6LoWPAN: UDP header decompression

This patch provides possibility to decompress UDP headers.
Derived from Contiki OS.

Signed-off-by: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 60 insertions, 1 deletions

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 9bf82d72bb9e..602f318a8d62 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -311,6 +311,62 @@ static u16 lowpan_fetch_skb_u16(struct sk_buff *skb)
         return ret;
 }
 
+static int
+lowpan_uncompress_udp_header(struct sk_buff *skb)
+{
+        struct udphdr *uh = udp_hdr(skb);
+        u8 tmp;
+
+        tmp = lowpan_fetch_skb_u8(skb);
+
+        if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
+                pr_debug("(%s): UDP header uncompression\n", __func__);
+                switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
+                case LOWPAN_NHC_UDP_CS_P_00:
+                        memcpy(&uh->source, &skb->data[0], 2);
+                        memcpy(&uh->dest, &skb->data[2], 2);
+                        skb_pull(skb, 4);
+                        break;
+                case LOWPAN_NHC_UDP_CS_P_01:
+                        memcpy(&uh->source, &skb->data[0], 2);
+                        uh->dest =
+                           skb->data[2] + LOWPAN_NHC_UDP_8BIT_PORT;
+                        skb_pull(skb, 3);
+                        break;
+                case LOWPAN_NHC_UDP_CS_P_10:
+                        uh->source = skb->data[0] + LOWPAN_NHC_UDP_8BIT_PORT;
+                        memcpy(&uh->dest, &skb->data[1], 2);
+                        skb_pull(skb, 3);
+                        break;
+                case LOWPAN_NHC_UDP_CS_P_11:
+                        uh->source =
+                           LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] >> 4);
+                        uh->dest =
+                           LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] & 0x0f);
+                        skb_pull(skb, 1);
+                        break;
+                default:
+                        pr_debug("(%s) ERROR: unknown UDP format\n", __func__);
+                        goto err;
+                        break;
+                }
+
+                pr_debug("(%s): uncompressed UDP ports: src = %d, dst = %d\n",
+                                        __func__, uh->source, uh->dest);
+
+                /* copy checksum */
+                memcpy(&uh->check, &skb->data[0], 2);
+                skb_pull(skb, 2);
+        } else {
+                pr_debug("(%s): ERROR: unsupported NH format\n", __func__);
+                goto err;
+        }
+
+        return 0;
+err:
+        return -EINVAL;
+}
+
 static int lowpan_header_create(struct sk_buff *skb,
                            struct net_device *dev,
                            unsigned short type, const void *_daddr,
@@ -842,7 +898,10 @@ lowpan_process_data(struct sk_buff *skb)
                         goto drop;
         }
 
-        /* TODO: UDP header parse */
+        /* UDP data uncompression */
+        if (iphc0 & LOWPAN_IPHC_NH_C)
+                if (lowpan_uncompress_udp_header(skb))
+                        goto drop;
 
         /* Not fragmented package */
         hdr.payload_len = htons(skb->len);