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type {\n CreateServicePolicyOptions,\n ServicePolicy,\n} from '@fortuna-wallet/controller-utils';\nimport {\n CircuitState,\n HttpError,\n createServicePolicy,\n handleWhen,\n} from '@fortuna-wallet/controller-utils';\nimport { JsonRpcError, rpcErrors } from '@metamask/rpc-errors';\nimport type { JsonRpcRequest } from '@metamask/utils';\nimport {\n getErrorMessage,\n hasProperty,\n type Json,\n type JsonRpcParams,\n type JsonRpcResponse,\n} from '@metamask/utils';\nimport deepmerge from 'deepmerge';\n\nimport type { AbstractRpcService } from './abstract-rpc-service';\nimport type { AddToCockatielEventData, FetchOptions } from './shared';\n\n/**\n * Options for the RpcService constructor.\n */\nexport type RpcServiceOptions = {\n /**\n * A function that can be used to convert a binary string into a\n * base64-encoded ASCII string. Used to encode authorization credentials.\n */\n btoa: typeof btoa;\n /**\n * The URL of the RPC endpoint to hit.\n */\n endpointUrl: URL | string;\n /**\n * An RPC service that represents a failover endpoint which will be invoked\n * while the circuit for _this_ service is open.\n */\n failoverService?: AbstractRpcService;\n /**\n * A function that can be used to make an HTTP request. If your JavaScript\n * environment supports `fetch` natively, you'll probably want to pass that;\n * otherwise you can pass an equivalent (such as `fetch` via `node-fetch`).\n */\n fetch: typeof fetch;\n /**\n * A common set of options that will be used to make every request. Can be\n * overridden on the request level (e.g. to add headers).\n */\n fetchOptions?: FetchOptions;\n /**\n * Options to pass to `createServicePolicy`. Note that `retryFilterPolicy` is\n * not accepted, as it is overwritten. See {@link createServicePolicy}.\n */\n policyOptions?: Omit;\n};\n\n/**\n * The maximum number of times that a failing service should be re-run before\n * giving up.\n */\nexport const DEFAULT_MAX_RETRIES = 4;\n\n/**\n * The maximum number of times that the service is allowed to fail before\n * pausing further retries. This is set to a value such that if given a\n * service that continually fails, the policy needs to be executed 3 times\n * before further retries are paused.\n */\nexport const DEFAULT_MAX_CONSECUTIVE_FAILURES = (1 + DEFAULT_MAX_RETRIES) * 3;\n\n/**\n * The list of error messages that represent a failure to connect to the network.\n *\n * This list was derived from Sindre Sorhus's `is-network-error` package:\n * \n */\nexport const CONNECTION_ERRORS = [\n // Chrome\n {\n constructorName: 'TypeError',\n pattern: /network error/u,\n },\n // Chrome\n {\n constructorName: 'TypeError',\n pattern: /Failed to fetch/u,\n },\n // Firefox\n {\n constructorName: 'TypeError',\n pattern: /NetworkError when attempting to fetch resource\\./u,\n },\n // Safari 16\n {\n constructorName: 'TypeError',\n pattern: /The Internet connection appears to be offline\\./u,\n },\n // Safari 17+\n {\n constructorName: 'TypeError',\n pattern: /Load failed/u,\n },\n // `cross-fetch`\n {\n constructorName: 'TypeError',\n pattern: /Network request failed/u,\n },\n // `node-fetch`\n {\n constructorName: 'FetchError',\n pattern: /request to (.+) failed/u,\n },\n // Undici (Node.js)\n {\n constructorName: 'TypeError',\n pattern: /fetch failed/u,\n },\n // Undici (Node.js)\n {\n constructorName: 'TypeError',\n pattern: /terminated/u,\n },\n];\n\n/**\n * Custom JSON-RPC error codes for specific cases.\n *\n * These should be moved to `@metamask/rpc-errors` eventually.\n */\nexport const CUSTOM_RPC_ERRORS = {\n unauthorized: -32006,\n httpClientError: -32080,\n} as const;\n\n/**\n * Determines whether the given error represents a failure to reach the network\n * after request parameters have been validated.\n *\n * This is somewhat difficult to verify because JavaScript engines (and in\n * some cases libraries) produce slightly different error messages for this\n * particular scenario, and we need to account for this.\n *\n * @param error - The error.\n * @returns True if the error indicates that the network cannot be connected to,\n * and false otherwise.\n */\nexport function isConnectionError(error: unknown) {\n if (!(typeof error === 'object' && error !== null && 'message' in error)) {\n return false;\n }\n\n const { message } = error;\n\n return (\n typeof message === 'string' &&\n !isNockError(message) &&\n CONNECTION_ERRORS.some(({ constructorName, pattern }) => {\n return (\n error.constructor.name === constructorName && pattern.test(message)\n );\n })\n );\n}\n\n/**\n * Determines whether the given error message refers to a Nock error.\n *\n * It's important that if we failed to mock a request in a test, the resulting\n * error does not cause the request to be retried so that we can see it right\n * away.\n *\n * @param message - The error message to test.\n * @returns True if the message indicates a missing Nock mock, false otherwise.\n */\nfunction isNockError(message: string) {\n return message.includes('Nock:');\n}\n\n/**\n * Determine whether the given error message indicates a failure to parse JSON.\n *\n * This is different in tests vs. implementation code because it may manifest as\n * a FetchError or a SyntaxError.\n *\n * @param error - The error object to test.\n * @returns True if the error indicates a JSON parse error, false otherwise.\n */\nfunction isJsonParseError(error: unknown) {\n return (\n error instanceof SyntaxError ||\n /invalid json/iu.test(getErrorMessage(error))\n );\n}\n\n/**\n * Guarantees a URL, even given a string. This is useful for checking components\n * of that URL.\n *\n * @param endpointUrlOrUrlString - Either a URL object or a string that\n * represents the URL of an endpoint.\n * @returns A URL object.\n */\nfunction getNormalizedEndpointUrl(endpointUrlOrUrlString: URL | string): URL {\n return endpointUrlOrUrlString instanceof URL\n ? endpointUrlOrUrlString\n : new URL(endpointUrlOrUrlString);\n}\n\n/**\n * This class is responsible for making a request to an endpoint that implements\n * the JSON-RPC protocol. It is designed to gracefully handle network and server\n * failures, retrying requests using exponential backoff. It also offers a hook\n * which can used to respond to slow requests.\n */\nexport class RpcService implements AbstractRpcService {\n /**\n * The function used to make an HTTP request.\n */\n readonly #fetch: typeof fetch;\n\n /**\n * The URL of the RPC endpoint.\n */\n readonly endpointUrl: URL;\n\n /**\n * A common set of options that the request options will extend.\n */\n readonly #fetchOptions: FetchOptions;\n\n /**\n * An RPC service that represents a failover endpoint which will be invoked\n * while the circuit for _this_ service is open.\n */\n readonly #failoverService: RpcServiceOptions['failoverService'];\n\n /**\n * The policy that wraps the request.\n */\n readonly #policy: ServicePolicy;\n\n /**\n * Constructs a new RpcService object.\n *\n * @param options - The options. See {@link RpcServiceOptions}.\n */\n constructor(options: RpcServiceOptions) {\n const {\n btoa: givenBtoa,\n endpointUrl,\n failoverService,\n fetch: givenFetch,\n fetchOptions = {},\n policyOptions = {},\n } = options;\n\n this.#fetch = givenFetch;\n this.endpointUrl = getNormalizedEndpointUrl(endpointUrl);\n this.#fetchOptions = this.#getDefaultFetchOptions(\n this.endpointUrl,\n fetchOptions,\n givenBtoa,\n );\n this.#failoverService = failoverService;\n\n const policy = createServicePolicy({\n maxRetries: DEFAULT_MAX_RETRIES,\n maxConsecutiveFailures: DEFAULT_MAX_CONSECUTIVE_FAILURES,\n ...policyOptions,\n retryFilterPolicy: handleWhen((error) => {\n return (\n // Ignore errors where the request failed to establish\n isConnectionError(error) ||\n // Ignore server sent HTML error pages or truncated JSON responses\n isJsonParseError(error) ||\n // Ignore server overload errors\n ('httpStatus' in error &&\n (error.httpStatus === 502 ||\n error.httpStatus === 503 ||\n error.httpStatus === 504)) ||\n (hasProperty(error, 'code') &&\n (error.code === 'ETIMEDOUT' || error.code === 'ECONNRESET'))\n );\n }),\n });\n this.#policy = policy;\n }\n\n /**\n * Listens for when the RPC service retries the request.\n *\n * @param listener - The callback to be called when the retry occurs.\n * @returns What {@link ServicePolicy.onRetry} returns.\n * @see {@link createServicePolicy}\n */\n onRetry(\n listener: AddToCockatielEventData<\n Parameters[0],\n { endpointUrl: string }\n >,\n ) {\n return this.#policy.onRetry((data) => {\n listener({ ...data, endpointUrl: this.endpointUrl.toString() });\n });\n }\n\n /**\n * Listens for when the RPC service retries the request too many times in a\n * row.\n *\n * @param listener - The callback to be called when the circuit is broken.\n * @returns What {@link ServicePolicy.onBreak} returns.\n * @see {@link createServicePolicy}\n */\n onBreak(\n listener: AddToCockatielEventData<\n Parameters[0],\n { endpointUrl: string; failoverEndpointUrl?: string }\n >,\n ) {\n return this.#policy.onBreak((data) => {\n listener({\n ...data,\n endpointUrl: this.endpointUrl.toString(),\n failoverEndpointUrl: this.#failoverService\n ? this.#failoverService.endpointUrl.toString()\n : undefined,\n });\n });\n }\n\n /**\n * Listens for when the policy underlying this RPC service detects a slow\n * request.\n *\n * @param listener - The callback to be called when the request is slow.\n * @returns What {@link ServicePolicy.onDegraded} returns.\n * @see {@link createServicePolicy}\n */\n onDegraded(\n listener: AddToCockatielEventData<\n Parameters[0],\n { endpointUrl: string }\n >,\n ) {\n return this.#policy.onDegraded(() => {\n listener({ endpointUrl: this.endpointUrl.toString() });\n });\n }\n\n /**\n * Makes a request to the RPC endpoint. If the circuit is open because this\n * request has failed too many times, the request is forwarded to a failover\n * service (if provided).\n *\n * This overload is specifically designed for `eth_getBlockByNumber`, which\n * can return a `result` of `null` despite an expected `Result` being\n * provided.\n *\n * @param jsonRpcRequest - The JSON-RPC request to send to the endpoint.\n * @param fetchOptions - An options bag for {@link fetch} which further\n * specifies the request.\n * @returns The decoded JSON-RPC response from the endpoint.\n * @throws An \"authorized\" JSON-RPC error (code -32006) if the response HTTP status is 401.\n * @throws A \"rate limiting\" JSON-RPC error (code -32005) if the response HTTP status is 429.\n * @throws A \"resource unavailable\" JSON-RPC error (code -32002) if the response HTTP status is 402, 404, or any 5xx.\n * @throws A generic HTTP client JSON-RPC error (code -32050) for any other 4xx HTTP status codes.\n * @throws A \"parse\" JSON-RPC error (code -32700) if the response is not valid JSON.\n */\n async request(\n jsonRpcRequest: JsonRpcRequest & { method: 'eth_getBlockByNumber' },\n fetchOptions?: FetchOptions,\n ): Promise | JsonRpcResponse>;\n\n /**\n * Makes a request to the RPC endpoint. If the circuit is open because this\n * request has failed too many times, the request is forwarded to a failover\n * service (if provided).\n *\n * This overload is designed for all RPC methods except for\n * `eth_getBlockByNumber`, which are expected to return a `result` of the\n * expected `Result`.\n *\n * @param jsonRpcRequest - The JSON-RPC request to send to the endpoint.\n * @param fetchOptions - An options bag for {@link fetch} which further\n * specifies the request.\n * @returns The decoded JSON-RPC response from the endpoint.\n * @throws An \"authorized\" JSON-RPC error (code -32006) if the response HTTP status is 401.\n * @throws A \"rate limiting\" JSON-RPC error (code -32005) if the response HTTP status is 429.\n * @throws A \"resource unavailable\" JSON-RPC error (code -32002) if the response HTTP status is 402, 404, or any 5xx.\n * @throws A generic HTTP client JSON-RPC error (code -32050) for any other 4xx HTTP status codes.\n * @throws A \"parse\" JSON-RPC error (code -32700) if the response is not valid JSON.\n */\n async request(\n jsonRpcRequest: JsonRpcRequest,\n fetchOptions?: FetchOptions,\n ): Promise>;\n\n async request(\n jsonRpcRequest: JsonRpcRequest,\n fetchOptions: FetchOptions = {},\n ): Promise> {\n const completeFetchOptions = this.#getCompleteFetchOptions(\n jsonRpcRequest,\n fetchOptions,\n );\n\n try {\n return await this.#processRequest(completeFetchOptions);\n } catch (error) {\n if (\n this.#policy.circuitBreakerPolicy.state === CircuitState.Open &&\n this.#failoverService !== undefined\n ) {\n return await this.#failoverService.request(\n jsonRpcRequest,\n completeFetchOptions,\n );\n }\n throw error;\n }\n }\n\n /**\n * Constructs a default set of options to `fetch`.\n *\n * If a username and password are present in the URL, they are extracted to an\n * Authorization header.\n *\n * @param endpointUrl - The endpoint URL.\n * @param fetchOptions - The options to `fetch`.\n * @param givenBtoa - An implementation of `btoa`.\n * @returns The default fetch options.\n */\n #getDefaultFetchOptions(\n endpointUrl: URL,\n fetchOptions: FetchOptions,\n givenBtoa: (stringToEncode: string) => string,\n ): FetchOptions {\n if (endpointUrl.username && endpointUrl.password) {\n const authString = `${endpointUrl.username}:${endpointUrl.password}`;\n const encodedCredentials = givenBtoa(authString);\n return deepmerge(fetchOptions, {\n headers: { Authorization: `Basic ${encodedCredentials}` },\n });\n }\n\n return fetchOptions;\n }\n\n /**\n * Constructs a final set of options to pass to `fetch`. Note that the method\n * defaults to `post`, and the JSON-RPC request is automatically JSON-encoded.\n *\n * @param jsonRpcRequest - The JSON-RPC request.\n * @param fetchOptions - Custom `fetch` options.\n * @returns The complete set of `fetch` options.\n */\n #getCompleteFetchOptions(\n jsonRpcRequest: JsonRpcRequest,\n fetchOptions: FetchOptions,\n ): FetchOptions {\n const defaultOptions = {\n method: 'POST',\n headers: {\n Accept: 'application/json',\n 'Content-Type': 'application/json',\n },\n };\n const mergedOptions = deepmerge(\n defaultOptions,\n deepmerge(this.#fetchOptions, fetchOptions),\n );\n\n const { id, jsonrpc, method, params } = jsonRpcRequest;\n const body = JSON.stringify({\n id,\n jsonrpc,\n method,\n params,\n });\n\n return { ...mergedOptions, body };\n }\n\n /**\n * Makes the request using the Cockatiel policy that this service creates.\n *\n * @param fetchOptions - The options for `fetch`; will be combined with the\n * fetch options passed to the constructor\n * @returns The decoded JSON-RPC response from the endpoint.\n * @throws An \"authorized\" JSON-RPC error (code -32006) if the response HTTP status is 401.\n * @throws A \"rate limiting\" JSON-RPC error (code -32005) if the response HTTP status is 429.\n * @throws A \"resource unavailable\" JSON-RPC error (code -32002) if the response HTTP status is 402, 404, or any 5xx.\n * @throws A generic HTTP client JSON-RPC error (code -32050) for any other 4xx HTTP status codes.\n * @throws A \"parse\" JSON-RPC error (code -32700) if the response is not valid JSON.\n */\n async #processRequest(\n fetchOptions: FetchOptions,\n ): Promise | JsonRpcResponse> {\n let response: Response | undefined;\n try {\n return await this.#policy.execute(async () => {\n response = await this.#fetch(this.endpointUrl, fetchOptions);\n if (!response.ok) {\n throw new HttpError(response.status);\n }\n return await response.json();\n });\n } catch (error) {\n if (error instanceof HttpError) {\n const status = error.httpStatus;\n if (status === 401) {\n throw new JsonRpcError(\n CUSTOM_RPC_ERRORS.unauthorized,\n 'Unauthorized.',\n {\n httpStatus: status,\n },\n );\n }\n if (status === 429) {\n throw rpcErrors.limitExceeded({\n message: 'Request is being rate limited.',\n data: {\n httpStatus: status,\n },\n });\n }\n if (status >= 500 || status === 402 || status === 404) {\n throw rpcErrors.resourceUnavailable({\n message: 'RPC endpoint not found or unavailable.',\n data: {\n httpStatus: status,\n },\n });\n }\n\n // Handle all other 4xx errors as generic HTTP client errors\n throw new JsonRpcError(\n CUSTOM_RPC_ERRORS.httpClientError,\n 'RPC endpoint returned HTTP client error.',\n {\n httpStatus: status,\n },\n );\n } else if (isJsonParseError(error)) {\n throw rpcErrors.parse({\n message: 'RPC endpoint did not return JSON.',\n });\n }\n throw error;\n }\n }\n}\n"]}