websockets: A PHP repository from nusje2000

Websocket server

Almost fully compatible with https://tools.ietf.org/html/rfc6455

Simple version can be found here: https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers

Data framing

The following data frame was used to parse messages from and to the clients.

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-------+-+-------------+-------------------------------+
|F|R|R|R| opcode|M| Payload len |    Extended payload length    |
|I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
|N|V|V|V|       |S|             |   (if payload len==126/127)   |
| |1|2|3|       |K|             |                               |
+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
|   Extended payload length continued, if payload len == 127    |
+ - - - - - - - - - - - - - - - +-------------------------------+
|                               |Masking-key, if MASK set to 1  |
+-------------------------------+-------------------------------+
| Masking-key (continued)       |          Payload Data         |
+-------------------------------- - - - - - - - - - - - - - - - +
:                     Payload Data continued ...                :
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
|                     Payload Data continued ...                |
+---------------------------------------------------------------+

Opcodes

hex	int	text	const	control
0x0	0	Continuation	OpcodeEnum::CONTINUE	true
0x1	1	Text	OpcodeEnum::TEXT	false
0x2	2	Binary	OpcodeEnum::BIN	false
0x3	3	No meaning	OpcodeEnum::OPCODE_3	false
0x4	4	No meaning	OpcodeEnum::OPCODE_4	false
0x5	5	No meaning	OpcodeEnum::OPCODE_5	false
0x6	6	No meaning	OpcodeEnum::OPCODE_6	false
0x7	7	No meaning	OpcodeEnum::OPCODE_7	false
0x8	8	Close	OpcodeEnum::CLOSE	true
0x9	9	Ping	OpcodeEnum::PING	true
0xA	10	Pong	OpcodeEnum::PONG	true
0xB	11	No meaning	OpcodeEnum::OPCODE_11	true
0xC	12	No meaning	OpcodeEnum::OPCODE_12	true
0xD	13	No meaning	OpcodeEnum::OPCODE_13	true
0xE	14	No meaning	OpcodeEnum::OPCODE_14	true
0xF	15	No meaning	OpcodeEnum::OPCODE_15	true

Mapping

All incomming frames are being mapped to the Frame class, this class is basically an oop version of the dataframe displayed above. The following mapping is used:

FIN => Frame::isFinal(): bool
RSV1 => none
RSV2 => none
RSV3 => none
OPCODE => Frame::getOpcode(): int
MASK => Frame::isMasked(): bool
PAYLOAD_LENGTH => Frame::getPayloadLength(): int
MASKING_KEY => Frame::getMaskingKey(): string
PAYLOAD_DATA => Frame::getPayload(): string

Additional functionallity

There are a few functions added to the Frame for ease of use:

Frame::isClosing(): bool => is true when opcode = 0x8
Frame::isControl(): bool => is true when opcode is for contol
Frame::isNonControl(): bool => is true when opcode is not for contol

Events

The websocket makes use of the symfony event dispatcher. Because of this, each incomming dataframe wil dispatch an event. This event can be used to react on incomming frames. The following is a list of events that can be listened to:

Event class	Reason
HandshakeEvent	first data sent over a new connection will be treated as handshake request
ConnectEvent	new connection (handshake is already done when this event is triggered)
DataEvent	received data (triggered when data is received)
FrameEvent	received frame (triggered when a frame is received)
MessageEvent	received message (only works when the FrameEventSubscriber is an active listener, triggered when a frame is received with TEXT opcode)
DisconnectEvent	disconnected (triggered when a connection is disconned)

For all events to be dispatched there are 4 event dispatchers. The following is a list of the dispatchters and their in-/outgoning events:

Dispatcher	Incomming events	Outgoing events	Purpose
HandshakeEventSubscriber	HandshakeEvent	ConnectEvent	Handle handshake and dispatch a connect event when successfull
ConnectionEventSubscriber	ConnectEvent, DisconnectEvent	DataEvent, DisconnectEvent	Handle connection and map connection events
DataEventSubscriber	DataEvent	FrameEvent	Parse incomming data to a frame and dispatch as frame event
FrameEventSubscriber	FrameEvent	MessageEvent	Handle incomming frame event and dispatch a Message event if the opcode is TEXT

Running the example

There is a simple chat application included in this project. To run this, use the following commands:

php example/socket.php
php -S 127.0.0.1:8080 -t ./example/web

You must run both commands separate from each other

Known issues

Fragmentations is not supported yet
Encode function of the encoder does not yet support masking
Strings longer than 65536 cannot be received due to buffering

nusje2000/websockets