This diff modifies the construction of a dialer to allow one
to insert custom dialer wrappers into the dialers chain.
The point of the chain in which we allow custom wrappers is the
optimal one for connect, read, and write measurements.
This new design is better than the previous netx design since
we don't need to construct the whole chain manually now.
The work in this diff is part of the effort to make engine/netx
just a tiny wrapper around netxlite.
See https://github.com/ooni/probe/issues/2121.
This diff addresses another point of https://github.com/ooni/probe/issues/1956:
> - [ ] observe that we're still using a bunch of private interfaces for common interfaces such as the `Dialer`, so we can get rid of these private interfaces and always use the ones in `model`, which allows us to remove a bunch of legacy wrappers
Additional cleanups may still be possible. The more I cleanup, the more I see
there's extra legacy code we can dispose of (which seems good?).
This diff implements the first two cleanups defined at https://github.com/ooni/probe/issues/1956:
> - [ ] observe that `netxlite` and `netx` differ in error wrapping only in the way in which we set `ErrWrapper.Operation`. Observe that the code using `netxlite` does not care about such a field. Therefore, we can modify `netxlite` to set such a field using the code of `netx` and we can remove `netx` specific code for errors (which currently lives inside of the `./internal/engine/legacy/errorsx` package
>
> - [ ] after we've done the previous cleanup, we can make all the classifiers code private, since there's no code outside `netxlite` that needs them
A subsequent diff will address the remaining cleanup.
While there, notice that there are failing, unrelated obfs4 tests, so disable them in short mode. (I am confident these tests are unrelated because they fail for me when running test locally from the `master` branch.)
We need still to add similar wrappers to internal/netxlite but we
will adopt a saner approach to error wrapping this time.
See https://github.com/ooni/probe/issues/1591
Like we did before for the resolver, a dialer should propagate the
request to close idle connections to underlying types.
See https://github.com/ooni/probe/issues/1591
What do I mean by pivoting? Netx is currently organized by row:
```
| dialer | quicdialer | resolver | ...
saving | | | | ...
errorwrapping | | | | ...
logging | | | | ...
mocking/sys | | | | ...
```
Every row needs to implement saving, errorwrapping, logging, mocking (or
adapting to the system or to some underlying library).
This causes cross package dependencies and, in turn, complexity. For
example, we need the `trace` package for supporting saving.
And `dialer`, `quickdialer`, et al. need to depend on such a package.
The same goes for errorwrapping.
This arrangement further complicates testing. For example, I am
currently working on https://github.com/ooni/probe/issues/1505 and
I realize it need to repeat integration tests in multiple places.
Let's say instead we pivot the above matrix as follows:
```
| saving | errorwrapping | logging | ...
dialer | | | | ...
quicdialer | | | | ...
logging | | | | ...
mocking/sys | | | | ...
...
```
In this way, now every row contains everything related to a specific
action to perform. We can now share code without relying on extra
support packages. What's more, we can write tests and, judding from
the way in which things are made, it seems we only need integration
testing in `errorwrapping` because it's where data quality matters
whereas, in all other cases, unit testing is fine.
I am going, therefore, to proceed with these changes and "pivot"
`netx`. Hopefully, it won't be too painful.
* refactor(netx/dialer): hide implementation complexity
This follows the blueprint of `module.Config` and `nodule.New`
described at https://github.com/ooni/probe/issues/1591.
* fix: ndt7 bug where we were not using the right resolver
* fix(legacy/netx): clarify irrelevant implementation change
* fix: improve comments
* fix(hhfm): do not use dialer.New b/c it breaks it
Unclear to me why this is happening. Still, improve upon the
previous situation by adding a timeout.
It does not seem a priority to look into this issue now.
