Today, when looking up DKIM keys via DNS, we go through all the TXT
records that are published. This is already more lenient than what's
allowed by many implementations (as documented in the code).
Potentially, someone could craft a domain with a lot of TXT records to
make us waste time processing those keys.
To help reduce that possibility, this patch limits the lookup to 3
records. This is still more than normal and may be limited further to 1
in the future.
Many of our tests rely on helpers that predate features which are now
available in the standard library.
This patch replaces them with the standard equivalents:
- MustTempDir/RemoveIfOk -> t.ArtifactDir() or t.TempDir() (depending on
whether it is useful to keep the data on request).
- GetFreePort + waitForServer -> opening the listeners before starting
the servers. To support this, localrpc.Server gains a Serve method. We
may re-introduce these in the future if more use cases appear.
- WaitFor and real-time timing checks -> testing/synctest.
- context.Background() -> t.Context().
- Benchmark b.N loops -> b.Loop().
- reflect.DeepEqual -> cmp.Diff, and proto.Equal for protobufs.
staticcheck found a couple of minor code cleanup improvements, like
unused variables or an out-of-order defer, mostly in tests.
This patch fixes those problems by making the necessary adjustments.
They're all fairly small, and should not change the logic in any
significant way.
Alberto Bertogli