MTU configure

client.go

@@ -111,6 +111,11 @@ func (c *Client) nat() error {
 	if err := tun.SetNetmask(c.nat_info.Netmask); err != nil {
 		return err
 	}
+	if c.nat_info.MTU > 0 {
+		if err := tun.SetMTU(c.nat_info.MTU); err != nil {
+			return err
+		}
+	}
 
 	tun_ch, err := tun.ReadChan()
 	if err != nil {

proto.go

@@ -13,6 +13,7 @@ type NatInfo struct {
 	IP      net.IP
 	Gateway net.IP
 	Netmask net.IPMask
+	MTU     int
 }
 
 type AuthResult struct {

ser.cfg.example

@@ -14,6 +14,7 @@
     },
     "nat": {
         "net": "192.168.10.0/24",
-        "gateway": "192.168.10.1"
+        "gateway": "192.168.10.1",
+        "mtu": 1500
     }
 }

server.go

@@ -13,6 +13,7 @@ type Server struct {
 	cfg    map[string]map[string]interface{}
 	tunnel ServerTunnel
 	ippool IPPool
+	mtu    int
 }
 
 func NewServer(cfg map[string]map[string]interface{}) (ser Server, err error) {
@@ -53,6 +54,28 @@ func NewServer(cfg map[string]map[string]interface{}) (ser Server, err error) {
 		if err != nil {
 			return
 		}
+
+		if imtu, ok := nat_cfg["mtu"]; ok {
+			switch v := imtu.(type) {
+			case int:
+				ser.mtu = v
+			case int64:
+				ser.mtu = int(v)
+			case float32:
+				ser.mtu = int(v)
+			case float64:
+				ser.mtu = int(v)
+			default:
+				err = fmt.Errorf("nat.mtu invalid type (int desired)")
+				return
+			}
+			if ser.mtu < 0 {
+				err = fmt.Errorf("nat.mtu must be a positive int")
+				return
+			}
+		} else {
+			ser.mtu = 0
+		}
 	}
 
 	tunnel_cfg, ok := cfg["tunnel"]
@@ -132,6 +155,7 @@ func (s *Server) auth(cli_ch *ClientChan) (nf NatInfo, err error) {
 		rst.NatInfo.Gateway = s.ippool.Gateway
 		rst.NatInfo.Netmask = s.ippool.IPNet.Mask
 		rst.NatInfo.IP = s.ippool.Next()
+		rst.NatInfo.MTU = s.mtu
 		nf = rst.NatInfo
 	}
 
@@ -158,6 +182,11 @@ func (s *Server) nat(cli_ch *ClientChan, nat_info NatInfo) error {
 	if err := tun.SetNetmask(nat_info.Netmask); err != nil {
 		return err
 	}
+	if s.mtu > 0 {
+		if err := tun.SetMTU(s.mtu); err != nil {
+			return err
+		}
+	}
 
 	tun_ch, err := tun.ReadChan()
 	if err != nil {