Add tun_darwin.go which uses ifconfig instead of iproute2

src/yggdrasil/tun_darwin.go

@@ -0,0 +1,48 @@
+package yggdrasil
+
+// The darwin platform specific tun parts
+// macOS/Darwin is BSD-derived and doesn't have iproute2. This code instead
+// uses ifconfig. There is actually code that tries to do this properly using
+// syscalls in github.com/neilalexander/yggdrasil-go branch "macos-interface"
+// but for some reason it doesn't work as expected!
+
+import "fmt"
+import "os/exec"
+import "strings"
+
+import water "github.com/songgao/water"
+
+func (tun *tunDevice) setup(ifname string, addr string, mtu int) error {
+	config := water.Config{DeviceType: water.TUN}
+	iface, err := water.New(config)
+	if err != nil {
+		panic(err)
+	}
+	tun.iface = iface
+	tun.mtu = mtu //1280 // Lets default to the smallest thing allowed for now
+	return tun.setupAddress(addr)
+}
+
+func (tun *tunDevice) setupAddress(addr string) error {
+	// Set address
+	cmd := exec.Command("ifconfig", tun.iface.Name(), "inet6",
+		"add", addr)
+	tun.core.log.Printf("ifconfig command: %v", strings.Join(cmd.Args, " "))
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		tun.core.log.Printf("Darwin ifconfig failed: %v.", err)
+		tun.core.log.Println(string(output))
+		return err
+	}
+	// Set MTU and bring device up
+	cmd = exec.Command("ifconfig", tun.iface.Name(), "mtu",
+		fmt.Sprintf("%d", tun.mtu))
+	tun.core.log.Printf("ifconfig command: %v", strings.Join(cmd.Args, " "))
+	output, err = cmd.CombinedOutput()
+	if err != nil {
+		tun.core.log.Printf("Darwin ifconfig failed: %v.", err)
+		tun.core.log.Println(string(output))
+		return err
+	}
+	return nil
+}

src/yggdrasil/tun_other.go

@@ -1,4 +1,5 @@
 // +build !linux
+// +build !darwin
 
 package yggdrasil