SSL_get_peer_cert_chain() returns a pointer to STACKOF(X509) certificates
forming the certificate chain of the peer. If called on the client side,
the stack also contains the peer's certificate; if called on the server
side, the peer's certificate must be obtained separately using
SSL_get_peer_certificate(3).
If the peer did not present a certificate, NULL is returned.
NOTES
The peer certificate chain is not necessarily available after reusing
a session, in which case a NULL pointer is returned.
The reference count of the STACKOF(X509) object is not incremented.
If the corresponding session is freed, the pointer must not be used
any longer.
RETURN VALUES
The following return values can occur:
NULL
No certificate was presented by the peer or no connection was established
or the certificate chain is no longer available when a session is reused.
Pointer to a STACKOF(X509)
The return value points to the certificate chain presented by the peer.
