As per the docstring, (*forwarder).forwardWithDestChan should either send to responseChan
and returns nil, or returns a non-nil error (without sending to the channel).
However, this does not hold when all upstream DNS servers replied with an error.
We've been handling this special error path in (*Resolver).Query but not in (*Resolver).HandlePeerDNSQuery.
As a result, SERVFAIL responses from upstream servers were being converted into HTTP 503 responses,
instead of being properly forwarded as SERVFAIL within a successful HTTP response, as per RFC 8484, section 4.2.1:
A successful HTTP response with a 2xx status code (see Section 6.3 of [RFC7231]) is used for any valid DNS response,
regardless of the DNS response code. For example, a successful 2xx HTTP status code is used even with a DNS message
whose DNS response code indicates failure, such as SERVFAIL or NXDOMAIN.
In this PR we fix (*forwarder).forwardWithDestChan to no longer return an error when it sends a response to responseChan,
and remove the special handling in (*Resolver).Query, as it is no longer necessary.
Updates #13571
Signed-off-by: Nick Hill <mykola.khyl@gmail.com>
It is sometimes necessary to defer initialization steps until the first actual usage
or until certain prerequisites have been met. For example, policy setting and
policy source registration should not occur during package initialization.
Instead, they should be deferred until the syspolicy package is actually used.
Additionally, any errors should be properly handled and reported, rather than
causing a panic within the package's init function.
In this PR, we add DeferredInit, to facilitate the registration and invocation
of deferred initialization functions.
Updates #12687
Signed-off-by: Nick Hill <mykola.khyl@gmail.com>
Nick HillandNick Khyl