2012/6/11 Tony Cheneau <tony.chene...@amnesiak.org>:
> Lenght field should be encoded (and accessed) the other way around.
> As it is currently written, it could lead to interroperability issues.
What kind of "interroperability issues" can occur? Please describe it
in details, I can't read your mind. And again, can these problems be
caused by the byte-order mismatch?
>
> Also, I rewrote the code so that iphc0 argument of
> lowpan_alloc_new_frame could be removed.
> ---
> net/ieee802154/6lowpan.c | 20 ++++++++++++--------
> 1 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
> index af2f12e..b400156 100644
> --- a/net/ieee802154/6lowpan.c
> +++ b/net/ieee802154/6lowpan.c
> @@ -654,7 +654,7 @@ static void lowpan_fragment_timer_expired(unsigned
> long entry_addr) }
>
> static struct lowpan_fragment *
> -lowpan_alloc_new_frame(struct sk_buff *skb, u8 iphc0, u8 len, u16 tag)
> +lowpan_alloc_new_frame(struct sk_buff *skb, u16 len, u16 tag)
> {
> struct lowpan_fragment *frame;
>
> @@ -665,7 +665,7 @@ lowpan_alloc_new_frame(struct sk_buff *skb, u8
> iphc0, u8 len, u16 tag)
> INIT_LIST_HEAD(&frame->list);
>
> - frame->length = (iphc0 & 7) | (len << 3);
> + frame->length = len;
> frame->tag = tag;
>
> /* allocate buffer for frame assembling */
> @@ -721,13 +721,17 @@ lowpan_process_data(struct sk_buff *skb)
> case LOWPAN_DISPATCH_FRAGN:
> {
> struct lowpan_fragment *frame;
> - u8 len, offset;
> - u16 tag;
> + /* slen stores the rightmost 8 bits of the 11 bits
> length */
> + u8 slen, offset;
> + u16 len, tag;
> bool found = false;
>
> - len = lowpan_fetch_skb_u8(skb); /* frame length */
> + slen = lowpan_fetch_skb_u8(skb); /* frame length */
> tag = lowpan_fetch_skb_u16(skb);
>
> + /* adds the 3 MSB to the 8 LSB to retrieve the 11 bits
> length */
> + len = ((iphc0 & 7) << 8) | slen;
> +
> /*
> * check if frame assembling with the same tag is
> * already in progress
> @@ -742,7 +746,7 @@ lowpan_process_data(struct sk_buff *skb)
>
> /* alloc new frame structure */
> if (!found) {
> - frame = lowpan_alloc_new_frame(skb, iphc0,
> len, tag);
> + frame = lowpan_alloc_new_frame(skb, len, tag);
> if (!frame)
> goto unlock_and_drop;
> }
> @@ -1000,8 +1004,8 @@ lowpan_skb_fragmentation(struct sk_buff *skb)
> tag = fragment_tag++;
>
> /* first fragment header */
> - head[0] = LOWPAN_DISPATCH_FRAG1 | (payload_length & 0x7);
> - head[1] = (payload_length >> 3) & 0xff;
> + head[0] = LOWPAN_DISPATCH_FRAG1 | ((payload_length >> 8) &
> 0x7);
> + head[1] = payload_length & 0xff;
> head[2] = tag >> 8;
> head[3] = tag & 0xff;
>
> --
> 1.7.3.4
>
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