CRYPTO_EX_INDEX_ECDH
CRYPTO_new_ex_data(CRYPTO_EX_INDEX_ECDH, ret, &ret->ex_data);
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_ECDH, r, &r->ex_data);
return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_ECDH, argl, argp,