forked from mirrors/gecko-dev
46b0bdd213
Differential Revision: https://phabricator.services.mozilla.com/D46260 --HG-- extra : moz-landing-system : lando
1366 lines
44 KiB
JavaScript
1366 lines
44 KiB
JavaScript
// The implementation of the [HTTP/2 Header Compression][http2-compression] spec is separated from
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// the 'integration' part which handles HEADERS and PUSH_PROMISE frames. The compression itself is
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// implemented in the first part of the file, and consists of three classes: `HeaderTable`,
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// `HeaderSetDecompressor` and `HeaderSetCompressor`. The two latter classes are
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// [Transform Stream][node-transform] subclasses that operate in [object mode][node-objectmode].
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// These transform chunks of binary data into `[name, value]` pairs and vice versa, and store their
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// state in `HeaderTable` instances.
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//
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// The 'integration' part is also implemented by two [Transform Stream][node-transform] subclasses
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// that operate in [object mode][node-objectmode]: the `Compressor` and the `Decompressor`. These
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// provide a layer between the [framer](framer.html) and the
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// [connection handling component](connection.html).
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//
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// [node-transform]: https://nodejs.org/api/stream.html#stream_class_stream_transform
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// [node-objectmode]: https://nodejs.org/api/stream.html#stream_new_stream_readable_options
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// [http2-compression]: https://tools.ietf.org/html/rfc7541
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exports.HeaderTable = HeaderTable;
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exports.HuffmanTable = HuffmanTable;
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exports.HeaderSetCompressor = HeaderSetCompressor;
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exports.HeaderSetDecompressor = HeaderSetDecompressor;
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exports.Compressor = Compressor;
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exports.Decompressor = Decompressor;
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var TransformStream = require('stream').Transform;
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var assert = require('assert');
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var util = require('util');
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// Header compression
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// ==================
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// The HeaderTable class
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// ---------------------
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// The [Header Table] is a component used to associate headers to index values. It is basically an
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// ordered list of `[name, value]` pairs, so it's implemented as a subclass of `Array`.
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// In this implementation, the Header Table and the [Static Table] are handled as a single table.
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// [Header Table]: https://tools.ietf.org/html/rfc7541#section-2.3.2
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// [Static Table]: https://tools.ietf.org/html/rfc7541#section-2.3.1
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function HeaderTable(log, limit) {
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var self = HeaderTable.staticTable.map(entryFromPair);
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self._log = log;
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self._limit = limit || DEFAULT_HEADER_TABLE_LIMIT;
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self._staticLength = self.length;
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self._size = 0;
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self._enforceLimit = HeaderTable.prototype._enforceLimit;
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self.add = HeaderTable.prototype.add;
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self.setSizeLimit = HeaderTable.prototype.setSizeLimit;
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return self;
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}
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function entryFromPair(pair) {
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var entry = pair.slice();
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entry._size = size(entry);
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return entry;
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}
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// The encoder decides how to update the header table and as such can control how much memory is
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// used by the header table. To limit the memory requirements on the decoder side, the header table
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// size is bounded.
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//
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// * The default header table size limit is 4096 bytes.
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// * The size of an entry is defined as follows: the size of an entry is the sum of its name's
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// length in bytes, of its value's length in bytes and of 32 bytes.
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// * The size of a header table is the sum of the size of its entries.
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var DEFAULT_HEADER_TABLE_LIMIT = 4096;
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function size(entry) {
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return (Buffer.from(entry[0] + entry[1], 'utf8')).length + 32;
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}
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// The `add(index, entry)` can be used to [manage the header table][tablemgmt]:
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// [tablemgmt]: https://tools.ietf.org/html/rfc7541#section-4
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//
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// * it pushes the new `entry` at the beggining of the table
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// * before doing such a modification, it has to be ensured that the header table size will stay
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// lower than or equal to the header table size limit. To achieve this, entries are evicted from
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// the end of the header table until the size of the header table is less than or equal to
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// `(this._limit - entry.size)`, or until the table is empty.
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//
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// <---------- Index Address Space ---------->
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// <-- Static Table --> <-- Header Table -->
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// +---+-----------+---+ +---+-----------+---+
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// | 0 | ... | k | |k+1| ... | n |
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// +---+-----------+---+ +---+-----------+---+
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// ^ |
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// | V
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// Insertion Point Drop Point
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HeaderTable.prototype._enforceLimit = function _enforceLimit(limit) {
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var droppedEntries = [];
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while ((this._size > 0) && (this._size > limit)) {
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var dropped = this.pop();
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this._size -= dropped._size;
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droppedEntries.unshift(dropped);
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}
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return droppedEntries;
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};
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HeaderTable.prototype.add = function(entry) {
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var limit = this._limit - entry._size;
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var droppedEntries = this._enforceLimit(limit);
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if (this._size <= limit) {
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this.splice(this._staticLength, 0, entry);
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this._size += entry._size;
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}
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return droppedEntries;
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};
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// The table size limit can be changed externally. In this case, the same eviction algorithm is used
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HeaderTable.prototype.setSizeLimit = function setSizeLimit(limit) {
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this._limit = limit;
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this._enforceLimit(this._limit);
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};
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// [The Static Table](https://tools.ietf.org/html/rfc7541#section-2.3.1)
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// ------------------
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// The table is generated with feeding the table from the spec to the following sed command:
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//
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// sed -re "s/\s*\| [0-9]+\s*\| ([^ ]*)/ [ '\1'/g" -e "s/\|\s([^ ]*)/, '\1'/g" -e 's/ \|/],/g'
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HeaderTable.staticTable = [
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[ ':authority' , '' ],
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[ ':method' , 'GET' ],
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[ ':method' , 'POST' ],
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[ ':path' , '/' ],
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[ ':path' , '/index.html' ],
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[ ':scheme' , 'http' ],
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[ ':scheme' , 'https' ],
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[ ':status' , '200' ],
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[ ':status' , '204' ],
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[ ':status' , '206' ],
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[ ':status' , '304' ],
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[ ':status' , '400' ],
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[ ':status' , '404' ],
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[ ':status' , '500' ],
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[ 'accept-charset' , '' ],
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[ 'accept-encoding' , 'gzip, deflate'],
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[ 'accept-language' , '' ],
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[ 'accept-ranges' , '' ],
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[ 'accept' , '' ],
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[ 'access-control-allow-origin' , '' ],
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[ 'age' , '' ],
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[ 'allow' , '' ],
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[ 'authorization' , '' ],
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[ 'cache-control' , '' ],
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[ 'content-disposition' , '' ],
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[ 'content-encoding' , '' ],
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[ 'content-language' , '' ],
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[ 'content-length' , '' ],
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[ 'content-location' , '' ],
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[ 'content-range' , '' ],
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[ 'content-type' , '' ],
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[ 'cookie' , '' ],
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[ 'date' , '' ],
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[ 'etag' , '' ],
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[ 'expect' , '' ],
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[ 'expires' , '' ],
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[ 'from' , '' ],
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[ 'host' , '' ],
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[ 'if-match' , '' ],
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[ 'if-modified-since' , '' ],
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[ 'if-none-match' , '' ],
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[ 'if-range' , '' ],
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[ 'if-unmodified-since' , '' ],
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[ 'last-modified' , '' ],
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[ 'link' , '' ],
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[ 'location' , '' ],
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[ 'max-forwards' , '' ],
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[ 'proxy-authenticate' , '' ],
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[ 'proxy-authorization' , '' ],
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[ 'range' , '' ],
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[ 'referer' , '' ],
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[ 'refresh' , '' ],
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[ 'retry-after' , '' ],
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[ 'server' , '' ],
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[ 'set-cookie' , '' ],
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[ 'strict-transport-security' , '' ],
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[ 'transfer-encoding' , '' ],
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[ 'user-agent' , '' ],
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[ 'vary' , '' ],
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[ 'via' , '' ],
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[ 'www-authenticate' , '' ]
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];
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// The HeaderSetDecompressor class
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// -------------------------------
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// A `HeaderSetDecompressor` instance is a transform stream that can be used to *decompress a
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// single header set*. Its input is a stream of binary data chunks and its output is a stream of
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// `[name, value]` pairs.
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//
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// Currently, it is not a proper streaming decompressor implementation, since it buffer its input
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// until the end os the stream, and then processes the whole header block at once.
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util.inherits(HeaderSetDecompressor, TransformStream);
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function HeaderSetDecompressor(log, table) {
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TransformStream.call(this, { objectMode: true });
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this._log = log.child({ component: 'compressor' });
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this._table = table;
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this._chunks = [];
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}
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// `_transform` is the implementation of the [corresponding virtual function][_transform] of the
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// TransformStream class. It collects the data chunks for later processing.
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// [_transform]: https://nodejs.org/api/stream.html#stream_transform_transform_chunk_encoding_callback
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HeaderSetDecompressor.prototype._transform = function _transform(chunk, encoding, callback) {
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this._chunks.push(chunk);
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callback();
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};
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// `execute(rep)` executes the given [header representation][representation].
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// [representation]: https://tools.ietf.org/html/rfc7541#section-6
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// The *JavaScript object representation* of a header representation:
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//
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// {
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// name: String || Integer, // string literal or index
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// value: String || Integer, // string literal or index
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// index: Boolean // with or without indexing
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// }
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//
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// *Important:* to ease the indexing of the header table, indexes start at 0 instead of 1.
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//
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// Examples:
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//
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// Indexed:
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// { name: 2 , value: 2 , index: false }
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// Literal:
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// { name: 2 , value: 'X', index: false } // without indexing
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// { name: 2 , value: 'Y', index: true } // with indexing
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// { name: 'A', value: 'Z', index: true } // with indexing, literal name
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HeaderSetDecompressor.prototype._execute = function _execute(rep) {
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this._log.trace({ key: rep.name, value: rep.value, index: rep.index },
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'Executing header representation');
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var entry, pair;
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if (rep.contextUpdate) {
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this._table.setSizeLimit(rep.newMaxSize);
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}
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// * An _indexed representation_ entails the following actions:
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// * The header field corresponding to the referenced entry is emitted
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else if (typeof rep.value === 'number') {
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var index = rep.value;
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entry = this._table[index];
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pair = entry.slice();
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this.push(pair);
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}
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// * A _literal representation_ that is _not added_ to the header table entails the following
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// action:
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// * The header is emitted.
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// * A _literal representation_ that is _added_ to the header table entails the following further
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// actions:
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// * The header is added to the header table.
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// * The header is emitted.
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else {
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if (typeof rep.name === 'number') {
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pair = [this._table[rep.name][0], rep.value];
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} else {
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pair = [rep.name, rep.value];
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}
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if (rep.index) {
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entry = entryFromPair(pair);
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this._table.add(entry);
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}
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this.push(pair);
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}
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};
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// `_flush` is the implementation of the [corresponding virtual function][_flush] of the
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// TransformStream class. The whole decompressing process is done in `_flush`. It gets called when
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// the input stream is over.
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// [_flush]: https://nodejs.org/api/stream.html#stream_transform_flush_callback
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HeaderSetDecompressor.prototype._flush = function _flush(callback) {
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var buffer = concat(this._chunks);
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// * processes the header representations
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buffer.cursor = 0;
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while (buffer.cursor < buffer.length) {
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this._execute(HeaderSetDecompressor.header(buffer));
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}
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callback();
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};
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// The HeaderSetCompressor class
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// -----------------------------
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// A `HeaderSetCompressor` instance is a transform stream that can be used to *compress a single
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// header set*. Its input is a stream of `[name, value]` pairs and its output is a stream of
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// binary data chunks.
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//
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// It is a real streaming compressor, since it does not wait until the header set is complete.
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//
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// The compression algorithm is (intentionally) not specified by the spec. Therefore, the current
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// compression algorithm can probably be improved in the future.
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util.inherits(HeaderSetCompressor, TransformStream);
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function HeaderSetCompressor(log, table) {
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TransformStream.call(this, { objectMode: true });
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this._log = log.child({ component: 'compressor' });
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this._table = table;
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this.push = TransformStream.prototype.push.bind(this);
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}
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HeaderSetCompressor.prototype.send = function send(rep) {
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this._log.trace({ key: rep.name, value: rep.value, index: rep.index },
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'Emitting header representation');
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if (!rep.chunks) {
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rep.chunks = HeaderSetCompressor.header(rep);
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}
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rep.chunks.forEach(this.push);
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};
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// `_transform` is the implementation of the [corresponding virtual function][_transform] of the
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// TransformStream class. It processes the input headers one by one:
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// [_transform]: https://nodejs.org/api/stream.html#stream_transform_transform_chunk_encoding_callback
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HeaderSetCompressor.prototype._transform = function _transform(pair, encoding, callback) {
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var name = pair[0].toLowerCase();
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var value = pair[1];
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var entry, rep;
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// * tries to find full (name, value) or name match in the header table
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var nameMatch = -1, fullMatch = -1;
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for (var droppedIndex = 0; droppedIndex < this._table.length; droppedIndex++) {
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entry = this._table[droppedIndex];
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if (entry[0] === name) {
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if (entry[1] === value) {
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fullMatch = droppedIndex;
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break;
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} else if (nameMatch === -1) {
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nameMatch = droppedIndex;
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}
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}
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}
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var mustNeverIndex = ((name === 'cookie' && value.length < 20) ||
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(name === 'set-cookie' && value.length < 20) ||
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name === 'authorization');
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if (fullMatch !== -1 && !mustNeverIndex) {
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this.send({ name: fullMatch, value: fullMatch, index: false });
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}
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// * otherwise, it will be a literal representation (with a name index if there's a name match)
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else {
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entry = entryFromPair(pair);
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var indexing = (entry._size < this._table._limit / 2) && !mustNeverIndex;
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if (indexing) {
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this._table.add(entry);
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}
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this.send({ name: (nameMatch !== -1) ? nameMatch : name, value: value, index: indexing, mustNeverIndex: mustNeverIndex, contextUpdate: false });
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}
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callback();
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};
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// `_flush` is the implementation of the [corresponding virtual function][_flush] of the
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// TransformStream class. It gets called when there's no more header to compress. The final step:
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// [_flush]: https://nodejs.org/api/stream.html#stream_transform_flush_callback
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HeaderSetCompressor.prototype._flush = function _flush(callback) {
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callback();
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};
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// [Detailed Format](https://tools.ietf.org/html/rfc7541#section-5)
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// -----------------
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// ### Integer representation ###
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//
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// The algorithm to represent an integer I is as follows:
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//
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// 1. If I < 2^N - 1, encode I on N bits
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// 2. Else, encode 2^N - 1 on N bits and do the following steps:
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// 1. Set I to (I - (2^N - 1)) and Q to 1
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// 2. While Q > 0
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// 1. Compute Q and R, quotient and remainder of I divided by 2^7
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// 2. If Q is strictly greater than 0, write one 1 bit; otherwise, write one 0 bit
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// 3. Encode R on the next 7 bits
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// 4. I = Q
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HeaderSetCompressor.integer = function writeInteger(I, N) {
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var limit = Math.pow(2,N) - 1;
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if (I < limit) {
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return [Buffer.from([I])];
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}
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var bytes = [];
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if (N !== 0) {
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bytes.push(limit);
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}
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I -= limit;
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var Q = 1, R;
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while (Q > 0) {
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Q = Math.floor(I / 128);
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R = I % 128;
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if (Q > 0) {
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R += 128;
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}
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bytes.push(R);
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I = Q;
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}
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return [Buffer.from(bytes)];
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};
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// The inverse algorithm:
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//
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// 1. Set I to the number coded on the lower N bits of the first byte
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// 2. If I is smaller than 2^N - 1 then return I
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// 2. Else the number is encoded on more than one byte, so do the following steps:
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// 1. Set M to 0
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// 2. While returning with I
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// 1. Let B be the next byte (the first byte if N is 0)
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// 2. Read out the lower 7 bits of B and multiply it with 2^M
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// 3. Increase I with this number
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// 4. Increase M by 7
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// 5. Return I if the most significant bit of B is 0
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HeaderSetDecompressor.integer = function readInteger(buffer, N) {
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var limit = Math.pow(2,N) - 1;
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var I = buffer[buffer.cursor] & limit;
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if (N !== 0) {
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buffer.cursor += 1;
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}
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if (I === limit) {
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var M = 0;
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do {
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I += (buffer[buffer.cursor] & 127) << M;
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M += 7;
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buffer.cursor += 1;
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} while (buffer[buffer.cursor - 1] & 128);
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}
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return I;
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};
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// ### Huffman Encoding ###
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function HuffmanTable(table) {
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function createTree(codes, position) {
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if (codes.length === 1) {
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return [table.indexOf(codes[0])];
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}
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else {
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position = position || 0;
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var zero = [];
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var one = [];
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for (var i = 0; i < codes.length; i++) {
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var string = codes[i];
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if (string[position] === '0') {
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zero.push(string);
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} else {
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one.push(string);
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}
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}
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return [createTree(zero, position + 1), createTree(one, position + 1)];
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}
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}
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this.tree = createTree(table);
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this.codes = table.map(function(bits) {
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return parseInt(bits, 2);
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});
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this.lengths = table.map(function(bits) {
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return bits.length;
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});
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}
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HuffmanTable.prototype.encode = function encode(buffer) {
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var result = [];
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var space = 8;
|
|
|
|
function add(data) {
|
|
if (space === 8) {
|
|
result.push(data);
|
|
} else {
|
|
result[result.length - 1] |= data;
|
|
}
|
|
}
|
|
|
|
for (var i = 0; i < buffer.length; i++) {
|
|
var byte = buffer[i];
|
|
var code = this.codes[byte];
|
|
var length = this.lengths[byte];
|
|
|
|
while (length !== 0) {
|
|
if (space >= length) {
|
|
add(code << (space - length));
|
|
code = 0;
|
|
space -= length;
|
|
length = 0;
|
|
} else {
|
|
var shift = length - space;
|
|
var msb = code >> shift;
|
|
add(msb);
|
|
code -= msb << shift;
|
|
length -= space;
|
|
space = 0;
|
|
}
|
|
|
|
if (space === 0) {
|
|
space = 8;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (space !== 8) {
|
|
add(this.codes[256] >> (this.lengths[256] - space));
|
|
}
|
|
|
|
return Buffer.from(result);
|
|
};
|
|
|
|
HuffmanTable.prototype.decode = function decode(buffer) {
|
|
var result = [];
|
|
var subtree = this.tree;
|
|
|
|
for (var i = 0; i < buffer.length; i++) {
|
|
var byte = buffer[i];
|
|
|
|
for (var j = 0; j < 8; j++) {
|
|
var bit = (byte & 128) ? 1 : 0;
|
|
byte = byte << 1;
|
|
|
|
subtree = subtree[bit];
|
|
if (subtree.length === 1) {
|
|
result.push(subtree[0]);
|
|
subtree = this.tree;
|
|
}
|
|
}
|
|
}
|
|
|
|
return Buffer.from(result);
|
|
};
|
|
|
|
// The initializer arrays for the Huffman tables are generated with feeding the tables from the
|
|
// spec to this sed command:
|
|
//
|
|
// sed -e "s/^.* [|]//g" -e "s/|//g" -e "s/ .*//g" -e "s/^/ '/g" -e "s/$/',/g"
|
|
|
|
HuffmanTable.huffmanTable = new HuffmanTable([
|
|
'1111111111000',
|
|
'11111111111111111011000',
|
|
'1111111111111111111111100010',
|
|
'1111111111111111111111100011',
|
|
'1111111111111111111111100100',
|
|
'1111111111111111111111100101',
|
|
'1111111111111111111111100110',
|
|
'1111111111111111111111100111',
|
|
'1111111111111111111111101000',
|
|
'111111111111111111101010',
|
|
'111111111111111111111111111100',
|
|
'1111111111111111111111101001',
|
|
'1111111111111111111111101010',
|
|
'111111111111111111111111111101',
|
|
'1111111111111111111111101011',
|
|
'1111111111111111111111101100',
|
|
'1111111111111111111111101101',
|
|
'1111111111111111111111101110',
|
|
'1111111111111111111111101111',
|
|
'1111111111111111111111110000',
|
|
'1111111111111111111111110001',
|
|
'1111111111111111111111110010',
|
|
'111111111111111111111111111110',
|
|
'1111111111111111111111110011',
|
|
'1111111111111111111111110100',
|
|
'1111111111111111111111110101',
|
|
'1111111111111111111111110110',
|
|
'1111111111111111111111110111',
|
|
'1111111111111111111111111000',
|
|
'1111111111111111111111111001',
|
|
'1111111111111111111111111010',
|
|
'1111111111111111111111111011',
|
|
'010100',
|
|
'1111111000',
|
|
'1111111001',
|
|
'111111111010',
|
|
'1111111111001',
|
|
'010101',
|
|
'11111000',
|
|
'11111111010',
|
|
'1111111010',
|
|
'1111111011',
|
|
'11111001',
|
|
'11111111011',
|
|
'11111010',
|
|
'010110',
|
|
'010111',
|
|
'011000',
|
|
'00000',
|
|
'00001',
|
|
'00010',
|
|
'011001',
|
|
'011010',
|
|
'011011',
|
|
'011100',
|
|
'011101',
|
|
'011110',
|
|
'011111',
|
|
'1011100',
|
|
'11111011',
|
|
'111111111111100',
|
|
'100000',
|
|
'111111111011',
|
|
'1111111100',
|
|
'1111111111010',
|
|
'100001',
|
|
'1011101',
|
|
'1011110',
|
|
'1011111',
|
|
'1100000',
|
|
'1100001',
|
|
'1100010',
|
|
'1100011',
|
|
'1100100',
|
|
'1100101',
|
|
'1100110',
|
|
'1100111',
|
|
'1101000',
|
|
'1101001',
|
|
'1101010',
|
|
'1101011',
|
|
'1101100',
|
|
'1101101',
|
|
'1101110',
|
|
'1101111',
|
|
'1110000',
|
|
'1110001',
|
|
'1110010',
|
|
'11111100',
|
|
'1110011',
|
|
'11111101',
|
|
'1111111111011',
|
|
'1111111111111110000',
|
|
'1111111111100',
|
|
'11111111111100',
|
|
'100010',
|
|
'111111111111101',
|
|
'00011',
|
|
'100011',
|
|
'00100',
|
|
'100100',
|
|
'00101',
|
|
'100101',
|
|
'100110',
|
|
'100111',
|
|
'00110',
|
|
'1110100',
|
|
'1110101',
|
|
'101000',
|
|
'101001',
|
|
'101010',
|
|
'00111',
|
|
'101011',
|
|
'1110110',
|
|
'101100',
|
|
'01000',
|
|
'01001',
|
|
'101101',
|
|
'1110111',
|
|
'1111000',
|
|
'1111001',
|
|
'1111010',
|
|
'1111011',
|
|
'111111111111110',
|
|
'11111111100',
|
|
'11111111111101',
|
|
'1111111111101',
|
|
'1111111111111111111111111100',
|
|
'11111111111111100110',
|
|
'1111111111111111010010',
|
|
'11111111111111100111',
|
|
'11111111111111101000',
|
|
'1111111111111111010011',
|
|
'1111111111111111010100',
|
|
'1111111111111111010101',
|
|
'11111111111111111011001',
|
|
'1111111111111111010110',
|
|
'11111111111111111011010',
|
|
'11111111111111111011011',
|
|
'11111111111111111011100',
|
|
'11111111111111111011101',
|
|
'11111111111111111011110',
|
|
'111111111111111111101011',
|
|
'11111111111111111011111',
|
|
'111111111111111111101100',
|
|
'111111111111111111101101',
|
|
'1111111111111111010111',
|
|
'11111111111111111100000',
|
|
'111111111111111111101110',
|
|
'11111111111111111100001',
|
|
'11111111111111111100010',
|
|
'11111111111111111100011',
|
|
'11111111111111111100100',
|
|
'111111111111111011100',
|
|
'1111111111111111011000',
|
|
'11111111111111111100101',
|
|
'1111111111111111011001',
|
|
'11111111111111111100110',
|
|
'11111111111111111100111',
|
|
'111111111111111111101111',
|
|
'1111111111111111011010',
|
|
'111111111111111011101',
|
|
'11111111111111101001',
|
|
'1111111111111111011011',
|
|
'1111111111111111011100',
|
|
'11111111111111111101000',
|
|
'11111111111111111101001',
|
|
'111111111111111011110',
|
|
'11111111111111111101010',
|
|
'1111111111111111011101',
|
|
'1111111111111111011110',
|
|
'111111111111111111110000',
|
|
'111111111111111011111',
|
|
'1111111111111111011111',
|
|
'11111111111111111101011',
|
|
'11111111111111111101100',
|
|
'111111111111111100000',
|
|
'111111111111111100001',
|
|
'1111111111111111100000',
|
|
'111111111111111100010',
|
|
'11111111111111111101101',
|
|
'1111111111111111100001',
|
|
'11111111111111111101110',
|
|
'11111111111111111101111',
|
|
'11111111111111101010',
|
|
'1111111111111111100010',
|
|
'1111111111111111100011',
|
|
'1111111111111111100100',
|
|
'11111111111111111110000',
|
|
'1111111111111111100101',
|
|
'1111111111111111100110',
|
|
'11111111111111111110001',
|
|
'11111111111111111111100000',
|
|
'11111111111111111111100001',
|
|
'11111111111111101011',
|
|
'1111111111111110001',
|
|
'1111111111111111100111',
|
|
'11111111111111111110010',
|
|
'1111111111111111101000',
|
|
'1111111111111111111101100',
|
|
'11111111111111111111100010',
|
|
'11111111111111111111100011',
|
|
'11111111111111111111100100',
|
|
'111111111111111111111011110',
|
|
'111111111111111111111011111',
|
|
'11111111111111111111100101',
|
|
'111111111111111111110001',
|
|
'1111111111111111111101101',
|
|
'1111111111111110010',
|
|
'111111111111111100011',
|
|
'11111111111111111111100110',
|
|
'111111111111111111111100000',
|
|
'111111111111111111111100001',
|
|
'11111111111111111111100111',
|
|
'111111111111111111111100010',
|
|
'111111111111111111110010',
|
|
'111111111111111100100',
|
|
'111111111111111100101',
|
|
'11111111111111111111101000',
|
|
'11111111111111111111101001',
|
|
'1111111111111111111111111101',
|
|
'111111111111111111111100011',
|
|
'111111111111111111111100100',
|
|
'111111111111111111111100101',
|
|
'11111111111111101100',
|
|
'111111111111111111110011',
|
|
'11111111111111101101',
|
|
'111111111111111100110',
|
|
'1111111111111111101001',
|
|
'111111111111111100111',
|
|
'111111111111111101000',
|
|
'11111111111111111110011',
|
|
'1111111111111111101010',
|
|
'1111111111111111101011',
|
|
'1111111111111111111101110',
|
|
'1111111111111111111101111',
|
|
'111111111111111111110100',
|
|
'111111111111111111110101',
|
|
'11111111111111111111101010',
|
|
'11111111111111111110100',
|
|
'11111111111111111111101011',
|
|
'111111111111111111111100110',
|
|
'11111111111111111111101100',
|
|
'11111111111111111111101101',
|
|
'111111111111111111111100111',
|
|
'111111111111111111111101000',
|
|
'111111111111111111111101001',
|
|
'111111111111111111111101010',
|
|
'111111111111111111111101011',
|
|
'1111111111111111111111111110',
|
|
'111111111111111111111101100',
|
|
'111111111111111111111101101',
|
|
'111111111111111111111101110',
|
|
'111111111111111111111101111',
|
|
'111111111111111111111110000',
|
|
'11111111111111111111101110',
|
|
'111111111111111111111111111111'
|
|
]);
|
|
|
|
// ### String literal representation ###
|
|
//
|
|
// Literal **strings** can represent header names or header values. There's two variant of the
|
|
// string encoding:
|
|
//
|
|
// String literal with Huffman encoding:
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 1 | Value Length Prefix (7) |
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | Value Length (0-N bytes) |
|
|
// +---+---+---+---+---+---+---+---+
|
|
// ...
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | Huffman Encoded Data |Padding|
|
|
// +---+---+---+---+---+---+---+---+
|
|
//
|
|
// String literal without Huffman encoding:
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | Value Length Prefix (7) |
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | Value Length (0-N bytes) |
|
|
// +---+---+---+---+---+---+---+---+
|
|
// ...
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | Field Bytes Without Encoding |
|
|
// +---+---+---+---+---+---+---+---+
|
|
|
|
HeaderSetCompressor.string = function writeString(str) {
|
|
str = Buffer.from(str, 'utf8');
|
|
|
|
var huffman = HuffmanTable.huffmanTable.encode(str);
|
|
if (huffman.length < str.length) {
|
|
var length = HeaderSetCompressor.integer(huffman.length, 7);
|
|
length[0][0] |= 128;
|
|
return length.concat(huffman);
|
|
}
|
|
|
|
else {
|
|
length = HeaderSetCompressor.integer(str.length, 7);
|
|
return length.concat(str);
|
|
}
|
|
};
|
|
|
|
HeaderSetDecompressor.string = function readString(buffer) {
|
|
var huffman = buffer[buffer.cursor] & 128;
|
|
var length = HeaderSetDecompressor.integer(buffer, 7);
|
|
var encoded = buffer.slice(buffer.cursor, buffer.cursor + length);
|
|
buffer.cursor += length;
|
|
return (huffman ? HuffmanTable.huffmanTable.decode(encoded) : encoded).toString('utf8');
|
|
};
|
|
|
|
// ### Header represenations ###
|
|
|
|
// The JavaScript object representation is described near the
|
|
// `HeaderSetDecompressor.prototype._execute()` method definition.
|
|
//
|
|
// **All binary header representations** start with a prefix signaling the representation type and
|
|
// an index represented using prefix coded integers:
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 1 | Index (7+) | Indexed Representation
|
|
// +---+---------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 1 | Index (6+) |
|
|
// +---+---+---+-------------------+ Literal w/ Indexing
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+ w/ Indexed Name
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 1 | 0 |
|
|
// +---+---+---+-------------------+
|
|
// | Name Length (8+) |
|
|
// +-------------------------------+ Literal w/ Indexing
|
|
// | Name String (Length octets) |
|
|
// +-------------------------------+ w/ New Name
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 0 | 0 | 0 | Index (4+) |
|
|
// +---+---+---+-------------------+ Literal w/o Incremental Indexing
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+ w/ Indexed Name
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 0 | 0 | 0 | 0 |
|
|
// +---+---+---+-------------------+
|
|
// | Name Length (8+) |
|
|
// +-------------------------------+ Literal w/o Incremental Indexing
|
|
// | Name String (Length octets) |
|
|
// +-------------------------------+ w/ New Name
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 0 | 0 | 1 | Index (4+) |
|
|
// +---+---+---+-------------------+ Literal never indexed
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+ w/ Indexed Name
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// 0 1 2 3 4 5 6 7
|
|
// +---+---+---+---+---+---+---+---+
|
|
// | 0 | 0 | 0 | 1 | 0 |
|
|
// +---+---+---+-------------------+
|
|
// | Name Length (8+) |
|
|
// +-------------------------------+ Literal never indexed
|
|
// | Name String (Length octets) |
|
|
// +-------------------------------+ w/ New Name
|
|
// | Value Length (8+) |
|
|
// +-------------------------------+
|
|
// | Value String (Length octets) |
|
|
// +-------------------------------+
|
|
//
|
|
// The **Indexed Representation** consists of the 1-bit prefix and the Index that is represented as
|
|
// a 7-bit prefix coded integer and nothing else.
|
|
//
|
|
// After the first bits, **all literal representations** specify the header name, either as a
|
|
// pointer to the Header Table (Index) or a string literal. When the string literal representation
|
|
// is used, the Index is set to 0 and the string literal starts at the second byte.
|
|
//
|
|
// For **all literal representations**, the specification of the header value comes next. It is
|
|
// always represented as a string.
|
|
|
|
var representations = {
|
|
indexed : { prefix: 7, pattern: 0x80 },
|
|
literalIncremental : { prefix: 6, pattern: 0x40 },
|
|
contextUpdate : { prefix: 0, pattern: 0x20 },
|
|
literalNeverIndexed : { prefix: 4, pattern: 0x10 },
|
|
literal : { prefix: 4, pattern: 0x00 }
|
|
};
|
|
|
|
HeaderSetCompressor.header = function writeHeader(header) {
|
|
var representation, buffers = [];
|
|
|
|
if (header.contextUpdate) {
|
|
representation = representations.contextUpdate;
|
|
} else if (typeof header.value === 'number') {
|
|
representation = representations.indexed;
|
|
} else if (header.index) {
|
|
representation = representations.literalIncremental;
|
|
} else if (header.mustNeverIndex) {
|
|
representation = representations.literalNeverIndexed;
|
|
} else {
|
|
representation = representations.literal;
|
|
}
|
|
|
|
if (representation === representations.contextUpdate) {
|
|
buffers.push(HeaderSetCompressor.integer(header.newMaxSize, 5));
|
|
}
|
|
|
|
else if (representation === representations.indexed) {
|
|
buffers.push(HeaderSetCompressor.integer(header.value + 1, representation.prefix));
|
|
}
|
|
|
|
else {
|
|
if (typeof header.name === 'number') {
|
|
buffers.push(HeaderSetCompressor.integer(header.name + 1, representation.prefix));
|
|
} else {
|
|
buffers.push(HeaderSetCompressor.integer(0, representation.prefix));
|
|
buffers.push(HeaderSetCompressor.string(header.name));
|
|
}
|
|
buffers.push(HeaderSetCompressor.string(header.value));
|
|
}
|
|
|
|
buffers[0][0][0] |= representation.pattern;
|
|
|
|
return Array.prototype.concat.apply([], buffers); // array of arrays of buffers -> array of buffers
|
|
};
|
|
|
|
HeaderSetDecompressor.header = function readHeader(buffer) {
|
|
var representation, header = {};
|
|
|
|
var firstByte = buffer[buffer.cursor];
|
|
if (firstByte & 0x80) {
|
|
representation = representations.indexed;
|
|
} else if (firstByte & 0x40) {
|
|
representation = representations.literalIncremental;
|
|
} else if (firstByte & 0x20) {
|
|
representation = representations.contextUpdate;
|
|
} else if (firstByte & 0x10) {
|
|
representation = representations.literalNeverIndexed;
|
|
} else {
|
|
representation = representations.literal;
|
|
}
|
|
|
|
header.value = header.name = -1;
|
|
header.index = false;
|
|
header.contextUpdate = false;
|
|
header.newMaxSize = 0;
|
|
header.mustNeverIndex = false;
|
|
|
|
if (representation === representations.contextUpdate) {
|
|
header.contextUpdate = true;
|
|
header.newMaxSize = HeaderSetDecompressor.integer(buffer, 5);
|
|
}
|
|
|
|
else if (representation === representations.indexed) {
|
|
header.value = header.name = HeaderSetDecompressor.integer(buffer, representation.prefix) - 1;
|
|
}
|
|
|
|
else {
|
|
header.name = HeaderSetDecompressor.integer(buffer, representation.prefix) - 1;
|
|
if (header.name === -1) {
|
|
header.name = HeaderSetDecompressor.string(buffer);
|
|
}
|
|
header.value = HeaderSetDecompressor.string(buffer);
|
|
header.index = (representation === representations.literalIncremental);
|
|
header.mustNeverIndex = (representation === representations.literalNeverIndexed);
|
|
}
|
|
|
|
return header;
|
|
};
|
|
|
|
// Integration with HTTP/2
|
|
// =======================
|
|
|
|
// This section describes the interaction between the compressor/decompressor and the rest of the
|
|
// HTTP/2 implementation. The `Compressor` and the `Decompressor` makes up a layer between the
|
|
// [framer](framer.html) and the [connection handling component](connection.html). They let most
|
|
// frames pass through, except HEADERS and PUSH_PROMISE frames. They convert the frames between
|
|
// these two representations:
|
|
//
|
|
// { {
|
|
// type: 'HEADERS', type: 'HEADERS',
|
|
// flags: {}, flags: {},
|
|
// stream: 1, <===> stream: 1,
|
|
// headers: { data: Buffer
|
|
// N1: 'V1', }
|
|
// N2: ['V1', 'V2', ...],
|
|
// // ...
|
|
// }
|
|
// }
|
|
//
|
|
// There are possibly several binary frame that belong to a single non-binary frame.
|
|
|
|
var MAX_HTTP_PAYLOAD_SIZE = 16384;
|
|
|
|
// The Compressor class
|
|
// --------------------
|
|
|
|
// The Compressor transform stream is basically stateless.
|
|
util.inherits(Compressor, TransformStream);
|
|
function Compressor(log, type) {
|
|
TransformStream.call(this, { objectMode: true });
|
|
|
|
this._log = log.child({ component: 'compressor' });
|
|
|
|
assert((type === 'REQUEST') || (type === 'RESPONSE'));
|
|
this._table = new HeaderTable(this._log);
|
|
|
|
this.tableSizeChangePending = false;
|
|
this.lowestTableSizePending = 0;
|
|
this.tableSizeSetting = DEFAULT_HEADER_TABLE_LIMIT;
|
|
}
|
|
|
|
// Changing the header table size
|
|
Compressor.prototype.setTableSizeLimit = function setTableSizeLimit(size) {
|
|
this._table.setSizeLimit(size);
|
|
if (!this.tableSizeChangePending || size < this.lowestTableSizePending) {
|
|
this.lowestTableSizePending = size;
|
|
}
|
|
this.tableSizeSetting = size;
|
|
this.tableSizeChangePending = true;
|
|
};
|
|
|
|
// `compress` takes a header set, and compresses it using a new `HeaderSetCompressor` stream
|
|
// instance. This means that from now on, the advantages of streaming header encoding are lost,
|
|
// but the API becomes simpler.
|
|
Compressor.prototype.compress = function compress(headers) {
|
|
var compressor = new HeaderSetCompressor(this._log, this._table);
|
|
|
|
if (this.tableSizeChangePending) {
|
|
if (this.lowestTableSizePending < this.tableSizeSetting) {
|
|
compressor.send({contextUpdate: true, newMaxSize: this.lowestTableSizePending,
|
|
name: "", value: "", index: 0});
|
|
}
|
|
compressor.send({contextUpdate: true, newMaxSize: this.tableSizeSetting,
|
|
name: "", value: "", index: 0});
|
|
this.tableSizeChangePending = false;
|
|
}
|
|
var colonHeaders = [];
|
|
var nonColonHeaders = [];
|
|
|
|
// To ensure we send colon headers first
|
|
for (var name in headers) {
|
|
if (name.trim()[0] === ':') {
|
|
colonHeaders.push(name);
|
|
} else {
|
|
nonColonHeaders.push(name);
|
|
}
|
|
}
|
|
|
|
function compressHeader(name) {
|
|
var value = headers[name];
|
|
name = String(name).toLowerCase();
|
|
|
|
// * To allow for better compression efficiency, the Cookie header field MAY be split into
|
|
// separate header fields, each with one or more cookie-pairs.
|
|
if (name == 'cookie') {
|
|
if (!(value instanceof Array)) {
|
|
value = [value];
|
|
}
|
|
value = Array.prototype.concat.apply([], value.map(function(cookie) {
|
|
return String(cookie).split(';').map(trim);
|
|
}));
|
|
}
|
|
|
|
if (value instanceof Array) {
|
|
for (var i = 0; i < value.length; i++) {
|
|
compressor.write([name, String(value[i])]);
|
|
}
|
|
} else {
|
|
compressor.write([name, String(value)]);
|
|
}
|
|
}
|
|
|
|
colonHeaders.forEach(compressHeader);
|
|
nonColonHeaders.forEach(compressHeader);
|
|
|
|
compressor.end();
|
|
|
|
var chunk, chunks = [];
|
|
while (chunk = compressor.read()) {
|
|
chunks.push(chunk);
|
|
}
|
|
return concat(chunks);
|
|
};
|
|
|
|
// When a `frame` arrives
|
|
Compressor.prototype._transform = function _transform(frame, encoding, done) {
|
|
// * and it is a HEADERS or PUSH_PROMISE frame
|
|
// * it generates a header block using the compress method
|
|
// * cuts the header block into `chunks` that are not larger than `MAX_HTTP_PAYLOAD_SIZE`
|
|
// * for each chunk, it pushes out a chunk frame that is identical to the original, except
|
|
// the `data` property which holds the given chunk, the type of the frame which is always
|
|
// CONTINUATION except for the first frame, and the END_HEADERS/END_PUSH_STREAM flag that
|
|
// marks the last frame and the END_STREAM flag which is always false before the end
|
|
if (frame.type === 'HEADERS' || frame.type === 'PUSH_PROMISE') {
|
|
var buffer = this.compress(frame.headers);
|
|
|
|
// This will result in CONTINUATIONs from a PUSH_PROMISE being 4 bytes shorter than they could
|
|
// be, but that's not the end of the world, and it prevents us from going over MAX_HTTP_PAYLOAD_SIZE
|
|
// on the initial PUSH_PROMISE frame.
|
|
var adjustment = frame.type === 'PUSH_PROMISE' ? 4 : 0;
|
|
var chunks = cut(buffer, MAX_HTTP_PAYLOAD_SIZE - adjustment);
|
|
|
|
for (var i = 0; i < chunks.length; i++) {
|
|
var chunkFrame;
|
|
var first = (i === 0);
|
|
var last = (i === chunks.length - 1);
|
|
|
|
if (first) {
|
|
chunkFrame = util._extend({}, frame);
|
|
chunkFrame.flags = util._extend({}, frame.flags);
|
|
chunkFrame.flags['END_' + frame.type] = last;
|
|
} else {
|
|
chunkFrame = {
|
|
type: 'CONTINUATION',
|
|
flags: { END_HEADERS: last },
|
|
stream: frame.stream
|
|
};
|
|
}
|
|
chunkFrame.data = chunks[i];
|
|
|
|
this.push(chunkFrame);
|
|
}
|
|
}
|
|
|
|
// * otherwise, the frame is forwarded without taking any action
|
|
else {
|
|
this.push(frame);
|
|
}
|
|
|
|
done();
|
|
};
|
|
|
|
// The Decompressor class
|
|
// ----------------------
|
|
|
|
// The Decompressor is a stateful transform stream, since it has to collect multiple frames first,
|
|
// and the decoding comes after unifying the payload of those frames.
|
|
//
|
|
// If there's a frame in progress, `this._inProgress` is `true`. The frames are collected in
|
|
// `this._frames`, and the type of the frame and the stream identifier is stored in `this._type`
|
|
// and `this._stream` respectively.
|
|
util.inherits(Decompressor, TransformStream);
|
|
function Decompressor(log, type) {
|
|
TransformStream.call(this, { objectMode: true });
|
|
|
|
this._log = log.child({ component: 'compressor' });
|
|
|
|
assert((type === 'REQUEST') || (type === 'RESPONSE'));
|
|
this._table = new HeaderTable(this._log);
|
|
|
|
this._inProgress = false;
|
|
this._base = undefined;
|
|
}
|
|
|
|
// Changing the header table size
|
|
Decompressor.prototype.setTableSizeLimit = function setTableSizeLimit(size) {
|
|
this._table.setSizeLimit(size);
|
|
};
|
|
|
|
// `decompress` takes a full header block, and decompresses it using a new `HeaderSetDecompressor`
|
|
// stream instance. This means that from now on, the advantages of streaming header decoding are
|
|
// lost, but the API becomes simpler.
|
|
Decompressor.prototype.decompress = function decompress(block) {
|
|
var decompressor = new HeaderSetDecompressor(this._log, this._table);
|
|
decompressor.end(block);
|
|
|
|
var seenNonColonHeader = false;
|
|
var headers = {};
|
|
var pair;
|
|
while (pair = decompressor.read()) {
|
|
var name = pair[0];
|
|
var value = pair[1];
|
|
var isColonHeader = (name.trim()[0] === ':');
|
|
if (seenNonColonHeader && isColonHeader) {
|
|
this.emit('error', 'PROTOCOL_ERROR');
|
|
return headers;
|
|
}
|
|
seenNonColonHeader = !isColonHeader;
|
|
if (name in headers) {
|
|
if (headers[name] instanceof Array) {
|
|
headers[name].push(value);
|
|
} else {
|
|
headers[name] = [headers[name], value];
|
|
}
|
|
} else {
|
|
headers[name] = value;
|
|
}
|
|
}
|
|
|
|
// * If there are multiple Cookie header fields after decompression, these MUST be concatenated
|
|
// into a single octet string using the two octet delimiter of 0x3B, 0x20 (the ASCII
|
|
// string "; ").
|
|
if (('cookie' in headers) && (headers['cookie'] instanceof Array)) {
|
|
headers['cookie'] = headers['cookie'].join('; ');
|
|
}
|
|
|
|
return headers;
|
|
};
|
|
|
|
// When a `frame` arrives
|
|
Decompressor.prototype._transform = function _transform(frame, encoding, done) {
|
|
// * and the collection process is already `_inProgress`, the frame is simply stored, except if
|
|
// it's an illegal frame
|
|
if (this._inProgress) {
|
|
if ((frame.type !== 'CONTINUATION') || (frame.stream !== this._base.stream)) {
|
|
this._log.error('A series of HEADER frames were not continuous');
|
|
this.emit('error', 'PROTOCOL_ERROR');
|
|
return;
|
|
}
|
|
this._frames.push(frame);
|
|
}
|
|
|
|
// * and the collection process is not `_inProgress`, but the new frame's type is HEADERS or
|
|
// PUSH_PROMISE, a new collection process begins
|
|
else if ((frame.type === 'HEADERS') || (frame.type === 'PUSH_PROMISE')) {
|
|
this._inProgress = true;
|
|
this._base = util._extend({}, frame);
|
|
this._frames = [frame];
|
|
}
|
|
|
|
// * otherwise, the frame is forwarded without taking any action
|
|
else {
|
|
this.push(frame);
|
|
}
|
|
|
|
// * When the frame signals that it's the last in the series, the header block chunks are
|
|
// concatenated, the headers are decompressed, and a new frame gets pushed out with the
|
|
// decompressed headers.
|
|
if (this._inProgress && (frame.flags.END_HEADERS || frame.flags.END_PUSH_PROMISE)) {
|
|
var buffer = concat(this._frames.map(function(frame) {
|
|
return frame.data;
|
|
}));
|
|
try {
|
|
var headers = this.decompress(buffer);
|
|
} catch(error) {
|
|
this._log.error({ err: error }, 'Header decompression error');
|
|
this.emit('error', 'COMPRESSION_ERROR');
|
|
return;
|
|
}
|
|
this.push(util._extend(this._base, { headers: headers }));
|
|
this._inProgress = false;
|
|
}
|
|
|
|
done();
|
|
};
|
|
|
|
// Helper functions
|
|
// ================
|
|
|
|
// Concatenate an array of buffers into a new buffer
|
|
function concat(buffers) {
|
|
var size = 0;
|
|
for (var i = 0; i < buffers.length; i++) {
|
|
size += buffers[i].length;
|
|
}
|
|
|
|
var concatenated = Buffer.alloc(size);
|
|
for (var cursor = 0, j = 0; j < buffers.length; cursor += buffers[j].length, j++) {
|
|
buffers[j].copy(concatenated, cursor);
|
|
}
|
|
|
|
return concatenated;
|
|
}
|
|
|
|
// Cut `buffer` into chunks not larger than `size`
|
|
function cut(buffer, size) {
|
|
var chunks = [];
|
|
var cursor = 0;
|
|
do {
|
|
var chunkSize = Math.min(size, buffer.length - cursor);
|
|
chunks.push(buffer.slice(cursor, cursor + chunkSize));
|
|
cursor += chunkSize;
|
|
} while(cursor < buffer.length);
|
|
return chunks;
|
|
}
|
|
|
|
function trim(string) {
|
|
return string.trim();
|
|
}
|