Routing config: Add processName (#5489)

common/net/net.go

@@ -1,7 +1,13 @@
 // Package net is a drop-in replacement to Golang's net package, with some more functionalities.
 package net // import "github.com/xtls/xray-core/common/net"
 
-import "time"
+import (
+	"net"
+	"sync/atomic"
+	"time"
+
+	"github.com/xtls/xray-core/common/errors"
+)
 
 // defines the maximum time an idle TCP session can survive in the tunnel, so
 // it should be consistent across HTTP versions and with other transports.
@@ -12,3 +18,37 @@ const QuicgoH3KeepAlivePeriod = 10 * time.Second
 
 // consistent with chrome
 const ChromeH2KeepAlivePeriod = 45 * time.Second
+
+var ErrNotLocal = errors.New("the source address is not from local machine.")
+
+type localIPCahceEntry struct {
+	addrs      []net.Addr
+	lastUpdate time.Time
+}
+
+var localIPCahce = atomic.Pointer[localIPCahceEntry]{}
+
+func IsLocal(ip net.IP) (bool, error) {
+	var addrs []net.Addr
+	if entry := localIPCahce.Load(); entry == nil || time.Since(entry.lastUpdate) > time.Minute {
+		var err error
+		addrs, err = net.InterfaceAddrs()
+		if err != nil {
+			return false, err
+		}
+		localIPCahce.Store(&localIPCahceEntry{
+			addrs:      addrs,
+			lastUpdate: time.Now(),
+		})
+	} else {
+		addrs = entry.addrs
+	}
+	for _, addr := range addrs {
+		if ipnet, ok := addr.(*net.IPNet); ok {
+			if ipnet.IP.Equal(ip) {
+				return true, nil
+			}
+		}
+	}
+	return false, nil
+}