session_regenerate_id

    (PHP 4 >= 4.3.2, PHP 5, PHP 7, PHP 8)

    session_regenerate_id — Update the current session id with a newly generated one

    Description

    session_regenerate_id(bool$delete_old_session = false): bool

    session_regenerate_id() will replace the current session id with a new one, and keep the current session information.

    When session.use_trans_sid is enabled, output must be started after session_regenerate_id() call. Otherwise, old session ID is used.

    Warning

    Currently, session_regenerate_id does not handle an unstable network well, e.g. Mobile and WiFi network. Therefore, you may experience a lost session by calling session_regenerate_id.

    You should not destroy old session data immediately, but should use destroy time-stamp and control access to old session ID. Otherwise, concurrent access to page may result in inconsistent state, or you may have lost session, or it may cause client(browser) side race condition and may create many session ID needlessly. Immediate session data deletion disables session hijack attack detection and prevention also.

    Parameters

    delete_old_session

    Whether to delete the old associated session file or not. You should not delete old session if you need to avoid races caused by deletion or detect/avoid session hijack attacks.

    Return Values

    Returns true on success or false on failure.

    Examples

    Example #1 A session_regenerate_id() example

    <?php
    // NOTE: This code is not fully working code, but an example!

    session_start();

    // Check destroyed time-stamp
    if (isset($_SESSION['destroyed'])
    &&     $_SESSION['destroyed'] < time() - 300) {
    // Should not happen usually. This could be attack or due to unstable network.

    Current session module does not handle unstable network well. You should manage session ID to avoid lost session by session_regenerate_id.

    Example #2 Avoiding lost session by session_regenerate_id()

    <?php
    // NOTE: This code is not fully working code, but an example!
    // my_session_start() and my_session_regenerate_id() avoid lost sessions by
    // unstable network. In addition, this code may prevent exploiting stolen
    // session by attackers.

    function my_session_start() {
    session_start();
    if (isset(    $_SESSION['destroyed'])) {
    if (    $_SESSION['destroyed'] < time()-300) {
    // Should not happen usually. This could be attack or due to unstable network.

    See Also

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