3 namespace Drupal\Component\Uuid;
5 use Drupal\Component\Utility\Crypt;
8 * Generates a UUID v4 (RFC 4122 section 4.4) using PHP code.
10 * @see http://www.rfc-editor.org/rfc/rfc4122.txt
11 * @see http://www.rfc-editor.org/errata_search.php?rfc=4122&eid=3546
13 class Php implements UuidInterface {
18 public function generate() {
19 // Obtain a random string of 32 hex characters.
20 $hex = bin2hex(Crypt::randomBytes(16));
22 // The variable names $time_low, $time_mid, $time_hi_and_version,
23 // $clock_seq_hi_and_reserved, $clock_seq_low, and $node correlate to
24 // the fields defined in RFC 4122 section 4.1.2.
26 // Use characters 0-11 to generate 32-bit $time_low and 16-bit $time_mid.
27 $time_low = substr($hex, 0, 8);
28 $time_mid = substr($hex, 8, 4);
30 // Use characters 12-15 to generate 16-bit $time_hi_and_version.
31 // The 4 most significant bits are the version number (0100 == 0x4).
32 // We simply skip character 12 from $hex, and concatenate the strings.
33 $time_hi_and_version = '4' . substr($hex, 13, 3);
35 // Use characters 16-17 to generate 8-bit $clock_seq_hi_and_reserved.
36 // The 2 most significant bits are set to one and zero respectively.
37 $clock_seq_hi_and_reserved = base_convert(substr($hex, 16, 2), 16, 10);
38 $clock_seq_hi_and_reserved &= 0b00111111;
39 $clock_seq_hi_and_reserved |= 0b10000000;
41 // Use characters 18-19 to generate 8-bit $clock_seq_low.
42 $clock_seq_low = substr($hex, 18, 2);
43 // Use characters 20-31 to generate 48-bit $node.
44 $node = substr($hex, 20);
46 // Re-combine as a UUID. $clock_seq_hi_and_reserved is still an integer.
47 $uuid = sprintf('%s-%s-%s-%02x%s-%s',
48 $time_low, $time_mid, $time_hi_and_version,
49 $clock_seq_hi_and_reserved, $clock_seq_low,