+our $ERROR_WANT_READ;
+our $ERROR_ZERO_RETURN;
+sub _tls_error {
+   my ($self, $err) = @_;
+      warn "$err,$!\n";#d#
+   return $self->_error ($!, 1)
+      if $err == Net::SSLeay::ERROR_SYSCALL ();
+   $self->_error (&Errno::EPROTO, 1,
+                  Net::SSLeay::ERR_error_string (Net::SSLeay::ERR_get_error ()));
+}
+# poll the write BIO and send the data if applicable
+# also decode read data if possible
+# this is basiclaly our TLS state machine
+# more efficient implementations are possible with openssl,
+# but not with the buggy and incomplete Net::SSLeay.
 sub _dotls {
    my ($self) = @_;
-   my $buf;
+   my $tmp;
    if (length $self->{_tls_wbuf}) {
-      while ((my $len = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
+      while (($tmp = Net::SSLeay::write ($self->{tls}, $self->{_tls_wbuf})) > 0) {
-         substr $self->{_tls_wbuf}, 0, $len, "";
+         substr $self->{_tls_wbuf}, 0, $tmp, "";
       }
-   }
+      $tmp = Net::SSLeay::get_error ($self->{tls}, $tmp);
+      return $self->_tls_error ($tmp)
+         if $tmp != $ERROR_WANT_READ
+            && ($tmp != $ERROR_SYSCALL || $!)
+            && $tmp != $ERROR_ZERO_RETURN;
+   }
-   while (defined ($buf = Net::SSLeay::read ($self->{tls}))) {
+   while (defined ($tmp = Net::SSLeay::read ($self->{tls}))) {
-      unless (length $buf) {
+      unless (length $tmp) {
          # let's treat SSL-eof as we treat normal EOF
          delete $self->{_rw};
          $self->{_eof} = 1;
          &_freetls;
       }
-      $self->{rbuf} .= $buf;
+      $self->{_tls_rbuf} .= $tmp;
       $self->_drain_rbuf unless $self->{_in_drain};
       $self->{tls} or return; # tls session might have gone away in callback
    }
-   my $err = Net::SSLeay::get_error ($self->{tls}, -1);
+   $tmp = Net::SSLeay::get_error ($self->{tls}, -1);
-   if ($err!= Net::SSLeay::ERROR_WANT_READ ()) {
-      if ($err == Net::SSLeay::ERROR_SYSCALL ()) {
-         return $self->_error ($!, 1);
+   return $self->_tls_error ($tmp)
-      } elsif ($err == Net::SSLeay::ERROR_SSL ())  {
+      if $tmp != $ERROR_WANT_READ
-         return $self->_error (&Errno::EIO, 1);
+         && ($tmp != $ERROR_SYSCALL || $!)
-      }
+         && $tmp != $ERROR_ZERO_RETURN;
-      # all others are fine for our purposes
-   }
-   if (length ($buf = Net::SSLeay::BIO_read ($self->{_wbio}))) {
+   while (length ($tmp = Net::SSLeay::BIO_read ($self->{_wbio}))) {
-      $self->{wbuf} .= $buf;
+      $self->{wbuf} .= $tmp;
       $self->_drain_wbuf;
    }
 }
 =item $handle->starttls ($tls[, $tls_ctx])
 C<starttls>.
 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<Net::SSLeay::CTX> object that is
+The second argument is the optional C<AnyEvent::TLS> object that is used
-used when AnyEvent::Handle has to create its own TLS connection object.
+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} >> after this
+The TLS connection object will end up in C<< $handle->{tls} >>, the TLS
-call and can be used or changed to your liking. Note that the handshake
+context in C<< $handle->{tls_ctx} >> after this call and can be used or
-might have already started when this function returns.
+changed to your liking. Note that the handshake might have already started
+when this function returns.
 If it an error to start a TLS handshake more than once per
 AnyEvent::Handle object (this is due to bugs in OpenSSL).
 =cut
 sub starttls {
    my ($self, $ssl, $ctx) = @_;
    require Net::SSLeay;
-   Carp::croak "it is an error to call starttls more than once on an Anyevent::Handle object"
+   Carp::croak "it is an error to call starttls more than once on an AnyEvent::Handle object"
       if $self->{tls};
+   $ERROR_SYSCALL     = Net::SSLeay::ERROR_SYSCALL     ();
+   $ERROR_WANT_READ   = Net::SSLeay::ERROR_WANT_READ   ();
+   $ERROR_ZERO_RETURN = Net::SSLeay::ERROR_ZERO_RETURN ();
+   $ctx ||= $self->{tls_ctx};
+   if ("HASH" eq ref $ctx) {
+      require AnyEvent::TLS;
+      local $Carp::CarpLevel = 1; # skip ourselves when creating a new context
+      $ctx = new AnyEvent::TLS %$ctx;
+   }
-   if ($ssl eq "accept") {
+   $self->{tls_ctx} = $ctx || TLS_CTX ();
-      $ssl = Net::SSLeay::new ($ctx || TLS_CTX ());
+   $self->{tls}     = $ssl = $self->{tls_ctx}->_get_session ($ssl, $self, $self->{peername});
-      Net::SSLeay::set_accept_state ($ssl);
-   } elsif ($ssl eq "connect") {
-      $ssl = Net::SSLeay::new ($ctx || TLS_CTX ());
-      Net::SSLeay::set_connect_state ($ssl);
-   }
-   $self->{tls} = $ssl;
    # basically, this is deep magic (because SSL_read should have the same issues)
    # but the openssl maintainers basically said: "trust us, it just works".
    # (unfortunately, we have to hardcode constants because the abysmally misdesigned
    # and mismaintained ssleay-module doesn't even offer them).
    #
    # note that we do not try to keep the length constant between writes as we are required to do.
    # we assume that most (but not all) of this insanity only applies to non-blocking cases,
    # and we drive openssl fully in blocking mode here. Or maybe we don't - openssl seems to
    # have identity issues in that area.
-   Net::SSLeay::CTX_set_mode ($self->{tls},
+#   Net::SSLeay::CTX_set_mode ($ssl,
-      (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
+#      (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ENABLE_PARTIAL_WRITE () } || 1)
-      | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
+#      | (eval { local $SIG{__DIE__}; Net::SSLeay::MODE_ACCEPT_MOVING_WRITE_BUFFER () } || 2));
+   Net::SSLeay::CTX_set_mode ($ssl, 1|2);
    $self->{_rbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
    $self->{_wbio} = Net::SSLeay::BIO_new (Net::SSLeay::BIO_s_mem ());
    Net::SSLeay::set_bio ($ssl, $self->{_rbio}, $self->{_wbio});
 sub _freetls {
    my ($self) = @_;
    return unless $self->{tls};
-   Net::SSLeay::free (delete $self->{tls});
+   $self->{tls_ctx}->_put_session (delete $self->{tls});
    delete @$self{qw(_rbio _wbio _tls_wbuf)};
 }
 sub DESTROY {
-   my $self = shift;
+   my ($self) = @_;
    &_freetls;
    my $linger = exists $self->{linger} ? $self->{linger} : 3600;
          @linger = ();
       });
    }
 }
+=item $handle->destroy
+Shuts down the handle object as much as possible - this call ensures that
+no further callbacks will be invoked and resources will be freed as much
+as possible. You must not call any methods on the object afterwards.
+Normally, you can just "forget" any references to an AnyEvent::Handle
+object and it will simply shut down. This works in fatal error and EOF
+callbacks, as well as code outside. It does I<NOT> work in a read or write
+callback, so when you want to destroy the AnyEvent::Handle object from
+within such an callback. You I<MUST> call C<< ->destroy >> explicitly in
+that case.
+The handle might still linger in the background and write out remaining
+data, as specified by the C<linger> option, however.
+=cut
+sub destroy {
+   my ($self) = @_;
+   $self->DESTROY;
+   %$self = ();
+}
 =item AnyEvent::Handle::TLS_CTX
-This function creates and returns the Net::SSLeay::CTX object used by
+This function creates and returns the AnyEvent::TLS object used by default
-default for TLS mode.
+for TLS mode.
-The context is created like this:
+The context is created by calling L<AnyEvent::TLS> without any arguments.
-   Net::SSLeay::load_error_strings;
-   Net::SSLeay::SSLeay_add_ssl_algorithms;
-   Net::SSLeay::randomize;
-   my $CTX = Net::SSLeay::CTX_new;
-   Net::SSLeay::CTX_set_options $CTX, Net::SSLeay::OP_ALL
 =cut
 our $TLS_CTX;
 sub TLS_CTX() {
-   $TLS_CTX || do {
+   $TLS_CTX ||= do {
-      require Net::SSLeay;
+      require AnyEvent::TLS;
-      Net::SSLeay::load_error_strings ();
+      new AnyEvent::TLS
-      Net::SSLeay::SSLeay_add_ssl_algorithms ();
-      Net::SSLeay::randomize ();
-      $TLS_CTX = Net::SSLeay::CTX_new ();
-      Net::SSLeay::CTX_set_options ($TLS_CTX, Net::SSLeay::OP_ALL ());
-      $TLS_CTX
    }
 }
 =back
+=head1 NONFREQUENTLY ASKED QUESTIONS
+=over 4
+=item I C<undef> the AnyEvent::Handle reference inside my callback and
+still get further invocations!
+That's because AnyEvent::Handle keeps a reference to itself when handling
+read or write callbacks.
+It is only safe to "forget" the reference inside EOF or error callbacks,
+from within all other callbacks, you need to explicitly call the C<<
+->destroy >> method.
+=item I get different callback invocations in TLS mode/Why can't I pause
+reading?
+Unlike, say, TCP, TLS connections do not consist of two independent
+communication channels, one for each direction. Or put differently. The
+read and write directions are not independent of each other: you cannot
+write data unless you are also prepared to read, and vice versa.
+This can mean than, in TLS mode, you might get C<on_error> or C<on_eof>
+callback invocations when you are not expecting any read data - the reason
+is that AnyEvent::Handle always reads in TLS mode.
+During the connection, you have to make sure that you always have a
+non-empty read-queue, or an C<on_read> watcher. At the end of the
+connection (or when you no longer want to use it) you can call the
+C<destroy> method.
+=item How do I read data until the other side closes the connection?
+If you just want to read your data into a perl scalar, the easiest way
+to achieve this is by setting an C<on_read> callback that does nothing,
+clearing the C<on_eof> callback and in the C<on_error> callback, the data
+will be in C<$_[0]{rbuf}>:
+   $handle->on_read (sub { });
+   $handle->on_eof (undef);
+   $handle->on_error (sub {
+      my $data = delete $_[0]{rbuf};
+      undef $handle;
+   });
+The reason to use C<on_error> is that TCP connections, due to latencies
+and packets loss, might get closed quite violently with an error, when in
+fact, all data has been received.
+It is usually better to use acknowledgements when transferring data,
+to make sure the other side hasn't just died and you got the data
+intact. This is also one reason why so many internet protocols have an
+explicit QUIT command.
+=item I don't want to destroy the handle too early - how do I wait until
+all data has been written?
+After writing your last bits of data, set the C<on_drain> callback
+and destroy the handle in there - with the default setting of
+C<low_water_mark> this will be called precisely when all data has been
+written to the socket:
+   $handle->push_write (...);
+   $handle->on_drain (sub {
+      warn "all data submitted to the kernel\n";
+      undef $handle;
+   });
+=back
 =head1 SUBCLASSING AnyEvent::Handle
 In many cases, you might want to subclass AnyEvent::Handle.

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Comparing AnyEvent/lib/AnyEvent/Handle.pm (file contents): Revision 1.94 by root, Wed Oct 1 15:50:33 2008 UTC vs. Revision 1.134 by root, Fri Jul 3 00:09:04 2009 UTC

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Comparing AnyEvent/lib/AnyEvent/Handle.pm (file contents):
Revision 1.94 by root, Wed Oct 1 15:50:33 2008 UTC vs.
Revision 1.134 by root, Fri Jul 3 00:09:04 2009 UTC