msgpack-javascript/src/Decoder.ts at master · keybase/msgpack-javascript · GitHub

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import { prettyByte } from "./utils/prettyByte";

import { ExtensionCodec } from "./ExtensionCodec";

import { getInt64, getUint64 } from "./utils/int";

import { utf8DecodeJs, TEXT_ENCODING_AVAILABLE, TEXT_DECODER_THRESHOLD, utf8DecodeTD } from "./utils/utf8";

import { createDataView, ensureUint8Array } from "./utils/typedArrays";

import { WASM_AVAILABLE, WASM_STR_THRESHOLD, utf8DecodeWasm } from "./wasmFunctions";

import { CachedKeyDecoder } from "./CachedKeyDecoder";

const enum State {

ARRAY,

MAP_KEY,

MAP_VALUE,

}

type MapKeyType = string | number;

const isValidMapKeyType = (key: unknown): key is MapKeyType => {

const keyType = typeof key;

return keyType === "string" || keyType === "number";

};

type StackMapState = {

type: State.MAP_KEY | State.MAP_VALUE;

size: number;

key: MapKeyType | null;

readCount: number;

map: Record<string, unknown>;

};

type StackArrayState = {

type: State.ARRAY;

size: number;

array: Array<unknown>;

position: number;

};

type StackState = StackArrayState | StackMapState;

const HEAD_BYTE_REQUIRED = -1;

const EMPTY_VIEW = new DataView(new ArrayBuffer(0));

const EMPTY_BYTES = new Uint8Array(EMPTY_VIEW.buffer);

// IE11: Hack to support IE11.

// IE11: Drop this hack and just use RangeError when IE11 is obsolete.

export const DataViewIndexOutOfBoundsError: typeof Error = (() => {

try {

// IE11: The spec says it should throw RangeError,

// IE11: but in IE11 it throws TypeError.

EMPTY_VIEW.getInt8(0);

} catch (e) {

return e.constructor;

}

throw new Error("never reached");

})();

const MORE_DATA = new DataViewIndexOutOfBoundsError("Insufficient data");

const DEFAULT_MAX_LENGTH = 0xffff_ffff; // uint32_max

const sharedCachedKeyDecoder = new CachedKeyDecoder();

export class Decoder {

totalPos = 0;

pos = 0;

view = EMPTY_VIEW;

bytes = EMPTY_BYTES;

headByte = HEAD_BYTE_REQUIRED;

readonly stack: Array<StackState> = [];

constructor(

readonly extensionCodec = ExtensionCodec.defaultCodec,

readonly maxStrLength = DEFAULT_MAX_LENGTH,

readonly maxBinLength = DEFAULT_MAX_LENGTH,

readonly maxArrayLength = DEFAULT_MAX_LENGTH,

readonly maxMapLength = DEFAULT_MAX_LENGTH,

readonly maxExtLength = DEFAULT_MAX_LENGTH,

readonly cachedKeyDecoder: CachedKeyDecoder | null = sharedCachedKeyDecoder,

) {}

setBuffer(buffer: ArrayLike<number> | ArrayBuffer): void {

this.bytes = ensureUint8Array(buffer);

this.view = createDataView(this.bytes);

this.pos = 0;

}

appendBuffer(buffer: ArrayLike<number>) {

if (this.headByte === HEAD_BYTE_REQUIRED && !this.hasRemaining()) {

this.setBuffer(buffer);

} else {

// retried because data is insufficient

const remainingData = this.bytes.subarray(this.pos);

const newData = ensureUint8Array(buffer);

const concated = new Uint8Array(remainingData.length + newData.length);

concated.set(remainingData);

concated.set(newData, remainingData.length);

this.setBuffer(concated);

}

hasRemaining(size = 1) {

return this.view.byteLength - this.pos >= size;

}

createNoExtraBytesError(posToShow: number): Error {

const { view, pos } = this;

return new RangeError(`Extra ${view.byteLength - pos} byte(s) found at buffer[${posToShow}]`);

}

decodeSingleSync(): unknown {

const object = this.decodeSync();

if (this.hasRemaining()) {

throw this.createNoExtraBytesError(this.pos);

}

return object;

}

async decodeSingleAsync(stream: AsyncIterable<ArrayLike<number>>): Promise<unknown> {

let decoded = false;

let object: unknown;

for await (const buffer of stream) {

if (decoded) {

throw this.createNoExtraBytesError(this.totalPos);

}

this.appendBuffer(buffer);

try {

object = this.decodeSync();

decoded = true;

} catch (e) {

if (!(e instanceof DataViewIndexOutOfBoundsError)) {

throw e; // rethrow

}

// fallthrough

}

this.totalPos += this.pos;

}

if (decoded) {

if (this.hasRemaining()) {

throw this.createNoExtraBytesError(this.totalPos);

}

return object;

}

const { headByte, pos, totalPos } = this;

throw new RangeError(

`Insufficient data in parcing ${prettyByte(headByte)} at ${totalPos} (${pos} in the current buffer)`,

);

}

decodeArrayStream(stream: AsyncIterable<ArrayLike<number>>) {

return this.decodeMultiAsync(stream, true);

}

decodeStream(stream: AsyncIterable<ArrayLike<number>>) {

return this.decodeMultiAsync(stream, false);

}

private async *decodeMultiAsync(stream: AsyncIterable<ArrayLike<number>>, isArray: boolean) {

let isArrayHeaderRequired = isArray;

let arrayItemsLeft = -1;

for await (const buffer of stream) {

if (isArray && arrayItemsLeft === 0) {

throw this.createNoExtraBytesError(this.totalPos);

}

this.appendBuffer(buffer);

if (isArrayHeaderRequired) {

arrayItemsLeft = this.readArraySize();

isArrayHeaderRequired = false;

this.complete();

}

try {

while (true) {

yield this.decodeSync();

if (--arrayItemsLeft === 0) {

break;

}

} catch (e) {

if (!(e instanceof DataViewIndexOutOfBoundsError)) {

throw e; // rethrow

}

// fallthrough

}

this.totalPos += this.pos;

}

decodeSync(): unknown {

DECODE: while (true) {

const headByte = this.readHeadByte();

let object: unknown;

if (headByte >= 0xe0) {

// negative fixint (111x xxxx) 0xe0 - 0xff

object = headByte - 0x100;

} else if (headByte < 0xc0) {

if (headByte < 0x80) {

// positive fixint (0xxx xxxx) 0x00 - 0x7f

object = headByte;

} else if (headByte < 0x90) {

// fixmap (1000 xxxx) 0x80 - 0x8f

const size = headByte - 0x80;

if (size !== 0) {

this.pushMapState(size);

this.complete();

continue DECODE;

} else {

object = {};

}

} else if (headByte < 0xa0) {

// fixarray (1001 xxxx) 0x90 - 0x9f

const size = headByte - 0x90;

if (size !== 0) {

this.pushArrayState(size);

this.complete();

continue DECODE;

} else {

object = [];

}

} else {

// fixstr (101x xxxx) 0xa0 - 0xbf

const byteLength = headByte - 0xa0;

object = this.decodeUtf8String(byteLength, 0);

}

} else if (headByte === 0xc0) {

// nil

object = null;

} else if (headByte === 0xc2) {

// false

object = false;

} else if (headByte === 0xc3) {

// true

object = true;

} else if (headByte === 0xca) {

// float 32

object = this.readF32();

} else if (headByte === 0xcb) {

// float 64

object = this.readF64();

} else if (headByte === 0xcc) {

// uint 8

object = this.readU8();

} else if (headByte === 0xcd) {

// uint 16

object = this.readU16();

} else if (headByte === 0xce) {

// uint 32

object = this.readU32();

} else if (headByte === 0xcf) {

// uint 64

object = this.readU64();

} else if (headByte === 0xd0) {

// int 8

object = this.readI8();

} else if (headByte === 0xd1) {

// int 16

object = this.readI16();

} else if (headByte === 0xd2) {

// int 32

object = this.readI32();

} else if (headByte === 0xd3) {

// int 64

object = this.readI64();

} else if (headByte === 0xd9) {

// str 8

const byteLength = this.lookU8();

object = this.decodeUtf8String(byteLength, 1);

} else if (headByte === 0xda) {

// str 16

const byteLength = this.lookU16();

object = this.decodeUtf8String(byteLength, 2);

} else if (headByte === 0xdb) {

// str 32

const byteLength = this.lookU32();

object = this.decodeUtf8String(byteLength, 4);

} else if (headByte === 0xdc) {

// array 16

const size = this.readU16();

if (size !== 0) {

this.pushArrayState(size);

this.complete();

continue DECODE;

} else {

object = [];

}

} else if (headByte === 0xdd) {

// array 32

const size = this.readU32();

if (size !== 0) {

this.pushArrayState(size);

this.complete();

continue DECODE;

} else {

object = [];

}

} else if (headByte === 0xde) {

// map 16

const size = this.readU16();

if (size !== 0) {

this.pushMapState(size);

this.complete();

continue DECODE;

} else {

object = {};

}

} else if (headByte === 0xdf) {

// map 32

const size = this.readU32();

if (size !== 0) {

this.pushMapState(size);

this.complete();

continue DECODE;

} else {

object = {};

}

} else if (headByte === 0xc4) {

// bin 8

const size = this.lookU8();

object = this.decodeBinary(size, 1);

} else if (headByte === 0xc5) {

// bin 16

const size = this.lookU16();

object = this.decodeBinary(size, 2);

} else if (headByte === 0xc6) {

// bin 32

const size = this.lookU32();

object = this.decodeBinary(size, 4);

} else if (headByte === 0xd4) {

// fixext 1

object = this.decodeExtension(1, 0);

} else if (headByte === 0xd5) {

// fixext 2

object = this.decodeExtension(2, 0);

} else if (headByte === 0xd6) {

// fixext 4

object = this.decodeExtension(4, 0);

} else if (headByte === 0xd7) {

// fixext 8

object = this.decodeExtension(8, 0);

} else if (headByte === 0xd8) {

// fixext 16

object = this.decodeExtension(16, 0);

} else if (headByte === 0xc7) {

// ext 8

const size = this.lookU8();

object = this.decodeExtension(size, 1);

} else if (headByte === 0xc8) {

// ext 16

const size = this.lookU16();

object = this.decodeExtension(size, 2);

} else if (headByte === 0xc9) {

// ext 32

const size = this.lookU32();

object = this.decodeExtension(size, 4);

} else {

throw new Error(`Unrecognized type byte: ${prettyByte(headByte)}`);

}

this.complete();

const stack = this.stack;

while (stack.length > 0) {

// arrays and maps

const state = stack[stack.length - 1];

if (state.type === State.ARRAY) {

state.array[state.position] = object;

state.position++;

if (state.position === state.size) {

stack.pop();

object = state.array;

} else {

continue DECODE;

}

} else if (state.type === State.MAP_KEY) {

if (!isValidMapKeyType(object)) {

throw new Error("The type of key must be string or number but " + typeof object);

}

state.key = object;

state.type = State.MAP_VALUE;

continue DECODE;

} else if (state.type === State.MAP_VALUE) {

// eslint-disable-next-line @typescript-eslint/no-non-null-assertion

state.map[state.key!] = object;

state.readCount++;

if (state.readCount === state.size) {

stack.pop();

object = state.map;

} else {

state.key = null;

state.type = State.MAP_KEY;

continue DECODE;

}

return object;

}

readHeadByte(): number {

if (this.headByte === HEAD_BYTE_REQUIRED) {

this.headByte = this.readU8();

// console.log("headByte", prettyByte(this.headByte));

}

return this.headByte;

}

complete(): void {

this.headByte = HEAD_BYTE_REQUIRED;

}

readArraySize(): number {

const headByte = this.readHeadByte();

switch (headByte) {

case 0xdc:

return this.readU16();

case 0xdd:

return this.readU32();

default: {

if (headByte < 0xa0) {

return headByte - 0x90;

} else {

throw new Error(`Unrecognized array type byte: ${prettyByte(headByte)}`);

}

pushMapState(size: number) {

if (size > this.maxMapLength) {

throw new Error(`Max length exceeded: map length (${size}) > maxMapLengthLength (${this.maxMapLength})`);

}

this.stack.push({

type: State.MAP_KEY,

size,

key: null,

readCount: 0,

map: {},

});

}

pushArrayState(size: number) {

if (size > this.maxArrayLength) {

throw new Error(`Max length exceeded: array length (${size}) > maxArrayLength (${this.maxArrayLength})`);

}

this.stack.push({

type: State.ARRAY,

size,

array: new Array<unknown>(size),

position: 0,

});

}

decodeUtf8String(byteLength: number, headerOffset: number): string {

if (byteLength > this.maxStrLength) {

throw new Error(`Max length exceeded: UTF-8 byte length (${byteLength}) > maxStrLength (${this.maxStrLength})`);

}

if (this.bytes.byteLength < this.pos + headerOffset + byteLength) {

throw MORE_DATA;

}

const offset = this.pos + headerOffset;

let object: string;

if (this.cachedKeyDecoder && this.stateIsMapKey() && this.cachedKeyDecoder.canBeCached(byteLength)) {

object = this.cachedKeyDecoder.decode(this.bytes, offset, byteLength);

} else if (TEXT_ENCODING_AVAILABLE && byteLength > TEXT_DECODER_THRESHOLD) {

object = utf8DecodeTD(this.bytes, offset, byteLength);

} else if (WASM_AVAILABLE && byteLength > WASM_STR_THRESHOLD) {

object = utf8DecodeWasm(this.bytes, offset, byteLength);

} else {

object = utf8DecodeJs(this.bytes, offset, byteLength);

}

this.pos += headerOffset + byteLength;

return object;

}

stateIsMapKey(): boolean {

if (this.stack.length > 0) {

const state = this.stack[this.stack.length - 1];

return state.type === State.MAP_KEY;

}

return false;

}

decodeBinary(byteLength: number, headOffset: number): Uint8Array {

if (byteLength > this.maxBinLength) {

throw new Error(`Max length exceeded: bin length (${byteLength}) > maxBinLength (${this.maxBinLength})`);

}

if (!this.hasRemaining(byteLength + headOffset)) {

throw MORE_DATA;

}

const offset = this.pos + headOffset;

const object = this.bytes.subarray(offset, offset + byteLength);

this.pos += headOffset + byteLength;

return object;

}

decodeExtension(size: number, headOffset: number): unknown {

if (size > this.maxExtLength) {

throw new Error(`Max length exceeded: ext length (${size}) > maxExtLength (${this.maxExtLength})`);

}

const extType = this.view.getInt8(this.pos + headOffset);

const data = this.decodeBinary(size, headOffset + 1 /* extType */);

return this.extensionCodec.decode(data, extType);

}

lookU8() {

return this.view.getUint8(this.pos);

}

lookU16() {

return this.view.getUint16(this.pos);

}

lookU32() {

return this.view.getUint32(this.pos);

}

readU8(): number {

const value = this.view.getUint8(this.pos);

this.pos++;

return value;

}

readI8(): number {

const value = this.view.getInt8(this.pos);

this.pos++;

return value;

}

readU16(): number {

const value = this.view.getUint16(this.pos);

this.pos += 2;

return value;

}

readI16(): number {

const value = this.view.getInt16(this.pos);

this.pos += 2;

return value;

}

readU32(): number {

const value = this.view.getUint32(this.pos);

this.pos += 4;

return value;

}

readI32(): number {

const value = this.view.getInt32(this.pos);

this.pos += 4;

return value;

}

readU64(): number {

const value = getUint64(this.view, this.pos);

this.pos += 8;

return value;

}

readI64(): number {

const value = getInt64(this.view, this.pos);

this.pos += 8;

return value;

}

readF32() {

const value = this.view.getFloat32(this.pos);

this.pos += 4;

return value;

}

readF64() {

const value = this.view.getFloat64(this.pos);

this.pos += 8;

return value;

}

msgpack-javascript/src/Decoder.ts at master · keybase/msgpack-javascript · GitHub

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