From 925cb21c1d18772152bae0f8ade7b03863944e7e Mon Sep 17 00:00:00 2001
From: Travis Warlick <twarlick@maxmedia.com>
Date: Tue, 27 Jul 2021 21:12:07 -0400
Subject: [PATCH] Handle chunked responses where the final chunk and EOM code
 are in separate packets and where there is an additional data chunk in the
 same packet before the final chunk and EOM code.

---
 src/index.js         | 53 ++++++++++++++++++++++++++------------------
 test/main.js         | 22 ++++++++++++++++++
 test/utils/server.js | 18 +++++++++++++++
 3 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/src/index.js b/src/index.js
index 9e1151bc7..4799917b4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -287,35 +287,44 @@ export default async function fetch(url, options_) {
 }
 
 function fixResponseChunkedTransferBadEnding(request, errorCallback) {
-	const LAST_CHUNK = Buffer.from('0\r\n');
-	let socket;
+	const LAST_CHUNK = Buffer.from('0\r\n\r\n');
 
-	request.on('socket', s => {
-		socket = s;
-	});
+	let isChunkedTransfer = false;
+	let properLastChunkReceived = false;
+	let prevChunk;
 
 	request.on('response', response => {
 		const {headers} = response;
-		if (headers['transfer-encoding'] === 'chunked' && !headers['content-length']) {
-			let properLastChunkReceived = false;
+		isChunkedTransfer = headers['transfer-encoding'] === 'chunked' && !headers['content-length'];
+	});
 
-			socket.on('data', buf => {
-				properLastChunkReceived = Buffer.compare(buf.slice(-3), LAST_CHUNK) === 0;
-			});
+	request.on('socket', socket => {
+		const onSocketClose = () => {
+			if (isChunkedTransfer && !properLastChunkReceived) {
+				const error = new Error('Premature close');
+				error.code = 'ERR_STREAM_PREMATURE_CLOSE';
+				errorCallback(error);
+			}
+		};
 
-			const onSocketClose = () => {
-				if (!properLastChunkReceived) {
-					const error = new Error('Premature close');
-					error.code = 'ERR_STREAM_PREMATURE_CLOSE';
-					errorCallback(error);
-				}
-			};
+		socket.prependListener('close', onSocketClose);
 
-			socket.prependListener('close', onSocketClose);
+		request.on('abort', () => {
+			socket.removeListener('close', onSocketClose);
+		});
 
-			request.on('abort', () => {
-				socket.removeListener('close', onSocketClose);
-			});
-		}
+		socket.on('data', buf => {
+			properLastChunkReceived = Buffer.compare(buf.slice(-5), LAST_CHUNK) === 0;
+
+			// Sometimes final 0-length chunk and end of message code are in separate packets
+			if (!properLastChunkReceived && prevChunk) {
+				properLastChunkReceived = (
+					Buffer.compare(prevChunk.slice(-3), LAST_CHUNK.slice(0, 3)) === 0 &&
+					Buffer.compare(buf.slice(-2), LAST_CHUNK.slice(3)) === 0
+				);
+			}
+
+			prevChunk = buf;
+		});
 	});
 }
diff --git a/test/main.js b/test/main.js
index a777cf583..1e1f368c3 100644
--- a/test/main.js
+++ b/test/main.js
@@ -692,6 +692,28 @@ describe('node-fetch', () => {
 		});
 	});
 
+	it('should handle chunked response with more than 1 chunk in the final packet', () => {
+		const url = `${base}chunked/multiple-ending`;
+		return fetch(url).then(res => {
+			expect(res.ok).to.be.true;
+
+			return res.text().then(result => {
+				expect(result).to.equal('foobar');
+			});
+		});
+	});
+
+	it('should handle chunked response with final chunk and EOM in separate packets', () => {
+		const url = `${base}chunked/split-ending`;
+		return fetch(url).then(res => {
+			expect(res.ok).to.be.true;
+
+			return res.text().then(result => {
+				expect(result).to.equal('foobar');
+			});
+		});
+	});
+
 	it('should handle DNS-error response', () => {
 		const url = 'http://domain.invalid';
 		return expect(fetch(url)).to.eventually.be.rejected
diff --git a/test/utils/server.js b/test/utils/server.js
index 32aa070fe..9bfe1c5af 100644
--- a/test/utils/server.js
+++ b/test/utils/server.js
@@ -352,6 +352,24 @@ export default class TestServer {
 			}, 400);
 		}
 
+		if (p === '/chunked/split-ending') {
+			res.socket.write('HTTP/1.1 200\r\nTransfer-Encoding: chunked\r\n\r\n');
+			res.socket.write('3\r\nfoo\r\n3\r\nbar\r\n');
+
+			setTimeout(() => {
+				res.socket.write('0\r\n');
+			}, 10);
+
+			setTimeout(() => {
+				res.socket.end('\r\n');
+			}, 20);
+		}
+
+		if (p === '/chunked/multiple-ending') {
+			res.socket.write('HTTP/1.1 200\r\nTransfer-Encoding: chunked\r\n\r\n');
+			res.socket.write('3\r\nfoo\r\n3\r\nbar\r\n0\r\n\r\n');
+		}
+
 		if (p === '/error/json') {
 			res.statusCode = 200;
 			res.setHeader('Content-Type', 'application/json');