Pop quiz: Downloading in ADC
June 24, 2006 11 Comments
The second pop quiz is as follows;
‘Jake’ using an unmodified version of DC++ 0.691. He’s connected to 2 (two) ADC hubs with the nicks “jake99” and “mary77”. He’s looking for the file A. He find user “foobar” in one of the hubs who have the files he’s looking for. This user is also using an unmodified version of DC++ 0.691. He start to download the file, going in 20 KiB/s and everything’s fine. But, he start to think, “what will happen if the user goes offline? better I auto search for it to check if there’s more sources”. And he does, and find user “john111”. Jake adds the user to list of sources (through the right click command menu).
Interesting in things as Jake is, he want to see what other goodies “john111” has in his share. Jake tries to get the file list. Nothing. Nothing happens. He checks the queue, DC++ has properly queued the file list, but isn’t connecting. Nothing appear in the transfer view. The transfer view columns are fine, Jake can see that he has two downloads going (one of them the file A) and three uploads.
Â But there’s no error message in the queue or the transfer view window. He deletes the file list from the queue, and tries again to download it. Same thing. Now, why can’t Jake download the file list? “john111” isn’t blocking uploads by the looks of it in the search window (Jake can see that “john111” has 5 slots open out of 7). Jake and “john111” is both connected with Active mode.
The two hubs are both resident on the same university campus, where a lot of people connect from. Meaning, a lot of people have the same external IP. (Jake find out that “john111” has the same IP as “foobar” and one of Jake’s uploads, and he draws the conclusion that those three are all living on the same campus.)
Jake asks his friend in the other room to try to download “john111″‘s file list (and other files), and it works fine. It also works for other users in the same hub. Jake asks “john111” to change his nickname to “john112”. No change in connectivity. “john112” tell Jake to try and search for file B and try to download it. Same thing happens with file B. File B is now queued, but there’s no connectivity and no error message.
So; why can’t Jake download the file list or any other file? (File A has been downloading the entire time, now at 34 %.)
a) Jake is using different user names.
b) there’s a bug in Jake’s copy of DC++.
c) “john112” and everyone else is lying, at Jake’s expense.
d) none of the above… (fill in what the reason is)
It would be neat if you have an explanation why you chose that particular option, but you don’t have to; I’ll explain later which option/answer is correct, and why.