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metashrew-view.ts
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metashrew-view.ts
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import express from "express";
import rocksdb from "rocksdb";
import bodyParser from "body-parser";
import { getLogger } from "./logger";
import EventEmitter from "events";
import rlp from "rlp";
import { ethers } from "ethers";
const DB_LOCATION = process.env.DB_LOCATION;
const logger = getLogger();
export const readArrayBufferAsUtf8 = (
memory: WebAssembly.Memory,
ptr: number
) => {
return Buffer.from(
Array.from(new Uint8Array(readArrayBuffer(memory, ptr)))
).toString("utf8");
};
export const readArrayBufferAsHex = (
memory: WebAssembly.Memory,
ptr: number
) => {
return (
"0x" +
Buffer.from(
Array.from(new Uint8Array(readArrayBuffer(memory, ptr)))
).toString("hex")
);
};
export const readArrayBuffer = (memory: WebAssembly.Memory, ptr: number) => {
const ary = Array.from(new Uint8Array(memory.buffer));
const data = Buffer.from(ary);
const length = data.readUInt32LE(ptr - 4);
return new Uint8Array(ary.slice(ptr, ptr + length)).buffer;
};
const stripHexPrefix = (s) => (s.substr(0, 2) === "0x" ? s.substr(2) : s);
const addHexPrefix = (s) => (s.substr(0, 2) === "0x" ? s : "0x" + s);
async function get(db: any, key: Buffer): Promise<Buffer> {
try {
return await new Promise((resolve, reject) =>
db.get(key, (err, result) => (err ? reject(err) : resolve(result)))
);
} catch (e) {
if (String(e).match("NotFound")) return Buffer.from([]);
else throw e;
}
}
function swizzle(bytes: Buffer): Buffer {
return Buffer.from(Array.from(bytes).reverse());
}
function leftPad(hex: string, n: number): string {
return "0".repeat(n - hex.length) + hex;
}
function makeIndexKey(key: Buffer, length: number): Buffer {
const data = Array.from(key);
return Buffer.from(
data.concat(
Array.from(swizzle(Buffer.from(leftPad(length.toString(16), 8), "hex")))
)
);
}
function makeLengthKey(key: Buffer): Buffer {
return makeIndexKey(key, 0xffffffff);
}
function bytesToNumber<T>(bytes: Array<T> | Buffer): number {
return Number("0x" + Buffer.from(bytes as any).toString("hex"));
}
async function getValueForBlock(
db: any,
key: Buffer,
blockTag: string
): Promise<Buffer> {
const blockNumber = blockTag === "latest" ? 0xffffffff : Number(blockTag);
let i = (await getLengthAtKey(db, key)) - 1;
//logger.info("keylength: " + i);
while (i >= 0) {
const result = Array.from(await get(db, makeIndexKey(key, i)));
const resultHeight = bytesToNumber(result.slice(-4));
if (resultHeight <= blockNumber) return Buffer.from(result.slice(0, -4));
i--;
}
return Buffer.from([]);
}
export async function getLengthAtKey(db: any, key: Buffer): Promise<number> {
const length = await get(db, makeLengthKey(key));
if (length.length === 0) return 0;
return Number("0x" + Buffer.from(length as any).toString("hex"));
}
export class IndexSandbox extends EventEmitter {
public input: string;
public program: ArrayBuffer;
public kv: any;
public db: any;
constructor(program: ArrayBuffer) {
super();
this.program = program;
this.db = rocksdb(DB_LOCATION);
}
async openDatabase() {
return await new Promise((resolve, reject) =>
this.db.open({ readOnly: true }, (err) => {
if (err) return reject(err);
resolve(this);
})
);
}
get memory() {
return (this as any).instance.instance.exports.memory;
}
__log(ptr: number): void {
const ary = Array.from(new Uint8Array(this.memory.buffer));
const data = Buffer.from(ary);
const length = data.readUInt32LE(ptr - 4);
this.emit(
"log",
Buffer.from(ary.slice(ptr, ptr + length)).toString("utf8")
);
}
__load_input(ptr: number): void {
const view = new Uint8Array(this.memory.buffer);
const input = Buffer.from(stripHexPrefix(this.input), "hex");
for (let i = 0; i < input.length; i++) {
view[i + ptr] = input.readUInt8(i);
}
}
__host_len(): number {
return stripHexPrefix(this.input).length / 2;
}
__flush(v: number): void {}
async __get(blockTag: string, k: number, v: number): Promise<void> {
const key = readArrayBufferAsHex(this.memory, k);
const value = await getValueForBlock(
this.db,
Buffer.from(key.substr(2), "hex"),
blockTag
);
const view = new Uint8Array(this.memory.buffer);
const valueData = value;
for (let i = 0; i < valueData.length; i++) {
view[v + i] = valueData.readUInt8(i);
}
}
async __get_len(blockTag: string, k: number): Promise<number> {
const key = readArrayBufferAsHex(this.memory, k);
const value: Buffer = await getValueForBlock(
this.db,
Buffer.from(key.substr(2), "hex"),
blockTag
);
return value.length;
}
abort() {
this.emit("abort");
throw Error("abort!");
}
setInput(input: string): IndexSandbox {
this.input = input;
return this;
}
async run(symbol: string, blockTag: string) {
(this as any).instance = await WebAssembly.instantiate(this.program, {
env: {
abort: (...args) => (this as any).abort(...args),
__log: (...args) => (this as any).__log(...args),
__flush: (...args) => (this as any).__flush(...args),
__get: (...args) => (this as any).__get(blockTag, ...args),
__get_len: (...args) => (this as any).__get_len(blockTag, ...args),
__host_len: () => (this as any).__host_len(),
__load_input: (ptr: number) => (this as any).__load_input(ptr),
},
});
return await (this as any).instance.instance.exports[symbol]();
}
}
export function dumpJSONRPCPayload(payload) {
if (!payload.method || !payload.params) return "null";
return payload.method + "/" + payload.params.join("/") + "/";
}
export function logMiddleware(req, res, next) {
const ip = req.get("X-Real-IP") || "127.0.0.1";
logger.info(ip + "|" + dumpJSONRPCPayload(req.body));
next();
}
export async function run(program: ArrayBuffer) {
const _programHash = ethers.solidityPackedKeccak256(
["bytes"],
[
addHexPrefix(
Buffer.from(Array.from(new Uint8Array(program))).toString("hex")
),
]
);
logger.info("program hash: " + _programHash);
const app = express();
app.use(bodyParser.json());
app.use(logMiddleware);
app.post("/", (req, res) => {
(async () => {
if (!req.body) return res.json({ success: "NO" });
const { id, method, params } = req.body;
try {
if (method === "metashrew_view") {
const [programHash, fn, input, blockTag] = params;
if (addHexPrefix(programHash) !== _programHash)
throw Error("program hash invalid for process handler");
logger.info("input: " + input);
const sandbox = new IndexSandbox(program);
sandbox.setInput(input);
await sandbox.openDatabase();
sandbox.on("log", (log) => logger.debug(log));
const ptr = await sandbox.run(fn, blockTag);
res.json({
id,
result: readArrayBufferAsHex(sandbox.memory, ptr),
jsonrpc: "2.0",
});
} else {
throw Error(`method "${method}" not handled by metashrew-view`);
}
} catch (e) {
logger.error(e);
res.json({
jsonrpc: "2.0",
id,
error: e.message,
});
}
})().catch((err) => logger.error(err));
});
return await new Promise((resolve, reject) =>
app.listen(
process.env.PORT || 3000,
process.env.HOST || "0.0.0.0",
(err) => {
if (err) reject(err);
else resolve(app);
}
)
);
}