DH_check_pub_key
if (!DH_check_pub_key(dh, pub_key, &flags))
if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
int DH_check_pub_key(const DH *dh,const BIGNUM *pub_key, int *codes);
if (!DH_check_pub_key(dh, DH_get0_pub_key(dh), &check_flags))