From 4c55a28392ab65ca9a7ff0f1725436b55f90be0d Mon Sep 17 00:00:00 2001
From: kenjis <kenji.uui@gmail.com>
Date: Wed, 15 Nov 2023 06:56:38 +0900
Subject: [PATCH] feat: add error check to getHeaderLine()

---
 system/HTTP/Message.php           |  9 +++++++++
 tests/system/HTTP/MessageTest.php | 19 +++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/system/HTTP/Message.php b/system/HTTP/Message.php
index 9d0b517778a4..6de3835ddcdd 100644
--- a/system/HTTP/Message.php
+++ b/system/HTTP/Message.php
@@ -11,6 +11,8 @@
 
 namespace CodeIgniter\HTTP;
 
+use InvalidArgumentException;
+
 /**
  * An HTTP message
  *
@@ -112,6 +114,13 @@ public function hasHeader(string $name): bool
      */
     public function getHeaderLine(string $name): string
     {
+        if ($this->hasMultipleHeaders($name)) {
+            throw new InvalidArgumentException(
+                'The header "' . $name . '" already has multiple headers.'
+                . ' You cannot use getHeaderLine().'
+            );
+        }
+
         $origName = $this->getHeaderName($name);
 
         if (! array_key_exists($origName, $this->headers)) {
diff --git a/tests/system/HTTP/MessageTest.php b/tests/system/HTTP/MessageTest.php
index c6cfb4d874cd..1403605a0287 100644
--- a/tests/system/HTTP/MessageTest.php
+++ b/tests/system/HTTP/MessageTest.php
@@ -355,4 +355,23 @@ public function testAppendHeaderWithMultipleHeaders(): void
 
         $this->message->appendHeader('Set-Cookie', 'HttpOnly');
     }
+
+    public function testGetHeaderLineWithMultipleHeaders(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'The header "Set-Cookie" already has multiple headers. You cannot use getHeaderLine().'
+        );
+
+        $this->message->addHeader(
+            'Set-Cookie',
+            'logged_in=no; Path=/'
+        );
+        $this->message->addHeader(
+            'Set-Cookie',
+            'sessid=123456; Path=/'
+        );
+
+        $this->message->getHeaderLine('Set-Cookie');
+    }
 }