copy_session_state

Possibly copies session state from one connection to another, for use in TLS session resumption.

This is not normally needed, but may be used when the same session needs to be used between different endpoints, as is required by some protocols, such as FTP over TLS. source should have already completed a handshake and, since TLS 1.3, it should have been used to read data at least once. this should not have completed a handshake.

It is not possible to know whether a call to this function will actually do anything. Because session resumption is normally used only for performance benefit, the TLS backend might not implement this function. Even if implemented, it may not actually succeed in allowing this to resume source's TLS session, because the server may not have sent a session resumption token to source, or it may refuse to accept the token from this. There is no way to know whether a call to this function is actually successful.

Using this function is not required to benefit from session resumption. If the TLS backend supports session resumption, the session will be resumed automatically if it is possible to do so without weakening the privacy guarantees normally provided by TLS, without need to call this function. For example, with TLS 1.3, a session ticket will be automatically copied from any TlsClientConnection that has previously received session tickets from the server, provided a ticket is available that has not previously been used for session resumption, since session ticket reuse would be a privacy weakness. Using this function causes the ticket to be copied without regard for privacy considerations.

Parameters: