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/*-
 *   BSD LICENSE
 * 
 *   Copyright(c) 2010-2012 Intel Corporation. All rights reserved.
 *   All rights reserved.
 * 
 *   Redistribution and use in source and binary forms, with or without 
 *   modification, are permitted provided that the following conditions 
 *   are met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in 
 *       the documentation and/or other materials provided with the 
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its 
 *       contributors may be used to endorse or promote products derived 
 *       from this software without specific prior written permission.
 * 
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#ifndef __INCLUDE_RTE_IPV4_FRAG_H__
#define __INCLUDE_RTE_IPV4_FRAG_H__
#include <rte_ip.h>

/**
 * @file
 * RTE IPv4 Fragmentation
 *
 * Implementation of IPv4 fragmentation.
 *
 */

/*
 * Default byte size for the IPv4 Maximum Transfer Unit (MTU).
 * This value includes the size of IPv4 header.
 */
#define	IPV4_MTU_DEFAULT	ETHER_MTU

/*
 * Default payload in bytes for the IPv4 packet.
 */
#define	IPV4_DEFAULT_PAYLOAD	(IPV4_MTU_DEFAULT - sizeof(struct ipv4_hdr))

/*
 * MAX number of fragments per packet allowed.
 */
#define	IPV4_MAX_FRAGS_PER_PACKET	0x80


/* Debug on/off */
#ifdef RTE_IPV4_FRAG_DEBUG

#define	RTE_IPV4_FRAG_ASSERT(exp)					\
if (!(exp))	{							\
	rte_panic("function %s, line%d\tassert \"" #exp "\" failed\n",	\
		__func__, __LINE__);					\
}

#else /*RTE_IPV4_FRAG_DEBUG*/

#define RTE_IPV4_FRAG_ASSERT(exp)	do { } while(0)

#endif /*RTE_IPV4_FRAG_DEBUG*/

/* Fragment Offset */
#define	IPV4_HDR_DF_SHIFT			14
#define	IPV4_HDR_MF_SHIFT			13
#define	IPV4_HDR_FO_SHIFT			3

#define	IPV4_HDR_DF_MASK			(1 << IPV4_HDR_DF_SHIFT)
#define	IPV4_HDR_MF_MASK			(1 << IPV4_HDR_MF_SHIFT)

#define	IPV4_HDR_FO_MASK			((1 << IPV4_HDR_FO_SHIFT) - 1)

static inline void __fill_ipv4hdr_frag(struct ipv4_hdr *dst,
		const struct ipv4_hdr *src, uint16_t len, uint16_t fofs,
		uint16_t dofs, uint32_t mf)
{
	rte_memcpy(dst, src, sizeof(*dst));
	fofs = (uint16_t)(fofs + (dofs >> IPV4_HDR_FO_SHIFT));
	fofs = (uint16_t)(fofs | mf << IPV4_HDR_MF_SHIFT);
	dst->fragment_offset = rte_cpu_to_be_16(fofs);
	dst->total_length = rte_cpu_to_be_16(len);
	dst->hdr_checksum = 0;
}

static inline void __free_fragments(struct rte_mbuf *mb[], uint32_t num)
{
	uint32_t i;
	for (i = 0; i != num; i++)
		rte_pktmbuf_free(mb[i]);
}

/**
 * IPv4 fragmentation.
 *
 * This function implements the fragmentation of IPv4 packets.
 *
 * @param pkt_in
 *   The input packet.
 * @param pkts_out
 *   Array storing the output fragments.
 * @param mtu_size
 *   Size in bytes of the Maximum Transfer Unit (MTU) for the outgoing IPv4
 *   datagrams. This value includes the size of the IPv4 header.
 * @param pool_direct
 *   MBUF pool used for allocating direct buffers for the output fragments.
 * @param pool_indirect
 *   MBUF pool used for allocating indirect buffers for the output fragments.
 * @return
 *   Upon successful completion - number of output fragments placed
 *   in the pkts_out array.
 *   Otherwise - (-1) * <errno>.
 */
static inline int32_t rte_ipv4_fragmentation(struct rte_mbuf *pkt_in,
	struct rte_mbuf **pkts_out,
	uint16_t nb_pkts_out,
	uint16_t mtu_size,
	struct rte_mempool *pool_direct,
	struct rte_mempool *pool_indirect)
{
	struct rte_mbuf *in_seg = NULL;
	struct ipv4_hdr *in_hdr;
	uint32_t out_pkt_pos, in_seg_data_pos;
	uint32_t more_in_segs;
	uint16_t fragment_offset, flag_offset, frag_size;

	frag_size = (uint16_t)(mtu_size - sizeof(struct ipv4_hdr));

	/* Fragment size should be a multiply of 8. */
	RTE_IPV4_FRAG_ASSERT((frag_size & IPV4_HDR_FO_MASK) == 0);

	/* Fragment size should be a multiply of 8. */
	RTE_IPV4_FRAG_ASSERT(IPV4_MAX_FRAGS_PER_PACKET * frag_size >=
	    (uint16_t)(pkt_in->pkt.pkt_len - sizeof (struct ipv4_hdr)));

	in_hdr = (struct ipv4_hdr*) pkt_in->pkt.data;
	flag_offset = rte_cpu_to_be_16(in_hdr->fragment_offset);

	/* If Don't Fragment flag is set */
	if (unlikely ((flag_offset & IPV4_HDR_DF_MASK) != 0))
		return (-ENOTSUP);

	/* Check that pkts_out is big enough to hold all fragments */
	if (unlikely (frag_size * nb_pkts_out <
	    (uint16_t)(pkt_in->pkt.pkt_len - sizeof (struct ipv4_hdr))))
		return (-EINVAL);

	in_seg = pkt_in;
	in_seg_data_pos = sizeof(struct ipv4_hdr);
	out_pkt_pos = 0;
	fragment_offset = 0;

	more_in_segs = 1;
	while (likely(more_in_segs)) {
		struct rte_mbuf *out_pkt = NULL, *out_seg_prev = NULL;
		uint32_t more_out_segs;
		struct ipv4_hdr *out_hdr;

		/* Allocate direct buffer */
		out_pkt = rte_pktmbuf_alloc(pool_direct);
		if (unlikely(out_pkt == NULL)) {
			__free_fragments(pkts_out, out_pkt_pos);
			return (-ENOMEM);
		}

		/* Reserve space for the IP header that will be built later */
		out_pkt->pkt.data_len = sizeof(struct ipv4_hdr);
		out_pkt->pkt.pkt_len = sizeof(struct ipv4_hdr);

		out_seg_prev = out_pkt;
		more_out_segs = 1;
		while (likely(more_out_segs && more_in_segs)) {
			struct rte_mbuf *out_seg = NULL;
			uint32_t len;

			/* Allocate indirect buffer */
			out_seg = rte_pktmbuf_alloc(pool_indirect);
			if (unlikely(out_seg == NULL)) {
				rte_pktmbuf_free(out_pkt);
				__free_fragments(pkts_out, out_pkt_pos);
				return (-ENOMEM);
			}
			out_seg_prev->pkt.next = out_seg;
			out_seg_prev = out_seg;

			/* Prepare indirect buffer */
			rte_pktmbuf_attach(out_seg, in_seg);
			len = mtu_size - out_pkt->pkt.pkt_len;
			if (len > (in_seg->pkt.data_len - in_seg_data_pos)) {
				len = in_seg->pkt.data_len - in_seg_data_pos;
			}
			out_seg->pkt.data = (char*) in_seg->pkt.data + (uint16_t)in_seg_data_pos;
			out_seg->pkt.data_len = (uint16_t)len;
			out_pkt->pkt.pkt_len = (uint16_t)(len +
			    out_pkt->pkt.pkt_len);
			out_pkt->pkt.nb_segs += 1;
			in_seg_data_pos += len;

			/* Current output packet (i.e. fragment) done ? */
			if (unlikely(out_pkt->pkt.pkt_len >= mtu_size)) {
				more_out_segs = 0;
			}

			/* Current input segment done ? */
			if (unlikely(in_seg_data_pos == in_seg->pkt.data_len)) {
				in_seg = in_seg->pkt.next;
				in_seg_data_pos = 0;

				if (unlikely(in_seg == NULL)) {
					more_in_segs = 0;
				}
			}
		}

		/* Build the IP header */

		out_hdr = (struct ipv4_hdr*) out_pkt->pkt.data;

		__fill_ipv4hdr_frag(out_hdr, in_hdr,
		    (uint16_t)out_pkt->pkt.pkt_len,
		    flag_offset, fragment_offset, more_in_segs);

		fragment_offset = (uint16_t)(fragment_offset +
		    out_pkt->pkt.pkt_len - sizeof(struct ipv4_hdr));

		out_pkt->ol_flags |= PKT_TX_IP_CKSUM;
		out_pkt->pkt.l3_len = sizeof(struct ipv4_hdr);

		/* Write the fragment to the output list */
		pkts_out[out_pkt_pos] = out_pkt;
		out_pkt_pos ++;
	}

	return (out_pkt_pos);
}

#endif