147 lines
4.1 KiB
TypeScript
147 lines
4.1 KiB
TypeScript
"use strict";
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//See: https://github.com/ethereum/wiki/wiki/RLP
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import { arrayify, BytesLike, hexlify } from "@ethersproject/bytes";
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function arrayifyInteger(value: number): Array<number> {
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let result = [];
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while (value) {
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result.unshift(value & 0xff);
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value >>= 8;
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}
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return result;
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}
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function unarrayifyInteger(data: Uint8Array, offset: number, length: number): number {
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let result = 0;
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for (let i = 0; i < length; i++) {
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result = (result * 256) + data[offset + i];
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}
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return result;
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}
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function _encode(object: Array<any> | string): Array<number> {
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if (Array.isArray(object)) {
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let payload: Array<number> = [];
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object.forEach(function(child) {
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payload = payload.concat(_encode(child));
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});
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if (payload.length <= 55) {
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payload.unshift(0xc0 + payload.length)
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return payload;
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}
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let length = arrayifyInteger(payload.length);
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length.unshift(0xf7 + length.length);
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return length.concat(payload);
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}
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let data: Array<number> = Array.prototype.slice.call(arrayify(object));
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if (data.length === 1 && data[0] <= 0x7f) {
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return data;
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} else if (data.length <= 55) {
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data.unshift(0x80 + data.length);
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return data;
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}
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let length = arrayifyInteger(data.length);
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length.unshift(0xb7 + length.length);
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return length.concat(data);
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}
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export function encode(object: any): string {
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return hexlify(_encode(object));
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}
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type Decoded = {
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result: any;
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consumed: number;
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};
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function _decodeChildren(data: Uint8Array, offset: number, childOffset: number, length: number): Decoded {
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let result = [];
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while (childOffset < offset + 1 + length) {
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let decoded = _decode(data, childOffset);
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result.push(decoded.result);
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childOffset += decoded.consumed;
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if (childOffset > offset + 1 + length) {
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throw new Error("invalid rlp");
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}
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}
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return {consumed: (1 + length), result: result};
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}
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// returns { consumed: number, result: Object }
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function _decode(data: Uint8Array, offset: number): { consumed: number, result: any } {
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if (data.length === 0) { throw new Error("invalid rlp data"); }
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// Array with extra length prefix
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if (data[offset] >= 0xf8) {
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let lengthLength = data[offset] - 0xf7;
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if (offset + 1 + lengthLength > data.length) {
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throw new Error("too short");
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}
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let length = unarrayifyInteger(data, offset + 1, lengthLength);
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if (offset + 1 + lengthLength + length > data.length) {
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throw new Error("to short");
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}
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return _decodeChildren(data, offset, offset + 1 + lengthLength, lengthLength + length);
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} else if (data[offset] >= 0xc0) {
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let length = data[offset] - 0xc0;
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if (offset + 1 + length > data.length) {
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throw new Error("invalid rlp data");
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}
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return _decodeChildren(data, offset, offset + 1, length);
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} else if (data[offset] >= 0xb8) {
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let lengthLength = data[offset] - 0xb7;
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if (offset + 1 + lengthLength > data.length) {
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throw new Error("invalid rlp data");
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}
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let length = unarrayifyInteger(data, offset + 1, lengthLength);
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if (offset + 1 + lengthLength + length > data.length) {
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throw new Error("invalid rlp data");
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}
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let result = hexlify(data.slice(offset + 1 + lengthLength, offset + 1 + lengthLength + length));
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return { consumed: (1 + lengthLength + length), result: result }
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} else if (data[offset] >= 0x80) {
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let length = data[offset] - 0x80;
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if (offset + 1 + length > data.length) {
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throw new Error("invlaid rlp data");
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}
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let result = hexlify(data.slice(offset + 1, offset + 1 + length));
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return { consumed: (1 + length), result: result }
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}
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return { consumed: 1, result: hexlify(data[offset]) };
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}
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export function decode(data: BytesLike): any {
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let bytes = arrayify(data);
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let decoded = _decode(bytes, 0);
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if (decoded.consumed !== bytes.length) {
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throw new Error("invalid rlp data");
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}
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return decoded.result;
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}
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