Function ng_pptpgre_rcvdata_lower

freebsd/netgraph/ng_pptpgre.c:744–1054

* Handle an incoming packet. The packet includes the IP header. */

 * Handle an incoming packet.  The packet includes the IP header.
 */
static int
ng_pptpgre_rcvdata_lower(hook_p hook, item_p item)
{
	hpriv_p hpriv;
	node_p node = NG_HOOK_NODE(hook);
	const priv_p priv = NG_NODE_PRIVATE(node);
	int iphlen, grelen, extralen;
	const struct greheader *gre;
	const struct ip *ip;
	int error = 0;
	struct mbuf *m;

	roqh sendq = SLIST_HEAD_INITIALIZER(sendq);  /* send queue on stack */
	struct ng_pptpgre_roq *last = NULL;	/* last packet in the sendq */
	struct ng_pptpgre_roq *np, *prev;
	struct ng_pptpgre_roq temp = { { NULL }, NULL, 0 };
	long diff;
	u_int32_t seq;

	m = NGI_M(item);
	/* Update stats */
	priv->stats.recvPackets++;
	priv->stats.recvOctets += m->m_pkthdr.len;

	/* Sanity check packet length */
	if (m->m_pkthdr.len < sizeof(*ip) + sizeof(*gre)) {
		priv->stats.recvRunts++;
		ERROUT(EINVAL);
	}

	/* Safely pull up the complete IP+GRE headers */
	if (m->m_len < sizeof(*ip) + sizeof(*gre)) {
		if ((m = m_pullup(m, sizeof(*ip) + sizeof(*gre))) == NULL) {
			priv->stats.memoryFailures++;
			_NGI_M(item) = NULL;
			ERROUT(ENOBUFS);
		}
		_NGI_M(item) = m;
	}
	ip = mtod(m, const struct ip *);
	iphlen = ip->ip_hl << 2;
	if (m->m_len < iphlen + sizeof(*gre)) {
		if ((m = m_pullup(m, iphlen + sizeof(*gre))) == NULL) {
			priv->stats.memoryFailures++;
			_NGI_M(item) = NULL;
			ERROUT(ENOBUFS);
		}
		_NGI_M(item) = m;
		ip = mtod(m, const struct ip *);
	}
	gre = (const struct greheader *)((const u_char *)ip + iphlen);
	grelen = sizeof(*gre) + sizeof(u_int32_t) * (gre->hasSeq + gre->hasAck);
	if (m->m_pkthdr.len < iphlen + grelen) {
		priv->stats.recvRunts++;
		ERROUT(EINVAL);
	}
	if (m->m_len < iphlen + grelen) {
		if ((m = m_pullup(m, iphlen + grelen)) == NULL) {