feat: @discordjs/proxy (#7925)

Co-authored-by: Parbez <imranbarbhuiya.fsd@gmail.com>

packages/proxy/.eslintrc.json

@@ -0,0 +1,11 @@
+{
+	"root": true,
+	"extends": "marine/prettier/node",
+	"parserOptions": {
+		"project": "./tsconfig.eslint.json"
+	},
+	"ignorePatterns": ["**/dist/*"],
+	"env": {
+		"jest": true
+	}
+}

packages/proxy/.gitignore

@@ -0,0 +1,32 @@
+# Packages
+node_modules/
+
+# Log files
+logs/
+*.log
+npm-debug.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+
+# Env
+.env
+
+# Dist
+dist/
+typings/
+docs/**/*
+!docs/index.yml
+!docs/README.md
+
+# Miscellaneous
+.tmp/
+coverage/
+tsconfig.tsbuildinfo
+.turbo
+
+# Yarn files
+.yarn/install-state.gz
+.yarn/build-state.yml

packages/proxy/.prettierrc.json

@@ -0,0 +1,8 @@
+{
+	"printWidth": 120,
+	"useTabs": true,
+	"singleQuote": true,
+	"quoteProps": "as-needed",
+	"trailingComma": "all",
+	"endOfLine": "lf"
+}

packages/proxy/LICENSE

@@ -0,0 +1,191 @@
+                                 Apache License
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+                        http://www.apache.org/licenses/
+
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+   Copyright 2022 Noel Buechler
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packages/proxy/README.md

@@ -0,0 +1,46 @@
+<div align="center">
+  <br />
+  <p>
+    <a href="https://discord.js.org"><img src="https://discord.js.org/static/logo.svg" width="546" alt="discord.js" /></a>
+  </p>
+  <br />
+  <p>
+    <a href="https://discord.gg/djs"><img src="https://img.shields.io/discord/222078108977594368?color=5865F2&logo=discord&logoColor=white" alt="Discord server" /></a>
+    <a href="https://www.npmjs.com/package/@discordjs/proxy"><img src="https://img.shields.io/npm/v/@discordjs/proxy.svg?maxAge=3600" alt="npm version" /></a>
+    <a href="https://www.npmjs.com/package/@discordjs/proxy"><img src="https://img.shields.io/npm/dt/@discordjs/proxy.svg?maxAge=3600" alt="npm downloads" /></a>
+    <a href="https://github.com/discordjs/discord.js/actions"><img src="https://github.com/discordjs/discord.js/actions/workflows/test.yml/badge.svg" alt="Build status" /></a>
+  </p>
+</div>
+
+## About
+
+`@discordjs/proxy` is a powerful wrapper around `@discordjs/rest` for running an HTTP proxy in front of Discord's API
+
+## Installation
+
+**Node.js 16.9.0 or newer is required.**
+
+```sh-session
+npm install @discordjs/proxy
+yarn add @discordjs/proxy
+pnpm add @discordjs/proxy
+```
+
+## Links
+
+- [Website](https://discord.js.org/) ([source](https://github.com/discordjs/website))
+- [Documentation](https://discord.js.org/#/docs/proxy)
+- [discord.js Discord server](https://discord.gg/djs)
+- [GitHub](https://github.com/discordjs/discord.js/tree/main/packages/proxy)
+- [npm](https://www.npmjs.com/package/@discordjs/proxy)
+
+## Contributing
+
+Before creating an issue, please ensure that it hasn't already been reported/suggested, and double-check the
+[documentation](https://discord.js.org/#/docs/proxy).  
+See [the contribution guide](https://github.com/discordjs/discord.js/blob/main/.github/CONTRIBUTING.md) if you'd like to submit a PR.
+
+## Help
+
+If you don't understand something in the documentation, you are experiencing problems, or you just need a gentle
+nudge in the right direction, please don't hesitate to join our official [discord.js Server](https://discord.gg/djs).

packages/proxy/__tests__/proxyRequests.test.ts

@@ -0,0 +1,83 @@
+import { createServer } from 'node:http';
+import { REST } from '@discordjs/rest';
+import supertest from 'supertest';
+import { MockAgent, Interceptable, setGlobalDispatcher } from 'undici';
+import type { MockInterceptor } from 'undici/types/mock-interceptor';
+import { proxyRequests } from '../src';
+
+let mockAgent: MockAgent;
+let mockPool: Interceptable;
+
+const responseOptions: MockInterceptor.MockResponseOptions = {
+	headers: {
+		'content-type': 'application/json',
+	},
+};
+
+const api = new REST().setToken('A-Very-Fake-Token');
+// eslint-disable-next-line @typescript-eslint/no-misused-promises
+const server = createServer(proxyRequests(api));
+
+beforeEach(() => {
+	mockAgent = new MockAgent();
+	mockAgent.disableNetConnect(); // prevent actual requests to Discord
+	setGlobalDispatcher(mockAgent); // enabled the mock client to intercept requests
+
+	mockPool = mockAgent.get('https://discord.com');
+});
+
+afterEach(async () => {
+	await mockAgent.close();
+});
+
+afterAll(() => {
+	server.close();
+});
+
+test('simple GET', async () => {
+	mockPool
+		.intercept({
+			path: '/api/v10/simpleGet',
+			method: 'GET',
+		})
+		.reply(() => ({
+			data: { test: true },
+			statusCode: 200,
+			responseOptions: {
+				...responseOptions,
+				headers: {
+					...responseOptions.headers,
+					'x-ratelimit-limit': '10',
+				},
+			},
+		}));
+
+	const res = await supertest(server).get('/api/v10/simpleGet');
+	const headers = res.headers as Record<string, string>;
+
+	expect(headers['content-type']).toEqual(expect.stringMatching(/^application\/json/));
+	// Ratelimit headers should be dropped
+	expect(headers).not.toHaveProperty('x-ratelimit-limit');
+	expect(res.statusCode).toBe(200);
+	expect(res.body).toStrictEqual({ test: true });
+});
+
+test('failed request', async () => {
+	mockPool
+		.intercept({
+			path: '/api/v10/simpleGet',
+			method: 'GET',
+		})
+		.reply(() => ({
+			data: { code: 404, message: 'Not Found' },
+			statusCode: 404,
+			responseOptions,
+		}));
+
+	const res = await supertest(server).get('/api/v10/simpleGet');
+	const headers = res.headers as Record<string, string>;
+
+	expect(headers['content-type']).toEqual(expect.stringMatching(/^application\/json/));
+	expect(res.statusCode).toBe(404);
+	expect(res.body).toStrictEqual({ code: 404, message: 'Not Found' });
+});

packages/proxy/babel.config.js

@@ -0,0 +1,17 @@
+/**
+ * @type {import('@babel/core').TransformOptions}
+ */
+module.exports = {
+	parserOpts: { strictMode: true },
+	sourceMaps: 'inline',
+	presets: [
+		[
+			'@babel/preset-env',
+			{
+				targets: { node: 'current' },
+				modules: 'commonjs',
+			},
+		],
+		'@babel/preset-typescript',
+	],
+};

packages/proxy/cliff.toml

@@ -0,0 +1,65 @@
+[changelog]
+header = """
+# Changelog
+
+All notable changes to this project will be documented in this file.\n
+"""
+body = """
+{% if version %}\
+	# [{{ version | trim_start_matches(pat="v") }}]\
+	{% if previous %}\
+		{% if previous.version %}\
+			(https://github.com/discordjs/discord.js/compare/{{ previous.version }}...{{ version }})\
+		{% else %}
+			(https://github.com/discordjs/discord.js/tree/{{ version }})\
+		{% endif %}\
+	{% endif %} \
+	- ({{ timestamp | date(format="%Y-%m-%d") }})
+{% else %}\
+	# [unreleased]
+{% endif %}\
+{% for group, commits in commits | group_by(attribute="group") %}
+	## {{ group | upper_first }}
+	{% for commit in commits %}
+		- {% if commit.scope %}\
+			**{{commit.scope}}:** \
+		  {% endif %}\
+			{{ commit.message | upper_first }} ([{{ commit.id | truncate(length=7, end="") }}](https://github.com/discordjs/discord.js/commit/{{ commit.id }}))\
+		{% if commit.breaking %}\
+			\n\n {% raw %}  {% endraw %} ### Breaking Changes:\n \
+			{% for breakingChange in commit.footers %}\
+				{% raw %}  {% endraw %} - {{ breakingChange }}\n\
+			{% endfor %}\
+		{% endif %}\
+	{% endfor %}
+{% endfor %}\n
+"""
+trim = true
+footer = ""
+
+[git]
+conventional_commits = true
+filter_unconventional = true
+commit_parsers = [
+	{ message = "^feat", group = "Features"},
+	{ message = "^fix", group = "Bug Fixes"},
+	{ message = "^docs", group = "Documentation"},
+	{ message = "^perf", group = "Performance"},
+	{ message = "^refactor", group = "Refactor"},
+	{ message = "^typings", group = "Typings"},
+	{ message = "^types", group = "Typings"},
+	{ message = ".*deprecated", body = ".*deprecated", group = "Deprecation"},
+	{ message = "^revert", skip = true},
+	{ message = "^style", group = "Styling"},
+	{ message = "^test", group = "Testing"},
+	{ message = "^chore", skip = true},
+	{ message = "^ci", skip = true},
+	{ message = "^build", skip = true},
+	{ body = ".*security", group = "Security"},
+]
+filter_commits = true
+tag_pattern = "@discordjs\\/proxy@.*"
+skip_tags = "v[0-9]*|11|12"
+ignore_tags = ""
+topo_order = false
+sort_commits = "newest"

packages/proxy/docs/README.md

@@ -0,0 +1 @@
+## [View the documentation here.](https://discord.js.org/#/docs/proxy)

packages/proxy/docs/index.yml

@@ -0,0 +1,5 @@
+- name: General
+  files:
+    - name: Welcome
+      id: welcome
+      path: ../../README.md

packages/proxy/jest.config.js

@@ -0,0 +1,11 @@
+/**
+ * @type {import('@jest/types').Config.InitialOptions}
+ */
+module.exports = {
+	testMatch: ['**/+(*.)+(spec|test).+(ts|js)?(x)'],
+	testEnvironment: 'node',
+	collectCoverage: true,
+	collectCoverageFrom: ['src/**/*.ts'],
+	coverageDirectory: 'coverage',
+	coverageReporters: ['text', 'lcov', 'clover'],
+};

packages/proxy/package.json

@@ -0,0 +1,89 @@
+{
+	"name": "@discordjs/proxy",
+	"version": "0.1.0-dev",
+	"description": "Tools for running an HTTP proxy for Discord's API",
+	"scripts": {
+		"build": "tsup && tsc --emitDeclarationOnly --incremental",
+		"test": "jest --pass-with-no-tests --collect-coverage",
+		"lint": "prettier --check . && eslint src __tests__ --ext mjs,js,ts",
+		"format": "prettier --write . && eslint src __tests__ --ext mjs,js,ts --fix",
+		"docs": "typedoc --json docs/typedoc-out.json src/index.ts && node scripts/docs.mjs",
+		"prepublishOnly": "yarn build && yarn lint && yarn test",
+		"changelog": "git cliff --prepend ./CHANGELOG.md -u -c ./cliff.toml -r ../../ --include-path 'packages/proxy/*'"
+	},
+	"main": "./dist/index.js",
+	"module": "./dist/index.mjs",
+	"typings": "./dist/index.d.ts",
+	"exports": {
+		"import": "./dist/index.mjs",
+		"require": "./dist/index.js",
+		"types": "./dist/index.d.ts"
+	},
+	"directories": {
+		"lib": "src",
+		"test": "__tests__"
+	},
+	"files": [
+		"dist"
+	],
+	"contributors": [
+		"Crawl <icrawltogo@gmail.com>",
+		"Amish Shah <amishshah.2k@gmail.com>",
+		"SpaceEEC <spaceeec@yahoo.com>",
+		"Vlad Frangu <kingdgrizzle@gmail.com>",
+		"Antonio Roman <kyradiscord@gmail.com>",
+		"DD <didinele.dev@gmail.com>"
+	],
+	"license": "Apache-2.0",
+	"keywords": [
+		"discord",
+		"api",
+		"rest",
+		"proxy",
+		"discordapp",
+		"discordjs"
+	],
+	"repository": {
+		"type": "git",
+		"url": "git+https://github.com/discordjs/discord.js.git"
+	},
+	"bugs": {
+		"url": "https://github.com/discordjs/discord.js/issues"
+	},
+	"homepage": "https://discord.js.org",
+	"dependencies": {
+		"@discordjs/rest": "workspace:^",
+		"tslib": "^2.4.0",
+		"undici": "^5.4.0"
+	},
+	"devDependencies": {
+		"@babel/core": "^7.18.2",
+		"@babel/plugin-proposal-decorators": "^7.18.2",
+		"@babel/preset-env": "^7.18.2",
+		"@babel/preset-typescript": "^7.17.12",
+		"@discordjs/ts-docgen": "^0.4.1",
+		"@types/jest": "^28.1.0",
+		"@types/node": "^16.11.38",
+		"@types/supertest": "^2.0.12",
+		"@typescript-eslint/eslint-plugin": "^5.27.0",
+		"@typescript-eslint/parser": "^5.27.0",
+		"babel-plugin-const-enum": "^1.2.0",
+		"babel-plugin-transform-typescript-metadata": "^0.3.2",
+		"eslint": "^8.17.0",
+		"eslint-config-marine": "^9.4.1",
+		"eslint-config-prettier": "^8.5.0",
+		"eslint-plugin-import": "^2.26.0",
+		"jest": "^28.1.0",
+		"prettier": "^2.6.2",
+		"supertest": "^6.2.3",
+		"tsup": "^6.0.1",
+		"typedoc": "^0.22.17",
+		"typescript": "^4.7.3"
+	},
+	"engines": {
+		"node": ">=16.9.0"
+	},
+	"publishConfig": {
+		"access": "public"
+	}
+}

packages/proxy/src/handlers/proxyRequests.ts

@@ -0,0 +1,55 @@
+import { URL } from 'node:url';
+import { DiscordAPIError, HTTPError, RateLimitError, RequestMethod, REST, RouteLike } from '@discordjs/rest';
+import {
+	populateAbortErrorResponse,
+	populateGeneralErrorResponse,
+	populateSuccessfulResponse,
+	populateRatelimitErrorResponse,
+} from '../util/responseHelpers';
+import type { RequestHandler } from '../util/util';
+
+/**
+ * Creates an HTTP handler used to forward requests to Discord
+ * @param rest REST instance to use for the requests
+ */
+export function proxyRequests(rest: REST): RequestHandler {
+	return async (req, res) => {
+		const { method, url } = req;
+
+		if (!method || !url) {
+			throw new TypeError(
+				'Invalid request. Missing method and/or url, implying that this is not a Server IncomingMesage',
+			);
+		}
+
+		// The 2nd parameter is here so the URL constructor doesn't complain about an "invalid url" when the origin is missing
+		// we don't actually care about the origin and the value passed is irrelevant
+		const fullRoute = new URL(url, 'http://noop').pathname.replace(/^\/api(\/v\d+)?/, '') as RouteLike;
+
+		try {
+			const discordResponse = await rest.raw({
+				body: req,
+				fullRoute,
+				// This type cast is technically incorrect, but we want Discord to throw Method Not Allowed for us
+				method: method as RequestMethod,
+				passThroughBody: true,
+			});
+
+			await populateSuccessfulResponse(res, discordResponse);
+		} catch (error) {
+			if (error instanceof DiscordAPIError || error instanceof HTTPError) {
+				populateGeneralErrorResponse(res, error);
+			} else if (error instanceof RateLimitError) {
+				populateRatelimitErrorResponse(res, error);
+			} else if (error instanceof Error && error.name === 'AbortError') {
+				populateAbortErrorResponse(res);
+			} else {
+				// Unclear if there's better course of action here for unknown erorrs. Any web framework allows to pass in an error handler for something like this
+				// at which point the user could dictate what to do with the error - otherwise we could just 500
+				throw error;
+			}
+		} finally {
+			res.end();
+		}
+	};
+}

packages/proxy/src/index.ts

@@ -0,0 +1,3 @@
+export * from './handlers/proxyRequests';
+export * from './util/responseHelpers';
+export { RequestHandler } from './util/util';

packages/proxy/src/util/responseHelpers.ts

@@ -0,0 +1,54 @@
+import type { ServerResponse } from 'node:http';
+import { pipeline } from 'node:stream/promises';
+import type { DiscordAPIError, HTTPError, RateLimitError } from '@discordjs/rest';
+import type { Dispatcher } from 'undici';
+
+/**
+ * Populates a server response with the data from a Discord 2xx REST response
+ * @param res The server response to populate
+ * @param data The data to populate the response with
+ */
+export async function populateSuccessfulResponse(res: ServerResponse, data: Dispatcher.ResponseData): Promise<void> {
+	res.statusCode = data.statusCode;
+
+	for (const header of Object.keys(data.headers)) {
+		// Strip ratelimit headers
+		if (header.startsWith('x-ratelimit')) {
+			continue;
+		}
+
+		res.setHeader(header, data.headers[header]!);
+	}
+
+	await pipeline(data.body, res);
+}
+
+/**
+ * Populates a server response with the data from a Discord non-2xx REST response that is NOT a 429
+ * @param res The server response to populate
+ * @param error The error to populate the response with
+ */
+export function populateGeneralErrorResponse(res: ServerResponse, error: DiscordAPIError | HTTPError): void {
+	res.statusCode = error.status;
+	res.statusMessage = error.message;
+
+	if ('rawError' in error) {
+		res.setHeader('Content-Type', 'application/json');
+		res.write(JSON.stringify(error.rawError));
+	}
+}
+
+/**
+ * Populates a server response with the data from a Discord 429 REST response
+ * @param res The server response to populate
+ * @param error The error to populate the response with
+ */
+export function populateRatelimitErrorResponse(res: ServerResponse, error: RateLimitError): void {
+	res.statusCode = 429;
+	res.setHeader('Retry-After', error.timeToReset / 1000);
+}
+
+export function populateAbortErrorResponse(res: ServerResponse): void {
+	res.statusCode = 504;
+	res.statusMessage = 'Upstream timed out';
+}

packages/proxy/src/util/util.ts

@@ -0,0 +1,10 @@
+import type { IncomingMessage, ServerResponse } from 'node:http';
+
+/**
+ * Represents a potentially awaitable value
+ */
+export type Awaitable<T> = T | PromiseLike<T>;
+/**
+ * Represents a simple HTTP request handler
+ */
+export type RequestHandler = (req: IncomingMessage, res: ServerResponse) => Awaitable<void>;

packages/proxy/tsconfig.eslint.json

@@ -0,0 +1,20 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"allowJs": true
+	},
+	"include": [
+		"**/*.ts",
+		"**/*.tsx",
+		"**/*.js",
+		"**/*.mjs",
+		"**/*.jsx",
+		"**/*.test.ts",
+		"**/*.test.js",
+		"**/*.test.mjs",
+		"**/*.spec.ts",
+		"**/*.spec.js",
+		"**/*.spec.mjs"
+	],
+	"exclude": []
+}

packages/proxy/tsconfig.json

@@ -0,0 +1,4 @@
+{
+	"extends": "../../tsconfig.json",
+	"include": ["src/**/*.ts"]
+}

packages/proxy/tsup.config.ts

@@ -0,0 +1,20 @@
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+	clean: true,
+	dts: true,
+	entryPoints: ['src/index.ts'],
+	format: ['esm', 'cjs'],
+	minify: false,
+	keepNames: true,
+	skipNodeModulesBundle: true,
+	sourcemap: true,
+	target: 'es2021',
+	esbuildOptions: (options, context) => {
+		if (context.format === 'cjs') {
+			options.banner = {
+				js: '"use strict";',
+			};
+		}
+	},
+});