EVP_MD_CTX_ctrl
int EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void *p2);
&& EVP_MD_CTX_ctrl(mac_ctx, EVP_MD_CTRL_TLSTREE, 0, seq) <= 0)
|| EVP_MD_CTX_ctrl(mctx, EVP_CTRL_SSL3_MASTER_SECRET,
|| EVP_MD_CTX_ctrl(mctx, EVP_CTRL_SSL3_MASTER_SECRET,