SSL_CTX_set_srp_client_pwd_callback
SSL_CTX_set_srp_client_pwd_callback(ctx, ssl_give_srp_client_pwd_cb);
SSL_CTX_set_srp_client_pwd_callback(ctx, dummy_srp);
int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx,
SSL_CTX_set_srp_client_pwd_callback(client_ctx, client_srp_cb);