Blocking Downloads on a per user basis

[WhiteKnuckles]

The senerio I am looking at is a script that would allow individual users to choose who they will allow to download from them and who they will block from downloading.
Eg. Hub has 4 users A, B, C & D
User A is happy for everyone to download from them, so no blocking
User B is happy for A & D to download from them but not for C to download.
User C is happy for A & D to download from them but not for B to download.
User D is happy for user C to download but not for A & B.

Is there any way of allowing users such control?
An option to allow for downloads of filelists only (or files below a certain size) would also be desirable.
In the situation I am looking at, the default position for new users coming on would be everyone blocking them.

The issue on our hub is that downloads & uploads are limited by our ISP and I am looking to give users some control over who they wish to share with in order to stop leechers.  It is envisaged that people will use chat to arrange file exchanges.

[CrazyGuy]

If the problem is caused by ISP restrictions, an easy solution may be to only allow file transfers from people within the same IP-range.

[WhiteKnuckles]

First of all thanks for all your excellent scripting Mutor - the customisations you make for Ptoka are awesome.

Regarding this issue there is no problem with the upload being blocked as well - this would only be fair.

As mentioned in the initial post it is for a specific situation where we have limits by our ISP on amounts uploaded. 
Without such a mechanism then no-one is prepared to upload.  Limits in Australia range from 200MB (yes that is MB!) up to 150GB (although these incorporate most of the allowance as off peak which is usually very narrowly defined).  An average sort of upload limit would be about 20GB a month with those that the hub is aimed at.
Some ISP's in Australia have download limits but not upload limits.  Changing ISP is not really a viable option due to cost.

I have looked at Omniblocker and whilst it does the blocking by profile fine, that is of little use for the situation I am looking at.  I note it can do by individual users as well but the difference being that it is applied across the board for that user rather than on a user by user basis.
I also run a hub that runs on our ISP's local ADSL exchange and we have unlimited data on this network and hence no such controls are in place.

If you block download from a user you must also block
that same user's upload or the block will be broken.

You are not the first person to want this and you
certainly will not be last. Personally I think it's lousy.
These types of blocks should be applied on a profile
level, not a per user basis.

To that end you may want to see:
OmniBlocker 1.0f LUA 5.1x [Strict][API 2]
in the finished scripts section. It can block transfers
by users or profiles as described above.