On Sat, Nov 29, 2014 at 10:14:42PM +0100, Alexander Aring wrote:
> This patch adds a generic next header compression layer interface. There
> exists various methods to do a header compression after 6LoWPAN header
> to save payload. This introduce a generic nhc header which allow a
> simple adding of a new header compression format instead of a static
> implementation inside the 6LoWPAN header compression and uncompression
> function.
>
> Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx>
> Cc: Jukka Rissanen <jukka.rissanen@xxxxxxxxxxxxxxx>
> Cc: Martin Townsend <mtownsend1973@xxxxxxxxx>
> ---
> net/6lowpan/Makefile | 2 +-
> net/6lowpan/nhc.c | 175 +++++++++++++++++++++++++++++++++++++++++++++++++++
> net/6lowpan/nhc.h | 130 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 306 insertions(+), 1 deletion(-)
> create mode 100644 net/6lowpan/nhc.c
> create mode 100644 net/6lowpan/nhc.h
>
> diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
> index 415886b..4215602 100644
> --- a/net/6lowpan/Makefile
> +++ b/net/6lowpan/Makefile
> @@ -1,3 +1,3 @@
> obj-$(CONFIG_6LOWPAN) := 6lowpan.o
>
> -6lowpan-y := iphc.o
> +6lowpan-y := iphc.o nhc.o
> diff --git a/net/6lowpan/nhc.c b/net/6lowpan/nhc.c
> new file mode 100644
> index 0000000..f64b244
> --- /dev/null
> +++ b/net/6lowpan/nhc.c
> @@ -0,0 +1,175 @@
> +/*
> + * 6LoWPAN next header compression
> + *
> + *
> + * Authors:
> + * Alexander Aring <aar@xxxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/netdevice.h>
> +
> +#include <net/ipv6.h>
> +
> +#include "nhc.h"
> +
> +static struct rb_root rb_root = RB_ROOT;
> +static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
> +
> +static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
> +{
> + struct rb_node **new = &rb_root.rb_node, *parent = NULL;
> +
> + /* Figure out where to put new node */
> + while (*new) {
> + struct lowpan_nhc *this = container_of(*new, struct lowpan_nhc,
> + node);
> + int result, len_dif, len;
> +
> + len_dif = nhc->idlen - this->idlen;
> +
> + if (nhc->idlen < this->idlen)
> + len = nhc->idlen;
> + else
> + len = this->idlen;
> +
> + result = memcmp(nhc->id, this->id, len);
> + if (!result)
> + result = len_dif;
> +
> + parent = *new;
> + if (result < 0)
> + new = &((*new)->rb_left);
> + else if (result > 0)
> + new = &((*new)->rb_right);
> + else
> + return -EEXIST;
> + }
> +
> + /* Add new node and rebalance tree. */
> + rb_link_node(&nhc->node, parent, new);
> + rb_insert_color(&nhc->node, &rb_root);
> +
> + return 0;
> +}
> +
> +static void lowpan_nhc_remove(struct lowpan_nhc *nhc)
> +{
> + rb_erase(&nhc->node, &rb_root);
> +}
> +
> +struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb)
> +{
> + struct rb_node *node = rb_root.rb_node;
> + const u8 *nhcid_skb_ptr = skb->data;
> +
> + while (node) {
> + struct lowpan_nhc *nhc = container_of(node, struct lowpan_nhc,
> + node);
> + u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN];
> + int result, i;
> +
> + if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len)
> + return NULL;
> +
> + /* copy and mask afterwards the nhid value from skb */
> + memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen);
> + for (i = 0; i < nhc->idlen; i++)
> + nhcid_skb_ptr_masked[i] &= nhc->idmask[i];
> +
> + result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen);
> + if (result < 0)
> + node = node->rb_left;
> + else if (result > 0)
> + node = node->rb_right;
> + else
> + return nhc;
> + }
> +
> + return NULL;
> +}
> +
> +struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr)
> +{
> + return lowpan_nexthdr_nhcs[nexthdr];
> +}
> +
> +int lowpan_nhc_do_compression(struct lowpan_nhc *nhc, struct sk_buff *skb,
> + u8 **hc_ptr, u8 *iphc0)
> +{
> + int ret;
> +
> + if (!nhc)
> + return 0;
> +
> + ret = nhc->compress(skb, hc_ptr);
> + if (ret == 0)
> + *iphc0 |= LOWPAN_IPHC_NH_C;
> +
> + return ret;
> +}
> +
> +int lowpan_nhc_do_uncompression(struct sk_buff *skb, struct ipv6hdr *hdr)
> +{
> + struct lowpan_nhc *nhc;
> + /* default dropping if nothing found */
> + int ret = 0;
> +
this should be ret = -ENOENT;
To avoid sending garbage to next higher layer. I changed this is here
from -EINVAL to 0. Sorry some mistake is happend here, now it's real
dropped afterwards.
> + nhc = lowpan_nhc_by_nhcid(skb);
> + if (nhc) {
> + ret = nhc->uncompress(skb, sizeof(*hdr) + nhc->nexthdrlen);
> + if (ret == 0) {
> + hdr->nexthdr = nhc->nexthdr;
> + skb_reset_transport_header(skb);
> + raw_dump_table(__func__, "raw transport header dump",
> + skb_transport_header(skb),
> + nhc->nexthdrlen);
> + } else if (ret == -ENOTSUPP) {
> + netdev_warn(skb->dev, "received %s which is not supported for uncompression.\n",
> + nhc->name);
> + }
> + } else {
> + netdev_warn(skb->dev, "received nhc which is not supported. Dropping.\n");
> + }
> +
> + return ret;
> +}
> +
- Alex
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