Fixed large number of SERVFAILs (#413)

* removed suspicious code, test case passing. Need to confirm why that was added

* remove unused fn

Author: phillip-stephens

src/zdns/lookup.go

@@ -404,30 +404,6 @@ func (r *Resolver) cachedRetryingLookup(ctx context.Context, q Question, nameSer
 		}
 	}
 
-	// Now, we check the authoritative:
-	name := strings.ToLower(q.Name)
-	layer = strings.ToLower(layer)
-	authName, err := nextAuthority(name, layer)
-	if err != nil {
-		var r SingleQueryResult
-		return r, isCached, StatusAuthFail, 0, err
-	}
-	if name != layer && authName != layer {
-		if authName == "" {
-			var r SingleQueryResult
-			return r, isCached, StatusAuthFail, 0, nil
-		}
-		var qAuth Question
-		qAuth.Name = authName
-		qAuth.Type = dns.TypeNS
-		qAuth.Class = dns.ClassINET
-
-		if cachedResult, ok = r.cache.GetCachedResult(qAuth, true, depth+2); ok {
-			isCached = true
-			return cachedResult, isCached, StatusNoError, 0, nil
-		}
-	}
-
 	// Alright, we're not sure what to do, go to the wire.
 	result, status, try, err := r.retryingLookup(ctx, q, nameServer, false)
 

src/zdns/util.go

@@ -15,7 +15,6 @@
 package zdns
 
 import (
-	"errors"
 	"fmt"
 	"net"
 	"strings"
@@ -56,37 +55,6 @@ func nameIsBeneath(name, layer string) (bool, string) {
 	return false, ""
 }
 
-func nextAuthority(name, layer string) (string, error) {
-	// We are our own authority for PTRs
-	// (This is dealt with elsewhere)
-	if strings.HasSuffix(name, "in-addr.arpa") && layer == "." {
-		return "in-addr.arpa", nil
-	}
-
-	idx := strings.LastIndex(name, ".")
-	if idx < 0 || (idx+1) >= len(name) {
-		return name, nil
-	}
-	if layer == "." {
-		return name[idx+1:], nil
-	}
-
-	if !strings.HasSuffix(name, layer) {
-		return "", errors.New("server did not provide appropriate resolvers to continue recursion")
-	}
-
-	// Limit the search space to the prefix of the string that isnt layer
-	idx = strings.LastIndex(name, layer) - 1
-	if idx < 0 || (idx+1) >= len(name) {
-		// Out of bounds. We are our own authority
-		return name, nil
-	}
-	// Find the next step in the layer
-	idx = strings.LastIndex(name[0:idx], ".")
-	next := name[idx+1:]
-	return next, nil
-}
-
 func checkGlue(server string, result SingleQueryResult) (SingleQueryResult, Status) {
 	for _, additional := range result.Additional {
 		ans, ok := additional.(Answer)