Class: EventMachine::Connection

Inherits:
Object
  • Object
show all
Defined in:
lib/em/connection.rb

Overview

EventMachine::Connection is a class that is instantiated by EventMachine's processing loop whenever a new connection is created. (New connections can be either initiated locally to a remote server or accepted locally from a remote client.) When a Connection object is instantiated, it mixes in the functionality contained in the user-defined module specified in calls to connect or start_server. User-defined handler modules may redefine any or all of the standard methods defined here, as well as add arbitrary additional code that will also be mixed in.

EventMachine manages one object inherited from EventMachine::Connection (and containing the mixed-in user code) for every network connection that is active at any given time. The event loop will automatically call methods on EventMachine::Connection objects whenever specific events occur on the corresponding connections, as described below.

This class is never instantiated by user code, and does not publish an initialize method. The instance methods of EventMachine::Connection which may be called by the event loop are:

All of the other instance methods defined here are called only by user code.

See Also:

Direct Known Subclasses

DNS::Socket, DeferrableChildProcess, FileWatch, ProcessWatch, Protocols::HeaderAndContentProtocol, Protocols::HttpClient, Protocols::HttpClient2, Protocols::LineAndTextProtocol, Protocols::Postgres3, Protocols::SmtpClient, Protocols::SmtpServer, Protocols::Socks4

Instance Method Summary (collapse)

Instance Method Details

- (Object) close_connection(after_writing = false)

EventMachine::Connection#close_connection is called only by user code, and never by the event loop. You may call this method against a connection object in any callback handler, whether or not the callback was made against the connection you want to close. close_connection schedules the connection to be closed at the next available opportunity within the event loop. You may not assume that the connection is closed when close_connection returns. In particular, the framework will callback the unbind method for the particular connection at a point shortly after you call close_connection. You may assume that the unbind callback will take place sometime after your call to close_connection completes. In other words, the unbind callback will not re-enter your code "inside" of your call to close_connection. However, it's not guaranteed that a future version of EventMachine will not change this behavior.

#close_connection will silently discard any outbound data which you have sent to the connection using #send_data but which has not yet been sent across the network. If you want to avoid this behavior, use #close_connection_after_writing.



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# File 'lib/em/connection.rb', line 265

def close_connection after_writing = false
  EventMachine::close_connection @signature, after_writing
end

- (Object) close_connection_after_writing

A variant of #close_connection. All of the descriptive comments given for close_connection also apply to close_connection_after_writing, with one exception: if the connection has outbound data sent using send_dat but which has not yet been sent across the network, close_connection_after_writing will schedule the connection to be closed after all of the outbound data has been safely written to the remote peer.

Depending on the amount of outgoing data and the speed of the network, considerable time may elapse between your call to close_connection_after_writing and the actual closing of the socket (at which time the unbind callback will be called by the event loop). During this time, you may not call send_data to transmit additional data (that is, the connection is closed for further writes). In very rare cases, you may experience a receive_data callback after your call to #close_connection_after_writing, depending on whether incoming data was in the process of being received on the connection at the moment when you called #close_connection_after_writing. Your protocol handler must be prepared to properly deal with such data (probably by ignoring it).



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# File 'lib/em/connection.rb', line 302

def close_connection_after_writing
  close_connection true
end

- (Object) comm_inactivity_timeout

comm_inactivity_timeout returns the current value (float in seconds) of the inactivity-timeout property of network-connection and datagram-socket objects. A nonzero value indicates that the connection or socket will automatically be closed if no read or write activity takes place for at least that number of seconds. A zero value (the default) specifies that no automatic timeout will take place.



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# File 'lib/em/connection.rb', line 589

def comm_inactivity_timeout
  EventMachine::get_comm_inactivity_timeout @signature
end

- (Object) comm_inactivity_timeout=(value) Also known as: set_comm_inactivity_timeout

Allows you to set the inactivity-timeout property for a network connection or datagram socket. Specify a non-negative float value in seconds. If the value is greater than zero, the connection or socket will automatically be closed if no read or write activity takes place for at least that number of seconds. Specify a value of zero to indicate that no automatic timeout should take place. Zero is the default value.



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# File 'lib/em/connection.rb', line 599

def comm_inactivity_timeout= value
  EventMachine::set_comm_inactivity_timeout @signature, value.to_f
end

- (Object) connection_completed

Called by the event loop when a remote TCP connection attempt completes successfully. You can expect to get this notification after calls to EventMachine.connect. Remember that EventMachine makes remote connections asynchronously, just as with any other kind of network event. This method is intended primarily to assist with network diagnostics. For normal protocol handling, use #post_init to perform initial work on a new connection (such as sending initial set of data). #post_init will always be called. This method will only be called in case of a successful completion. A connection attempt which fails will result a call to #unbind after the failure.



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# File 'lib/em/connection.rb', line 362

def connection_completed
end

- (Object) detach

Removes given connection from the event loop. The connection's socket remains open and its file descriptor number is returned.



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# File 'lib/em/connection.rb', line 271

def detach
  EventMachine::detach_fd @signature
end

- (Boolean) error?

Returns true if the connection is in an error state, false otherwise.

In general, you can detect the occurrence of communication errors or unexpected disconnection by the remote peer by handing the #unbind method. In some cases, however, it's useful to check the status of the connection using #error? before attempting to send data. This function is synchronous but it will return immediately without blocking.

Returns:

  • (Boolean)

    true if the connection is in an error state, false otherwise



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# File 'lib/em/connection.rb', line 339

def error?
  errno = EventMachine::report_connection_error_status(@signature)
  case errno
  when 0
    false
  when -1
    true
  else
    EventMachine::ERRNOS[errno]
  end
end

- (Object) get_idle_time

The number of seconds since the last send/receive activity on this connection.



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# File 'lib/em/connection.rb', line 580

def get_idle_time
  EventMachine::get_idle_time @signature
end

- (String) get_peer_cert

If TLS is active on the connection, returns the remote X509 certificate as a string, in the popular PEM format. This can then be used for arbitrary validation of a peer's certificate in your code.

This should be called in/after the #ssl_handshake_completed callback, which indicates that SSL/TLS is active. Using this callback is important, because the certificate may not be available until the time it is executed. Using #post_init or #connection_completed is not adequate, because the SSL handshake may still be taking place.

This method will return nil if:

  • EventMachine is not built with OpenSSL support
  • TLS is not active on the connection
  • TLS handshake is not yet complete
  • Remote peer for any other reason has not presented a certificate

You can do whatever you want with the certificate String, such as load it as a certificate object using the OpenSSL library, and check its fields.

Examples:

Getting peer TLS certificate information in EventMachine

module Handler
  def post_init
    puts "Starting TLS"
    start_tls
  end

  def ssl_handshake_completed
    puts get_peer_cert
    close_connection
  end

  def unbind
    EventMachine::stop_event_loop
  end
end

 EventMachine.run do
   EventMachine.connect "mail.google.com", 443, Handler
end

# Will output:
# -----BEGIN CERTIFICATE-----
# MIIDIjCCAougAwIBAgIQbldpChBPqv+BdPg4iwgN8TANBgkqhkiG9w0BAQUFADBM
# MQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkg
# THRkLjEWMBQGA1UEAxMNVGhhd3RlIFNHQyBDQTAeFw0wODA1MDIxNjMyNTRaFw0w
# OTA1MDIxNjMyNTRaMGkxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlh
# MRYwFAYDVQQHEw1Nb3VudGFpbiBWaWV3MRMwEQYDVQQKEwpHb29nbGUgSW5jMRgw
# FgYDVQQDEw9tYWlsLmdvb2dsZS5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJ
# AoGBALlkxdh2QXegdElukCSOV2+8PKiONIS+8Tu9K7MQsYpqtLNC860zwOPQ2NLI
# 3Zp4jwuXVTrtzGuiqf5Jioh35Ig3CqDXtLyZoypjZUQcq4mlLzHlhIQ4EhSjDmA7
# Ffw9y3ckSOQgdBQWNLbquHh9AbEUjmhkrYxIqKXeCnRKhv6nAgMBAAGjgecwgeQw
# KAYDVR0lBCEwHwYIKwYBBQUHAwEGCCsGAQUFBwMCBglghkgBhvhCBAEwNgYDVR0f
# BC8wLTAroCmgJ4YlaHR0cDovL2NybC50aGF3dGUuY29tL1RoYXd0ZVNHQ0NBLmNy
# bDByBggrBgEFBQcBAQRmMGQwIgYIKwYBBQUHMAGGFmh0dHA6Ly9vY3NwLnRoYXd0
# ZS5jb20wPgYIKwYBBQUHMAKGMmh0dHA6Ly93d3cudGhhd3RlLmNvbS9yZXBvc2l0
# b3J5L1RoYXd0ZV9TR0NfQ0EuY3J0MAwGA1UdEwEB/wQCMAAwDQYJKoZIhvcNAQEF
# BQADgYEAsRwpLg1dgCR1gYDK185MFGukXMeQFUvhGqF8eT/CjpdvezyKVuz84gSu
# 6ccMXgcPQZGQN/F4Xug+Q01eccJjRSVfdvR5qwpqCj+6BFl5oiKDBsveSkrmL5dz
# s2bn7TdTSYKcLeBkjXxDLHGBqLJ6TNCJ3c4/cbbG5JhGvoema94=
# -----END CERTIFICATE-----

Returns:

See Also:



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# File 'lib/em/connection.rb', line 487

def get_peer_cert
  EventMachine::get_peer_cert @signature
end

- (Object) get_peername

This method is used with stream-connections to obtain the identity of the remotely-connected peer. If a peername is available, this method returns a sockaddr structure. The method returns nil if no peername is available. You can use Socket.unpack_sockaddr_in and its variants to obtain the values contained in the peername structure returned from #get_peername.

Examples:

How to get peer IP address and port with EventMachine

require 'socket'

module Handler
  def receive_data data
    port, ip = Socket.unpack_sockaddr_in(get_peername)
    puts "got #{data.inspect} from #{ip}:#{port}"
  end
end


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# File 'lib/em/connection.rb', line 538

def get_peername
  EventMachine::get_peername @signature
end

- (Integer) get_pid

Returns the PID (kernel process identifier) of a subprocess associated with this Connection object. For use with EventMachine.popen and similar methods. Returns nil when there is no meaningful subprocess.

Returns:

  • (Integer)


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# File 'lib/em/connection.rb', line 567

def get_pid
  EventMachine::get_subprocess_pid @signature
end

- (Object) get_proxied_bytes

The number of bytes proxied to another connection. Reset to zero when EventMachine::Connection#proxy_incoming_to is called, and incremented whenever data is proxied.



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# File 'lib/em/connection.rb', line 243

def get_proxied_bytes
  EventMachine::get_proxied_bytes(@signature)
end

- (Object) get_sock_opt(level, option)



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# File 'lib/em/connection.rb', line 275

def get_sock_opt level, option
  EventMachine::get_sock_opt @signature, level, option
end

- (Object) get_sockname

Used with stream-connections to obtain the identity of the local side of the connection. If a local name is available, this method returns a sockaddr structure. The method returns nil if no local name is available. You can use Socket.unpack_sockaddr_in and its variants to obtain the values contained in the local-name structure returned from this method.

Examples:

require 'socket'

module Handler
  def receive_data data
    port, ip = Socket.unpack_sockaddr_in(get_sockname)
    puts "got #{data.inspect}"
  end
end


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# File 'lib/em/connection.rb', line 558

def get_sockname
  EventMachine::get_sockname @signature
end

- (Integer) get_status

Returns a subprocess exit status. Only useful for EventMachine.popen. Call it in your #unbind handler.

Returns:

  • (Integer)


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# File 'lib/em/connection.rb', line 575

def get_status
  EventMachine::get_subprocess_status @signature
end

- (Object) notify_readable=(mode)

Watches connection for readability. Only possible if the connection was created using EventMachine.attach and had EventMachine.notify_readable/EventMachine.notify_writable defined on the handler.

See Also:



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# File 'lib/em/connection.rb', line 671

def notify_readable= mode
  EventMachine::set_notify_readable @signature, mode
end

- (Boolean) notify_readable?

True if the connection is being watched for readability.

Returns:

  • (Boolean)

    true if the connection is being watched for readability.



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# File 'lib/em/connection.rb', line 676

def notify_readable?
  EventMachine::is_notify_readable @signature
end

- (Object) notify_writable=(mode)

Watches connection for writeability. Only possible if the connection was created using EventMachine.attach and had EventMachine.notify_readable/EventMachine.notify_writable defined on the handler.

See Also:



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# File 'lib/em/connection.rb', line 684

def notify_writable= mode
  EventMachine::set_notify_writable @signature, mode
end

- (Boolean) notify_writable?

Returns true if the connection is being watched for writability.

Returns:

  • (Boolean)


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# File 'lib/em/connection.rb', line 689

def notify_writable?
  EventMachine::is_notify_writable @signature
end

- (Object) pause

Pause a connection so that #send_data and #receive_data events are not fired until #resume is called.

See Also:



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# File 'lib/em/connection.rb', line 695

def pause
  EventMachine::pause_connection @signature
end

- (Boolean) paused?

True if the connect was paused using #pause.

Returns:

  • (Boolean)

    true if the connect was paused using #pause.

See Also:



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# File 'lib/em/connection.rb', line 708

def paused?
  EventMachine::connection_paused? @signature
end

- (Object) pending_connect_timeout=(value) Also known as: set_pending_connect_timeout

Sets the duration after which a TCP connection in a connecting state will fail.

Parameters:

  • value (Float, #to_f)

    Connection timeout in seconds



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# File 'lib/em/connection.rb', line 618

def pending_connect_timeout= value
  EventMachine::set_pending_connect_timeout @signature, value.to_f
end

- (Object) post_init

Called by the event loop immediately after the network connection has been established, and before resumption of the network loop. This method is generally not called by user code, but is called automatically by the event loop. The base-class implementation is a no-op. This is a very good place to initialize instance variables that will be used throughout the lifetime of the network connection.



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# File 'lib/em/connection.rb', line 81

def post_init
end

- (Object) proxy_completed

called when the reactor finished proxying all of the requested bytes.



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# File 'lib/em/connection.rb', line 224

def proxy_completed
end

- (Object) proxy_incoming_to(conn, bufsize = 0)

EventMachine::Connection#proxy_incoming_to is called only by user code. It sets up a low-level proxy relay for all data inbound for this connection, to the connection given as the argument. This is essentially just a helper method for enable_proxy.



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# File 'lib/em/connection.rb', line 232

def proxy_incoming_to(conn,bufsize=0)
  EventMachine::enable_proxy(self, conn, bufsize)
end

- (Object) proxy_target_unbound

Called by the reactor after attempting to relay incoming data to a descriptor (set as a proxy target descriptor with EventMachine.enable_proxy) that has already been closed.



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# File 'lib/em/connection.rb', line 219

def proxy_target_unbound
end

- (Object) receive_data(data)

Note:

Depending on the protocol, buffer sizes and OS networking stack configuration, incoming data may or may not be "a complete message". It is up to this handler to detect content boundaries to determine whether all the content (for example, full HTTP request) has been received and can be processed.

Called by the event loop whenever data has been received by the network connection. It is never called by user code. #receive_data is called with a single parameter, a String containing the network protocol data, which may of course be binary. You will generally redefine this method to perform your own processing of the incoming data.

Here's a key point which is essential to understanding the event-driven programming model: EventMachine knows absolutely nothing about the protocol which your code implements. You must not make any assumptions about the size of the incoming data packets, or about their alignment on any particular intra-message or PDU boundaries (such as line breaks). receive_data can and will send you arbitrary chunks of data, with the only guarantee being that the data is presented to your code in the order it was collected from the network. Don't even assume that the chunks of data will correspond to network packets, as EventMachine can and will coalesce several incoming packets into one, to improve performance. The implication for your code is that you generally will need to implement some kind of a state machine in your redefined implementation of receive_data. For a better understanding of this, read through the examples of specific protocol handlers in EventMachine::Protocols

The base-class implementation (which will be invoked only if you didn't override it in your protocol handler) simply prints incoming data packet size to stdout.

Parameters:

  • data (String)

    Opaque incoming data.

See Also:



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# File 'lib/em/connection.rb', line 116

def receive_data data
  puts "............>>>#{data.length}"
end

- (Object) resume

Resume a connection's #send_data and #receive_data events.

See Also:



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# File 'lib/em/connection.rb', line 701

def resume
  EventMachine::resume_connection @signature
end

- (Object) send_data(data)

Call this method to send data to the remote end of the network connection. It takes a single String argument, which may contain binary data. Data is buffered to be sent at the end of this event loop tick (cycle).

When used in a method that is event handler (for example, #post_init or #connection_completed, it will send data to the other end of the connection that generated the event. You can also call #send_data to write to other connections. For more information see The Chat Server Example in the EventMachine tutorial.

If you want to send some data and then immediately close the connection, make sure to use #close_connection_after_writing instead of #close_connection.

Parameters:

  • data (String)

    Data to send asynchronously

See Also:



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# File 'lib/em/connection.rb', line 324

def send_data data
  data = data.to_s
  size = data.bytesize if data.respond_to?(:bytesize)
  size ||= data.size
  EventMachine::send_data @signature, data, size
end

- (Object) send_datagram(data, recipient_address, recipient_port)

Sends UDP messages.

This method may be called from any Connection object that refers to an open datagram socket (see EventMachine#open_datagram_socket). The method sends a UDP (datagram) packet containing the data you specify, to a remote peer specified by the IP address and port that you give as parameters to the method. Observe that you may send a zero-length packet (empty string). However, you may not send an arbitrarily-large data packet because your operating system will enforce a platform-specific limit on the size of the outbound packet. (Your kernel will respond in a platform-specific way if you send an overlarge packet: some will send a truncated packet, some will complain, and some will silently drop your request). On LANs, it's usually OK to send datagrams up to about 4000 bytes in length, but to be really safe, send messages smaller than the Ethernet-packet size (typically about 1400 bytes). Some very restrictive WANs will either drop or truncate packets larger than about 500 bytes.

Parameters:

  • data (String)

    Data to send asynchronously

  • recipient_address (String)

    IP address of the recipient

  • recipient_port (String)

    Port of the recipient



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# File 'lib/em/connection.rb', line 514

def send_datagram data, recipient_address, recipient_port
  data = data.to_s
  size = data.bytesize if data.respond_to?(:bytesize)
  size ||= data.size
  EventMachine::send_datagram @signature, data, size, recipient_address, Integer(recipient_port)
end

- (Object) send_file_data(filename)

Like #send_data, this sends data to the remote end of the network connection. #send_file_data takes a filename as an argument, though, and sends the contents of the file, in one chunk.

Parameters:

  • filename (String)

    Local path of the file to send

See Also:

Author:

  • Kirk Haines



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# File 'lib/em/connection.rb', line 641

def send_file_data filename
  EventMachine::send_file_data @signature, filename
end

- (Object) set_sock_opt(level, optname, optval)



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# File 'lib/em/connection.rb', line 279

def set_sock_opt level, optname, optval
  EventMachine::set_sock_opt @signature, level, optname, optval
end

- (Object) ssl_handshake_completed

Called by EventMachine when the SSL/TLS handshake has been completed, as a result of calling #start_tls to initiate SSL/TLS on the connection.

This callback exists because #post_init and #connection_completed are not reliable for indicating when an SSL/TLS connection is ready to have its certificate queried for.

See Also:



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# File 'lib/em/connection.rb', line 127

def ssl_handshake_completed
end

- (Object) ssl_verify_peer(cert)

Called by EventMachine when :verify_peer => true has been passed to #start_tls. It will be called with each certificate in the certificate chain provided by the remote peer.

The cert will be passed as a String in PEM format, the same as in #get_peer_cert. It is up to user defined code to perform a check on the certificates. The return value from this callback is used to accept or deny the peer. A return value that is not nil or false triggers acceptance. If the peer is not accepted, the connection will be subsequently closed.

Examples:

This server always accepts all peers

module AcceptServer
  def post_init
    start_tls(:verify_peer => true)
  end

  def ssl_verify_peer(cert)
    true
  end

  def ssl_handshake_completed
    $server_handshake_completed = true
  end
end

This server never accepts any peers

module DenyServer
  def post_init
    start_tls(:verify_peer => true)
  end

  def ssl_verify_peer(cert)
    # Do not accept the peer. This should now cause the connection to shut down
    # without the SSL handshake being completed.
    false
  end

  def ssl_handshake_completed
    $server_handshake_completed = true
  end
end

See Also:



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# File 'lib/em/connection.rb', line 174

def ssl_verify_peer(cert)
end

- (Object) start_tls(args = {})

TODO:

support passing an encryption parameter, which can be string or Proc, to get a passphrase

TODO:

support passing key material via raw strings or Procs that return strings instead of

Call #start_tls at any point to initiate TLS encryption on connected streams. The method is smart enough to know whether it should perform a server-side or a client-side handshake. An appropriate place to call #start_tls is in your redefined #post_init method, or in the #connection_completed handler for an outbound connection.

for encrypted private keys. just filenames.

Examples:

Using TLS with EventMachine

require 'rubygems'
require 'eventmachine'

module Handler
  def post_init
    start_tls(:private_key_file => '/tmp/server.key', :cert_chain_file => '/tmp/server.crt', :verify_peer => false)
  end
end

 EventMachine.run do
  EventMachine.start_server("127.0.0.1", 9999, Handler)
end

Parameters:

  • args (Hash) (defaults to: {})

Options Hash (args):

  • :cert_chain_file (String) — default: nil

    local path of a readable file that contants a chain of X509 certificates in the PEM format, with the most-resolved certificate at the top of the file, successive intermediate certs in the middle, and the root (or CA) cert at the bottom.

  • :private_key_file (String) — default: nil

    local path of a readable file that must contain a private key in the PEM format.

  • :verify_peer (String) — default: false

    indicates whether a server should request a certificate from a peer, to be verified by user code. If true, the #ssl_verify_peer callback on the EventMachine::Connection object is called with each certificate in the certificate chain provided by the peer. See documentation on #ssl_verify_peer for how to use this.

See Also:



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# File 'lib/em/connection.rb', line 406

def start_tls args={}

- (Object) stop_proxying

A helper method for EventMachine.disable_proxy



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# File 'lib/em/connection.rb', line 237

def stop_proxying
  EventMachine::disable_proxy(self)
end

- (EventMachine::Deferrable) stream_file_data(filename, args = {})

Open a file on the filesystem and send it to the remote peer. This returns an object of type Deferrable. The object's callbacks will be executed on the reactor main thread when the file has been completely scheduled for transmission to the remote peer. Its errbacks will be called in case of an error (such as file-not-found). This method employs various strategies to achieve the fastest possible performance, balanced against minimum consumption of memory.

Warning: this feature has an implicit dependency on an outboard extension, evma_fastfilereader. You must install this extension in order to use #stream_file_data with files larger than a certain size (currently 8192 bytes).

Parameters:

  • filename (String)

    Local path of the file to stream

  • args (Hash) (defaults to: {})

    Options

Options Hash (args):

  • :http_chunks (Boolean) — default: false

    If true, this method will stream the file data in a format compatible with the HTTP chunked-transfer encoding

Returns:



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# File 'lib/em/connection.rb', line 663

def stream_file_data filename, args={}

- (Object) unbind

called by the framework whenever a connection (either a server or client connection) is closed. The close can occur because your code intentionally closes it (using #close_connection and #close_connection_after_writing), because the remote peer closed the connection, or because of a network error. You may not assume that the network connection is still open and able to send or receive data when the callback to unbind is made. This is intended only to give you a chance to clean up associations your code may have made to the connection object while it was open.

If you want to detect which peer has closed the connection, you can override #close_connection in your protocol handler and set an @ivar.

Examples:

Overriding Connection#close_connection to distinguish connections closed on our side

class MyProtocolHandler < EventMachine::Connection

  # ...

  def close_connection(*args)
    @intentionally_closed_connection = true
    super(*args)
  end

  def unbind
    if @intentionally_closed_connection
      # ...
    end
  end

  # ...

end

See Also:



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# File 'lib/em/connection.rb', line 212

def unbind
end