Add custom routes

tun.go

@@ -37,6 +37,8 @@ type Options struct {
 	MTU                uint32
 	AutoRoute          bool
 	StrictRoute        bool
+	Inet4RouteAddress  []netip.Prefix
+	Inet6RouteAddress  []netip.Prefix
 	IncludeUID         []ranges.Range[uint32]
 	ExcludeUID         []ranges.Range[uint32]
 	IncludeAndroidUser []int

tun_darwin.go

@@ -241,7 +241,11 @@ func configure(tunFd int, ifIndex int, name string, options Options) error {
 	}
 	if options.AutoRoute {
 		if len(options.Inet4Address) > 0 {
-			for _, subnet := range []netip.Prefix{
+			var routes []netip.Prefix
+			if len(options.Inet4RouteAddress) > 0 {
+				routes = append(options.Inet4RouteAddress, netip.PrefixFrom(options.Inet4Address[0].Addr().Next(), 32))
+			} else {
+				routes = []netip.Prefix{
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{1, 0, 0, 0}), 8),
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{2, 0, 0, 0}), 7),
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{4, 0, 0, 0}), 6),
@@ -250,18 +254,29 @@ func configure(tunFd int, ifIndex int, name string, options Options) error {
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{32, 0, 0, 0}), 3),
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{64, 0, 0, 0}), 2),
 					netip.PrefixFrom(netip.AddrFrom4([4]byte{128, 0, 0, 0}), 1),
-			} {
+				}
+			}
+			for _, subnet := range routes {
 				err = addRoute(subnet, options.Inet4Address[0].Addr())
 				if err != nil {
-					return E.Cause(err, "add ipv4 route "+subnet.String())
+					return E.Cause(err, "add ipv4 route ", subnet)
 				}
 			}
 		}
 		if len(options.Inet6Address) > 0 {
-			subnet := netip.PrefixFrom(netip.AddrFrom16([16]byte{32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}), 3)
+			var routes []netip.Prefix
+			if len(options.Inet6RouteAddress) > 0 {
+				routes = append(options.Inet6RouteAddress, netip.PrefixFrom(options.Inet6Address[0].Addr().Next(), 128))
+			} else {
+				routes = []netip.Prefix{
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}), 3),
+				}
+			}
+			for _, subnet := range routes {
 				err = addRoute(subnet, options.Inet6Address[0].Addr())
 				if err != nil {
-				return E.Cause(err, "add ipv6 route "+subnet.String())
+					return E.Cause(err, "add ipv6 route ", subnet)
+				}
 			}
 		}
 	}

tun_linux.go

@@ -171,6 +171,18 @@ func (t *NativeTun) routes(tunLink netlink.Link) []netlink.Route {
 	var routes []netlink.Route
 	if len(t.options.Inet4Address) > 0 {
 		if t.options.AutoRoute {
+			if len(t.options.Inet4RouteAddress) > 0 {
+				for _, addr := range t.options.Inet4RouteAddress {
+					routes = append(routes, netlink.Route{
+						Dst: &net.IPNet{
+							IP:   addr.Addr().AsSlice(),
+							Mask: net.CIDRMask(addr.Bits(), 32),
+						},
+						LinkIndex: tunLink.Attrs().Index,
+						Table:     t.options.TableIndex,
+					})
+				}
+			} else {
 				routes = append(routes, netlink.Route{
 					Dst: &net.IPNet{
 						IP:   net.IPv4zero,
@@ -181,7 +193,20 @@ func (t *NativeTun) routes(tunLink netlink.Link) []netlink.Route {
 				})
 			}
 		}
+	}
 	if len(t.options.Inet6Address) > 0 {
+		if len(t.options.Inet6RouteAddress) > 0 {
+			for _, addr := range t.options.Inet6RouteAddress {
+				routes = append(routes, netlink.Route{
+					Dst: &net.IPNet{
+						IP:   addr.Addr().AsSlice(),
+						Mask: net.CIDRMask(addr.Bits(), 128),
+					},
+					LinkIndex: tunLink.Attrs().Index,
+					Table:     t.options.TableIndex,
+				})
+			}
+		} else {
 			routes = append(routes, netlink.Route{
 				Dst: &net.IPNet{
 					IP:   net.IPv6zero,
@@ -191,6 +216,7 @@ func (t *NativeTun) routes(tunLink netlink.Link) []netlink.Route {
 				Table:     t.options.TableIndex,
 			})
 		}
+	}
 	return routes
 }
 

tun_windows.go

@@ -108,12 +108,29 @@ func (t *NativeTun) configure() error {
 			}
 		} else {
 			if len(t.options.Inet4Address) > 0 {
+				if len(t.options.Inet4RouteAddress) > 0 {
+					for _, addr := range t.options.Inet4RouteAddress {
+						err := luid.AddRoute(addr, netip.IPv4Unspecified(), 0)
+						if err != nil {
+							return E.Cause(err, "add ipv4 route: ", addr)
+						}
+					}
+				} else {
 					err := luid.AddRoute(netip.PrefixFrom(netip.IPv4Unspecified(), 0), netip.IPv4Unspecified(), 0)
 					if err != nil {
 						return E.Cause(err, "set ipv4 route")
 					}
 				}
+			}
 			if len(t.options.Inet6Address) > 0 {
+				if len(t.options.Inet6RouteAddress) > 0 {
+					for _, addr := range t.options.Inet6RouteAddress {
+						err := luid.AddRoute(addr, netip.IPv6Unspecified(), 0)
+						if err != nil {
+							return E.Cause(err, "add ipv6 route: ", addr)
+						}
+					}
+				} else {
 					err := luid.AddRoute(netip.PrefixFrom(netip.IPv6Unspecified(), 0), netip.IPv6Unspecified(), 0)
 					if err != nil {
 						return E.Cause(err, "set ipv6 route")
@@ -121,6 +138,7 @@ func (t *NativeTun) configure() error {
 				}
 			}
 		}
+	}
 	if len(t.options.Inet4Address) > 0 {
 		inetIf, err := luid.IPInterface(winipcfg.AddressFamily(windows.AF_INET))
 		if err != nil {