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diff --git a/frontend-old/node_modules/websocket-extensions/README.md b/frontend-old/node_modules/websocket-extensions/README.md new file mode 100644 index 0000000..68694ea --- /dev/null +++ b/frontend-old/node_modules/websocket-extensions/README.md @@ -0,0 +1,331 @@ +# websocket-extensions [](http://travis-ci.org/faye/websocket-extensions-node) + +A minimal framework that supports the implementation of WebSocket extensions in +a way that's decoupled from the main protocol. This library aims to allow a +WebSocket extension to be written and used with any protocol library, by +defining abstract representations of frames and messages that allow modules to +co-operate. + +`websocket-extensions` provides a container for registering extension plugins, +and provides all the functions required to negotiate which extensions to use +during a session via the `Sec-WebSocket-Extensions` header. By implementing the +APIs defined in this document, an extension may be used by any WebSocket library +based on this framework. + +## Installation + +``` +$ npm install websocket-extensions +``` + +## Usage + +There are two main audiences for this library: authors implementing the +WebSocket protocol, and authors implementing extensions. End users of a +WebSocket library or an extension should be able to use any extension by passing +it as an argument to their chosen protocol library, without needing to know how +either of them work, or how the `websocket-extensions` framework operates. + +The library is designed with the aim that any protocol implementation and any +extension can be used together, so long as they support the same abstract +representation of frames and messages. + +### Data types + +The APIs provided by the framework rely on two data types; extensions will +expect to be given data and to be able to return data in these formats: + +#### *Frame* + +*Frame* is a structure representing a single WebSocket frame of any type. Frames +are simple objects that must have at least the following properties, which +represent the data encoded in the frame: + +| property | description | +| ------------ | ------------------------------------------------------------------ | +| `final` | `true` if the `FIN` bit is set, `false` otherwise | +| `rsv1` | `true` if the `RSV1` bit is set, `false` otherwise | +| `rsv2` | `true` if the `RSV2` bit is set, `false` otherwise | +| `rsv3` | `true` if the `RSV3` bit is set, `false` otherwise | +| `opcode` | the numeric opcode (`0`, `1`, `2`, `8`, `9`, or `10`) of the frame | +| `masked` | `true` if the `MASK` bit is set, `false` otherwise | +| `maskingKey` | a 4-byte `Buffer` if `masked` is `true`, otherwise `null` | +| `payload` | a `Buffer` containing the (unmasked) application data | + +#### *Message* + +A *Message* represents a complete application message, which can be formed from +text, binary and continuation frames. It has the following properties: + +| property | description | +| -------- | ----------------------------------------------------------------- | +| `rsv1` | `true` if the first frame of the message has the `RSV1` bit set | +| `rsv2` | `true` if the first frame of the message has the `RSV2` bit set | +| `rsv3` | `true` if the first frame of the message has the `RSV3` bit set | +| `opcode` | the numeric opcode (`1` or `2`) of the first frame of the message | +| `data` | the concatenation of all the frame payloads in the message | + +### For driver authors + +A driver author is someone implementing the WebSocket protocol proper, and who +wishes end users to be able to use WebSocket extensions with their library. + +At the start of a WebSocket session, on both the client and the server side, +they should begin by creating an extension container and adding whichever +extensions they want to use. + +```js +var Extensions = require('websocket-extensions'), + deflate = require('permessage-deflate'); + +var exts = new Extensions(); +exts.add(deflate); +``` + +In the following examples, `exts` refers to this `Extensions` instance. + +#### Client sessions + +Clients will use the methods `generateOffer()` and `activate(header)`. + +As part of the handshake process, the client must send a +`Sec-WebSocket-Extensions` header to advertise that it supports the registered +extensions. This header should be generated using: + +```js +request.headers['sec-websocket-extensions'] = exts.generateOffer(); +``` + +This returns a string, for example `"permessage-deflate; +client_max_window_bits"`, that represents all the extensions the client is +offering to use, and their parameters. This string may contain multiple offers +for the same extension. + +When the client receives the handshake response from the server, it should pass +the incoming `Sec-WebSocket-Extensions` header in to `exts` to activate the +extensions the server has accepted: + +```js +exts.activate(response.headers['sec-websocket-extensions']); +``` + +If the server has sent any extension responses that the client does not +recognize, or are in conflict with one another for use of RSV bits, or that use +invalid parameters for the named extensions, then `exts.activate()` will +`throw`. In this event, the client driver should fail the connection with +closing code `1010`. + +#### Server sessions + +Servers will use the method `generateResponse(header)`. + +A server session needs to generate a `Sec-WebSocket-Extensions` header to send +in its handshake response: + +```js +var clientOffer = request.headers['sec-websocket-extensions'], + extResponse = exts.generateResponse(clientOffer); + +response.headers['sec-websocket-extensions'] = extResponse; +``` + +Calling `exts.generateResponse(header)` activates those extensions the client +has asked to use, if they are registered, asks each extension for a set of +response parameters, and returns a string containing the response parameters for +all accepted extensions. + +#### In both directions + +Both clients and servers will use the methods `validFrameRsv(frame)`, +`processIncomingMessage(message)` and `processOutgoingMessage(message)`. + +The WebSocket protocol requires that frames do not have any of the `RSV` bits +set unless there is an extension in use that allows otherwise. When processing +an incoming frame, sessions should pass a *Frame* object to: + +```js +exts.validFrameRsv(frame) +``` + +If this method returns `false`, the session should fail the WebSocket connection +with closing code `1002`. + +To pass incoming messages through the extension stack, a session should +construct a *Message* object according to the above datatype definitions, and +call: + +```js +exts.processIncomingMessage(message, function(error, msg) { + // hand the message off to the application +}); +``` + +If any extensions fail to process the message, then the callback will yield an +error and the session should fail the WebSocket connection with closing code +`1010`. If `error` is `null`, then `msg` should be passed on to the application. + +To pass outgoing messages through the extension stack, a session should +construct a *Message* as before, and call: + +```js +exts.processOutgoingMessage(message, function(error, msg) { + // write message to the transport +}); +``` + +If any extensions fail to process the message, then the callback will yield an +error and the session should fail the WebSocket connection with closing code +`1010`. If `error` is `null`, then `message` should be converted into frames +(with the message's `rsv1`, `rsv2`, `rsv3` and `opcode` set on the first frame) +and written to the transport. + +At the end of the WebSocket session (either when the protocol is explicitly +ended or the transport connection disconnects), the driver should call: + +```js +exts.close(function() {}) +``` + +The callback is invoked when all extensions have finished processing any +messages in the pipeline and it's safe to close the socket. + +### For extension authors + +An extension author is someone implementing an extension that transforms +WebSocket messages passing between the client and server. They would like to +implement their extension once and have it work with any protocol library. + +Extension authors will not install `websocket-extensions` or call it directly. +Instead, they should implement the following API to allow their extension to +plug into the `websocket-extensions` framework. + +An `Extension` is any object that has the following properties: + +| property | description | +| -------- | ---------------------------------------------------------------------------- | +| `name` | a string containing the name of the extension as used in negotiation headers | +| `type` | a string, must be `"permessage"` | +| `rsv1` | either `true` if the extension uses the RSV1 bit, `false` otherwise | +| `rsv2` | either `true` if the extension uses the RSV2 bit, `false` otherwise | +| `rsv3` | either `true` if the extension uses the RSV3 bit, `false` otherwise | + +It must also implement the following methods: + +```js +ext.createClientSession() +``` + +This returns a *ClientSession*, whose interface is defined below. + +```js +ext.createServerSession(offers) +``` + +This takes an array of offer params and returns a *ServerSession*, whose +interface is defined below. For example, if the client handshake contains the +offer header: + +``` +Sec-WebSocket-Extensions: permessage-deflate; server_no_context_takeover; server_max_window_bits=8, \ + permessage-deflate; server_max_window_bits=15 +``` + +then the `permessage-deflate` extension will receive the call: + +```js +ext.createServerSession([ + { server_no_context_takeover: true, server_max_window_bits: 8 }, + { server_max_window_bits: 15 } +]); +``` + +The extension must decide which set of parameters it wants to accept, if any, +and return a *ServerSession* if it wants to accept the parameters and `null` +otherwise. + +#### *ClientSession* + +A *ClientSession* is the type returned by `ext.createClientSession()`. It must +implement the following methods, as well as the *Session* API listed below. + +```js +clientSession.generateOffer() +// e.g. -> [ +// { server_no_context_takeover: true, server_max_window_bits: 8 }, +// { server_max_window_bits: 15 } +// ] +``` + +This must return a set of parameters to include in the client's +`Sec-WebSocket-Extensions` offer header. If the session wants to offer multiple +configurations, it can return an array of sets of parameters as shown above. + +```js +clientSession.activate(params) // -> true +``` + +This must take a single set of parameters from the server's handshake response +and use them to configure the client session. If the client accepts the given +parameters, then this method must return `true`. If it returns any other value, +the framework will interpret this as the client rejecting the response, and will +`throw`. + +#### *ServerSession* + +A *ServerSession* is the type returned by `ext.createServerSession(offers)`. It +must implement the following methods, as well as the *Session* API listed below. + +```js +serverSession.generateResponse() +// e.g. -> { server_max_window_bits: 8 } +``` + +This returns the set of parameters the server session wants to send in its +`Sec-WebSocket-Extensions` response header. Only one set of parameters is +returned to the client per extension. Server sessions that would confict on +their use of RSV bits are not activated. + +#### *Session* + +The *Session* API must be implemented by both client and server sessions. It +contains two methods, `processIncomingMessage(message)` and +`processOutgoingMessage(message)`. + +```js +session.processIncomingMessage(message, function(error, msg) { ... }) +``` + +The session must implement this method to take an incoming *Message* as defined +above, transform it in any way it needs, then return it via the callback. If +there is an error processing the message, this method should yield an error as +the first argument. + +```js +session.processOutgoingMessage(message, function(error, msg) { ... }) +``` + +The session must implement this method to take an outgoing *Message* as defined +above, transform it in any way it needs, then return it via the callback. If +there is an error processing the message, this method should yield an error as +the first argument. + +Note that both `processIncomingMessage()` and `processOutgoingMessage()` can +perform their logic asynchronously, are allowed to process multiple messages +concurrently, and are not required to complete working on messages in the same +order the messages arrive. `websocket-extensions` will reorder messages as your +extension emits them and will make sure every extension is given messages in the +order they arrive from the driver. This allows extensions to maintain state that +depends on the messages' wire order, for example keeping a DEFLATE compression +context between messages. + +```js +session.close() +``` + +The framework will call this method when the WebSocket session ends, allowing +the session to release any resources it's using. + +## Examples + +- Consumer: [websocket-driver](https://github.com/faye/websocket-driver-node) +- Provider: [permessage-deflate](https://github.com/faye/permessage-deflate-node) |