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jsonRpcHttpClient.ts
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jsonRpcHttpClient.ts
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import {EventEmitter} from "events";
import StrictEventEmitter from "strict-event-emitter-types";
import {fetch} from "@lodestar/api";
import {ErrorAborted, TimeoutError, isValidHttpUrl, retry} from "@lodestar/utils";
import {IGauge, IHistogram} from "../../metrics/interface.js";
import {IJson, RpcPayload} from "../interface.js";
import {encodeJwtToken} from "./jwt.js";
export enum JsonRpcHttpClientEvent {
/**
* When registered this event will be emitted before the client throws an error.
* This is useful for defining the error behavior in a common place at the time of declaration of the client.
*/
ERROR = "jsonRpcHttpClient:error",
/**
* When registered this event will be emitted before the client returns the valid response to the caller.
* This is useful for defining some common behavior for each request/response cycle
*/
RESPONSE = "jsonRpcHttpClient:response",
}
export type JsonRpcHttpClientEvents = {
[JsonRpcHttpClientEvent.ERROR]: (event: {payload?: unknown; error: Error}) => void;
[JsonRpcHttpClientEvent.RESPONSE]: (event: {payload?: unknown; response: unknown}) => void;
};
export class JsonRpcHttpClientEventEmitter extends (EventEmitter as {
new (): StrictEventEmitter<EventEmitter, JsonRpcHttpClientEvents>;
}) {}
/**
* Limits the amount of response text printed with RPC or parsing errors
*/
const maxStringLengthToPrint = 500;
const REQUEST_TIMEOUT = 30 * 1000;
interface RpcResponse<R> extends RpcResponseError {
result?: R;
}
interface RpcResponseError {
jsonrpc: "2.0";
id: number;
error: {
code: number; // -32601;
message: string; // "The method eth_none does not exist/is not available"
};
}
export type ReqOpts = {
timeout?: number;
// To label request metrics
routeId?: string;
// retry opts
retryAttempts?: number;
retryDelay?: number;
shouldRetry?: (lastError: Error) => boolean;
};
export type JsonRpcHttpClientMetrics = {
requestTime: IHistogram<"routeId">;
streamTime: IHistogram<"routeId">;
requestErrors: IGauge<"routeId">;
requestUsedFallbackUrl: IGauge<"routeId">;
activeRequests: IGauge<"routeId">;
configUrlsCount: IGauge;
retryCount: IGauge<"routeId">;
};
export interface IJsonRpcHttpClient {
fetch<R, P = IJson[]>(payload: RpcPayload<P>, opts?: ReqOpts): Promise<R>;
fetchWithRetries<R, P = IJson[]>(payload: RpcPayload<P>, opts?: ReqOpts): Promise<R>;
fetchBatch<R>(rpcPayloadArr: RpcPayload[], opts?: ReqOpts): Promise<R[]>;
emitter: JsonRpcHttpClientEventEmitter;
}
export class JsonRpcHttpClient implements IJsonRpcHttpClient {
private id = 1;
/**
* Optional: If provided, use this jwt secret to HS256 encode and add a jwt token in the
* request header which can be authenticated by the RPC server to provide access.
* A fresh token is generated on each requests as EL spec mandates the ELs to check
* the token freshness +-5 seconds (via `iat` property of the token claim)
*/
private readonly jwtSecret?: Uint8Array;
private readonly metrics: JsonRpcHttpClientMetrics | null;
readonly emitter = new JsonRpcHttpClientEventEmitter();
constructor(
private readonly urls: string[],
private readonly opts?: {
signal?: AbortSignal;
timeout?: number;
/** If returns true, do not fallback to other urls and throw early */
shouldNotFallback?: (error: Error) => boolean;
/**
* Optional: If provided, use this jwt secret to HS256 encode and add a jwt token in the
* request header which can be authenticated by the RPC server to provide access.
* A fresh token is generated on each requests as EL spec mandates the ELs to check
* the token freshness +-5 seconds (via `iat` property of the token claim)
*
* Otherwise the requests to the RPC server will be unauthorized
* and it might deny responses to the RPC requests.
*/
jwtSecret?: Uint8Array;
/** Retry attempts */
retryAttempts?: number;
/** Retry delay, only relevant with retry attempts */
retryDelay?: number;
/** Metrics for retry, could be expanded later */
metrics?: JsonRpcHttpClientMetrics | null;
}
) {
// Sanity check for all URLs to be properly defined. Otherwise it will error in loop on fetch
if (urls.length === 0) {
throw Error("No urls provided to JsonRpcHttpClient");
}
for (const [i, url] of urls.entries()) {
if (!url) {
throw Error(`JsonRpcHttpClient.urls[${i}] is empty or undefined: ${url}`);
}
if (!isValidHttpUrl(url)) {
throw Error(`JsonRpcHttpClient.urls[${i}] must be a valid URL: ${url}`);
}
}
this.jwtSecret = opts?.jwtSecret;
this.metrics = opts?.metrics ?? null;
this.metrics?.configUrlsCount.set(urls.length);
}
/**
* Perform RPC request
*/
async fetch<R, P = IJson[]>(payload: RpcPayload<P>, opts?: ReqOpts): Promise<R> {
return this.wrapWithEvents(
async () => {
const res: RpcResponse<R> = await this.fetchJson({jsonrpc: "2.0", id: this.id++, ...payload}, opts);
return parseRpcResponse(res, payload);
},
{payload}
);
}
/**
* Perform RPC request with retry
*/
async fetchWithRetries<R, P = IJson[]>(payload: RpcPayload<P>, opts?: ReqOpts): Promise<R> {
return this.wrapWithEvents(async () => {
const routeId = opts?.routeId ?? "unknown";
const res = await retry<RpcResponse<R>>(
async (attempt) => {
/** If this is a retry, increment the retry counter for this method */
if (attempt > 1) {
this.opts?.metrics?.retryCount.inc({routeId});
}
return this.fetchJson({jsonrpc: "2.0", id: this.id++, ...payload}, opts);
},
{
retries: opts?.retryAttempts ?? this.opts?.retryAttempts ?? 1,
retryDelay: opts?.retryDelay ?? this.opts?.retryDelay ?? 0,
shouldRetry: opts?.shouldRetry,
}
);
return parseRpcResponse(res, payload);
}, payload);
}
/**
* Perform RPC batched request
* Type-wise assumes all requests results have the same type
*/
async fetchBatch<R>(rpcPayloadArr: RpcPayload[], opts?: ReqOpts): Promise<R[]> {
return this.wrapWithEvents(async () => {
if (rpcPayloadArr.length === 0) return [];
const resArr: RpcResponse<R>[] = await this.fetchJson(
rpcPayloadArr.map(({method, params}) => ({jsonrpc: "2.0", method, params, id: this.id++})),
opts
);
if (!Array.isArray(resArr)) {
// Nethermind may reply to batch request with a JSON RPC error
if ((resArr as RpcResponseError).error !== undefined) {
throw new ErrorJsonRpcResponse(resArr as RpcResponseError, "batch");
}
throw Error(`expected array of results, got ${resArr} - ${jsonSerializeTry(resArr)}`);
}
return resArr.map((res, i) => parseRpcResponse(res, rpcPayloadArr[i]));
}, rpcPayloadArr);
}
private async wrapWithEvents<T>(func: () => Promise<T>, payload?: unknown): Promise<T> {
try {
const response = await func();
this.emitter.emit(JsonRpcHttpClientEvent.RESPONSE, {payload, response});
return response;
} catch (error) {
this.emitter.emit(JsonRpcHttpClientEvent.ERROR, {payload, error: error as Error});
throw error;
}
}
private async fetchJson<R, T = unknown>(json: T, opts?: ReqOpts): Promise<R> {
if (this.urls.length === 0) throw Error("No url provided");
const routeId = opts?.routeId ?? "unknown";
let lastError: Error | null = null;
for (let i = 0; i < this.urls.length; i++) {
if (i > 0) {
this.metrics?.requestUsedFallbackUrl.inc({routeId});
}
try {
return await this.fetchJsonOneUrl<R, T>(this.urls[i], json, opts);
} catch (e) {
lastError = e as Error;
if (this.opts?.shouldNotFallback?.(e as Error)) {
break;
}
}
}
throw lastError ?? Error("Unknown error");
}
/**
* Fetches JSON and throws detailed errors in case the HTTP request is not ok
*/
private async fetchJsonOneUrl<R, T = unknown>(url: string, json: T, opts?: ReqOpts): Promise<R> {
const controller = new AbortController();
const timeout = setTimeout(() => controller.abort(), opts?.timeout ?? this.opts?.timeout ?? REQUEST_TIMEOUT);
const onParentSignalAbort = (): void => controller.abort();
this.opts?.signal?.addEventListener("abort", onParentSignalAbort, {once: true});
// Default to "unknown" to prevent mixing metrics with others.
const routeId = opts?.routeId ?? "unknown";
const timer = this.metrics?.requestTime.startTimer({routeId});
this.metrics?.activeRequests.inc({routeId}, 1);
try {
const headers: Record<string, string> = {"Content-Type": "application/json"};
if (this.jwtSecret) {
/**
* ELs have a tight +-5 second freshness check on token's iat i.e. issued at
* so its better to generate a new token each time. Currently iat is the only claim
* we are encoding but potentially we can encode more claims.
* Also currently the algorithm for the token generation is mandated to HS256
*
* Jwt auth spec: https://github.com/ethereum/execution-apis/pull/167
*/
const token = encodeJwtToken({iat: Math.floor(new Date().getTime() / 1000)}, this.jwtSecret);
headers["Authorization"] = `Bearer ${token}`;
}
const res = await fetch(url, {
method: "post",
body: JSON.stringify(json),
headers,
signal: controller.signal,
});
const streamTimer = this.metrics?.streamTime.startTimer({routeId});
const bodyText = await res.text();
if (!res.ok) {
// Infura errors:
// - No project ID: Forbidden: {"jsonrpc":"2.0","id":0,"error":{"code":-32600,"message":"project ID is required","data":{"reason":"project ID not provided","see":"https://infura.io/dashboard"}}}
throw new HttpRpcError(res.status, `${res.statusText}: ${bodyText.slice(0, maxStringLengthToPrint)}`);
}
const bodyJson = parseJson<R>(bodyText);
streamTimer?.();
return bodyJson;
} catch (e) {
this.metrics?.requestErrors.inc({routeId});
if (controller.signal.aborted) {
// controller will abort on both parent signal abort + timeout of this specific request
if (this.opts?.signal?.aborted) {
throw new ErrorAborted("request");
} else {
throw new TimeoutError("request");
}
} else {
throw e;
}
} finally {
timer?.();
this.metrics?.activeRequests.dec({routeId}, 1);
clearTimeout(timeout);
this.opts?.signal?.removeEventListener("abort", onParentSignalAbort);
}
}
}
function parseRpcResponse<R, P>(res: RpcResponse<R>, payload: RpcPayload<P>): R {
if (res.result !== undefined) {
return res.result;
} else if (res.error !== undefined) {
throw new ErrorJsonRpcResponse(res, payload.method);
} else {
throw Error(`Invalid JSON RPC response, no result or error property: ${jsonSerializeTry(res)}`);
}
}
/**
* Util: Parse JSON but display the original source string in case of error
* Helps debug instances where an API returns a plain text instead of JSON,
* such as getting an HTML page due to a wrong API URL
*/
function parseJson<T>(json: string): T {
try {
return JSON.parse(json) as T;
} catch (e) {
throw new ErrorParseJson(json, e as Error);
}
}
export class ErrorParseJson extends Error {
constructor(json: string, e: Error) {
super(`Error parsing JSON: ${e.message}\n${json.slice(0, maxStringLengthToPrint)}`);
}
}
/** JSON RPC endpoint returned status code == 200, but with error property set */
export class ErrorJsonRpcResponse extends Error {
response: RpcResponseError;
constructor(res: RpcResponseError, payloadMethod: string) {
const errorMessage =
typeof res.error === "object"
? typeof res.error.message === "string"
? res.error.message
: typeof res.error.code === "number"
? parseJsonRpcErrorCode(res.error.code)
: JSON.stringify(res.error)
: String(res.error);
super(`JSON RPC error: ${errorMessage}, ${payloadMethod}`);
this.response = res;
}
}
/** JSON RPC endpoint returned status code != 200 */
export class HttpRpcError extends Error {
constructor(
readonly status: number,
message: string
) {
super(message);
}
}
/**
* JSON RPC spec errors https://www.jsonrpc.org/specification#response_object
*/
function parseJsonRpcErrorCode(code: number): string {
if (code === -32700) return "Parse request error";
if (code === -32600) return "Invalid request object";
if (code === -32601) return "Method not found";
if (code === -32602) return "Invalid params";
if (code === -32603) return "Internal error";
if (code <= -32000 && code >= -32099) return "Server error";
return `Unknown error code ${code}`;
}
function jsonSerializeTry(obj: unknown): string {
try {
return JSON.stringify(obj);
} catch (e) {
return `Unable to serialize ${String(obj)}: ${(e as Error).message}`;
}
}