Function ng_ppp_addproto

freebsd/netgraph/ng_ppp.c:2417–2429

* Prepend a possibly compressed PPP protocol number in front of a frame */

 * Prepend a possibly compressed PPP protocol number in front of a frame
 */
static struct mbuf *
ng_ppp_addproto(struct mbuf *m, uint16_t proto, int compOK)
{
	if (compOK && PROT_COMPRESSABLE(proto)) {
		uint8_t pbyte = (uint8_t)proto;

		return ng_ppp_prepend(m, &pbyte, 1);
	} else {
		uint16_t pword = htons((uint16_t)proto);

		return ng_ppp_prepend(m, &pword, 2);
	}
}

/*
 * Cut a possibly compressed PPP protocol number from the front of a frame.