IPv6 Support By Pluggable Transport
Tor clients can't send a proxy request for an ipv6 address connection to a pluggable transport if the PT says it supports socks4. This is not so good because IPv6 addresses are becoming more prevalent. The three options, as I see them, are:
- Change pt-spec to state that PTs can support either socks4a or socks5 (and change Tor and implementation to adhere to this)
- If a PT supports IPv6 addresses then it must use SOCKS5
- Allow a PT to claim it supports both socks4 and socks5 in the CMETHOD line and Tor will need to decide which SOCKS version to use depending on the IP version.
The first one seems like a good idea. The second requires no spec change but will cause some pain with existing PTs. The last seems useful but requires a lot of modifications and so it's unnecessary.
(Thanks to dcf1 and arma for their help)