Set to null if REMOTE_ADDR is empty or invalid

src/IpAddress.php

@@ -186,6 +186,11 @@ protected function determineClientIpAddress($request): ?string
                 $ipAddress = $remoteAddr;
             }
         }
+        if ($ipAddress === null) {
+            // do not continue if there isn't a valid remote address
+            return $ipAddress;
+        }
+
         if (!$this->checkProxyHeaders) {
             // do not check if configured to not check
             return $ipAddress;

tests/IpAddressTest.php

@@ -22,6 +22,17 @@ private function simpleRequest(IPAddress $middleware, $env, $attrName = 'ip_addr
         return $attributeValue;
     }
 
+    public function testMissingRemoteAddrSetsTheAttributeToNull()
+    {
+        $middleware = new IPAddress(true, []);
+        $env = [
+            'HTTP_X_FORWARDED_FOR' => '123.4.5.6',
+        ];
+        $ipAddress = $this->simpleRequest($middleware, $env);
+
+        $this->assertSame(null, $ipAddress);
+    }
+
     public function testIpAddressIsSetByRemoteAddrIfCheckProxyHeadersIsFalse()
     {
         $middleware = new IPAddress(false, [], 'IP');