Use TAP interface directly, without promiscuous mode

* This removes gopacket dependency
* However adds water-library small one

Signed-off-by: Sergey Matveev <stargrave@stargrave.org>

diff --git a/govpn.go b/govpn.go
index 885f5209a00ef8d609202300342c4876e364cb57..fbe4969703af2dddbc67caaaa14225a8a818e702 100644 (file)
--- a/govpn.go
+++ b/govpn.go
@@ -28,15 +28,14 @@ import (
 
        "code.google.com/p/go.crypto/poly1305"
        "code.google.com/p/go.crypto/salsa20"
-       "code.google.com/p/gopacket"
-       "code.google.com/p/gopacket/pcap"
+       "github.com/chon219/water"
 )
 
 const (
-       NonceSize       = 8
-       AliveTimeout    = time.Second * 90
+       NonceSize    = 8
+       AliveTimeout = time.Second * 90
        // S20BS is Salsa20's internal blocksize in bytes
-       S20BS           = 64
+       S20BS = 64
 )
 
 type Peer struct {
@@ -66,7 +65,7 @@ type UDPPkt struct {
 var (
        remoteAddr = flag.String("remote", "", "Remote server address")
        bindAddr   = flag.String("bind", "", "Bind to address")
-       ifaceName  = flag.String("iface", "eth0", "Network interface")
+       ifaceName  = flag.String("iface", "tap0", "TAP network interface")
        keyHex     = flag.String("key", "", "Authentication key")
        mtu        = flag.Int("mtu", 1500, "MTU")
 )
@@ -87,13 +86,23 @@ func main() {
        copy(key[:], keyDecoded)
 
        // Interface listening
-       iface, err := pcap.OpenLive(*ifaceName, int32(*mtu), true, 0)
+       maxIfacePktSize := *mtu - poly1305.TagSize - NonceSize
+       log.Println("Max MTU", maxIfacePktSize, "on interface", *ifaceName)
+       iface, err := water.NewTAP(*ifaceName)
        if err != nil {
                panic(err)
        }
-       ethSink := gopacket.NewPacketSource(iface, iface.LinkType()).Packets()
-       maxIfacePktSize := *mtu - poly1305.TagSize - NonceSize
-       log.Println("Max MTU", maxIfacePktSize, "on interface", *ifaceName)
+       ethSink := make(chan []byte)
+       go func() {
+               for {
+                       buf := make([]byte, maxIfacePktSize)
+                       n, err := iface.Read(buf)
+                       if err != nil {
+                               panic(err)
+                       }
+                       ethSink <- buf[:n]
+               }
+       }()
 
        // Network address parsing
        if (len(*bindAddr) > 1 && len(*remoteAddr) > 1) || (len(*bindAddr) == 0 && len(*remoteAddr) == 0) {
@@ -129,8 +138,8 @@ func main() {
 
        udpSink := make(chan UDPPkt)
        go func(conn *net.UDPConn, sink chan<- UDPPkt) {
-               data := make([]byte, *mtu)
                for {
+                       data := make([]byte, *mtu)
                        n, addr, err := conn.ReadFromUDP(data)
                        if err != nil {
                                fmt.Print("B")
@@ -141,7 +150,7 @@ func main() {
 
        // Process packets
        var udpPkt UDPPkt
-       var ethPkt gopacket.Packet
+       var ethPkt []byte
        var addr string
        var peer Peer
        var p *Peer
@@ -207,26 +216,26 @@ func main() {
                        }
                        peer.nonceRecv = nonceRecv
                        peer.SetAlive()
-                       if err := iface.WritePacketData(buf[S20BS : S20BS+len(udpPkt.data)-NonceSize-poly1305.TagSize]); err != nil {
+                       if _, err := iface.Write(buf[S20BS : S20BS+len(udpPkt.data)-NonceSize-poly1305.TagSize]); err != nil {
                                log.Println("Error writing to iface")
                        }
                        fmt.Print("r")
                case ethPkt = <-ethSink:
-                       if len(ethPkt.Data()) > maxIfacePktSize {
+                       if len(ethPkt) > maxIfacePktSize {
                                panic("Too large packet on interface")
                        }
                        if !peer.IsAlive() {
                                continue
                        }
                        peer.nonceOur = peer.nonceOur + 2
-                       pktData := ethPkt.Data()
                        binary.PutUvarint(nonce, peer.nonceOur)
-                       copy(buf[S20BS:], pktData)
+                       copy(buf[S20BS:], ethPkt)
                        salsa20.XORKeyStream(buf, buf, nonce, peer.key)
                        copy(buf[S20BS-NonceSize:S20BS], nonce)
                        copy(keyAuth[:], buf[:32])
-                       poly1305.Sum(tag, buf[S20BS-NonceSize:S20BS+len(pktData)], keyAuth)
-                       _, err := conn.WriteTo(append(buf[S20BS-NonceSize:S20BS+len(pktData)], tag[:]...), peer.addr)
+                       dataToSend := buf[S20BS-NonceSize : S20BS+len(ethPkt)]
+                       poly1305.Sum(tag, dataToSend, keyAuth)
+                       _, err := conn.WriteTo(append(dataToSend, tag[:]...), peer.addr)
                        if err != nil {
                                log.Println("Error sending UDP", err)
                        }