Transmission

According http://wiki.theory.org/BitTorrentSpecification#Tracker_HTTP.2FHTTPS_Protocol , extra '.', '-', '_', and '_' shouldn't be escape.

And, although rfc2396 said escaped letter can be upper character or lower character, but it's better to use lower case, er, as libtorrent, libtorrent-rasterbar ...

Now, transmission suppose that the tracker is ipv4:

if(( addr = tr_sessionGetPublicAddress( s, TR_AF_INET )))
curl_easy_setopt( e, CURLOPT_INTERFACE, tr_ntop_non_ts( addr ) );


Then, if the tracker is ipv6, curl will fail to connect:

* About to connect() to bt.neu6.edu.cn port 6969 (#0 ...