feat: respect --max-http-header-size Node.js flag (nodejs#2234)

* feat: respect  Node.js flag

* add test

* cleaner test

* fix test

* update docs

* revert empty space

* remove already default value

* add

* don't use `globalThis.fetch` to pass test in Node.js 16

* add test under `test/fetch`

* fix lint

* import from `undici-fetch`

* use correct paths, use `request` for pure undici test

* fix Node.js 14 test

docs/api/Client.md

@@ -24,7 +24,7 @@ Returns: `Client`
 * **keepAliveMaxTimeout** `number | null` (optional) - Default: `600e3` - The maximum allowed `keepAliveTimeout`, in milliseconds, when overridden by *keep-alive* hints from the server. Defaults to 10 minutes.
 * **keepAliveTimeout** `number | null` (optional) - Default: `4e3` - The timeout, in milliseconds, after which a socket without active requests will time out. Monitors time between activity on a connected socket. This value may be overridden by *keep-alive* hints from the server. See [MDN: HTTP - Headers - Keep-Alive directives](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Keep-Alive#directives) for more details. Defaults to 4 seconds.
 * **keepAliveTimeoutThreshold** `number | null` (optional) - Default: `1e3` - A number of milliseconds subtracted from server *keep-alive* hints when overriding `keepAliveTimeout` to account for timing inaccuracies caused by e.g. transport latency. Defaults to 1 second.
-* **maxHeaderSize** `number | null` (optional) - Default: `16384` - The maximum length of request headers in bytes. Defaults to 16KiB.
+* **maxHeaderSize** `number | null` (optional) - Default: `--max-http-header-size` or `16384` - The maximum length of request headers in bytes. Defaults to Node.js' --max-http-header-size or 16KiB.
 * **maxResponseSize** `number | null` (optional) - Default: `-1` - The maximum length of response body in bytes. Set to `-1` to disable.
 * **pipelining** `number | null` (optional) - Default: `1` - The amount of concurrent requests to be sent over the single TCP/TLS connection according to [RFC7230](https://tools.ietf.org/html/rfc7230#section-6.3.2). Carefully consider your workload and environment before enabling concurrent requests as pipelining may reduce performance if used incorrectly. Pipelining is sensitive to network stack settings as well as head of line blocking caused by e.g. long running requests. Set to `0` to disable keep-alive connections.
 * **connect** `ConnectOptions | Function | null` (optional) - Default: `null`.

lib/client.js

@@ -6,6 +6,7 @@
 
 const assert = require('assert')
 const net = require('net')
+const http = require('http')
 const { pipeline } = require('stream')
 const util = require('./core/util')
 const timers = require('./timers')
@@ -270,7 +271,7 @@ class Client extends DispatcherBase {
     this[kConnector] = connect
     this[kSocket] = null
     this[kPipelining] = pipelining != null ? pipelining : 1
-    this[kMaxHeadersSize] = maxHeaderSize || 16384
+    this[kMaxHeadersSize] = maxHeaderSize || http.maxHeaderSize
     this[kKeepAliveDefaultTimeout] = keepAliveTimeout == null ? 4e3 : keepAliveTimeout
     this[kKeepAliveMaxTimeout] = keepAliveMaxTimeout == null ? 600e3 : keepAliveMaxTimeout
     this[kKeepAliveTimeoutThreshold] = keepAliveTimeoutThreshold == null ? 1e3 : keepAliveTimeoutThreshold

test/client-node-max-header-size.js

@@ -0,0 +1,23 @@
+'use strict'
+
+const { execSync } = require('node:child_process')
+const { test } = require('tap')
+
+const command = 'node -e "require(\'.\').request(\'https://httpbin.org/get\')"'
+
+test("respect Node.js' --max-http-header-size", async (t) => {
+  t.throws(
+    // TODO: Drop the `--unhandled-rejections=throw` once we drop Node.js 14
+    () => execSync(`${command} --max-http-header-size=1 --unhandled-rejections=throw`),
+    /UND_ERR_HEADERS_OVERFLOW/,
+    'max-http-header-size=1 should throw'
+  )
+
+  t.doesNotThrow(
+    () => execSync(command),
+    /UND_ERR_HEADERS_OVERFLOW/,
+    'default max-http-header-size should not throw'
+  )
+
+  t.end()
+})

test/fetch/client-node-max-header-size.js

@@ -0,0 +1,23 @@
+'use strict'
+
+const { execSync } = require('node:child_process')
+const { test } = require('tap')
+
+const command = 'node -e "require(\'./undici-fetch.js\').fetch(\'https://httpbin.org/get\')"'
+
+test("respect Node.js' --max-http-header-size", async (t) => {
+  t.throws(
+    // TODO: Drop the `--unhandled-rejections=throw` once we drop Node.js 14
+    () => execSync(`${command} --max-http-header-size=1 --unhandled-rejections=throw`),
+    /UND_ERR_HEADERS_OVERFLOW/,
+    'max-http-header-size=1 should throw'
+  )
+
+  t.doesNotThrow(
+    () => execSync(command),
+    /UND_ERR_HEADERS_OVERFLOW/,
+    'default max-http-header-size should not throw'
+  )
+
+  t.end()
+})

types/client.d.ts

@@ -23,7 +23,7 @@ export declare namespace Client {
   export interface Options {
     /** TODO */
     interceptors?: OptionsInterceptors;
-    /** The maximum length of request headers in bytes. Default: `16384` (16KiB). */
+    /** The maximum length of request headers in bytes. Default: Node.js' `--max-http-header-size` or `16384` (16KiB). */
     maxHeaderSize?: number;
     /** The amount of time, in milliseconds, the parser will wait to receive the complete HTTP headers (Node 14 and above only). Default: `300e3` milliseconds (300s). */
     headersTimeout?: number;