From 9b061d091e198cf3b4629f3da3d205dfa9b3511c Mon Sep 17 00:00:00 2001
From: ryuhei shima <islandryu@ryuheis-Mac-Studio.local>
Date: Sun, 22 Mar 2026 00:52:59 +0900
Subject: [PATCH] fix: allow tabs around Content-Length

---
 src/llhttp/http.ts              |  2 +-
 test/request/content-length.md  | 27 +++++++++++++++++++++++++++
 test/response/content-length.md | 25 +++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/llhttp/http.ts b/src/llhttp/http.ts
index 8388c574..dbc9c607 100644
--- a/src/llhttp/http.ts
+++ b/src/llhttp/http.ts
@@ -782,7 +782,7 @@ export class HTTP {
       .otherwise(n('header_value_content_length_ws'));
 
     n('header_value_content_length_ws')
-      .match(' ', n('header_value_content_length_ws'))
+      .match([ ' ', '\t' ], n('header_value_content_length_ws'))
       .peek([ '\r', '\n' ],
         this.setFlag(FLAGS.CONTENT_LENGTH, 'header_value_otherwise'))
       .otherwise(invalidContentLength('Invalid character in Content-Length'));
diff --git a/test/request/content-length.md b/test/request/content-length.md
index 0485f127..8317b056 100644
--- a/test/request/content-length.md
+++ b/test/request/content-length.md
@@ -314,6 +314,33 @@ off=39 header_value complete
 off=41 headers complete method=3 v=1/1 flags=20 content_length=42
 ```
 
+### Tabs in `Content-Length` (surrounding)
+
+<!-- meta={"type": "request"} -->
+```http
+POST / HTTP/1.1
+Content-Length:\t42\t  
+
+
+```
+
+```log
+off=0 message begin
+off=0 len=4 span[method]="POST"
+off=4 method complete
+off=5 len=1 span[url]="/"
+off=7 url complete
+off=7 len=4 span[protocol]="HTTP"
+off=11 protocol complete
+off=12 len=3 span[version]="1.1"
+off=15 version complete
+off=17 len=14 span[header_field]="Content-Length"
+off=32 header_field complete
+off=33 len=5 span[header_value]="42\t  "
+off=40 header_value complete
+off=42 headers complete method=3 v=1/1 flags=20 content_length=42
+```
+
 ### Spaces in `Content-Length` #2
 
 <!-- meta={"type": "request"} -->
diff --git a/test/response/content-length.md b/test/response/content-length.md
index def15061..5b9be2d5 100644
--- a/test/response/content-length.md
+++ b/test/response/content-length.md
@@ -164,3 +164,28 @@ off=80 headers complete status=200 v=1/1 flags=20 content_length=456
 off=80 skip body
 off=80 message complete
 ```
+
+## Tabs in `Content-Length` (surrounding)
+
+<!-- meta={"type": "response"} -->
+```http
+HTTP/1.1 200 OK
+Content-Length:\t42\t
+
+
+```
+
+```log
+off=0 message begin
+off=0 len=4 span[protocol]="HTTP"
+off=4 protocol complete
+off=5 len=3 span[version]="1.1"
+off=8 version complete
+off=13 len=2 span[status]="OK"
+off=17 status complete
+off=17 len=14 span[header_field]="Content-Length"
+off=32 header_field complete
+off=33 len=3 span[header_value]="42\t"
+off=38 header_value complete
+off=40 headers complete status=200 v=1/1 flags=20 content_length=42
+```