On 11/2/11, Alexander Smirnov <alex.bluesman.smir...@gmail.com> wrote:
> This patch adds support for UDP header compression.
> Derived from Contiki OS.
>From my point of view, this code would also benefit from being refactored
to a separate function.
>
> Signed-off-by: Alexander Smirnov <alex.bluesman.smir...@gmail.com>
> ---
> net/ieee802154/6lowpan.c | 51
> ++++++++++++++++++++++++++++++++++++++++++---
> net/ieee802154/6lowpan.h | 5 ++++
> 2 files changed, 52 insertions(+), 4 deletions(-)
>
> diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
> index c4aae4e..6da3357 100644
> --- a/net/ieee802154/6lowpan.c
> +++ b/net/ieee802154/6lowpan.c
> @@ -365,8 +365,6 @@ 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 +452,53 @@ 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) {
> + 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;
> + }
> +
> + /* TODO: other NH types support? */
>
> head[0] = iphc0;
> head[1] = iphc1;
> diff --git a/net/ieee802154/6lowpan.h b/net/ieee802154/6lowpan.h
> index 5d2e5a0..aeff3f3 100644
> --- 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,
> --
> 1.7.2.5
>
>
--
With best wishes
Dmitry
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