localnet with hostnames/DNS is not compatible with remote dns - if remote dns
is activated we get an ip from the remote dns resolver in the connect() call,
so we don't know whether the destination would match any localnet - except
from the ANY localnet 0.0.0.0 - in which case we would need to do a real DNS
lookup with the remote DNS ip involving both the rdns resolver to get the
original hostname back and then call the native DNS resolver function - for
which there is only getaddrinfo() when we don't want to support the 5
different gethostbyname_r() variants in existence, or using getaddrinfo(),
which in turn requires memory allocation/free() - in other words a huge mess.
we also can't easily check in the resolver whether an ANY-destination localnet
is enabled and the port matches, because the resolver might only resolve the
hostname at this stage, but not the destination port.
addressing #358
since many users complain about issues with modern, ultracomplex
clusterfuck software such as chromium, nodejs, etc, i've reconsidered
one of my original ideas how to implement remote dns lookup support.
instead of having a background thread serving requests via a pipe,
the user manually starts a background daemon process before running
proxychains, and the two processes then communicate via UDP.
this requires much less hacks (like hooking of close() to prevent
pipes from getting closed) and doesn't need to call any async-signal
unsafe code like malloc(). this means it should be much more compatible
than the previous method, however it's not as practical and slightly
slower.
it's recommended that the proxychains4-daemon runs on localhost, and
if you use proxychains-ng a lot you might want to set ip up as a service
that starts on boot. a single proxychains4-daemon should theoretically
be able to serve many parallel proxychains4 instances, but this has not
yet been tested so far. it's also possible to run the daemon on other
computers, even over internet, but currently there is no error-checking/
timeout code at all; that means the UDP connection needs to be very
stable.
the library code used for the daemon sources are from my projects
libulz[0] and htab[1], and the server code is loosely based on
microsocks[2]. their licenses are all compatible with the GPL.
if not otherwise mentioned, they're released for this purpose under
the standard proxychains-ng license (see COPYING).
[0]: https://github.com/rofl0r/libulz
[1]: https://github.com/rofl0r/htab
[2]: https://github.com/rofl0r/microsocks
some lamer on IRC by the name of annoner/R3M0RS3/penis was complaining
that 3.1 is a lot better than proxychains-ng, because it happens to
work with the browser he's interested in.
since this wasn't the first time this is requested, let's give this
those lamers what they want: lame code!
Eero Häkkinen