Function ng_ppp_rcvdata

freebsd/netgraph/ng_ppp.c:1404–1463

* Receive data on a hook linkX. */

 * Receive data on a hook linkX.
 */
static int
ng_ppp_rcvdata(hook_p hook, item_p item)
{
	const node_p node = NG_HOOK_NODE(hook);
	const priv_p priv = NG_NODE_PRIVATE(node);
	const int index = (intptr_t)NG_HOOK_PRIVATE(hook);
	const uint16_t linkNum = (uint16_t)~index;
	struct ng_ppp_link * const link = &priv->links[linkNum];
	uint16_t proto;
	struct mbuf *m;
	int error = 0;

	KASSERT(linkNum < NG_PPP_MAX_LINKS,
	    ("%s: bogus index 0x%x", __func__, index));

	NGI_GET_M(item, m);

	mtx_lock(&priv->rmtx);

	/* Stats */
	link->stats.recvFrames++;
	link->stats.recvOctets += m->m_pkthdr.len;

	/* Strip address and control fields, if present. */
	if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL)
		ERROUT(ENOBUFS);
	if (mtod(m, uint8_t *)[0] == 0xff &&
	    mtod(m, uint8_t *)[1] == 0x03)
		m_adj(m, 2);

	/* Get protocol number */
	if ((m = ng_ppp_cutproto(m, &proto)) == NULL)
		ERROUT(ENOBUFS);
	NGI_M(item) = m; 	/* Put changed m back into item. */

	if (!PROT_VALID(proto)) {
		link->stats.badProtos++;
		ERROUT(EIO);
	}

	/* LCP packets must go directly to bypass. */
	if (proto >= 0xB000) {
		mtx_unlock(&priv->rmtx);
		return (ng_ppp_bypass(node, item, proto, linkNum));
	}

	/* Other packets are denied on a disabled link. */
	if (!link->conf.enableLink)
		ERROUT(ENXIO);

	/* Proceed to multilink layer. Mutex will be unlocked inside. */
	error = ng_ppp_mp_recv(node, item, proto, linkNum);
	mtx_assert(&priv->rmtx, MA_NOTOWNED);
	return (error);

done:
	mtx_unlock(&priv->rmtx);
	NG_FREE_ITEM(item);