This diff contains significant improvements over the previous
implementation of the torsf experiment.
We add support for configuring different rendezvous methods after
the convo at https://github.com/ooni/probe/issues/2004. In doing
that, I've tried to use a terminology that is consistent with the
names being actually used by tor developers.
In terms of what to do next, this diff basically instruments
torsf to always rendezvous using domain fronting. Yet, it's also
possible to change the rendezvous method from the command line,
when using miniooni, which allows to experiment a bit more. In the
same vein, by default we use a persistent tor datadir, but it's
also possible to use a temporary datadir using the cmdline.
Here's how a generic invocation of `torsf` looks like:
```bash
./miniooni -O DisablePersistentDatadir=true \
-O RendezvousMethod=amp \
-O DisableProgress=true \
torsf
```
(The default is `DisablePersistentDatadir=false` and
`RendezvousMethod=domain_fronting`.)
With this implementation, we can start measuring whether snowflake
and tor together can boostrap, which seems the most important thing
to focus on at the beginning. Understanding why the bootstrap most
often does not converge with a temporary datadir on Android devices
remains instead an open problem for now. (I'll also update the
relevant issues or create new issues after commit this.)
We also address some methodology improvements that were proposed
in https://github.com/ooni/probe/issues/1686. Namely:
1. we record the tor version;
2. we include the bootstrap percentage by reading the logs;
3. we set the anomaly key correctly;
4. we measure the bytes send and received (by `tor` not by `snowflake`, since
doing it for snowflake seems more complex at this stage).
What remains to be done is the possibility of including Snowflake
events into the measurement, which is not possible until the new
improvements at common/event in snowflake.git are included into a
tagged version of snowflake itself. (I'll make sure to mention
this aspect to @cohosh in https://github.com/ooni/probe/issues/2004.)
* feat: introduce ptx package for pluggable transports dialers
Version 2 of the pluggable transports specification defines a function
that's like `Dial() (net.Conn, error`).
Because we use contexts as much as possible in `probe-cli`, we are
wrapping such an interface into a `DialContext` func.
The code for obfs4 is adapted from https://github.com/ooni/probe-cli/pull/341.
The code for snowflake is significantly easier than it is in
https://github.com/ooni/probe-cli/pull/341, because now Snowflake
supports the PTv2 spec (thanks @cohosh!).
The code for setting up a pluggable transport listener has also
been adapted from https://github.com/ooni/probe-cli/pull/341.
We cannot merge this code yet, because we need unit testing, yet the
newly added code already seems suitable for these use cases:
1. testing by dialing and seeing whether we can dial (which is not
very useful but still better than not doing it);
2. spawning tor+pluggable transports for circumvention (we need a
little more hammering like we did in https://github.com/ooni/probe-cli/pull/341,
which is basically https://github.com/ooni/probe/issues/1565, and then
we will be able to do that, as demonstrated by the new, simple client which
already allows us to use pluggable transports with tor);
3. testing by launching tor (when available) with a set of
pluggable transports (which depends on https://github.com/ooni/probe-engine/issues/897
and has not been assigned an issue yet).
* fix: tweaks after self code-review
* feat: write quick tests for ptx/obfs4
(They run in 0.4s, so I think it's fine for them to always run.)
* feat(ptx/snowflake): write unit and integration tests
* feat: create a fake PTDialer
The idea is that we'll use this simpler PTDialer for testing.
* feat: finish writing tests for new package
* Apply suggestions from code review
* Update internal/ptx/dependencies_test.go
Co-authored-by: Arturo Filastò <arturo@openobservatory.org>
* Update internal/ptx/dependencies_test.go
Co-authored-by: Arturo Filastò <arturo@openobservatory.org>
* chore: use as testing bridge one that's used by tor browser
The previous testing bridge used to be used by tor browser but
it was subsequently removed here:
e26e91bef8
See https://github.com/ooni/probe-cli/pull/373#discussion_r649820724
Co-authored-by: Arturo Filastò <arturo@openobservatory.org>
