Removing FCS from SNDCP packages

Holger Freyther holger at freyther.de
Wed May 10 14:03:34 UTC 2017


> On 9. May 2017, at 14:12, Holger Freyther <holger at freyther.de> wrote:
> 
> 	npdu_len = (msg->data + msg->len) - npdu - 3;
> 
> What I wonder (and the commit message didn't say is) was the fragment
> part handled as well. The calculation is:
> 
>        /* make sure to subtract length of SNDCP header from 'len' */
>        rc = defrag_enqueue(sne, suh->seg_nr, data, len - (data - hdr)); 
> 
> and len is passed in from the TLV struct in gprs_llc_rcvmsg. I think the
> fragmented case is working okay.
> 
> Shall we try to unify the length calculation to rely on the local "len"
> variable instead of checking msg->data+msg->len?

Or to make it a bit more clear. The -3 assumes that something is beyond
the LLC IE. I think instead of assuming that we should use the IE len
(instead of msg->len). We already do that in the fragmented case.

holger


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