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Remove internal loop detection (#2647)

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* Remove internal loop detection

I can't actually think of a situation where we can create an internal
loop. Sure externally triggered cycles can happen, but this is where the
*loop* plugin comes in that detects those.

Fixes #2602

Signed-off-by: Miek Gieben <miek@miek.nl>

* Remove test

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben 2019-03-07 20:23:00 +00:00 • committed by GitHub
parent 18d305f4b3
commit 2b7e84a076
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2 changed files with 2 additions and 44 deletions
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31
core/dnsserver/server.go
View file

@ -230,12 +230,6 @@ func (s *Server) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
return
}
ctx, err := incrementDepthAndCheck(ctx)
if err != nil {
DefaultErrorFunc(ctx, w, r, dns.RcodeServerFailure)
return
}
q := r.Question[0].Name
b := make([]byte, len(q))
var off int
@ -356,35 +350,14 @@ func DefaultErrorFunc(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, rc
w.WriteMsg(answer)
}
// incrementDepthAndCheck increments the loop counter in the context, and returns an error if
// the counter exceeds the max number of re-entries
func incrementDepthAndCheck(ctx context.Context) (context.Context, error) {
// Loop counter for self directed lookups
loop := ctx.Value(loopKey{})
if loop == nil {
ctx = context.WithValue(ctx, loopKey{}, 0)
return ctx, nil
}
iloop := loop.(int) + 1
if iloop > maxreentries {
return ctx, fmt.Errorf("too deep")
}
ctx = context.WithValue(ctx, loopKey{}, iloop)
return ctx, nil
}
const (
tcp = 0
udp = 1
maxreentries = 10
)
type (
// Key is the context key for the current server
Key struct{}
loopKey struct{} // loopKey is the context key for counting self loops
)
// Key is the context key for the current server
type Key struct{}
// EnableChaos is a map with plugin names for which we should open CH class queries as we block these by default.
var EnableChaos = map[string]struct{}{

15
core/dnsserver/server_test.go
View file

@ -48,21 +48,6 @@ func TestNewServer(t *testing.T) {
}
}
func TestIncrementDepthAndCheck(t *testing.T) {
ctx := context.Background()
var err error
for i := 0; i <= maxreentries; i++ {
ctx, err = incrementDepthAndCheck(ctx)
if err != nil {
t.Errorf("Expected no error for depthCheck (i=%v), got %s", i, err)
}
}
_, err = incrementDepthAndCheck(ctx)
if err == nil {
t.Errorf("Expected error for depthCheck (i=%v)", maxreentries+1)
}
}
func BenchmarkCoreServeDNS(b *testing.B) {
s, err := NewServer("127.0.0.1:53", []*Config{testConfig("dns", testPlugin{})})
if err != nil {