Remove old utility ID-generator and move the code to the xsd-type

Author: tvdijen

src/XML/Utils/Random.php

@@ -4,10 +4,30 @@
 
 namespace SimpleSAML\XMLSchema\Type;
 
+use function bin2hex;
+use function random_bytes;
+
 /**
  * @package simplesaml/xml-common
  */
 class IDValue extends NCNameValue
 {
     public const string SCHEMA_TYPE = 'ID';
+
+    /**
+     * The fixed length of random identifiers.
+     *
+     * (41 - 1) / 2 = 20 → random_bytes(20) → 160 bits
+     */
+    public const int ID_LENGTH = 41;
+
+
+    /**
+     * This function will generate a unique ID that is valid for use
+     * in an xs:ID attribute
+     */
+    public static function generateID(?string $prefix = "_"): static
+    {
+        return new static($prefix . bin2hex(random_bytes((self::ID_LENGTH - 1) / 2)));
+    }
 }

src/XMLSchema/Type/IDValue.php

@@ -40,6 +40,23 @@ public function testID(bool $shouldPass, string $id): void
     }
 
 
+    /**
+     * Test for IDValue::generateID().
+     */
+    public function testGenerateID(): void
+    {
+        // check that it always starts with an underscore if no prefix is set
+        $this->assertStringStartsWith('_', IDValue::generateID()->getValue());
+        // check the length
+        $this->assertEquals(IDValue::ID_LENGTH, strlen(IDValue::generateID()->getValue()));
+
+        // check that it always starts with the prefix if set
+        $this->assertStringStartsWith('abc', IDValue::generateID('abc')->getValue());
+        // check the length
+        $this->assertEquals((IDValue::ID_LENGTH - 1) + strlen('abc'), strlen(IDValue::generateID('abc')->getValue()));
+    }
+
+
     /**
      * @return array<string, array{0: true, 1: string}>
      */