Get client working on OSX

src/github.com/songgao/water/syscalls_darwin.go

@@ -5,7 +5,9 @@ package water
 import (
 	"errors"
 	"fmt"
+	"io"
 	"os"
+	"sync"
 	"syscall"
 	"unsafe"
 )
@@ -112,12 +114,68 @@ func newTUN(string) (ifce *Interface, err error) {
 	}
 
 	return &Interface{
-		isTAP:           false,
-		name:            string(ifName.name[:ifNameSize-1 /* -1 is for \0 */]),
-		ReadWriteCloser: os.NewFile(uintptr(fd), string(ifName.name[:])),
+		isTAP: false,
+		name:  string(ifName.name[:ifNameSize-1 /* -1 is for \0 */]),
+		ReadWriteCloser: &tunReadCloser{
+			f: os.NewFile(uintptr(fd), string(ifName.name[:])),
+		},
 	}, nil
 }
 
+// tunReadCloser is a hack to work around the first 4 bytes "packet
+// information" because there doesn't seem to be an IFF_NO_PI for darwin.
+type tunReadCloser struct {
+	f io.ReadWriteCloser
+
+	rMu  sync.Mutex
+	rBuf []byte
+
+	wMu  sync.Mutex
+	wBuf []byte
+}
+
+var _ io.ReadWriteCloser = (*tunReadCloser)(nil)
+
+func (t *tunReadCloser) Read(to []byte) (int, error) {
+	t.rMu.Lock()
+	defer t.rMu.Unlock()
+
+	if cap(t.rBuf) < len(to)+4 {
+		t.rBuf = make([]byte, len(to)+4)
+	}
+	t.rBuf = t.rBuf[:len(to)+4]
+
+	n, err := t.f.Read(t.rBuf)
+	copy(to, t.rBuf[4:])
+	return n - 4, err
+}
+
+func (t *tunReadCloser) Write(from []byte) (int, error) {
+	t.wMu.Lock()
+	defer t.wMu.Unlock()
+
+	if cap(t.wBuf) < len(from)+4 {
+		t.wBuf = make([]byte, len(from)+4)
+	}
+	t.wBuf = t.wBuf[:len(from)+4]
+
+	t.wBuf[3] = 2 // Family: IP (2)
+	copy(t.wBuf[4:], from)
+
+	n, err := t.f.Write(t.wBuf)
+	return n - 4, err
+}
+
+func (t *tunReadCloser) Close() error {
+	// lock to make sure no read/write is in process.
+	t.rMu.Lock()
+	defer t.rMu.Unlock()
+	t.wMu.Lock()
+	defer t.wMu.Unlock()
+
+	return t.f.Close()
+}
+
 func newTAP(ifName string) (ifce *Interface, err error) {
 	return nil, errors.New("tap interface not implemented on this platform")
 }

src/subnet/client.go

@@ -15,9 +15,10 @@ import (
 
 // Client represents a connection to a subnet server.
 type Client struct {
-	newGateway string
-	serverAddr string
-	port       string
+	debugMessages bool
+	newGateway    string
+	serverAddr    string
+	port          string
 
 	wg             sync.WaitGroup
 	serverIP       net.IP
@@ -67,6 +68,7 @@ func NewClient(servAddr, port, network, iName string, newGateway string,
 	log.Printf("Created iface %s\n", intf.Name())
 
 	ret := &Client{
+		debugMessages: true,
 		intf:          intf,
 		newGateway:    newGateway,
 		serverAddr:    servAddr,
@@ -92,7 +94,7 @@ func (c *Client) init(serverAddr, port string) error {
 	c.tlsConn = tlsConn
 	c.connectionOk = true
 
-	if err := SetDevIP(c.intf.Name(), c.localAddr, c.localNetMask, false); err != nil {
+	if err := SetDevIP(c.intf.Name(), c.localAddr, c.localNetMask, c.debugMessages); err != nil {
 		return err
 	}
 	log.Printf("IP of %s set to %s, localNetMask %s\n", c.intf.Name(), c.localAddr.String(), net.IP(c.localNetMask.Mask).String())
@@ -107,7 +109,7 @@ func (c *Client) init(serverAddr, port string) error {
 		log.Printf("Default gateway is %s on %s\n", gateway, gatewayDevice)
 
 		// route all traffic to the VPN server through the current gateway device
-		if err := AddRoute(c.serverIP, gateway, gatewayDevice, false); err != nil {
+		if err := AddRoute(c.serverIP, gateway, gatewayDevice, c.debugMessages); err != nil {
 			return err
 		}
 		log.Printf("Traffic to %s now routed via %s on %s.\n", c.serverIP.String(), gw, gatewayDevice)
@@ -122,14 +124,14 @@ func (c *Client) init(serverAddr, port string) error {
 func (c *Client) Run() {
 
 	if c.newGateway != "" { //Redirect default traffic via our VPN
-		err := SetDefaultGateway(c.newGateway, c.intf.Name(), false)
+		err := SetDefaultGateway(c.newGateway, c.intf.Name(), c.debugMessages)
 		if err != nil {
 			log.Printf("Could set gateway: %s\n", err.Error())
 			return
 		}
 	}
 
-	err := SetInterfaceStatus(c.intf.Name(), true, false)
+	err := SetInterfaceStatus(c.intf.Name(), true, c.debugMessages)
 	if err != nil {
 		log.Printf("Could not bring up interface %s: %s\n", c.intf.Name(), err.Error())
 		return
@@ -153,7 +155,10 @@ func (c *Client) netSendRoutine() {
 		}
 
 		for c.connectionOk && connOK {
-			pkt := <-c.packetsIn
+			pkt, ok := <-c.packetsIn
+			if !ok{
+				break
+			}
 
 			if pkt.Dest.IsMulticast() { //Don't forward multicast
 				continue

src/subnet/helpers_darwin.go

@@ -0,0 +1,73 @@
+package subnet
+
+import (
+  "errors"
+  "fmt"
+  "net"
+  "os/exec"
+  "regexp"
+  "strings"
+)
+
+//SetInterfaceStatus brings up or down a network interface.
+func SetInterfaceStatus(iName string, up bool, debug bool) error {
+  statusString := "down"
+	if up {
+		statusString = "up"
+	}
+
+  //TODO: Support setting the QLEN
+	sargs := fmt.Sprintf("%s %s mtu %d", iName, statusString, devMtuSize)
+	return commandExec("ifconfig", strings.Split(sargs, " "), debug)}
+
+//SetDevIP sets the local IP address of a network interface.
+func SetDevIP(iName string, localAddr net.IP, addr *net.IPNet, debug bool) error {
+  sargs := fmt.Sprintf("set %s MANUAL %s 0x%s", iName, localAddr.String(), addr.Mask)
+	return commandExec("ipconfig", strings.Split(sargs, " "), debug)
+}
+
+// SetDefaultGateway sets the systems gateway to the IP / device specified.
+func SetDefaultGateway(gw, iName string, debug bool) error {
+  sargs := fmt.Sprintf("-n change default %s -interface %s", gw, iName)
+	args := strings.Split(sargs, " ")
+	return commandExec("route", args, debug)
+}
+
+// AddRoute routes all traffic for addr via interface iName.
+func AddRoute(addr, viaAddr net.IP, iName string, debug bool) error {
+  sargs := fmt.Sprintf("-n add %s %s -interface %s", addr.String(), viaAddr.String(), iName)
+	args := strings.Split(sargs, " ")
+	return commandExec("route", args, debug)
+}
+
+// DelRoute deletes the route in the system routing table to a specific destination.
+func DelRoute(addr, viaAddr net.IP, iName string, debug bool) error {
+  sargs := fmt.Sprintf("-n delete %s %s -interface %s", addr.String(), viaAddr.String(), iName)
+	args := strings.Split(sargs, " ")
+	return commandExec("route", args, debug)
+}
+
+var parseRouteGetRegex = regexp.MustCompile(`(?m)^\W*([^\:]+):\W(.*)$`)
+
+// GetNetGateway return net gateway (default route) and nic.
+func GetNetGateway() (gw, dev string, err error) {
+  cmd := exec.Command("route", "-n", "get", "default")
+	output, e := cmd.Output()
+	if e != nil {
+		return "", "", e
+	}
+
+  matches := parseRouteGetRegex.FindAllSubmatch(output, -1)
+  defaultRouteInfo := map[string]string{}
+  for _, match := range matches {
+    defaultRouteInfo[string(match[1])] = string(match[2])
+  }
+
+  _, gatewayExists := defaultRouteInfo["gateway"]
+  _, interfaceExists := defaultRouteInfo["interface"]
+  if !gatewayExists || !interfaceExists {
+    return "", "", errors.New("internal error: could not read gateway or interface")
+  }
+
+  return defaultRouteInfo["gateway"], defaultRouteInfo["interface"], nil
+}

src/subnet/net_test.go

@@ -0,0 +1,16 @@
+package subnet
+
+import (
+  "testing"
+)
+
+func TestNet(t *testing.T) {
+  gw, device, err := GetNetGateway()
+  if err != nil {
+    t.Fatal(err)
+  }
+  if len(device) < 2 || len(gw) < 3 {
+    t.Error(gw, device)
+    t.Fatal("Expected longer results for device and interface")
+  }
+}

src/subnet/reverser.go

@@ -31,7 +31,7 @@ func (r *Reverser) AddRouteEntry(destination net.IP, via net.IP, dev string) {
 // to system configuration.
 func (r *Reverser) Close() {
 	for _, route := range r.RouteDeletions {
-		e := DelRoute(route.dest, route.via, route.dev, false)
+		e := DelRoute(route.dest, route.via, route.dev, true)
 		if e == nil {
 			log.Printf("Deleted route to %s via %s on %s\n", route.dest.String(), route.via.String(), route.dev)
 		} else {

src/subnet/util.go

@@ -3,7 +3,9 @@ package subnet
 import (
 	"errors"
 	"math/rand"
+	"log"
 	"net"
+	"os/exec"
 	"time"
 )
 
@@ -19,3 +21,15 @@ func hostToIP(addr string) (net.IP, error) {
 	rand.Seed(time.Now().Unix())
 	return addrs[rand.Int()%len(addrs)], nil
 }
+
+func commandExec(command string, args []string, debug bool) error {
+	cmd := exec.Command(command, args...)
+	if debug {
+		log.Println("exec "+command+": ", args)
+	}
+	e := cmd.Run()
+	if e != nil {
+		log.Println("Command failed: ", e)
+	}
+	return e
+}