dns: add caches for server

There are two type of answer: local and non-local.
Local answer is a DNS record that is loaded from hosts file or master
zone file.
Non-local answer is a DNS record that is received from parent name
servers.

Server caches the DNS answers in two storages: map and list.
The map caches store local and non local answers, using domain name as a
key and list of answers as value,

	domain-name -> [{A,IN,...},{AAAA,IN,...}]

The list caches store non-local answers, ordered by last accessed time,
it is used to prune least frequently accessed answers.
Local caches will never get pruned.

1 files changed, 6 insertions, 5 deletions

diff --git a/lib/dns/dns_test.go b/lib/dns/dns_test.go
index 7929e168..ae2bc0fc 100644
--- a/lib/dns/dns_test.go
+++ b/lib/dns/dns_test.go
@@ -205,16 +205,14 @@ func (h *serverHandler) ServeDNS(req *Request) {
 }
 
 func TestMain(m *testing.M) {
+	var err error
+
 	log.SetFlags(log.Lmicroseconds)
 
 	_testHandler = &serverHandler{}
 
 	_testHandler.responses = generateTestResponses()
 
-	_testServer = &Server{
-		Handler: _testHandler,
-	}
-
 	serverOptions := &ServerOptions{
 		IPAddress:        "127.0.0.1",
 		UDPPort:          5300,
@@ -225,11 +223,14 @@ func TestMain(m *testing.M) {
 		DoHAllowInsecure: true,
 	}
 
-	err := _testServer.Start(serverOptions)
+	_testServer, err = NewServer(serverOptions, _testHandler)
 	if err != nil {
 		log.Fatal(err)
 	}
 
+	_testServer.Start()
+
+	// Wait for all listeners running.
 	time.Sleep(500 * time.Millisecond)
 
 	s := m.Run()