Stateless decompression mode 3 combines the MAC address from the MAC header
with link-local prefix FE80::/64 to reconstruct the original IPv6 address.
This patch corrects comments, variable llconf and lowpan_uncompress_addr
to be compatible with RFC 4644.
Signed-off-by: Ralph Droms <rdr...@cisco.com>
---
net/ieee802154/6lowpan.c | 50 +++++++++++++++++++++++++++------------------
1 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 55e1fd5..a7bac63 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -68,32 +68,32 @@ static const u8 lowpan_ttl_values[] = {0, 1, 64, 255};
static LIST_HEAD(lowpan_devices);
/*
- * Uncompression of linklocal:
+ * Uncompression of stateless unicast:
* 0 -> 16 bytes from packet
* 1 -> 2 bytes from prefix - bunch of zeroes and 8 from packet
* 2 -> 2 bytes from prefix - zeroes + 2 from packet
- * 3 -> 2 bytes from prefix - infer 8 bytes from lladdr
+ * 3 -> 2 bytes from prefix - IID == MAC
*
* NOTE: => the uncompress function does change 0xf to 0x10
* NOTE: 0x00 => no-autoconfig => unspecified
*/
-static const u8 lowpan_unc_llconf[] = {0x0f, 0x28, 0x22, 0x20};
+static const u8 lowpan_unc_slconf[] = {0x0f, 0x28, 0x22, 0x20};
/*
* Uncompression of ctx-based:
* 0 -> 0 bits from packet [unspecified / reserved]
* 1 -> 8 bytes from prefix - bunch of zeroes and 8 from packet
* 2 -> 8 bytes from prefix - zeroes + 2 from packet
- * 3 -> 8 bytes from prefix - infer 8 bytes from lladdr
+ * 3 -> 8 bytes from prefix - IID == MAC
*/
static const u8 lowpan_unc_ctxconf[] = {0x00, 0x88, 0x82, 0x80};
/*
- * Uncompression of ctx-base
+ * Uncompression of stateless multicast:
* 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
+ * 3 -> 2 bytes from prefix - infer 1 bytes from MAC
*/
static const u8 lowpan_unc_mxconf[] = {0x0f, 0x25, 0x23, 0x21};
@@ -208,7 +208,7 @@ lowpan_uip_ds6_set_addr_iid(struct in6_addr *ipaddr,
unsigned char *lladdr)
*/
static int
lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr *ipaddr,
- u8 const *prefix, u8 pref_post_count, unsigned char *lladdr)
+ u8 const *prefix, u8 pref_post_count, unsigned char *macaddr)
{
u8 prefcount = pref_post_count >> 4;
u8 postcount = pref_post_count & 0x0f;
@@ -217,9 +217,9 @@ lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr
*ipaddr,
prefcount = (prefcount == 15 ? 16 : prefcount);
postcount = (postcount == 15 ? 16 : postcount);
- if (lladdr)
+ if (macaddr)
lowpan_raw_dump_inline(__func__, "linklocal address",
- lladdr, IEEE802154_ADDR_LEN);
+ macaddr, IEEE802154_ADDR_LEN);
if (prefcount > 0)
memcpy(ipaddr, prefix, prefcount);
@@ -231,11 +231,11 @@ lowpan_uncompress_addr(struct sk_buff *skb, struct
in6_addr *ipaddr,
memcpy(&ipaddr->s6_addr[16 - postcount], skb->data, postcount);
skb_pull(skb, postcount);
} else if (prefcount > 0) {
- if (lladdr == NULL)
+ if (macaddr == NULL)
return -EINVAL;
/* no IID based configuration if no prefix and no data */
- lowpan_uip_ds6_set_addr_iid(ipaddr, lladdr);
+ lowpan_uip_ds6_set_addr_iid(ipaddr, macaddr);
}
pr_debug("uncompressing %d + %d => ", prefcount, postcount);
@@ -916,24 +916,34 @@ lowpan_process_data(struct sk_buff *skb)
tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
/* Source address uncompression */
- pr_debug("source address stateless compression\n");
- err = lowpan_uncompress_addr(skb, &hdr.saddr, lowpan_llprefix,
- lowpan_unc_llconf[tmp], skb->data);
- if (err)
+ pr_debug("source address uncompression - SAM %d\n", tmp);
+ if (iphc1 & LOWPAN_IPHC_SAC) {
+ pr_debug("stateful source uncompression not implemented\n");
goto drop;
+ } else {
+ pr_debug("stateless source uncompression\n");
+ err = lowpan_uncompress_addr(skb, &hdr.saddr, lowpan_llprefix,
+ lowpan_unc_slconf[tmp], skb->data);
+ if (err)
+ goto drop;
+ }
/* Extract DAM to the tmp variable */
tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
+ /* destination address uncompression */
+ pr_debug("source address uncompression - M %d, DAM %d\n",
+ iphc1 & LOWPAN_IPHC_M, tmp);
+
/* check for Multicast Compression */
if (iphc1 & LOWPAN_IPHC_M) {
if (iphc1 & LOWPAN_IPHC_DAC) {
- pr_debug("dest: context-based mcast compression\n");
- /* TODO: implement this */
+ pr_debug("context-based mcast uncompression not
implemented\n");
+ /* TODO: implement this; does not depend on contex
distribution */
} else {
u8 prefix[] = {0xff, 0x02};
- pr_debug("dest: non context-based mcast compression\n");
+ pr_debug("stateless mcast uncompression\n");
if (0 < tmp && tmp < 3) {
if (lowpan_fetch_skb_u8(skb, &prefix[1]))
goto drop;
@@ -945,9 +955,9 @@ lowpan_process_data(struct sk_buff *skb)
goto drop;
}
} else {
- pr_debug("dest: stateless compression\n");
+ pr_debug("stateless compression\n");
err = lowpan_uncompress_addr(skb, &hdr.daddr, lowpan_llprefix,
- lowpan_unc_llconf[tmp], skb->data);
+ lowpan_unc_slconf[tmp], skb->data);
if (err)
goto drop;
}
--
1.7.7.6
------------------------------------------------------------------------------
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