From 028bf323c5bee6d7974457d09ed61e6c40587db9 Mon Sep 17 00:00:00 2001
From: Abdul Malik Ikhsan <samsonasik@gmail.com>
Date: Fri, 12 Feb 2021 07:32:47 +0700
Subject: [PATCH] Fixes #4263

---
 system/HTTP/IncomingRequest.php           | 14 +++++++-----
 tests/system/HTTP/IncomingRequestTest.php | 28 +++++++++++++++++++++++
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/system/HTTP/IncomingRequest.php b/system/HTTP/IncomingRequest.php
index a05c00710a95..2d176f722c0f 100755
--- a/system/HTTP/IncomingRequest.php
+++ b/system/HTTP/IncomingRequest.php
@@ -718,8 +718,15 @@ protected function parseRequestURI(): string
 
 		if (isset($_SERVER['SCRIPT_NAME'][0]) && pathinfo($_SERVER['SCRIPT_NAME'], PATHINFO_EXTENSION) === 'php')
 		{
+			// if index.php is implied
+			if (strpos($uri, dirname($_SERVER['SCRIPT_NAME'])) === 0)
+			{
+				$uri = $uri === '/index.php'
+					? '/'
+					: (string) substr($uri, strlen(dirname($_SERVER['SCRIPT_NAME'])));
+			}
 			// strip the script name from the beginning of the URI
-			if (strpos($uri, $_SERVER['SCRIPT_NAME']) === 0)
+			elseif (strpos($uri, $_SERVER['SCRIPT_NAME']) === 0)
 			{
 				$uri = (string) substr($uri, strlen($_SERVER['SCRIPT_NAME']));
 			}
@@ -728,11 +735,6 @@ protected function parseRequestURI(): string
 			{
 				$uri = (string) substr($uri, strpos($uri, $_SERVER['SCRIPT_NAME']) + strlen($_SERVER['SCRIPT_NAME']));
 			}
-			// or if index.php is implied
-			elseif (strpos($uri, dirname($_SERVER['SCRIPT_NAME'])) === 0)
-			{
-				$uri = (string) substr($uri, strlen(dirname($_SERVER['SCRIPT_NAME'])));
-			}
 		}
 
 		// This section ensures that even on servers that require the URI to contain the query string (Nginx) a correct
diff --git a/tests/system/HTTP/IncomingRequestTest.php b/tests/system/HTTP/IncomingRequestTest.php
index 67371cce52d4..53a14af1686f 100644
--- a/tests/system/HTTP/IncomingRequestTest.php
+++ b/tests/system/HTTP/IncomingRequestTest.php
@@ -545,4 +545,32 @@ public function testGetPostIndexNotExists()
 		$this->assertNull($this->request->getPostGet('gc'));
 		$this->assertNull($this->request->getGetPost('gc'));
 	}
+
+	public function providePathChecks()
+	{
+		return [
+			'not /index.php' => [
+				'/test.php',
+				'test.php',
+			],
+			'/index.php'     => [
+				'/index.php',
+				'/',
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider providePathChecks
+	 */
+	public function testExtensionPHP($path, $detectPath)
+	{
+		$config          = new App();
+		$config->baseURL = 'http://example.com/';
+
+		$_SERVER['REQUEST_URI'] = $path;
+		$_SERVER['SCRIPT_NAME'] = $path;
+		$request                = new IncomingRequest($config, new URI($path), null, new UserAgent());
+		$this->assertEquals($detectPath, $request->detectPath());
+	}
 }