From 0207a7ac96caac7f43798c99a5ef13ef86d9a8b8 Mon Sep 17 00:00:00 2001
From: wwqgtxx <wwqgtxx@gmail.com>
Date: Sat, 23 Sep 2023 14:01:18 +0800
Subject: [PATCH] chore: resolver read system hosts file

---
 component/resolver/host.go         | 42 +++++++++++++++++++-----------
 component/resolver/host_windows.go | 19 ++++++++++++++
 2 files changed, 46 insertions(+), 15 deletions(-)
 create mode 100644 component/resolver/host_windows.go

diff --git a/component/resolver/host.go b/component/resolver/host.go
index 3b7e9a37..d6eb5873 100644
--- a/component/resolver/host.go
+++ b/component/resolver/host.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net/netip"
 	"strings"
+	_ "unsafe"
 
 	"github.com/Dreamacro/clash/common/utils"
 	"github.com/Dreamacro/clash/component/trie"
@@ -20,28 +21,39 @@ func NewHosts(hosts *trie.DomainTrie[HostValue]) Hosts {
 	}
 }
 
+// lookupStaticHost looks up the addresses and the canonical name for the given host from /etc/hosts.
+//
+//go:linkname lookupStaticHost net.lookupStaticHost
+func lookupStaticHost(host string) ([]string, string)
+
 // Return the search result and whether to match the parameter `isDomain`
 func (h *Hosts) Search(domain string, isDomain bool) (*HostValue, bool) {
-	value := h.DomainTrie.Search(domain)
-	if value == nil {
-		return nil, false
-	}
-	hostValue := value.Data()
-	for {
-		if isDomain && hostValue.IsDomain {
-			return &hostValue, true
-		} else {
-			if node := h.DomainTrie.Search(hostValue.Domain); node != nil {
-				hostValue = node.Data()
+	if value := h.DomainTrie.Search(domain); value != nil {
+		hostValue := value.Data()
+		for {
+			if isDomain && hostValue.IsDomain {
+				return &hostValue, true
 			} else {
-				break
+				if node := h.DomainTrie.Search(hostValue.Domain); node != nil {
+					hostValue = node.Data()
+				} else {
+					break
+				}
 			}
 		}
+		if isDomain == hostValue.IsDomain {
+			return &hostValue, true
+		}
+
+		return &hostValue, false
 	}
-	if isDomain == hostValue.IsDomain {
-		return &hostValue, true
+	if !isDomain {
+		addr, _ := lookupStaticHost(domain)
+		if hostValue, err := NewHostValue(addr); err == nil {
+			return &hostValue, true
+		}
 	}
-	return &hostValue, false
+	return nil, false
 }
 
 type HostValue struct {
diff --git a/component/resolver/host_windows.go b/component/resolver/host_windows.go
new file mode 100644
index 00000000..669f9547
--- /dev/null
+++ b/component/resolver/host_windows.go
@@ -0,0 +1,19 @@
+//go:build !go1.22
+
+// a simple standard lib fix from: https://github.com/golang/go/commit/33d4a5105cf2b2d549922e909e9239a48b8cefcc
+
+package resolver
+
+import (
+	"golang.org/x/sys/windows"
+	_ "unsafe"
+)
+
+//go:linkname testHookHostsPath net.testHookHostsPath
+var testHookHostsPath string
+
+func init() {
+	if dir, err := windows.GetSystemDirectory(); err == nil {
+		testHookHostsPath = dir + "/Drivers/etc/hosts"
+	}
+}