diff options
Diffstat (limited to 'packages/subproviders/src/subproviders/rpc_subprovider.ts')
-rw-r--r-- | packages/subproviders/src/subproviders/rpc_subprovider.ts | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/packages/subproviders/src/subproviders/rpc_subprovider.ts b/packages/subproviders/src/subproviders/rpc_subprovider.ts new file mode 100644 index 000000000..87c522271 --- /dev/null +++ b/packages/subproviders/src/subproviders/rpc_subprovider.ts @@ -0,0 +1,88 @@ +import { assert } from '@0xproject/assert'; +import { StatusCodes } from '@0xproject/types'; +import { fetchAsync } from '@0xproject/utils'; +import { JSONRPCRequestPayload } from 'ethereum-types'; +import JsonRpcError = require('json-rpc-error'); + +import { Callback, ErrorCallback } from '../types'; + +import { Subprovider } from './subprovider'; + +/** + * This class implements the [web3-provider-engine](https://github.com/MetaMask/provider-engine) subprovider interface. + * It forwards on JSON RPC requests to the supplied `rpcUrl` endpoint + */ +export class RPCSubprovider extends Subprovider { + private _rpcUrl: string; + constructor(rpcUrl: string) { + super(); + assert.isString('rpcUrl', rpcUrl); + this._rpcUrl = rpcUrl; + } + /** + * This method conforms to the web3-provider-engine interface. + * It is called internally by the ProviderEngine when it is this subproviders + * turn to handle a JSON RPC request. + * @param payload JSON RPC payload + * @param next Callback to call if this subprovider decides not to handle the request + * @param end Callback to call if subprovider handled the request and wants to pass back the request. + */ + // tslint:disable-next-line:prefer-function-over-method async-suffix + public async handleRequest(payload: JSONRPCRequestPayload, next: Callback, end: ErrorCallback): Promise<void> { + const finalPayload = Subprovider.createFinalPayload(payload); + const headers = new Headers({ + Accept: 'application/json', + 'Content-Type': 'application/json', + }); + const timeoutMs = 1000; + + let response; + try { + response = await fetchAsync( + this._rpcUrl, + { + method: 'POST', + headers, + body: JSON.stringify(finalPayload), + }, + timeoutMs, + ); + } catch (err) { + end(new JsonRpcError.InternalError(err)); + return; + } + + const text = await response.text(); + if (!response.ok) { + const statusCode = response.status; + switch (statusCode) { + case StatusCodes.MethodNotAllowed: + end(new JsonRpcError.MethodNotFound()); + return; + case StatusCodes.GatewayTimeout: + const errMsg = + 'Gateway timeout. The request took too long to process. This can happen when querying logs over too wide a block range.'; + const err = new Error(errMsg); + end(new JsonRpcError.InternalError(err)); + return; + default: + end(new JsonRpcError.InternalError(text)); + return; + } + } + + let data; + try { + data = JSON.parse(text); + } catch (err) { + end(new JsonRpcError.InternalError(err)); + return; + } + + if (data.error) { + end(data.error); + return; + } + end(null, data.result); + } +} |