Files
dnswatcher/internal/resolver/errors.go
T
clawbot d1024b2b20
check / check (push) Canceled after 0s
resolver: ask again over TCP when a reply offers recursion (closes #300)
dnswatcher never asks for recursion, so a reply marked recursion
available comes from a resolver on the network answering in the
server's place, as on a network that sends all DNS to one resolver.
Such a resolver answers only from its cache, or with SERVFAIL or
REFUSED, which made make check fail there.

A reply over UDP marked so is now asked again over TCP, which many such
networks leave alone, and the TCP reply is used. A reply from a root
server's address still marked so is not used, and when every root
server refuses or gives one, the error is the existing "this network
intercepts DNS queries".

Model: opus-5-5
2026-10-16 07:44:24 +00:00

87 lines
2.8 KiB
Go

package resolver
import "errors"
// NoAnswerError is returned when the walk to a name's nameservers
// reached a zone through a referral and none of that zone's
// nameservers, Nameservers as the referral names them, answered. Err
// says why they did not.
type NoAnswerError struct {
Nameservers []string
Err error
}
func (e *NoAnswerError) Error() string {
return e.Err.Error()
}
func (e *NoAnswerError) Unwrap() error {
return e.Err
}
// Sentinel errors returned by the resolver.
var (
// ErrNoNameservers is returned when no authoritative NS
// could be discovered for a domain.
ErrNoNameservers = errors.New(
"no authoritative nameservers found",
)
// ErrNXDomain is returned when the servers of the zone a domain
// is in answer NXDOMAIN: the domain does not exist.
ErrNXDomain = errors.New("domain does not exist")
// ErrNoNameserverAnswered is returned when every nameserver
// asked about a name timed out, failed or returned a referral,
// so whether the name has addresses is unknown.
ErrNoNameserverAnswered = errors.New("no nameserver answered")
// ErrNoNameserverAddress is returned when a nameserver is to be
// asked and no address for it was given.
ErrNoNameserverAddress = errors.New("nameserver has no address")
// ErrUnusableReply is returned when a server replied with an
// error such as SERVFAIL, or with a referral that leads no
// closer to the name asked about.
ErrUnusableReply = errors.New(
"reply is an error or a referral that leads no closer",
)
// ErrTruncated is the reason given for a reply too large for UDP
// whose retry over TCP failed.
ErrTruncated = errors.New(
"reply truncated and its retry over TCP failed",
)
// ErrRecursionAvailable is the reason a reply from a root server
// marked recursion available is not used. Root servers offer no
// recursion, so the reply came from something on the network
// answering in their place.
ErrRecursionAvailable = errors.New(
"reply marked recursion available, so not from a root server",
)
// ErrIntercepted is returned when every root server refused a
// query or gave a reply marked recursion available. Root servers do
// neither, so those replies came from something on the network
// answering in their place.
ErrIntercepted = errors.New("this network intercepts DNS queries")
// ErrCNAMEDepthExceeded is returned when a CNAME chain
// exceeds MaxCNAMEDepth.
ErrCNAMEDepthExceeded = errors.New(
"CNAME chain depth exceeded",
)
// ErrLookupDepthExceeded is returned when nameserver addresses
// were not looked up because lookups were already maxLookupDepth
// deep, one inside another.
ErrLookupDepthExceeded = errors.New(
"lookups of nameserver addresses go too deep",
)
// ErrContextCanceled wraps context cancellation for the
// resolver's iterative queries.
ErrContextCanceled = errors.New("context canceled")
)