From 969c235490bcfe5cd14a743a9e624d01ac8f8e1c Mon Sep 17 00:00:00 2001
From: H1JK <hell0jack@protonmail.com>
Date: Mon, 1 May 2023 12:41:36 +0800
Subject: [PATCH] chore: Remove default DNS in system resolver

---
 config/config.go      |  3 +++
 dns/system_windows.go | 10 ----------
 dns/util.go           |  6 +++++-
 docs/config.yaml      |  2 +-
 4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/config/config.go b/config/config.go
index 35929849..6425934e 100644
--- a/config/config.go
+++ b/config/config.go
@@ -1144,6 +1144,9 @@ func parseDNS(rawCfg *RawConfig, hosts *trie.DomainTrie[resolver.HostValue], rul
 	}
 	// check default nameserver is pure ip addr
 	for _, ns := range dnsCfg.DefaultNameserver {
+		if ns.Net == "system" {
+			continue
+		}
 		host, _, err := net.SplitHostPort(ns.Addr)
 		if err != nil || net.ParseIP(host) == nil {
 			u, err := url.Parse(ns.Addr)
diff --git a/dns/system_windows.go b/dns/system_windows.go
index 3e9736d0..2e0aa237 100644
--- a/dns/system_windows.go
+++ b/dns/system_windows.go
@@ -12,10 +12,6 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-var (
-	defaultNS = []string{"114.114.114.114:53"}
-)
-
 type dnsConfig struct {
 	servers []string // server addresses (in host:port form) to use
 }
@@ -27,7 +23,6 @@ func loadSystemResolver() (clients []dnsClient, err error) {
 	}
 	nameservers := content.servers
 	if len(nameservers) == 0 {
-		err = fmt.Errorf("no nameserver found in windows system")
 		return
 	}
 	servers := make([]NameServer, 0, len(nameservers))
@@ -42,11 +37,6 @@ func loadSystemResolver() (clients []dnsClient, err error) {
 
 func dnsReadConfig() (conf *dnsConfig, err error) {
 	conf = &dnsConfig{}
-	defer func() {
-		if len(conf.servers) == 0 {
-			conf.servers = defaultNS
-		}
-	}()
 	aas, err := adapterAddresses()
 	if err != nil {
 		return conf, err
diff --git a/dns/util.go b/dns/util.go
index 948687ac..d85deb17 100644
--- a/dns/util.go
+++ b/dns/util.go
@@ -82,7 +82,11 @@ func transform(servers []NameServer, resolver *Resolver) []dnsClient {
 		case "system":
 			clients, err := loadSystemResolver()
 			if err != nil {
-				log.Warnln("[DNS:system] load system resolver failed: %s", err.Error())
+				log.Errorln("[DNS:system] load system resolver failed: %s", err.Error())
+				continue
+			}
+			if len(clients) == 0 {
+				log.Errorln("[DNS:system] no nameserver found in system")
 				continue
 			}
 			ret = append(ret, clients...)
diff --git a/docs/config.yaml b/docs/config.yaml
index 2be8be37..66cab25c 100644
--- a/docs/config.yaml
+++ b/docs/config.yaml
@@ -177,7 +177,7 @@ dns:
     - 8.8.8.8
     - tls://1.12.12.12:853
     - tls://223.5.5.5:853
-    - system://  # get DNS server from system's configuration
+    - system://  # append DNS server from system configuration. If not found, it would print an error log and skip.
   enhanced-mode: fake-ip # or redir-host
   
   fake-ip-range: 198.18.0.1/16 # fake-ip 池设置