* chore(netxlite): add currently failing test case
This diff introduces a test cases that will fail because of the reason
explained in https://github.com/ooni/probe/issues/1965.
* chore(netxlite/iox_test.go): add failing unit tests
These tests directly show how the Go implementation of ReadAll
and Copy has the issue of checking for io.EOF equality.
* fix(netxlite): make {ReadAll,Copy}Context robust to wrapped io.EOF
The fix is simple: we just need to check for `errors.Is(err, io.EOF)`
after either io.ReadAll or io.Copy has returned. When this condition is
true, we need to convert the error back to `nil` as it ought to be.
While there, observe that the unit tests I committed in the previous
commit are wrongly asserting that the error must be wrapped. This
assertion is not correct, because in both cases we have just ensured
that the returned error is `nil` (i.e., success).
See https://github.com/ooni/probe/issues/1965.
* cleanup: remove previous workaround for wrapped io.EOF
These workarounds were partial, meaning that they would cover some
cases in which the issue occurred but not all of them.
Handling the problem in `netxlite.{ReadAll,Copy}Context` is the
right thing to do _as long as_ we always use these functions instead
of `io.{ReadAll,Copy}`.
This is why it's now important to ensure we clearly mention that
inside of the `CONTRIBUTING.md` guide and to also ensure that we're
not using these functions in the code base.
* fix(urlgetter): repair tests who assumed to see EOF error
Now that we have established that we should normalize EOF when
reading bodies like the stdlib does and now that it's clear why
our behavior diverged from the stdlib, we also need to repair
all the tests that assumed this incorrect behavior.
* fix(all): don't use io{,util}.{Copy,ReadAll}
* feat: add checks to ensure we don't use io.{Copy,ReadAll}
* doc(netxlite): document we know how to deal w/ wrapped io.EOF
* fix(nocopyreadall.bash): add exception for i/n/iox.go
This is the extension of https://github.com/ooni/probe-cli/pull/431, and my final deliverable for GSoC 2021.
The diff introduces:
1) The new `testhelper` which supports testing multiple IP endpoints per domain and introduces HTTP/3 control measurements. The specification of the `testhelper` can be found at https://github.com/ooni/spec/pull/219. The `testhelper` algorithm consists of three main steps:
* `InitialChecks` verifies that the input URL can be parsed, has an expected scheme, and contains a valid domain name.
* `Explore` enumerates all the URLs that it discovers by redirection from the original URL, or by detecting h3 support at the target host.
* `Generate` performs a step-by-step measurement of each discovered URL.
2) A prototype of the corresponding new experiment `websteps` which uses the control measurement of the `testhelper` to know which URLs to measure, and what to expect. The prototype does not yet have:
* unit and integration tests,
* an analysis tool to compare the control and the probe measurement.
This PR is my final deliverable as it is the outcome of the trials, considerations and efforts of my GSoC weeks at OONI.
It fully integrates HTTP/3 (QUIC) support which has been only used in the `urlgetter` experiment until now.
Related issues: https://github.com/ooni/probe/issues/1729 and https://github.com/ooni/probe/issues/1733.
