michael@0: var assert = require('assert');
michael@0: 
michael@0: var Serializer   = require('./framer').Serializer;
michael@0: var Deserializer = require('./framer').Deserializer;
michael@0: var Compressor   = require('./compressor').Compressor;
michael@0: var Decompressor = require('./compressor').Decompressor;
michael@0: var Connection   = require('./connection').Connection;
michael@0: var Duplex       = require('stream').Duplex;
michael@0: var Transform    = require('stream').Transform;
michael@0: 
michael@0: exports.Endpoint = Endpoint;
michael@0: 
michael@0: // The Endpoint class
michael@0: // ==================
michael@0: 
michael@0: // Public API
michael@0: // ----------
michael@0: 
michael@0: // - **new Endpoint(log, role, settings, filters)**: create a new Endpoint.
michael@0: //
michael@0: //   - `log`: bunyan logger of the parent
michael@0: //   - `role`: 'CLIENT' or 'SERVER'
michael@0: //   - `settings`: initial HTTP/2 settings
michael@0: //   - `filters`: a map of functions that filter the traffic between components (for debugging or
michael@0: //     intentional failure injection).
michael@0: //
michael@0: //     Filter functions get three arguments:
michael@0: //     1. `frame`: the current frame
michael@0: //     2. `forward(frame)`: function that can be used to forward a frame to the next component
michael@0: //     3. `done()`: callback to signal the end of the filter process
michael@0: //
michael@0: //     Valid filter names and their position in the stack:
michael@0: //     - `beforeSerialization`: after compression, before serialization
michael@0: //     - `beforeCompression`: after multiplexing, before compression
michael@0: //     - `afterDeserialization`: after deserialization, before decompression
michael@0: //     - `afterDecompression`: after decompression, before multiplexing
michael@0: //
michael@0: // * **Event: 'stream' (Stream)**: 'stream' event forwarded from the underlying Connection
michael@0: //
michael@0: // * **Event: 'error' (type)**: signals an error
michael@0: //
michael@0: // * **createStream(): Stream**: initiate a new stream (forwarded to the underlying Connection)
michael@0: //
michael@0: // * **close([error])**: close the connection with an error code
michael@0: 
michael@0: // Constructor
michael@0: // -----------
michael@0: 
michael@0: // The process of initialization:
michael@0: function Endpoint(log, role, settings, filters) {
michael@0:   Duplex.call(this);
michael@0: 
michael@0:   // * Initializing logging infrastructure
michael@0:   this._log = log.child({ component: 'endpoint', e: this });
michael@0: 
michael@0:   // * First part of the handshake process: sending and receiving the client connection header
michael@0:   //   prelude.
michael@0:   assert((role === 'CLIENT') || role === 'SERVER');
michael@0:   if (role === 'CLIENT') {
michael@0:     this._writePrelude();
michael@0:   } else {
michael@0:     this._readPrelude();
michael@0:   }
michael@0: 
michael@0:   // * Initialization of component. This includes the second part of the handshake process:
michael@0:   //   sending the first SETTINGS frame. This is done by the connection class right after
michael@0:   //   initialization.
michael@0:   this._initializeDataFlow(role, settings, filters || {});
michael@0: 
michael@0:   // * Initialization of management code.
michael@0:   this._initializeManagement();
michael@0: 
michael@0:   // * Initializing error handling.
michael@0:   this._initializeErrorHandling();
michael@0: }
michael@0: Endpoint.prototype = Object.create(Duplex.prototype, { constructor: { value: Endpoint } });
michael@0: 
michael@0: // Handshake
michael@0: // ---------
michael@0: 
michael@0: var CLIENT_PRELUDE = new Buffer('PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n');
michael@0: 
michael@0: // Writing the client header is simple and synchronous.
michael@0: Endpoint.prototype._writePrelude = function _writePrelude() {
michael@0:   this._log.debug('Sending the client connection header prelude.');
michael@0:   this.push(CLIENT_PRELUDE);
michael@0: };
michael@0: 
michael@0: // The asynchronous process of reading the client header:
michael@0: Endpoint.prototype._readPrelude = function _readPrelude() {
michael@0:   // * progress in the header is tracker using a `cursor`
michael@0:   var cursor = 0;
michael@0: 
michael@0:   // * `_write` is temporarily replaced by the comparator function
michael@0:   this._write = function _temporalWrite(chunk, encoding, done) {
michael@0:     // * which compares the stored header with the current `chunk` byte by byte and emits the
michael@0:     //   'error' event if there's a byte that doesn't match
michael@0:     var offset = cursor;
michael@0:     while(cursor < CLIENT_PRELUDE.length && (cursor - offset) < chunk.length) {
michael@0:       if (CLIENT_PRELUDE[cursor] !== chunk[cursor - offset]) {
michael@0:         this._log.fatal({ cursor: cursor, offset: offset, chunk: chunk },
michael@0:                         'Client connection header prelude does not match.');
michael@0:         this._error('handshake', 'PROTOCOL_ERROR');
michael@0:         return;
michael@0:       }
michael@0:       cursor += 1;
michael@0:     }
michael@0: 
michael@0:     // * if the whole header is over, and there were no error then restore the original `_write`
michael@0:     //   and call it with the remaining part of the current chunk
michael@0:     if (cursor === CLIENT_PRELUDE.length) {
michael@0:       this._log.debug('Successfully received the client connection header prelude.');
michael@0:       delete this._write;
michael@0:       chunk = chunk.slice(cursor - offset);
michael@0:       this._write(chunk, encoding, done);
michael@0:     }
michael@0:   };
michael@0: };
michael@0: 
michael@0: // Data flow
michael@0: // ---------
michael@0: 
michael@0: //     +---------------------------------------------+
michael@0: //     |                                             |
michael@0: //     |   +-------------------------------------+   |
michael@0: //     |   | +---------+ +---------+ +---------+ |   |
michael@0: //     |   | | stream1 | | stream2 | |   ...   | |   |
michael@0: //     |   | +---------+ +---------+ +---------+ |   |
michael@0: //     |   |             connection              |   |
michael@0: //     |   +-------------------------------------+   |
michael@0: //     |             |                 ^             |
michael@0: //     |        pipe |                 | pipe        |
michael@0: //     |             v                 |             |
michael@0: //     |   +------------------+------------------+   |
michael@0: //     |   |    compressor    |   decompressor   |   |
michael@0: //     |   +------------------+------------------+   |
michael@0: //     |             |                 ^             |
michael@0: //     |        pipe |                 | pipe        |
michael@0: //     |             v                 |             |
michael@0: //     |   +------------------+------------------+   |
michael@0: //     |   |    serializer    |   deserializer   |   |
michael@0: //     |   +------------------+------------------+   |
michael@0: //     |             |                 ^             |
michael@0: //     |     _read() |                 | _write()    |
michael@0: //     |             v                 |             |
michael@0: //     |      +------------+     +-----------+       |
michael@0: //     |      |output queue|     |input queue|       |
michael@0: //     +------+------------+-----+-----------+-------+
michael@0: //                   |                 ^
michael@0: //            read() |                 | write()
michael@0: //                   v                 |
michael@0: 
michael@0: function createTransformStream(filter) {
michael@0:   var transform = new Transform({ objectMode: true });
michael@0:   var push = transform.push.bind(transform);
michael@0:   transform._transform = function(frame, encoding, done) {
michael@0:     filter(frame, push, done);
michael@0:   };
michael@0:   return transform;
michael@0: }
michael@0: 
michael@0: function pipeAndFilter(stream1, stream2, filter) {
michael@0:   if (filter) {
michael@0:     stream1.pipe(createTransformStream(filter)).pipe(stream2);
michael@0:   } else {
michael@0:     stream1.pipe(stream2);
michael@0:   }
michael@0: }
michael@0: 
michael@0: var MAX_HTTP_PAYLOAD_SIZE = 16383;
michael@0: 
michael@0: Endpoint.prototype._initializeDataFlow = function _initializeDataFlow(role, settings, filters) {
michael@0:   var firstStreamId, compressorRole, decompressorRole;
michael@0:   if (role === 'CLIENT') {
michael@0:     firstStreamId = 1;
michael@0:     compressorRole = 'REQUEST';
michael@0:     decompressorRole = 'RESPONSE';
michael@0:   } else {
michael@0:     firstStreamId = 2;
michael@0:     compressorRole = 'RESPONSE';
michael@0:     decompressorRole = 'REQUEST';
michael@0:   }
michael@0: 
michael@0:   this._serializer   = new Serializer(this._log, MAX_HTTP_PAYLOAD_SIZE);
michael@0:   this._deserializer = new Deserializer(this._log, MAX_HTTP_PAYLOAD_SIZE);
michael@0:   this._compressor   = new Compressor(this._log, compressorRole);
michael@0:   this._decompressor = new Decompressor(this._log, decompressorRole);
michael@0:   this._connection   = new Connection(this._log, firstStreamId, settings);
michael@0: 
michael@0:   pipeAndFilter(this._connection, this._compressor, filters.beforeCompression);
michael@0:   pipeAndFilter(this._compressor, this._serializer, filters.beforeSerialization);
michael@0:   pipeAndFilter(this._deserializer, this._decompressor, filters.afterDeserialization);
michael@0:   pipeAndFilter(this._decompressor, this._connection, filters.afterDecompression);
michael@0: 
michael@0:   this._connection.on('ACKNOWLEDGED_SETTINGS_HEADER_TABLE_SIZE',
michael@0:                       this._decompressor.setTableSizeLimit.bind(this._decompressor))
michael@0:   this._connection.on('RECEIVING_SETTINGS_HEADER_TABLE_SIZE',
michael@0:                       this._compressor.setTableSizeLimit.bind(this._compressor))
michael@0: };
michael@0: 
michael@0: var noread = {};
michael@0: Endpoint.prototype._read = function _read() {
michael@0:   this._readableState.sync = true;
michael@0:   var moreNeeded = noread, chunk;
michael@0:   while (moreNeeded && (chunk = this._serializer.read())) {
michael@0:     moreNeeded = this.push(chunk);
michael@0:   }
michael@0:   if (moreNeeded === noread) {
michael@0:     this._serializer.once('readable', this._read.bind(this));
michael@0:   }
michael@0:   this._readableState.sync = false;
michael@0: };
michael@0: 
michael@0: Endpoint.prototype._write = function _write(chunk, encoding, done) {
michael@0:   this._deserializer.write(chunk, encoding, done);
michael@0: };
michael@0: 
michael@0: // Management
michael@0: // --------------
michael@0: 
michael@0: Endpoint.prototype._initializeManagement = function _initializeManagement() {
michael@0:   this._connection.on('stream', this.emit.bind(this, 'stream'));
michael@0: };
michael@0: 
michael@0: Endpoint.prototype.createStream = function createStream() {
michael@0:   return this._connection.createStream();
michael@0: };
michael@0: 
michael@0: // Error handling
michael@0: // --------------
michael@0: 
michael@0: Endpoint.prototype._initializeErrorHandling = function _initializeErrorHandling() {
michael@0:   this._serializer.on('error', this._error.bind(this, 'serializer'));
michael@0:   this._deserializer.on('error', this._error.bind(this, 'deserializer'));
michael@0:   this._compressor.on('error', this._error.bind(this, 'compressor'));
michael@0:   this._decompressor.on('error', this._error.bind(this, 'decompressor'));
michael@0:   this._connection.on('error', this._error.bind(this, 'connection'));
michael@0: 
michael@0:   this._connection.on('peerError', this.emit.bind(this, 'peerError'));
michael@0: };
michael@0: 
michael@0: Endpoint.prototype._error = function _error(component, error) {
michael@0:   this._log.fatal({ source: component, message: error }, 'Fatal error, closing connection');
michael@0:   this.close(error);
michael@0:   setImmediate(this.emit.bind(this, 'error', error));
michael@0: };
michael@0: 
michael@0: Endpoint.prototype.close = function close(error) {
michael@0:   this._connection.close(error);
michael@0: };
michael@0: 
michael@0: // Bunyan serializers
michael@0: // ------------------
michael@0: 
michael@0: exports.serializers = {};
michael@0: 
michael@0: var nextId = 0;
michael@0: exports.serializers.e = function(endpoint) {
michael@0:   if (!('id' in endpoint)) {
michael@0:     endpoint.id = nextId;
michael@0:     nextId += 1;
michael@0:   }
michael@0:   return endpoint.id;
michael@0: };