From 90393ae03beb40ee94835985254ace0a1e6c014e Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 1 Mar 2018 15:02:53 +0000
Subject: [PATCH] Set interface flags properly on OpenBSD

---
 src/yggdrasil/tun.go     |  2 ++
 src/yggdrasil/tun_bsd.go | 61 ++++++++++++++++++++++++++++------------
 2 files changed, 45 insertions(+), 18 deletions(-)

diff --git a/src/yggdrasil/tun.go b/src/yggdrasil/tun.go
index 49acff6..b22a341 100644
--- a/src/yggdrasil/tun.go
+++ b/src/yggdrasil/tun.go
@@ -2,6 +2,7 @@ package yggdrasil
 
 // This manages the tun driver to send/recv packets to/from applications
 
+import "os"
 import ethernet "github.com/songgao/packets/ethernet"
 
 const IPv6_HEADER_LENGTH = 40
@@ -14,6 +15,7 @@ type tunInterface interface {
 	Read(to []byte) (int, error)
 	Write(from []byte) (int, error)
 	Close() error
+	FD() *os.File
 }
 
 type tunDevice struct {
diff --git a/src/yggdrasil/tun_bsd.go b/src/yggdrasil/tun_bsd.go
index 67e3b6f..a6a5adc 100644
--- a/src/yggdrasil/tun_bsd.go
+++ b/src/yggdrasil/tun_bsd.go
@@ -2,16 +2,18 @@
 
 package yggdrasil
 
-import "fmt"
 import "os/exec"
 import "strings"
+import "unsafe"
+import "syscall"
+import "golang.org/x/sys/unix"
 
 import water "github.com/neilalexander/water"
 
 // This is to catch BSD platforms
 
-const TUNSIFINFO = (0x80000000) | ((4 & 0x1fff) << 16) | uint32(byte('t'))<<8 | 91
-const TUNGIFINFO = (0x40000000) | ((4 & 0x1fff) << 16) | uint32(byte('t'))<<8 | 92
+const TUNSIFINFO = (0x80000000) | ((12 & 0x1fff) << 16) | uint32(byte('t'))<<8 | 91
+const TUNGIFINFO = (0x40000000) | ((12 & 0x1fff) << 16) | uint32(byte('t'))<<8 | 92
 const SIOCAIFADDR_IN6 = (0x80000000) | ((4 & 0x1fff) << 16) | uint32(byte('i'))<<8 | 27
 
 type in6_addrlifetime struct {
@@ -40,10 +42,10 @@ type in6_aliasreq struct {
 }
 
 type tuninfo struct {
-	tun_baudrate int
-	tun_mtu      int16
-	tun_type     uint8
-	tun_dummy    uint8
+	tun_mtu     uint16
+	tun_type    uint32
+	tun_flags   uint32
+	tun_dummy   uint16
 }
 
 func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int) error {
@@ -67,23 +69,46 @@ func (tun *tunDevice) setup(ifname string, iftapmode bool, addr string, mtu int)
 }
 
 func (tun *tunDevice) setupAddress(addr string) error {
+	fd := tun.iface.FD().Fd()
+	var err error
+	var ti tuninfo
+
+	// Get the existing interface flags
+	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(TUNGIFINFO), uintptr(unsafe.Pointer(&ti))); errno != 0 {
+		err = errno
+		tun.core.log.Printf("Error in TUNGIFINFO: %v", errno)
+		return err
+	}
+	tun.core.log.Printf("TUNGIFINFO: %+v", ti)
+
+	// Set the new MTU
+	ti.tun_mtu = uint16(tun.mtu)
+
+	// Set the new interface flags
+	ti.tun_flags |= syscall.IFF_UP
+	switch {
+	case tun.iface.IsTAP():
+		ti.tun_flags |= syscall.IFF_MULTICAST
+		ti.tun_flags |= syscall.IFF_BROADCAST
+	case tun.iface.IsTUN():
+		ti.tun_flags |= syscall.IFF_POINTOPOINT
+	}
+
+	// Set the new interface flags
+	tun.core.log.Printf("TUNSIFINFO: %+v", ti)
+	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uintptr(TUNSIFINFO), uintptr(unsafe.Pointer(&ti))); errno != 0 {
+		err = errno
+		tun.core.log.Printf("Error in TUNSIFINFO: %v", errno)
+		return err
+	}
+
 	// Set address
 	cmd := exec.Command("ifconfig", tun.iface.Name(), "inet6", addr)
 	tun.core.log.Printf("ifconfig command: %v", strings.Join(cmd.Args, " "))
 	output, err := cmd.CombinedOutput()
 	if err != nil {
-		tun.core.log.Printf("ipconfig failed: %v.", err)
+		tun.core.log.Printf("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), "up")
-	tun.core.log.Printf("ifconfig command: %v", strings.Join(cmd.Args, " "))
-	output, err = cmd.CombinedOutput()
-	if err != nil {
-		tun.core.log.Printf("ipconfig failed: %v.", err)
-		tun.core.log.Println(string(output))
-		return err
 	}
 
 	return nil