6LoWPAN: UDP header compression

This patch adds support for UDP header compression.
Derived from Contiki OS.

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

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index 39ec6e01822738bc078c952e737183c57054613c..9bf82d72bb9e4f1936badd752e871bc8da23bda2 100644 (file)
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -246,6 +246,50 @@ lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr *ipaddr,
        return 0;
 }
 
+static void
+lowpan_compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
+{
+       struct udphdr *uh = udp_hdr(skb);
+
+       pr_debug("(%s): UDP header compression\n", __func__);
+
+       if (((uh->source & LOWPAN_NHC_UDP_4BIT_MASK) ==
+                               LOWPAN_NHC_UDP_4BIT_PORT) &&
+           ((uh->dest & LOWPAN_NHC_UDP_4BIT_MASK) ==
+                               LOWPAN_NHC_UDP_4BIT_PORT)) {
+               pr_debug("(%s): both ports compression to 4 bits\n", __func__);
+               **hc06_ptr = LOWPAN_NHC_UDP_CS_P_11;
+               **(hc06_ptr + 1) = /* subtraction is faster */
+                  (u8)((uh->dest - LOWPAN_NHC_UDP_4BIT_PORT) +
+                      ((uh->source & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
+               *hc06_ptr += 2;
+       } else if ((uh->dest & LOWPAN_NHC_UDP_8BIT_MASK) ==
+                       LOWPAN_NHC_UDP_8BIT_PORT) {
+               pr_debug("(%s): remove 8 bits of dest\n", __func__);
+               **hc06_ptr = LOWPAN_NHC_UDP_CS_P_01;
+               memcpy(*hc06_ptr + 1, &uh->source, 2);
+               **(hc06_ptr + 3) = (u8)(uh->dest - LOWPAN_NHC_UDP_8BIT_PORT);
+               *hc06_ptr += 4;
+       } else if ((uh->source & LOWPAN_NHC_UDP_8BIT_MASK) ==
+                       LOWPAN_NHC_UDP_8BIT_PORT) {
+               pr_debug("(%s): remove 8 bits of source\n", __func__);
+               **hc06_ptr = LOWPAN_NHC_UDP_CS_P_10;
+               memcpy(*hc06_ptr + 1, &uh->dest, 2);
+               **(hc06_ptr + 3) = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
+               *hc06_ptr += 4;
+       } else {
+               pr_debug("(%s): can't compress header\n", __func__);
+               **hc06_ptr = LOWPAN_NHC_UDP_CS_P_00;
+               memcpy(*hc06_ptr + 1, &uh->source, 2);
+               memcpy(*hc06_ptr + 3, &uh->dest, 2);
+               *hc06_ptr += 5;
+       }
+
+       /* checksum is always inline */
+       memcpy(*hc06_ptr, &uh->check, 2);
+       *hc06_ptr += 2;
+}
+
 static u8 lowpan_fetch_skb_u8(struct sk_buff *skb)
 {
        u8 ret;
@@ -365,8 +409,6 @@ static int lowpan_header_create(struct sk_buff *skb,
        if (hdr->nexthdr == UIP_PROTO_UDP)
                iphc0 |= LOWPAN_IPHC_NH_C;
 
-/* TODO: next header compression */
-
        if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
                *hc06_ptr = hdr->nexthdr;
                hc06_ptr += 1;
@@ -454,8 +496,9 @@ static int lowpan_header_create(struct sk_buff *skb,
                }
        }
 
-       /* TODO: UDP header compression */
-       /* TODO: Next Header compression */
+       /* UDP header compression */
+       if (hdr->nexthdr == UIP_PROTO_UDP)
+               lowpan_compress_udp_header(&hc06_ptr, skb);
 
        head[0] = iphc0;
        head[1] = iphc1;

diff --git a/net/ieee802154/6lowpan.h b/net/ieee802154/6lowpan.h
index 5d2e5a03742f1c9559e8acd05104c83888c0d992..aeff3f3104821ab3bdead00ed070d5d3fbb5164d 100644 (file)
--- a/net/ieee802154/6lowpan.h
+++ b/net/ieee802154/6lowpan.h
@@ -219,6 +219,11 @@
 #define LOWPAN_NHC_UDP_CHECKSUMC       0x04
 #define LOWPAN_NHC_UDP_CHECKSUMI       0x00
 
+#define LOWPAN_NHC_UDP_4BIT_PORT       0xF0B0
+#define LOWPAN_NHC_UDP_4BIT_MASK       0xFFF0
+#define LOWPAN_NHC_UDP_8BIT_PORT       0xF000
+#define LOWPAN_NHC_UDP_8BIT_MASK       0xFF00
+
 /* values for port compression, _with checksum_ ie bit 5 set to 0 */
 #define LOWPAN_NHC_UDP_CS_P_00 0xF0 /* all inline */
 #define LOWPAN_NHC_UDP_CS_P_01 0xF1 /* source 16bit inline,