Improve docs and disable method rewriting on 307 and 308 (#2145)

Josua Hunziker · web-flow · commit e049e945bd61 · 2022-09-18T20:03:11.000+02:00
diff --git a/documentation/2-options.md b/documentation/2-options.md
@@ -692,7 +692,7 @@ Defines if redirect responses should be followed automatically.
 
 #### **Note:**
 > - If a `303` is sent by the server in response to any request type (POST, DELETE, etc.), Got will request the resource pointed to in the location header via GET.\
->  This is in accordance with the [specification](https://tools.ietf.org/html/rfc7231#section-6.4.4).
+>  This is in accordance with the [specification](https://tools.ietf.org/html/rfc7231#section-6.4.4). You can optionally turn on this behavior also for other redirect codes - see [`methodRewriting`](#methodrewriting).
 
 ```js
 import got from 'got';
@@ -936,9 +936,12 @@ Optionally overrides the value of [`--max-http-header-size`](https://nodejs.org/
 **Type: `boolean`**\
 **Default: `false`**
 
-By default, requests will not use [method rewriting](https://datatracker.ietf.org/doc/html/rfc7231#section-6.4).
+Specifies if the HTTP request method should be [rewritten as `GET`](https://tools.ietf.org/html/rfc7231#section-6.4) on redirects.
 
-For example, when sending a `POST` request and receiving a `302`, it will resend the body to the new location using the same HTTP method (`POST` in this case). To rewrite the request as `GET`, set this option to `true`.
+As the [specification](https://tools.ietf.org/html/rfc7231#section-6.4) prefers to rewrite the HTTP method only on `303` responses, this is Got's default behavior. Setting `methodRewriting` to `true` will also rewrite `301` and `302` responses, as allowed by the spec. This is the behavior followed by `curl` and browsers.
+
+**Note:**
+> - Got never performs method rewriting on `307` and `308` responses, as this is [explicitly prohibited by the specification](https://www.rfc-editor.org/rfc/rfc7231#section-6.4.7).
 
 ### `enableUnixSockets`
 
diff --git a/source/core/index.ts b/source/core/index.ts
@@ -731,10 +731,11 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 
 			const updatedOptions = new Options(undefined, undefined, this.options);
 
-			const shouldBeGet = statusCode === 303 && updatedOptions.method !== 'GET' && updatedOptions.method !== 'HEAD';
-			if (shouldBeGet || updatedOptions.methodRewriting) {
-				// Server responded with "see other", indicating that the resource exists at another location,
-				// and the client should request it from that location via GET or HEAD.
+			const serverRequestedGet = statusCode === 303 && updatedOptions.method !== 'GET' && updatedOptions.method !== 'HEAD';
+			const canRewrite = statusCode !== 307 && statusCode !== 308;
+			const userRequestedGet = updatedOptions.methodRewriting && canRewrite;
+
+			if (serverRequestedGet || userRequestedGet) {
 				updatedOptions.method = 'GET';
 
 				updatedOptions.body = undefined;
diff --git a/source/core/options.ts b/source/core/options.ts
@@ -1764,7 +1764,7 @@ export default class Options {
 	Defines if redirect responses should be followed automatically.
 
 	Note that if a `303` is sent by the server in response to any request type (`POST`, `DELETE`, etc.), Got will automatically request the resource pointed to in the location header via `GET`.
-	This is in accordance with [the spec](https://tools.ietf.org/html/rfc7231#section-6.4.4).
+	This is in accordance with [the spec](https://tools.ietf.org/html/rfc7231#section-6.4.4). You can optionally turn on this behavior also for other redirect codes - see `methodRewriting`.
 
 	@default true
 	*/
@@ -1955,9 +1955,12 @@ export default class Options {
 	}
 
 	/**
-	Specifies if the redirects should be [rewritten as `GET`](https://tools.ietf.org/html/rfc7231#section-6.4).
+	Specifies if the HTTP request method should be [rewritten as `GET`](https://tools.ietf.org/html/rfc7231#section-6.4) on redirects.
 
-	If `false`, when sending a POST request and receiving a `302`, it will resend the body to the new location using the same HTTP method (`POST` in this case).
+	As the [specification](https://tools.ietf.org/html/rfc7231#section-6.4) prefers to rewrite the HTTP method only on `303` responses, this is Got's default behavior.
+	Setting `methodRewriting` to `true` will also rewrite `301` and `302` responses, as allowed by the spec. This is the behavior followed by `curl` and browsers.
+
+	__Note__: Got never performs method rewriting on `307` and `308` responses, as this is [explicitly prohibited by the specification](https://www.rfc-editor.org/rfc/rfc7231#section-6.4.7).
 
 	@default false
 	*/
diff --git a/test/redirects.ts b/test/redirects.ts
@@ -459,11 +459,20 @@ test('method rewriting', withServer, async (t, server, got) => {
 		});
 		response.end();
 	});
-
 	server.get('/', (_request, response) => {
 		response.end();
 	});
 
+	server.post('/temporaryRedirect', (_request, response) => {
+		response.writeHead(307, {
+			location: '/',
+		});
+		response.end();
+	});
+	server.post('/', (request, response) => {
+		request.pipe(response);
+	});
+
 	const {body} = await got.post('redirect', {
 		body: 'foobar',
 		methodRewriting: true,
@@ -477,6 +486,21 @@ test('method rewriting', withServer, async (t, server, got) => {
 	});
 
 	t.is(body, '');
+
+	// Do not rewrite method on 307 or 308
+	const {body: temporaryRedirectBody} = await got.post('temporaryRedirect', {
+		body: 'foobar',
+		methodRewriting: true,
+		hooks: {
+			beforeRedirect: [
+				options => {
+					t.is(options.body, 'foobar');
+				},
+			],
+		},
+	});
+
+	t.is(temporaryRedirectBody, 'foobar');
 });
 
 test('clears username and password when redirecting to a different hostname', withServer, async (t, server, got) => {
