Feature: add default hosts localhost

component/trie/domain.go

@@ -30,7 +30,11 @@ func validAndSplitDomain(domain string) ([]string, bool) {
 
 	parts := strings.Split(domain, domainStep)
 	if len(parts) == 1 {
-		return nil, false
+		if parts[0] == "" {
+			return nil, false
+		}
+
+		return parts, true
 	}
 
 	for _, part := range parts[1:] {

component/trie/domain_test.go

@@ -14,6 +14,7 @@ func TestTrie_Basic(t *testing.T) {
 	domains := []string{
 		"example.com",
 		"google.com",
+		"localhost",
 	}
 
 	for _, domain := range domains {
@@ -24,6 +25,8 @@ func TestTrie_Basic(t *testing.T) {
 	assert.NotNil(t, node)
 	assert.True(t, node.Data.(net.IP).Equal(localIP))
 	assert.NotNil(t, tree.Insert("", localIP))
+	assert.Nil(t, tree.Search(""))
+	assert.NotNil(t, tree.Search("localhost"))
 }
 
 func TestTrie_Wildcard(t *testing.T) {

config/config.go

@@ -418,6 +418,12 @@ func parseRules(cfg *RawConfig, proxies map[string]C.Proxy) ([]C.Rule, error) {
 
 func parseHosts(cfg *RawConfig) (*trie.DomainTrie, error) {
 	tree := trie.New()
+
+	// add default hosts
+	if err := tree.Insert("localhost", net.IP{127, 0, 0, 1}); err != nil {
+		println(err.Error())
+	}
+
 	if len(cfg.Hosts) != 0 {
 		for domain, ipStr := range cfg.Hosts {
 			ip := net.ParseIP(ipStr)