commit a96f70206da9c646bd7cb7fb6b1ca82a51dff548 Author: Ximin Luo <infinity0@gmx.com> Date: Sat Nov 9 15:44:28 2013 +0000 add more documentation on inner vs outer transports --- doc/design.txt | 34 +++++++++++++++++++++++++++++++++- facilitator/facilitator | 6 ++++-- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/doc/design.txt b/doc/design.txt index 94f8403..319dd9c 100644 --- a/doc/design.txt +++ b/doc/design.txt @@ -206,4 +206,36 @@ Design of flash proxies 10. Inner and outer transports - TODO: import discussion from #9349. + The client can talk to the relay using not only the Tor protocol, but + any transport protocol implemented by e.g. another pluggable transport + that sits between tor and the flashproxy PT. For the facilitator to + match a client with a relay that understands it, flashproxy-client + must be given the name of the transport protocol, via the --transport + option. This is divided into two parts, the inner and outer transport, + written like "inner|outer" or just "outer" if the inner transport is + the plain Tor protocol. + + The inner transport is the protocol that the non-flashproxy parts of + the client and relay talk to each other with, and must be the same for + each connected pair. Beyond that, the semantics of the transport are + opaque to flashproxy; it does not know or care. + + The outer transports are the protocols that the browser proxy uses to + talk to the client and relay, and may be different for each. The proxy + un-applies the outer transport of the client so that only the inner + traffic remains, then re-applies the outer transport of the relay to + this and sends it to the relay; and vice-versa for traffic going in + the opposite direction. + + Diagram: + + client <======outer-C=======> proxy <======outer-S=======> relay + <=======inner=========-------========inner========> + + Currently the only supported outer transport is "websocket", but we + will also add support for newer technologies such as webRTC. + + (We have also seen third-party proxies running outside the browser + on NodeJS that can open plain TCP connections, so that the outer + transport is effectively just "tcp", although this is not currently + recognised by the facilitator.) diff --git a/facilitator/facilitator b/facilitator/facilitator index ebce31b..3bc8f92 100755 --- a/facilitator/facilitator +++ b/facilitator/facilitator @@ -140,9 +140,11 @@ class Endpoints(object): return True def _findInnerForOuter(self, *supported_outer): - """ + """Find all endpoint addresses that support any of the given outer + transports. Results are grouped by the inner transport. + :returns: { inner: [addr] }, where each address supports some outer - from supported_outer. TODO(infinity0): describe better + transport from supported_outer. """ inners = defaultdict(set) for outer in set(supported_outer) & set(self._indexes.iterkeys()):