6lowpan: handle context based source address

Handle context based address when an unspecified address is given.
For other context based address we print a warning and drop the packet
because we don't support it right now.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Reviewed-by: Werner Almesberger <werner@almesberger.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 5ef9157..c85e71e 100644 (file)
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -242,6 +242,40 @@ lowpan_uncompress_addr(struct sk_buff *skb,
        return 0;
 }
 
+/* Uncompress address function for source context
+ * based address(non-multicast).
+ */
+static int
+lowpan_uncompress_context_based_src_addr(struct sk_buff *skb,
+               struct in6_addr *ipaddr,
+               const u8 sam)
+{
+       switch (sam) {
+       case LOWPAN_IPHC_ADDR_00:
+               /* unspec address ::
+                * Do nothing, address is already ::
+                */
+               break;
+       case LOWPAN_IPHC_ADDR_01:
+               /* TODO */
+       case LOWPAN_IPHC_ADDR_02:
+               /* TODO */
+       case LOWPAN_IPHC_ADDR_03:
+               /* TODO */
+               netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
+               return -EINVAL;
+       default:
+               pr_debug("Invalid sam value: 0x%x\n", sam);
+               return -EINVAL;
+       }
+
+       lowpan_raw_dump_inline(NULL,
+                       "Reconstructed context based ipv6 src addr is:\n",
+                       ipaddr->s6_addr, 16);
+
+       return 0;
+}
+
 /* Uncompress function for multicast destination address,
  * when M bit is set.
  */
@@ -970,9 +1004,18 @@ lowpan_process_data(struct sk_buff *skb)
        /* Extract SAM to the tmp variable */
        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, tmp, _saddr);
+       if (iphc1 & LOWPAN_IPHC_SAC) {
+               /* Source address context based uncompression */
+               pr_debug("SAC bit is set. Handle context based source address.\n");
+               err = lowpan_uncompress_context_based_src_addr(
+                               skb, &hdr.saddr, tmp);
+       } else {
+               /* Source address uncompression */
+               pr_debug("source address stateless compression\n");
+               err = lowpan_uncompress_addr(skb, &hdr.saddr, tmp, _saddr);
+       }
+
+       /* Check on error of previous branch */
        if (err)
                goto drop;