Acknowledge that transports MAY be used in isolation (i.e., outside
of a Resolver) and add support for wrapping.
Ensure that every factory that creates an unwrapped type is named
accordingly to hopefully ensure there are no surprises.
Implement DNSTransport wrapping and use a technique similar to the
one used by Dialer to customize the DNSTransport while constructing
more complex data types (e.g., a specific resolver).
Ensure that the stdlib resolver's own "getaddrinfo" transport (1)
is wrapped and (2) could be extended during construction.
This work is part of my ongoing effort to bring to this repository
websteps-illustrated changes relative to netxlite.
Ref issue: https://github.com/ooni/probe/issues/2096
This diff refactors the DNSTransport model to receive in input a DNSQuery and return in output a DNSResponse.
The design of DNSQuery and DNSResponse takes into account the use case of a transport using getaddrinfo, meaning that we don't need to serialize and deserialize messages when using getaddrinfo.
The current codebase does not use a getaddrinfo transport, but I wrote one such a transport in the Websteps Winter 2021 prototype (https://github.com/bassosimone/websteps-illustrated/).
The design conversation that lead to producing this diff is https://github.com/ooni/probe/issues/2099
These two small packages could easily be merged into the model
package, since they're clearly model-like packages.
Part of https://github.com/ooni/probe/issues/2115
This diff has been extracted and adapted from 8848c8c516
The reason to prefer composition over embedding is that we want the
build to break if we add new methods to interfaces we define. If the build
does not break, we may forget about wrapping methods we should
actually be wrapping. I noticed this issue inside netxlite when I was working
on websteps-illustrated and I added support for NS and PTR queries.
See https://github.com/ooni/probe/issues/2096
While there, perform comprehensive netxlite code review
and apply minor changes and improve the docs.
## 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
1. introduce implementations of HTTPTransport and HTTPClient
that apply an error wrapping policy using the constructor
for a generic top-level error wrapper
2. make sure we use the implementations in point 1 when we
are constructing HTTPTransport and HTTPClient
3. make sure we apply error wrapping using the constructor for
a generic top-level error wrapper when reading bodies
4. acknowledge that error wrapping would be broken if we do
not return the same classification _and_ operation when we wrap
an already wrapped error, so fix the to code to do that
5. acknowledge that the classifiers already deal with preserving
the error string and explain why this is a quirk and why we
cannot remove it right now and what needs to happen to safely
remove this quirk from the codebase
Closes https://github.com/ooni/probe/issues/1860
When preparing a tutorial for netxlite, I figured it is easier
to tell people "hey, this is the package you should use for all
low-level networking stuff" rather than introducing people to
a set of packages working together where some piece of functionality
is here and some other piece is there.
Part of https://github.com/ooni/probe/issues/1591
