Function ng_deflate_decompress

freebsd/netgraph/ng_deflate.c:525–701

* Decompress/decrypt packet and put the result in a new mbuf at *resultp. * The original mbuf is not free'd. */

 * The original mbuf is not free'd.
 */
static int
ng_deflate_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
{
	const priv_p 	priv = NG_NODE_PRIVATE(node);
	int 		outlen, inlen, datalen;
	int 		rtn;
	uint16_t	proto;
	int		offset;
	uint16_t	rseqnum;
	u_char		headbuf[5];
	static u_char	EMPTY_BLOCK[4] = { 0x00, 0x00, 0xff, 0xff };

	/* Initialize. */
	*resultp = NULL;

	inlen = m->m_pkthdr.len;

	if (inlen > DEFLATE_BUF_SIZE) {
		priv->stats.Errors++;
		NG_FREE_M(m);
		priv->seqnum = 0;
		return (ENOMEM);
	}

	/* We must own the mbuf chain exclusively to modify it. */
	m = m_unshare(m, M_NOWAIT);
	if (m == NULL) {
		priv->stats.Errors++;
		return (ENOMEM);
	}

	/* Work with contiguous regions of memory. */
	m_copydata(m, 0, inlen, (caddr_t)priv->inbuf);

	/* Separate proto. */
	if ((priv->inbuf[0] & 0x01) != 0) {
		proto = priv->inbuf[0];
		offset = 1;
	} else {
		proto = be16dec(priv->inbuf);
		offset = 2;
	}

	priv->stats.InOctets += inlen;

	/* Packet is compressed, so decompress. */
	if (proto == PROT_COMPD) {
		priv->stats.FramesComp++;

		/* Check sequence number. */
		rseqnum = be16dec(priv->inbuf + offset);
		offset += 2;
		if (rseqnum != priv->seqnum) {
			priv->stats.Errors++;
			log(LOG_NOTICE, "ng_deflate: wrong sequence: %u "
			    "instead of %u\n", rseqnum, priv->seqnum);
			NG_FREE_M(m);
			priv->seqnum = 0;