SSL_get_psk_identity.3ssl man page
SSL_get_psk_identity, SSL_get_psk_identity_hint — get PSK client identity and hint
#include <openssl/ssl.h> const char *SSL_get_psk_identity_hint(const SSL *ssl); const char *SSL_get_psk_identity(const SSL *ssl);
SSL_get_psk_identity_hint() is used to retrieve the PSK identity hint used during the connection setup related to SSL object ssl. Similarly, SSL_get_psk_identity() is used to retrieve the PSK identity used during the connection setup.
If non-NULL, SSL_get_psk_identity_hint() returns the PSK identity hint and SSL_get_psk_identity() returns the PSK identity. Both are NULL-terminated. SSL_get_psk_identity_hint() may return NULL if no PSK identity hint was used during the connection setup.
Note that the return value is valid only during the lifetime of the SSL object ssl.