Commit 96cb3eb7 authored by Alexander Aring's avatar Alexander Aring Committed by David S. Miller
Browse files

6lowpan: fix fragmentation on sending side 



This patch fix the fragmentation on sending side according to rfc4944.

Also add improvement to use the full payload of a PDU which calculate
the nearest divided to 8 payload length for the fragmentation datagram
size attribute.

The main issue is that the datagram size of fragmentation header use the
ipv6 payload length, but rfc4944 says it's the ipv6 payload length inclusive
network header size (and transport header size if compressed).

Signed-off-by: default avatarAlexander Aring <alex.aring@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 349aa7bc

net/ieee802154/6lowpan.c

+27 −10
Original line number Diff line number Diff line
@@ -422,44 +422,60 @@ lowpan_fragment_xmit(struct sk_buff *skb, u8 *head, 
static int

lowpan_skb_fragmentation(struct sk_buff *skb, struct net_device *dev)

{

	int  err, header_length, payload_length, tag, offset = 0;

	int err;

	u16 dgram_offset, dgram_size, payload_length, header_length,

	    lowpan_size, frag_plen, offset, tag;

	u8 head[5];



	header_length = skb->mac_len;

	payload_length = skb->len - header_length;

	tag = lowpan_dev_info(dev)->fragment_tag++;

	lowpan_size = skb_network_header_len(skb);

	dgram_size = lowpan_uncompress_size(skb, &dgram_offset) -

		     header_length;



	/* first fragment header */

	head[0] = LOWPAN_DISPATCH_FRAG1 | ((payload_length >> 8) & 0x7);

	head[1] = payload_length & 0xff;

	head[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x7);

	head[1] = dgram_size & 0xff;

	head[2] = tag >> 8;

	head[3] = tag & 0xff;



	err = lowpan_fragment_xmit(skb, head, header_length, LOWPAN_FRAG_SIZE,

				   0, LOWPAN_DISPATCH_FRAG1);

	/* calc the nearest payload length(divided to 8) for first fragment

	 * which fits into a IEEE802154_MTU

	 */

	frag_plen = round_down(IEEE802154_MTU - header_length -

			       LOWPAN_FRAG1_HEAD_SIZE - lowpan_size -

			       IEEE802154_MFR_SIZE, 8);



	err = lowpan_fragment_xmit(skb, head, header_length,

				   frag_plen + lowpan_size, 0,

				   LOWPAN_DISPATCH_FRAG1);

	if (err) {

		pr_debug("%s unable to send FRAG1 packet (tag: %d)",

			 __func__, tag);

		goto exit;

	}



	offset = LOWPAN_FRAG_SIZE;

	offset = lowpan_size + frag_plen;

	dgram_offset += frag_plen;



	/* next fragment header */

	head[0] &= ~LOWPAN_DISPATCH_FRAG1;

	head[0] |= LOWPAN_DISPATCH_FRAGN;



	frag_plen = round_down(IEEE802154_MTU - header_length -

			       LOWPAN_FRAGN_HEAD_SIZE - IEEE802154_MFR_SIZE, 8);



	while (payload_length - offset > 0) {

		int len = LOWPAN_FRAG_SIZE;

		int len = frag_plen;



		head[4] = offset / 8;

		head[4] = dgram_offset >> 3;



		if (payload_length - offset < len)

			len = payload_length - offset;



		err = lowpan_fragment_xmit(skb, head, header_length,

					   len, offset, LOWPAN_DISPATCH_FRAGN);

		err = lowpan_fragment_xmit(skb, head, header_length, len,

					   offset, LOWPAN_DISPATCH_FRAGN);

		if (err) {

			pr_debug("%s unable to send a subsequent FRAGN packet "

				 "(tag: %d, offset: %d", __func__, tag, offset);
@@ -467,6 +483,7 @@ lowpan_skb_fragmentation(struct sk_buff *skb, struct net_device *dev) 
		}



		offset += len;

		dgram_offset += len;

	}



exit:

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