This implements a basic typed event broadcast mechanism, as described in
arti#230: consumers of the new `tor-events` crate can emit `TorEvent`
events, which others can consume via the `TorEventReceiver`.
Under the hood, the crate uses the `async-broadcast`
(https://github.com/smol-rs/async-broadcast) crate, and a
`futures::mpsc::UnboundedSender` for the event emitters; these are glued
together in the `EventReactor`, which must be run in a background thread
for things to work. (This is done so event sending is always cheap and
non-blocking, since `async-broadcast` senders don't have this
functionality.)
Additionally, the `TorEventKind` type is used to implement selective
event reception / emission: receivers can subscribe to certain event
types (and in fact start out receiving nothing), which filters the set
of events they receive. Having no subscribers for a given event type
means it won't even be emitted in the first place, making things more
efficient.
This patch makes sure that for every* config type we have, the defaults
you get from a Builder match those you get from Serde, and that both
match the value that you get from arti_defaults.toml. Later down the
line I'll be adding some tests to keep these in sync.
* StorageConfig still has no defaults of its own, since we aren't so
sure we want other applications to use Arti's directories by default.
Since these shell-variables are hardwired to use org.torproject.Arti as
the program name, it isn't appropriate to call them "app-specific".
If we someday reinstate APP_FOO, it should be based on a user-provided
application name.
In order to handle explicitly specified path buffers directly, we now
let CfgPath be either a string (that gets expanded) or a PathBuf
(that doesn't).
This simplifies TorClientConfig::with_directories()
Now every section that the two configuration objects share has the
same type and name. This should help us in documenting our configuration
in a way that doesn't confuse people.
There is still lots of API work to go.
To do this at all neatly, I had to split out `tor-config` from
`arti-config` again, and putting the lower level stuff (paths,
builder errors) into tor-config. I also changed our use of
derive_builder to always use a common error type, to avoid
error type proliferation.
The `bad_extend_*` failures were caused by bad test code in
`bad_extend_test_impl` that used `futures::join!`; this meant that the
reactor could receive the `Extended2` cell before it actually got the
`ExtendNtor` request, which caused it to get (quite rightly) confused
and close the circuit. Spawning a background thread which has a short
delay before sending the `Extended2` cell seems to have alleviated this
problem.
`new_circ_create_failure` is similar; I think the reactor was getting
dropped before it had a chance to flush out its `CreateFast` cell
properly, because it had already gotten the result back (since the test
code sends it indiscriminately). This was "fixed" in much the same
manner as the other test: making it wait a bit before sending the result
cell back.
There seem to be other tests that use `futures::join!` (like
`begindir`?), and use similarly erroneous patterns; I haven't gotten any
to fail reliably enough to be able to debug them, though.
This field isn't used in modern Tor, and has never been used in
Arti. If tor!489 is merged, then it will no longer contain a useful
value in future consensuses. We shouldn't store it, or else
somebody else will get the smart idea of using it for something.
This commit breaks API compatibility for tor-netdoc with the
`build_docs` feature enabled. I haven't entered that into the
semver_status.md file, since we already have a pending tor-netdoc
API breaker in !129.
Nothing in arti currently uses this document type. Eventually it
will be useful for relays and for bridge clients.
I've left the "SHA1 digest of a router descriptor" type available
unconditinoally, however, since it does get used in a few places.
Part of #125.
We don't currently need a couple of the key manipulation features
that we have, since we aren't yet doing relays or onion service
clients.
Part of #125
Nick Mathewson
eta
Trinity Pointard