New getCookieDomain #10098

src/Utility.php

@@ -104,4 +104,24 @@ public static function quoteArray(array $value): string
 
         return implode(', ', $quoted);
     }
+
+    /**
+     * Return the domain to be used for cookie.
+     *
+     * We look for domain name to build the string ".mydomain.com" to specify
+     * that cookies (session) are available on all subdomains.
+     *
+     * This will not work for domain without TLD such as "localhost", because
+     * RFC specify the domain string must contain two "." characters.
+     */
+    public static function getCookieDomain(string $input): ?string
+    {
+        if ($input && preg_match('/([^.]+\.[^.:]+)(:\d+)?$/', $input, $match)) {
+            $cookieDomain = '.' . $match[1];
+        } else {
+            $cookieDomain = null;
+        }
+
+        return $cookieDomain;
+    }
 }

tests/UtilityTest.php

@@ -159,4 +159,23 @@ public static function providerQuoteArray(): iterable
         yield [[true], "'1'"];
         yield [[1.23], "'1.23'"];
     }
+
+    public function getCookieDomainProvider(): iterable
+    {
+        yield ['', null];
+        yield ['localhost', null];
+        yield ['example.com', '.example.com'];
+        yield ['www.example.com', '.example.com'];
+        yield ['example.com:123', '.example.com'];
+        yield ['www.example.com:123', '.example.com'];
+    }
+
+    /**
+     * @dataProvider getCookieDomainProvider
+     */
+    public function testGetCookieDomain(string $input, ?string $expected): void
+    {
+        $actual = Utility::getCookieDomain($input);
+        self::assertSame($expected, $actual);
+    }
 }