Tracking channel change

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mad_ady
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Tracking channel change

Post by mad_ady » Thu Sep 29, 2016 1:24 pm

Hello all!

I'd like to implement a monitoring solution to keep track on what my kids are watching on TV when I'm not home (and for how long). My plan is to use either log parsing or a hook when changing channels to record when the user switched to a particular channel. This information will be sent to a remote mysql server for proper logging via http POST or GET query.

The question is - is there a way of getting which channel the user changed to as an event? I know I could use polling and libChannelInfo.so to get the current channel, but I'm concerned that by injecting the lib every 10 seconds I could cause the TV to crash eventually (haven't tried). Is there a log I could parse or a library that allows me to execute something when the channel is changed?

Also, I'd need to get power ON/OFF events (I'm using SoftPowerOff).

Thanks!
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bugficks
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Re: Tracking channel change

Post by bugficks » Thu Sep 29, 2016 3:01 pm

i hope one day your kids are hiding a spy cam in your bed room and post vids on youtube...
payback is a bitch:)

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mad_ady
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Re: Tracking channel change

Post by mad_ady » Thu Sep 29, 2016 7:32 pm

:) I agree that a better mouse trap only makes a better mouse, but this way I encourage them to be honest and also inventive.
How about if I change the use case? Say I want to collect rating information to determine which channels/shows are preferred by a set of users. Or if I want to know if the nanny keeps the TV on while babysitting?
Regarding the webcam in the bedroom - it's already there, but youtube keeps blocking my videos :D
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bugficks
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Re: Tracking channel change

Post by bugficks » Thu Sep 29, 2016 8:07 pm

yeah right, so all the gov internet spying programs are nothing else than an education plan to make their citizens honest. id say the contrary is the case. all you end up with is that they will tell you nothing or anything but the truth. just put you in their position and remember your own childhood.
move your webcam from bed room to tv room, problem solved :)

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mad_ady
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Re: Tracking channel change

Post by mad_ady » Fri Sep 30, 2016 3:40 am

Sigh... I have a webcam in the TV room as well, but it's not pointing at the TV... Maybe I should install a mirror :) Wait a minute... libScreenshot already allows me to do this.
However this does not solve the polling issue and adds image recognition to the problem

Sorry that my problem makes me look like North Korea. I'm just trying to solve a domestic issue :)
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zoelechat
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Re: Tracking channel change

Post by zoelechat » Fri Sep 30, 2016 9:16 am

Well, about soft on/off, lib already owns a feature to execute scripts on events (CMD_ON, CMD_OFF, check usage) so it's almost ready.

And about retrieving watched channels, you'd just need a single hook to for example (exeAPP):

Code: Select all

TCWindowProxy::SetChannel(TCWindowProxy_t *this, const TCChannel *a2, int a3, int a4)
to catch info from TCChannel. You can check libLogChannel or libChanList sources for how to get channel name from channel, or simply its number, that would prevent struggling with UTF16->UTF8 text conversion.

For hook usage, any resident lib has much "samples" inside. It's maybe a good opportunity for you to have a look at code, what you want to achieve is very basic in difficulty. I let you the sql/query part :)
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mad_ady
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Re: Tracking channel change

Post by mad_ady » Fri Sep 30, 2016 9:29 am

Thank you zoe, I will have a look when I get a bit of time.
Will I need to analyze exeAPP in IDA to be able to write this code (maybe to understand code flow path or function offsets), or just overriding the correct functions (the one you pointed and the ones in the examples) should be enough and the rest is taken care by the loader?
Also, If I want to see if the user changed input to HDMI, I'd have to hook a different function, right? Otherwise I'd think the user watched channel X while they switched to HDMI instead.
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zoelechat
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Re: Tracking channel change

Post by zoelechat » Fri Sep 30, 2016 9:51 am

mad_ady wrote:Will I need to analyze exeAPP in IDA to be able to write this code (maybe to understand code flow path or function offsets), or just overriding the correct functions (the one you pointed and the ones in the examples) should be enough and the rest is taken care by the loader?
Always better to have IDA in a corner :) . Analyze is much quicker than it used to (from v6.5 IIRC), shouldn't take more than an hour for exeAPP. What you'll need are functions "symbols", for example the "real" name of the one I showed you above is:

Code: Select all

_ZN13TCWindowProxy10SetChannelEPK9TCChannelii
mad_ady wrote:Also, If I want to see if the user changed input to HDMI, I'd have to hook a different function, right? Otherwise I'd think the user watched channel X while they switched to HDMI instead.
Right, the same hooking way you should be able to get a "source number" from 2nd arg of:

Code: Select all

_ZN13TCWindowProxy9SetSourceEii
then retrieve its string from

Code: Select all

_ZN11SsPrintBase15GetSourceStringEi
Will surely seem you clearer once you'll have had a look at IDA. Beware that version with decompiler is mandatory (the magical key to switch from asm to pseudocode is TAB :) )
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mad_ady
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Re: Tracking channel change

Post by mad_ady » Fri Sep 30, 2016 10:08 am

Thank you. One more thing, if I may. Please don't implement this! It will give me an opportunity to get my hands dirty :D
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zoelechat
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Re: Tracking channel change

Post by zoelechat » Fri Sep 30, 2016 11:18 am

mad_ady wrote:Thank you. One more thing, if I may. Please don't implement this! It will give me an opportunity to get my hands dirty :D
Don't worry, now focusing on K ;)
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