[Live-devel] UDP checksums validated in liveMedia ?

[Glen Gray]

Ahhh, I'd a cut'n'paste error in my patch. Doh !

repeat after me, netstat -s -u is your friend

Glen Gray wrote:

> Hey Guys,
>
> Trying to get an mpeg decrypt module working with an MPEG2 TS from a 
> Kasenna server. And I'm running into some problems.
>
> Kernel has a callback function in udp.c, if the udp packet that was 
> received is for a particular port then it'll pass over a **skbuff to a 
> callback function. This function is in another module.
>
> In that function, if the TS_SCRAMBLING_CONTROL flags are set and I 
> clear them, then VLC never seems to get the data. However, if I simply 
> comment out the clear code, everything seems to be fine.
>
> Trying to figure out if I've a problem with my kernel patch (looking 
> less and less likely, it's pretty trivial) or if it's a problem with 
> liveMedia reading in the UDP data. I can't see any validation code in 
> liveMedia, so I'm hoping you guys might be able to shed some light on 
> this.
>
> Initially I thought it could be the udp checksums being invalidated in 
> the kernel after the manipulation of the mpeg data. So an addition 
> I've made to the patch was to do the validation checks on the skbuf 
> before handing it over to my external function. It also then sets the 
> CHECKSUM_UNNECESSARY flag on the skb so that later on, the data should 
> pass over the checksum checks. I'm not clear on if the checksums need 
> to be recalculated.
>
> Thanks in advance,
>


-- 
Glen Gray <glen at lincor.com>              Digital Depot, Thomas Street
Senior Software Engineer                            Dublin 8, Ireland
Lincor Solutions Ltd.                          Ph: +353 (0) 1 4893682