diff options
Diffstat (limited to 'packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts')
-rw-r--r-- | packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts b/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts new file mode 100644 index 000000000..5277efd6c --- /dev/null +++ b/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts @@ -0,0 +1,72 @@ +import { DataItem, SolidityTypes } from 'ethereum-types'; +import * as ethUtil from 'ethereumjs-util'; +import * as _ from 'lodash'; + +import { DataTypeFactory } from '../abstract_data_types/interfaces'; +import { AbstractBlobDataType } from '../abstract_data_types/types/blob'; +import { RawCalldata } from '../calldata/raw_calldata'; +import { constants } from '../utils/constants'; + +export class DynamicBytesDataType extends AbstractBlobDataType { + private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = false; + + public static matchType(type: string): boolean { + return type === SolidityTypes.Bytes; + } + + private static _sanityCheckValue(value: string | Buffer): void { + if (typeof value !== 'string') { + return; + } + if (!_.startsWith(value, '0x')) { + throw new Error(`Tried to encode non-hex value. Value must inlcude '0x' prefix.`); + } else if (value.length % 2 !== 0) { + throw new Error(`Tried to assign ${value}, which is contains a half-byte. Use full bytes only.`); + } + } + + public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) { + super(dataItem, dataTypeFactory, DynamicBytesDataType._SIZE_KNOWN_AT_COMPILE_TIME); + if (!DynamicBytesDataType.matchType(dataItem.type)) { + throw new Error(`Tried to instantiate Dynamic Bytes with bad input: ${dataItem}`); + } + } + + // Disable prefer-function-over-method for inherited abstract methods. + /* tslint:disable prefer-function-over-method */ + public encodeValue(value: string | Buffer): Buffer { + // Encoded value is of the form: <length><value>, with each field padded to be word-aligned. + // 1/3 Construct the length + const valueBuf = ethUtil.toBuffer(value); + const wordsToStoreValuePadded = Math.ceil(valueBuf.byteLength / constants.EVM_WORD_WIDTH_IN_BYTES); + const bytesToStoreValuePadded = wordsToStoreValuePadded * constants.EVM_WORD_WIDTH_IN_BYTES; + const lengthBuf = ethUtil.toBuffer(valueBuf.byteLength); + const lengthBufPadded = ethUtil.setLengthLeft(lengthBuf, constants.EVM_WORD_WIDTH_IN_BYTES); + // 2/3 Construct the value + DynamicBytesDataType._sanityCheckValue(value); + const valueBufPadded = ethUtil.setLengthRight(valueBuf, bytesToStoreValuePadded); + // 3/3 Combine length and value + const encodedValue = Buffer.concat([lengthBufPadded, valueBufPadded]); + return encodedValue; + } + + public decodeValue(calldata: RawCalldata): string { + // Encoded value is of the form: <length><value>, with each field padded to be word-aligned. + // 1/2 Decode length + const lengthBuf = calldata.popWord(); + const lengthHex = ethUtil.bufferToHex(lengthBuf); + const length = parseInt(lengthHex, constants.HEX_BASE); + // 2/2 Decode value + const wordsToStoreValuePadded = Math.ceil(length / constants.EVM_WORD_WIDTH_IN_BYTES); + const valueBufPadded = calldata.popWords(wordsToStoreValuePadded); + const valueBuf = valueBufPadded.slice(0, length); + const value = ethUtil.bufferToHex(valueBuf); + DynamicBytesDataType._sanityCheckValue(value); + return value; + } + + public getSignature(): string { + return SolidityTypes.Bytes; + } + /* tslint:enable prefer-function-over-method */ +} |