import {SandboxRequest} from 'app/common/ActionBundle'; import {ActiveDoc} from 'app/server/lib/ActiveDoc'; import {makeExceptionalDocSession} from 'app/server/lib/DocSession'; import {httpEncoding} from 'app/server/lib/httpEncoding'; import fetch from 'node-fetch'; import * as path from 'path'; import * as tmp from 'tmp'; import * as fse from 'fs-extra'; import log from 'app/server/lib/log'; import {proxyAgent} from "app/server/lib/ProxyAgent"; import chunk = require('lodash/chunk'); import fromPairs = require('lodash/fromPairs'); import zipObject = require('lodash/zipObject'); export class DocRequests { // Request responses are briefly cached in files only to handle multiple requests in a formula // and only as long as needed to finish calculating all formulas. // When _numPending reaches 0 again, _cacheDir is deleted. private _numPending: number = 0; private _cacheDir: tmp.SynchrounousResult | null = null; constructor(private readonly _activeDoc: ActiveDoc) {} public async handleRequestsBatchFromUserActions(requests: Record) { const numRequests = Object.keys(requests).length; this._numPending += numRequests; try { // Perform batches of requests in parallel for speed, and hope it doesn't cause rate limiting... for (const keys of chunk(Object.keys(requests), 10)) { const responses: Response[] = await Promise.all(keys.map(async key => { const request = requests[key]; const response = await this.handleSingleRequestWithCache(key, request); return { ...response, // Tells the engine which cell(s) made the request and should be recalculated to use the response deps: request.deps, }; })); // Tell the sandbox which previous responses we have cached in files. // This lets it know it can immediately and synchronously get those responses again. const cachedRequestKeys = await fse.readdir(this._cacheDir!.name); // Recalculate formulas using this batch of responses. const action = ["RespondToRequests", zipObject(keys, responses), cachedRequestKeys]; await this._activeDoc.applyUserActions(makeExceptionalDocSession("system"), [action]); } } finally { this._numPending -= numRequests; if (this._numPending === 0) { log.debug(`Removing DocRequests._cacheDir: ${this._cacheDir!.name}`); this._cacheDir!.removeCallback(); this._cacheDir = null; } } } public async handleSingleRequestWithCache(key: string, request: SandboxRequest): Promise { if (!this._cacheDir) { // Use the sync API because otherwise multiple requests being handled at the same time // all reach this point, `await`, and create different dirs. // `unsafeCleanup: true` means the directory can be deleted even if it's not empty, which is what we expect. this._cacheDir = tmp.dirSync({unsafeCleanup: true}); log.debug(`Created DocRequests._cacheDir: ${this._cacheDir.name}`); } const cachePath = path.resolve(this._cacheDir.name, key); try { const result = await fse.readJSON(cachePath); result.content = Buffer.from(result.content, "base64"); return result; } catch { const result = await this._handleSingleRequestRaw(request); const resultForJson = {...result} as any; if ('content' in result) { resultForJson.content = result.content.toString("base64"); } fse.writeJSON(cachePath, resultForJson).catch(e => log.warn(`Failed to save response to cache file: ${e}`)); return result; } } private async _handleSingleRequestRaw(request: SandboxRequest): Promise { try { if (process.env.GRIST_EXPERIMENTAL_PLUGINS != '1') { throw new Error("REQUEST is not enabled"); } const {url, params, headers} = request; const urlObj = new URL(url); log.rawInfo("Handling sandbox request", {host: urlObj.host, docId: this._activeDoc.docName}); for (const [param, value] of Object.entries(params || {})) { urlObj.searchParams.append(param, value); } const response = await fetch(urlObj.toString(), {headers: headers || {}, agent: proxyAgent(urlObj)}); const content = await response.buffer(); const {status, statusText} = response; const encoding = httpEncoding(response.headers.get('content-type'), content); return { content, status, statusText, encoding, headers: fromPairs([...response.headers]), }; } catch (e) { return {error: String(e)}; } } } interface SuccessfulResponse { content: Buffer; status: number; statusText: string; encoding?: string; headers: Record; } interface RequestError { error: string; } type Response = RequestError | SuccessfulResponse;