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Abstracted out encoding/decoding of numeric values into its own utility. Could be useful elsewhere.

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This commit is contained in:
Greg Hysen 2018-11-25 17:12:21 -08:00
parent 58a2dfbc4d
commit d2d89adbdd
9 changed files with 125 additions and 81 deletions
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6
packages/utils/src/abi_encoder/evm_data_types/array.ts
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@ -4,17 +4,17 @@ import { DataTypeFactory, MemberDataType } from '../abstract_data_types';
import * as Constants from '../utils/constants';
export class Array extends MemberDataType {
private static readonly _matcher = RegExp('^(.+)\\[([0-9]*)\\]$');
private static readonly _MATCHER = RegExp('^(.+)\\[([0-9]*)\\]$');
private readonly _arraySignature: string;
private readonly _elementType: string;
public static matchType(type: string): boolean {
return Array._matcher.test(type);
return Array._MATCHER.test(type);
}
public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
// Sanity check
const matches = Array._matcher.exec(dataItem.type);
const matches = Array._MATCHER.exec(dataItem.type);
if (matches === null || matches.length !== 3) {
throw new Error(`Could not parse array: ${dataItem.type}`);
} else if (matches[1] === undefined) {

6
packages/utils/src/abi_encoder/evm_data_types/int.ts
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@ -7,16 +7,16 @@ import { DataTypeFactory } from '../abstract_data_types';
import { Number } from './number';
export class Int extends Number {
private static readonly _matcher = RegExp(
private static readonly _MATCHER = RegExp(
'^int(8|16|24|32|40|48|56|64|72|88|96|104|112|120|128|136|144|152|160|168|176|184|192|200|208|216|224|232|240|248|256){0,1}$',
);
public static matchType(type: string): boolean {
return Int._matcher.test(type);
return Int._MATCHER.test(type);
}
public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
super(dataItem, Int._matcher, dataTypeFactory);
super(dataItem, Int._MATCHER, dataTypeFactory);
}
public getMaxValue(): BigNumber {

71
packages/utils/src/abi_encoder/evm_data_types/number.ts
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@ -1,11 +1,11 @@
import { DataItem } from 'ethereum-types';
import * as ethUtil from 'ethereumjs-util';
import * as _ from 'lodash';
import { BigNumber } from '../../configured_bignumber';
import { DataTypeFactory, PayloadDataType } from '../abstract_data_types';
import { RawCalldata } from '../calldata';
import * as Constants from '../utils/constants';
import * as EncoderMath from '../utils/math';
export abstract class Number extends PayloadDataType {
private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
@ -25,73 +25,14 @@ export abstract class Number extends PayloadDataType {
: (this._width = Number._DEFAULT_WIDTH);
}
public encodeValue(value_: BigNumber | string | number): Buffer {
const value = new BigNumber(value_, 10);
if (value.greaterThan(this.getMaxValue())) {
throw new Error(`Tried to assign value of ${value}, which exceeds max value of ${this.getMaxValue()}`);
} else if (value.lessThan(this.getMinValue())) {
throw new Error(`Tried to assign value of ${value}, which exceeds min value of ${this.getMinValue()}`);
}
let valueBuf: Buffer;
if (value.greaterThanOrEqualTo(0)) {
valueBuf = ethUtil.setLengthLeft(
ethUtil.toBuffer(`0x${value.toString(Constants.HEX_BASE)}`),
Constants.EVM_WORD_WIDTH_IN_BYTES,
);
} else {
// BigNumber can't write a negative hex value, so we use twos-complement conversion to do it ourselves.
// Step 1/3: Convert value to positive binary string
const binBase = 2;
const valueBin = value.times(-1).toString(binBase);
// Step 2/3: Invert binary value
let invertedValueBin = '1'.repeat(Constants.EVM_WORD_WIDTH_IN_BITS - valueBin.length);
_.each(valueBin, (bit: string) => {
invertedValueBin += bit === '1' ? '0' : '1';
});
const invertedValue = new BigNumber(invertedValueBin, binBase);
// Step 3/3: Add 1 to inverted value
// The result is the two's-complement represent of the input value.
const negativeValue = invertedValue.plus(1);
// Convert the negated value to a hex string
valueBuf = ethUtil.setLengthLeft(
ethUtil.toBuffer(`0x${negativeValue.toString(Constants.HEX_BASE)}`),
Constants.EVM_WORD_WIDTH_IN_BYTES,
);
}
return valueBuf;
public encodeValue(value: BigNumber | string | number): Buffer {
const encodedValue = EncoderMath.safeEncodeNumericValue(value, this.getMinValue(), this.getMaxValue());
return encodedValue;
}
public decodeValue(calldata: RawCalldata): BigNumber {
const paddedValueBuf = calldata.popWord();
const paddedValueHex = ethUtil.bufferToHex(paddedValueBuf);
let value = new BigNumber(paddedValueHex, 16);
if (this.getMinValue().lessThan(0)) {
// Check if we're negative
const valueBin = value.toString(Constants.BIN_BASE);
if (valueBin.length === Constants.EVM_WORD_WIDTH_IN_BITS && valueBin[0].startsWith('1')) {
// Negative
// Step 1/3: Invert binary value
let invertedValueBin = '';
_.each(valueBin, (bit: string) => {
invertedValueBin += bit === '1' ? '0' : '1';
});
const invertedValue = new BigNumber(invertedValueBin, Constants.BIN_BASE);
// Step 2/3: Add 1 to inverted value
// The result is the two's-complement represent of the input value.
const positiveValue = invertedValue.plus(1);
// Step 3/3: Invert positive value
const negativeValue = positiveValue.times(-1);
value = negativeValue;
}
}
const valueBuf = calldata.popWord();
const value = EncoderMath.safeDecodeNumericValue(valueBuf, this.getMinValue(), this.getMaxValue());
return value;
}

8
packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts
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@ -8,18 +8,18 @@ import * as Constants from '../utils/constants';
export class StaticBytes extends PayloadDataType {
private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
private static readonly _matcher = RegExp(
private static readonly _MATCHER = RegExp(
'^(byte|bytes(1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31|32))$',
);
private static readonly _DEFAULT_WIDTH = 1;
private readonly _width: number;
public static matchType(type: string): boolean {
return StaticBytes._matcher.test(type);
return StaticBytes._MATCHER.test(type);
}
private static _decodeWidthFromType(type: string): number {
const matches = StaticBytes._matcher.exec(type);
const matches = StaticBytes._MATCHER.exec(type);
const width = (matches !== null && matches.length === 3 && matches[2] !== undefined)
? parseInt(matches[2], Constants.DEC_BASE)
: StaticBytes._DEFAULT_WIDTH;
@ -55,7 +55,7 @@ export class StaticBytes extends PayloadDataType {
this._sanityCheckValue(value);
return value;
}
private _sanityCheckValue(value: string | Buffer): void {
if (typeof value === 'string') {
if (!value.startsWith('0x')) {

2
packages/utils/src/abi_encoder/evm_data_types/string.ts
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@ -13,7 +13,7 @@ export class String extends PayloadDataType {
public static matchType(type: string): boolean {
return type === 'string';
}
public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
super(dataItem, dataTypeFactory, String._SIZE_KNOWN_AT_COMPILE_TIME);
if (!String.matchType(dataItem.type)) {

2
packages/utils/src/abi_encoder/evm_data_types/tuple.ts
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@ -4,7 +4,7 @@ import { DataTypeFactory, MemberDataType } from '../abstract_data_types';
export class Tuple extends MemberDataType {
private readonly _signature: string;
public static matchType(type: string): boolean {
return type === 'tuple';
}

6
packages/utils/src/abi_encoder/evm_data_types/uint.ts
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@ -7,16 +7,16 @@ import { DataTypeFactory } from '../abstract_data_types';
import { Number } from './number';
export class UInt extends Number {
private static readonly _matcher = RegExp(
private static readonly _MATCHER = RegExp(
'^uint(8|16|24|32|40|48|56|64|72|88|96|104|112|120|128|136|144|152|160|168|176|184|192|200|208|216|224|232|240|248|256){0,1}$',
);
public static matchType(type: string): boolean {
return UInt._matcher.test(type);
return UInt._MATCHER.test(type);
}
public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
super(dataItem, UInt._matcher, dataTypeFactory);
super(dataItem, UInt._MATCHER, dataTypeFactory);
}
public getMaxValue(): BigNumber {

103
packages/utils/src/abi_encoder/utils/math.ts Normal file
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@ -0,0 +1,103 @@
import BigNumber from 'bignumber.js';
import * as ethUtil from 'ethereumjs-util';
import * as _ from 'lodash';
import * as Constants from '../utils/constants';
function sanityCheckBigNumberRange(value_: BigNumber | string | number, minValue: BigNumber, maxValue: BigNumber): void {
const value = new BigNumber(value_, 10);
if (value.greaterThan(maxValue)) {
throw new Error(`Tried to assign value of ${value}, which exceeds max value of ${maxValue}`);
} else if (value.lessThan(minValue)) {
throw new Error(`Tried to assign value of ${value}, which exceeds min value of ${minValue}`);
}
}
function bigNumberToPaddedBuffer(value: BigNumber): Buffer {
const valueHex = `0x${value.toString(Constants.HEX_BASE)}`;
const valueBuf = ethUtil.toBuffer(valueHex);
const valueBufPadded = ethUtil.setLengthLeft(valueBuf, Constants.EVM_WORD_WIDTH_IN_BYTES);
return valueBufPadded;
}
/**
* Takes a numeric value and returns its ABI-encoded value
* @param value_ The value to encode.
* @return ABI Encoded value
*/
export function encodeNumericValue(value_: BigNumber | string | number): Buffer {
const value = new BigNumber(value_, 10);
// Case 1/2: value is non-negative
if (value.greaterThanOrEqualTo(0)) {
const encodedPositiveValue = bigNumberToPaddedBuffer(value);
return encodedPositiveValue;
}
// Case 2/2: Value is negative
// Use two's-complement to encode the value
// Step 1/3: Convert negative value to positive binary string
const valueBin = value.times(-1).toString(Constants.BIN_BASE);
// Step 2/3: Invert binary value
let invertedValueBin = '1'.repeat(Constants.EVM_WORD_WIDTH_IN_BITS - valueBin.length);
_.each(valueBin, (bit: string) => {
invertedValueBin += bit === '1' ? '0' : '1';
});
const invertedValue = new BigNumber(invertedValueBin, Constants.BIN_BASE);
// Step 3/3: Add 1 to inverted value
const negativeValue = invertedValue.plus(1);
const encodedValue = bigNumberToPaddedBuffer(negativeValue);
return encodedValue;
}
/**
* Takes a numeric value and returns its ABI-encoded value.
* Performs an additional sanity check, given the min/max allowed value.
* @param value_ The value to encode.
* @return ABI Encoded value
*/
export function safeEncodeNumericValue(value: BigNumber | string | number, minValue: BigNumber, maxValue: BigNumber): Buffer {
sanityCheckBigNumberRange(value, minValue, maxValue);
const encodedValue = encodeNumericValue(value);
return encodedValue;
}
/**
* Takes an ABI-encoded numeric value and returns its decoded value as a BigNumber.
* @param encodedValue The encoded numeric value.
* @param minValue The minimum possible decoded value.
* @return ABI Decoded value
*/
export function decodeNumericValue(encodedValue: Buffer, minValue: BigNumber): BigNumber {
const valueHex = ethUtil.bufferToHex(encodedValue);
// Case 1/3: value is definitely non-negative because of numeric boundaries
const value = new BigNumber(valueHex, Constants.HEX_BASE);
if (!minValue.lessThan(0)) {
return value;
}
// Case 2/3: value is non-negative because there is no leading 1 (encoded as two's-complement)
const valueBin = value.toString(Constants.BIN_BASE);
const valueIsNegative = valueBin.length === Constants.EVM_WORD_WIDTH_IN_BITS && valueBin[0].startsWith('1');
if (!valueIsNegative) {
return value;
}
// Case 3/3: value is negative
// Step 1/3: Invert b inary value
let invertedValueBin = '';
_.each(valueBin, (bit: string) => {
invertedValueBin += bit === '1' ? '0' : '1';
});
const invertedValue = new BigNumber(invertedValueBin, Constants.BIN_BASE);
// Step 2/3: Add 1 to inverted value
// The result is the two's-complement representation of the input value.
const positiveValue = invertedValue.plus(1);
// Step 3/3: Invert positive value to get the negative value
const negativeValue = positiveValue.times(-1);
return negativeValue;
}
/**
* Takes an ABI-encoded numeric value and returns its decoded value as a BigNumber.
* Performs an additional sanity check, given the min/max allowed value.
* @param encodedValue The encoded numeric value.
* @param minValue The minimum possible decoded value.
* @return ABI Decoded value
*/
export function safeDecodeNumericValue(encodedValue: Buffer, minValue: BigNumber, maxValue: BigNumber): BigNumber {
const value = decodeNumericValue(encodedValue, minValue);
sanityCheckBigNumberRange(value, minValue, maxValue);
return value;
}

2
packages/utils/src/abi_encoder/utils/queue.ts
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@ -32,7 +32,7 @@ export class Queue<T> {
public getStore(): T[] {
return this._store;
}
public peekFront(): T | undefined {
return this._store.length >= 0 ? this._store[0] : undefined;
}