SSL_get_peer_certificate() returns a pointer to the X509 certificate the
peer presented. If the peer did not present a certificate, NULL is returned.
NOTES
Due to the protocol definition, a TLS/SSL server will always send a
certificate, if present. A client will only send a certificate when
explicitly requested to do so by the server (see
SSL_CTX_set_verify(3)). If an anonymous cipher
is used, no certificates are sent.
That a certificate is returned does not indicate information about the
verification state, use SSL_get_verify_result(3)
to check the verification state.
The reference count of the X509 object is incremented by one, so that it
will not be destroyed when the session containing the peer certificate is
freed. The X509 object must be explicitly freed using X509_free().
RETURN VALUES
The following return values can occur:
NULL
No certificate was presented by the peer or no connection was established.
Pointer to an X509 certificate
The return value points to the certificate presented by the peer.
