SSL_CTX_set_cert_verify_callback
void SSL_CTX_set_cert_verify_callback(SSL_CTX *ctx,
SSL_CTX_set_cert_verify_callback(client_ctx, &verify_accept_cb, NULL);
SSL_CTX_set_cert_verify_callback(client_ctx, &verify_retry_cb, NULL);
SSL_CTX_set_cert_verify_callback(client_ctx, &verify_reject_cb, NULL);
SSL_CTX_set_cert_verify_callback(cctx, non_io_retry_cert_verify_cb, &allow);
SSL_CTX_set_cert_verify_callback(s_ctx, app_verify_callback,
SSL_CTX_set_cert_verify_callback(s_ctx2, app_verify_callback,
SSL_CTX_set_cert_verify_callback(c_ctx, app_verify_callback,
SSL_CTX_set_cert_verify_callback(cctx, verify_retry_cb, NULL);