In https://github.com/ooni/probe-cli/pull/832's initial diff, I
mentioned it would be cool to flatten oohelperd's hier.
I'm doing this now, and just for the master branch.
This diff is mostly a mechanical refactoring with very light
and apparently rather safe manual changes.
This diff modifies the implementation of oohelperd in the master branch
to always use throw-away HTTPClient, Dialer, and Resolver.
The rationale of this change is to ensure we're not hitting limits of the
HTTPClient regarding the max number of connections per host.
This issue is described at https://github.com/ooni/probe/issues/2182.
While there, it feels more correct to use throw-away Dialer and Resolver.
We have a different patch for the release/3.15 branch because of
netx-related refactorings: https://github.com/ooni/probe-cli/pull/832.
## Checklist
- [x] I have read the [contribution guidelines](https://github.com/ooni/probe-cli/blob/master/CONTRIBUTING.md)
- [x] reference issue for this pull request: https://github.com/ooni/probe/issues/1885
- [x] related ooni/spec pull request: N/A
Location of the issue tracker: https://github.com/ooni/probe
## Description
This PR contains a set of changes to move important interfaces and data types into the `./internal/model` package.
The criteria for including an interface or data type in here is roughly that the type should be important and used by several packages. We are especially interested to move more interfaces here to increase modularity.
An additional side effect is that, by reading this package, one should be able to understand more quickly how different parts of the codebase interact with each other.
This is what I want to move in `internal/model`:
- [x] most important interfaces from `internal/netxlite`
- [x] everything that was previously part of `internal/engine/model`
- [x] mocks from `internal/netxlite/mocks` should also be moved in here as a subpackage
Reducing the errors is not done in a perfect way.
We have documented the most striking differences inside
https://github.com/ooni/probe/issues/1707#issuecomment-942283746 and
some attempts to improve the situation further inside
https://github.com/ooni/probe/issues/1707#issuecomment-942341255.
A better strategy for the future would be to introduce more
specific timeout errors, such as dns_timeout_error, etc.
More testing may be needed to further validate and compare the
old and the new TH, but this requires Jafar improvements to
more precisely simulate more complex censorship.
