Feature: add default-nameserver and outbound interface

component/dialer/hook.go

@@ -1,11 +1,142 @@
 package dialer
 
-import "net"
+import (
+	"errors"
+	"net"
+	"time"
 
-type DialerHookFunc = func(*net.Dialer)
+	"github.com/Dreamacro/clash/common/singledo"
+)
+
+type DialerHookFunc = func(dialer *net.Dialer)
+type DialHookFunc = func(dialer *net.Dialer, network string, ip net.IP)
 type ListenConfigHookFunc = func(*net.ListenConfig)
+type ListenPacketHookFunc = func() net.IP
 
 var (
-	DialerHook       DialerHookFunc       = nil
-	ListenConfigHook ListenConfigHookFunc = nil
+	DialerHook       DialerHookFunc
+	DialHook         DialHookFunc
+	ListenConfigHook ListenConfigHookFunc
+	ListenPacketHook ListenPacketHookFunc
 )
+
+var (
+	ErrAddrNotFound      = errors.New("addr not found")
+	ErrNetworkNotSupport = errors.New("network not support")
+)
+
+func lookupTCPAddr(ip net.IP, addrs []net.Addr) (*net.TCPAddr, error) {
+	ipv4 := ip.To4() != nil
+
+	for _, elm := range addrs {
+		addr, ok := elm.(*net.IPNet)
+		if !ok {
+			continue
+		}
+
+		addrV4 := addr.IP.To4() != nil
+
+		if addrV4 && ipv4 {
+			return &net.TCPAddr{IP: addr.IP, Port: 0}, nil
+		} else if !addrV4 && !ipv4 {
+			return &net.TCPAddr{IP: addr.IP, Port: 0}, nil
+		}
+	}
+
+	return nil, ErrAddrNotFound
+}
+
+func lookupUDPAddr(ip net.IP, addrs []net.Addr) (*net.UDPAddr, error) {
+	ipv4 := ip.To4() != nil
+
+	for _, elm := range addrs {
+		addr, ok := elm.(*net.IPNet)
+		if !ok {
+			continue
+		}
+
+		addrV4 := addr.IP.To4() != nil
+
+		if addrV4 && ipv4 {
+			return &net.UDPAddr{IP: addr.IP, Port: 0}, nil
+		} else if !addrV4 && !ipv4 {
+			return &net.UDPAddr{IP: addr.IP, Port: 0}, nil
+		}
+	}
+
+	return nil, ErrAddrNotFound
+}
+
+func ListenPacketWithInterface(name string) ListenPacketHookFunc {
+	single := singledo.NewSingle(5 * time.Second)
+
+	return func() net.IP {
+		elm, err, _ := single.Do(func() (interface{}, error) {
+			iface, err := net.InterfaceByName(name)
+			if err != nil {
+				return nil, err
+			}
+
+			addrs, err := iface.Addrs()
+			if err != nil {
+				return nil, err
+			}
+
+			return addrs, nil
+		})
+
+		if err != nil {
+			return nil
+		}
+
+		addrs := elm.([]net.Addr)
+
+		for _, elm := range addrs {
+			addr, ok := elm.(*net.IPNet)
+			if !ok || addr.IP.To4() == nil {
+				continue
+			}
+
+			return addr.IP
+		}
+
+		return nil
+	}
+}
+
+func DialerWithInterface(name string) DialHookFunc {
+	single := singledo.NewSingle(5 * time.Second)
+
+	return func(dialer *net.Dialer, network string, ip net.IP) {
+		elm, err, _ := single.Do(func() (interface{}, error) {
+			iface, err := net.InterfaceByName(name)
+			if err != nil {
+				return nil, err
+			}
+
+			addrs, err := iface.Addrs()
+			if err != nil {
+				return nil, err
+			}
+
+			return addrs, nil
+		})
+
+		if err != nil {
+			return
+		}
+
+		addrs := elm.([]net.Addr)
+
+		switch network {
+		case "tcp", "tcp4", "tcp6":
+			if addr, err := lookupTCPAddr(ip, addrs); err == nil {
+				dialer.LocalAddr = addr
+			}
+		case "udp", "udp4", "udp6":
+			if addr, err := lookupUDPAddr(ip, addrs); err == nil {
+				dialer.LocalAddr = addr
+			}
+		}
+	}
+}