[Go style says](https://blog.golang.org/package-names):
> Avoid stutter. Since client code uses the package name as a prefix
> when referring to the package contents, the names for those contents
> need not repeat the package name. The HTTP server provided by the
> http package is called Server, not HTTPServer. Client code refers to
> this type as http.Server, so there is no ambiguity.
Rename DNSClient, DNSClientImpl, NewDNSClientImpl,
NewTestDNSClientImpl, DNSError, and MockDNSClient to follow those
guidelines.
Unexport DNSClientImpl and MockTimeoutError (was only used internally).
Make New and NewTest return the Client interface rather than a concrete
`impl` type.
This patch removes all usages of the `core.XXXError` and almost all usages of `probs` outside of the WFE and VA and replaces them with a unified internal error type. Since the VA uses `probs.ProblemDetails` quite extensively in challenges, and currently stores them in the DB I've saved this change for another change (it'll also require a migration). Since `ProblemDetails` should only ever be exposed to end-users all of its related logic should be moved into the `WFE` but since it still needs to be exposed to the VA and SA I've left it in place for now.
The new internal `errors` package offers the same convenience functions as `probs` does as well as a new simpler type testing method. A few small changes have also been made to error messages, mainly adding the library and function name to internal server errors for easier debugging (i.e. where a number of functions return the exact same errors and there is no other way to distinguish which method threw the error).
Also adds proper encoding of internal errors transferred over gRPC (the current encoding scheme is kept for `core` and `probs` errors since it'll be ideally be removed after we deploy this and follow-up changes) using `grpc/metadata` instead of the gRPC status codes.
Fixes#2507. Updates #2254 and #2505.
* Split out CAA checking service (minus logging etc)
* Add example.yml config + follow general Boulder style
* Update protobuf package to correct version
* Add grpc client to va
* Add TLS authentication in both directions for CAA client/server
* Remove go lint check
* Add bcodes package listing custom codes for Boulder
* Add very basic (pull-only) gRPC metrics to VA + caa-service
Previously we would return a detailed errorString, which ProblemDetailsFromDNSError
would turn into a generic, uninformative "Server failure at resolver".
Now we return a new internal dnsError type, which ProblemDetailsFromDNSError can
turn into a more informative message to be shown to the user.
Moves the DNS code from core to dns and renames the dns package to bdns
to be clearer.
Fixes#1260 and will be good to have while we add retries and such.
Jacob Hoffman-Andrews
alexzorin
Roland Bracewell Shoemaker
Roland Bracewell Shoemaker
Jeff Hodges