Function ng_deflate_compress

freebsd/netgraph/ng_deflate.c:419–519

* Compress/encrypt a 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_compress(node_p node, struct mbuf *m, struct mbuf **resultp)
{
	const priv_p 	priv = NG_NODE_PRIVATE(node);
	int 		outlen, inlen;
	int 		rtn;

	/* Initialize. */
	*resultp = NULL;

	inlen = m->m_pkthdr.len;

	priv->stats.FramesPlain++;
	priv->stats.InOctets+=inlen;

	if (inlen > DEFLATE_BUF_SIZE) {
		priv->stats.Errors++;
		NG_FREE_M(m);
		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);
	outlen = DEFLATE_BUF_SIZE;

	/* Compress "inbuf" into "outbuf". */
	/* Prepare to compress. */
	if (priv->inbuf[0] != 0) {
		priv->cx.next_in = priv->inbuf;
		priv->cx.avail_in = inlen;
	} else {
		priv->cx.next_in = priv->inbuf + 1; /* compress protocol */
		priv->cx.avail_in = inlen - 1;
	}
	priv->cx.next_out = priv->outbuf + 2 + DEFLATE_HDRLEN;
	priv->cx.avail_out = outlen - 2 - DEFLATE_HDRLEN;

	/* Compress. */
	rtn = deflate(&priv->cx, Z_SYNC_FLUSH);

	/* Check return value. */
	if (rtn != Z_OK) {
		priv->stats.Errors++;
		log(LOG_NOTICE, "ng_deflate: compression error: %d (%s)\n",
		    rtn, priv->cx.msg);
		NG_FREE_M(m);
		return (EINVAL);
	}

	/* Calculate resulting size. */
	outlen -= priv->cx.avail_out;