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Commit 84c2e7bc authored by Alexander Aring's avatar Alexander Aring Committed by David S. Miller
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6lowpan: add function to uncompress multicast addr 



Add function to uncompress multicast address.
This function split the uncompress function for a multicast address
in a seperate function.

To uncompress a multicast address is different than a other
non-multicasts addresses according to rfc6282.

Signed-off-by: default avatarAlexander Aring <alex.aring@gmail.com>
Reviewed-by: default avatarWerner Almesberger <werner@almesberger.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4666669f

net/ieee802154/6lowpan.c

+59 −19
Original line number Diff line number Diff line
@@ -88,15 +88,6 @@ static const u8 lowpan_unc_llconf[] = {0x0f, 0x28, 0x22, 0x20}; 
 */

static const u8 lowpan_unc_ctxconf[] = {0x00, 0x88, 0x82, 0x80};



/*

 * Uncompression of ctx-base

 *   0 -> 0 bits from packet

 *   1 -> 2 bytes from prefix - bunch of zeroes 5 from packet

 *   2 -> 2 bytes from prefix - zeroes + 3 from packet

 *   3 -> 2 bytes from prefix - infer 1 bytes from lladdr

 */

static const u8 lowpan_unc_mxconf[] = {0x0f, 0x25, 0x23, 0x21};



/* Link local prefix */

static const u8 lowpan_llprefix[] = {0xfe, 0x80};
@@ -240,6 +231,63 @@ lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr *ipaddr, 
	return 0;

}



/* Uncompress function for multicast destination address,

 * when M bit is set.

 */

static int

lowpan_uncompress_multicast_daddr(struct sk_buff *skb,

		struct in6_addr *ipaddr,

		const u8 dam)

{

	bool fail;



	switch (dam) {

	case LOWPAN_IPHC_DAM_00:

		/* 00:  128 bits.  The full address

		 * is carried in-line.

		 */

		fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);

		break;

	case LOWPAN_IPHC_DAM_01:

		/* 01:  48 bits.  The address takes

		 * the form ffXX::00XX:XXXX:XXXX.

		 */

		ipaddr->s6_addr[0] = 0xFF;

		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);

		fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);

		break;

	case LOWPAN_IPHC_DAM_10:

		/* 10:  32 bits.  The address takes

		 * the form ffXX::00XX:XXXX.

		 */

		ipaddr->s6_addr[0] = 0xFF;

		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);

		fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);

		break;

	case LOWPAN_IPHC_DAM_11:

		/* 11:  8 bits.  The address takes

		 * the form ff02::00XX.

		 */

		ipaddr->s6_addr[0] = 0xFF;

		ipaddr->s6_addr[1] = 0x02;

		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);

		break;

	default:

		pr_debug("DAM value has a wrong value: 0x%x\n", dam);

		return -EINVAL;

	}



	if (fail) {

		pr_debug("Failed to fetch skb data\n");

		return -EIO;

	}



	lowpan_raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is:\n",

			ipaddr->s6_addr, 16);



	return 0;

}



static void

lowpan_compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)

{
@@ -927,16 +975,8 @@ lowpan_process_data(struct sk_buff *skb) 
			pr_debug("dest: context-based mcast compression\n");

			/* TODO: implement this */

		} else {

			u8 prefix[] = {0xff, 0x02};



			pr_debug("dest: non context-based mcast compression\n");

			if (0 < tmp && tmp < 3) {

				if (lowpan_fetch_skb_u8(skb, &prefix[1]))

					goto drop;

			}



			err = lowpan_uncompress_addr(skb, &hdr.daddr, prefix,

					lowpan_unc_mxconf[tmp], NULL);

			err = lowpan_uncompress_multicast_daddr(

					skb, &hdr.daddr, tmp);

			if (err)

				goto drop;

		}