Rework freebsd support

1 files changed, 138 insertions, 109 deletions

diff --git a/tun_freebsd.go b/tun_freebsd.go
index e83b8ef..e2ec511 100644
--- a/tun_freebsd.go
+++ b/tun_freebsd.go
@@ -12,11 +12,8 @@ import (
 	"fmt"
 	"golang.org/x/net/ipv6"
 	"golang.org/x/sys/unix"
-	"io/ioutil"
 	"net"
 	"os"
-	"path/filepath"
-	"time"
 	"unsafe"
 )
 
@@ -29,38 +26,93 @@ const _TUNSIFPID = 0x2000745f
 // Iface status string max len
 const _IFSTATMAX = 800
 
+const SIZEOF_UINTPTR = 4 << (^uintptr(0) >> 32 & 1)
+
+// structure for iface requests with a pointer
+type ifreq_ptr struct {
+	Name [unix.IFNAMSIZ]byte
+	Data uintptr
+	Pad0 [24 - SIZEOF_UINTPTR]byte
+}
+
 // Structure for iface mtu get/set ioctls
 type ifreq_mtu struct {
-	Name [_IFNAMESIZ]byte
+	Name [unix.IFNAMSIZ]byte
 	MTU  uint32
 	Pad0 [12]byte
 }
 
 // Structure for interface status request ioctl
 type ifstat struct {
-	IfsName [_IFNAMESIZ]byte
+	IfsName [unix.IFNAMSIZ]byte
 	Ascii   [_IFSTATMAX]byte
 }
 
-// NativeTun 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 NativeTun struct {
-	name                    string
-	fd                      *os.File
-	rwcancel                *rwcancel.RWCancel
-	mtu                     int
-	events                  chan TUNEvent
-	errors                  chan error
-	statusListenersShutdown chan struct{}
+	name        string
+	fd          *os.File
+	rwcancel    *rwcancel.RWCancel
+	events      chan TUNEvent
+	errors      chan error
+	routeSocket int
+}
+
+func (tun *NativeTun) RoutineRouteListener(tunIfindex int) {
+	var (
+		statusUp  bool
+		statusMTU int
+	)
+
+	defer close(tun.events)
+
+	data := make([]byte, os.Getpagesize())
+	for {
+		n, err := unix.Read(tun.routeSocket, data)
+		if err != nil {
+			tun.errors <- err
+			return
+		}
+
+		if n < 14 {
+			continue
+		}
+
+		if data[3 /* type */] != unix.RTM_IFINFO {
+			continue
+		}
+		ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */])))
+		if ifindex != tunIfindex {
+			continue
+		}
+
+		iface, err := net.InterfaceByIndex(ifindex)
+		if err != nil {
+			tun.errors <- err
+			return
+		}
+
+		// Up / Down event
+		up := (iface.Flags & net.FlagUp) != 0
+		if up != statusUp && up {
+			tun.events <- TUNEventUp
+		}
+		if up != statusUp && !up {
+			tun.events <- TUNEventDown
+		}
+		statusUp = up
+
+		// MTU changes
+		if iface.MTU != statusMTU {
+			tun.events <- TUNEventMTUUpdate
+		}
+		statusMTU = iface.MTU
+	}
 }
 
-// Figure out the interface name for an open tun device file descriptor
-func TunIfaceName(f *os.File) (string, error) {
+func tunName(fd uintptr) (string, error) {
 	//Terrible hack to make up for freebsd not having a TUNGIFNAME
 
-	fd := f.Fd()
 	//First, make sure the tun pid matches this proc's pid
-
 	_, _, errno := unix.Syscall(
 		unix.SYS_IOCTL,
 		uintptr(fd),
@@ -69,7 +121,7 @@ func TunIfaceName(f *os.File) (string, error) {
 	)
 
 	if errno != 0 {
-		return "", fmt.Errorf("Failed to set tun device PID: %s", errno.Error())
+		return "", fmt.Errorf("failed to set tun device PID: %s", errno.Error())
 	}
 
 	// Open iface control socket
@@ -80,12 +132,12 @@ func TunIfaceName(f *os.File) (string, error) {
 		0,
 	)
 
-	defer unix.Close(confd)
-
 	if err != nil {
 		return "", err
 	}
 
+	defer unix.Close(confd)
+
 	procPid := os.Getpid()
 
 	//Try to find interface with matching PID
@@ -97,8 +149,7 @@ func TunIfaceName(f *os.File) (string, error) {
 
 		// Structs for getting data in and out of SIOCGIFSTATUS ioctl
 		var ifstatus ifstat
-		ifname := iface.Name
-		copy(ifstatus.IfsName[:], ifname)
+		copy(ifstatus.IfsName[:], iface.Name)
 
 		// Make the syscall to get the status string
 		_, _, errno := unix.Syscall(
@@ -117,30 +168,26 @@ func TunIfaceName(f *os.File) (string, error) {
 		if i < 1 {
 			continue
 		}
-		if i != -1 {
-			nullStr = nullStr[:i]
-		}
-		statStr := string(nullStr)
+		statStr := string(nullStr[:i])
 		var pidNum int = 0
 
 		// Finally get the owning PID
 		// Format string taken from sys/net/if_tun.c
 		_, err := fmt.Sscanf(statStr, "\tOpened by PID %d\n", &pidNum)
 		if err != nil {
-			return "", err
+			continue
 		}
 
 		if pidNum == procPid {
-			return ifname, nil
+			return iface.Name, nil
 		}
-
 	}
 
 	return "", nil
 }
 
 // Destroy a named system interface
-func DestroyIface(name string) error {
+func tunDestroy(name string) error {
 	// open control socket
 	var fd int
 
@@ -168,21 +215,21 @@ func DestroyIface(name string) error {
 	)
 
 	if errno != 0 {
-		return fmt.Errorf("Failed to destroy interface %s: %s", name, errno.Error())
+		return fmt.Errorf("failed to destroy interface %s: %s", name, errno.Error())
 	}
 
 	return nil
 }
 
 func CreateTUN(name string) (TUNDevice, error) {
-	if len(name) > _IFNAMESIZ-1 {
-		return nil, errors.New("Interface name too long")
+	if len(name) > unix.IFNAMSIZ-1 {
+		return nil, errors.New("interface name too long")
 	}
 
 	// See if interface already exists
 	iface, _ := net.InterfaceByName(name)
 	if iface != nil {
-		return nil, fmt.Errorf("Interface %s already exists", name)
+		return nil, fmt.Errorf("interface %s already exists", name)
 	}
 
 	tunfile, err := os.OpenFile("/dev/tun", unix.O_RDWR, 0)
@@ -190,16 +237,13 @@ func CreateTUN(name string) (TUNDevice, error) {
 	if err != nil {
 		return nil, err
 	}
-
-	nameif, err := TunIfaceName(tunfile)
-
+	tunfd := tunfile.Fd()
+	assignedName, err := tunName(tunfd)
 	if err != nil {
 		tunfile.Close()
 		return nil, err
 	}
 
-	tunfd := tunfile.Fd()
-
 	// Enable ifhead mode, otherwise tun will complain if it gets a non-AF_INET packet
 	ifheadmode := 1
 	_, _, errno := unix.Syscall(
@@ -210,11 +254,10 @@ func CreateTUN(name string) (TUNDevice, error) {
 	)
 
 	if errno != 0 {
-		return nil, fmt.Errorf("Error %s", errno.Error())
+		return nil, fmt.Errorf("error %s", errno.Error())
 	}
 
-	/* Set TUN iface to broadcast mode. TUN inferfaces on freebsd come up
-	 * point to point by default */
+	// Set TUN iface to broadcast mode. TUN inferfaces on freebsd come up in point to point by default
 	ifmodemode := unix.IFF_BROADCAST
 	_, _, errno = unix.Syscall(
 		unix.SYS_IOCTL,
@@ -224,12 +267,13 @@ func CreateTUN(name string) (TUNDevice, error) {
 	)
 
 	if errno != 0 {
-		return nil, fmt.Errorf("Error %s", errno.Error())
+		return nil, fmt.Errorf("error %s", errno.Error())
 	}
 
 	// Rename tun interface
+
 	// Open control socket
-	ctfd, err := unix.Socket(
+	confd, err := unix.Socket(
 		unix.AF_INET,
 		unix.SOCK_DGRAM,
 		0,
@@ -239,27 +283,27 @@ func CreateTUN(name string) (TUNDevice, error) {
 		return nil, err
 	}
 
-	defer unix.Close(ctfd)
+	defer unix.Close(confd)
 
 	// set up struct for iface rename
-	var newnp [_IFNAMESIZ]byte
+	var newnp [unix.IFNAMSIZ]byte
 	copy(newnp[:], name)
 
 	var ifr ifreq_ptr
-	copy(ifr.Name[:], nameif)
+	copy(ifr.Name[:], assignedName)
 	ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
 
 	//do actual ioctl to rename iface
 	_, _, errno = unix.Syscall(
 		unix.SYS_IOCTL,
-		uintptr(ctfd),
+		uintptr(confd),
 		uintptr(unix.SIOCSIFNAME),
 		uintptr(unsafe.Pointer(&ifr)),
 	)
 	if errno != 0 {
 		tunfile.Close()
-		DestroyIface(name)
-		return nil, fmt.Errorf("Failed to rename %s to %s: %s", nameif, name, errno.Error())
+		tunDestroy(name)
+		return nil, fmt.Errorf("failed to rename %s to %s: %s", assignedName, name, errno.Error())
 	}
 
 	tun, err := CreateTUNFromFile(tunfile)
@@ -267,29 +311,34 @@ func CreateTUN(name string) (TUNDevice, error) {
 	if err != nil {
 		return nil, err
 	}
-
-	if err == nil && name == "tun" {
-		fname := os.Getenv("WG_FREEBSD_TUN_NAME_FILE")
-		if fname != "" {
-			os.MkdirAll(filepath.Dir(fname), 0700)
-			ioutil.WriteFile(fname, []byte(tun.(*NativeTun).name+"\n"), 0400)
-		}
-	}
-
 	return tun, err
 }
 
 func CreateTUNFromFile(file *os.File) (TUNDevice, error) {
 
 	tun := &NativeTun{
-		fd:                      file,
-		mtu:                     1500,
-		events:                  make(chan TUNEvent, 10),
-		errors:                  make(chan error, 1),
-		statusListenersShutdown: make(chan struct{}),
+		fd:     file,
+		events: make(chan TUNEvent, 10),
+		errors: make(chan error, 1),
 	}
 
-	_, err := tun.Name()
+	name, err := tun.Name()
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
+
+	tunIfindex, err := func() (int, error) {
+		iface, err := net.InterfaceByName(name)
+		if err != nil {
+			return -1, err
+		}
+		return iface.Index, nil
+	}()
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
 
 	if err != nil {
 		tun.fd.Close()
@@ -302,43 +351,13 @@ func CreateTUNFromFile(file *os.File) (TUNDevice, error) {
 		return nil, err
 	}
 
-	// TODO: Fix this very naive implementation
-	go func(tun *NativeTun) {
-		var (
-			statusUp  bool
-			statusMTU int
-		)
+	tun.routeSocket, err = unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, unix.AF_UNSPEC)
+	if err != nil {
+		tun.fd.Close()
+		return nil, err
+	}
 
-		for {
-			intr, err := net.InterfaceByName(tun.name)
-			if err != nil {
-				tun.errors <- err
-				return
-			}
-
-			// Up / Down event
-			up := (intr.Flags & net.FlagUp) != 0
-			if up != statusUp && up {
-				tun.events <- TUNEventUp
-			}
-			if up != statusUp && !up {
-				tun.events <- TUNEventDown
-			}
-			statusUp = up
-
-			// MTU changes
-			if intr.MTU != statusMTU {
-				tun.events <- TUNEventMTUUpdate
-			}
-			statusMTU = intr.MTU
-
-			select {
-			case <-time.After(time.Second / 10):
-			case <-tun.statusListenersShutdown:
-				return
-			}
-		}
-	}(tun)
+	go tun.RoutineRouteListener(tunIfindex)
 
 	// set default MTU
 	err = tun.setMTU(DefaultMTU)
@@ -351,7 +370,7 @@ func CreateTUNFromFile(file *os.File) (TUNDevice, error) {
 }
 
 func (tun *NativeTun) Name() (string, error) {
-	name, err := TunIfaceName(tun.fd)
+	name, err := tunName(tun.fd.Fd())
 	if err != nil {
 		return "", err
 	}
@@ -417,18 +436,28 @@ func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
 }
 
 func (tun *NativeTun) Close() error {
-	close(tun.statusListenersShutdown)
+	var err4 error
 	err1 := tun.rwcancel.Cancel()
 	err2 := tun.fd.Close()
-	err3 := DestroyIface(tun.name)
-	close(tun.events)
+	err3 := tunDestroy(tun.name)
+	if tun.routeSocket != -1 {
+		// Surprisingly, on FreeBSD, simply closing a route socket is enough to unblock it.
+		// We don't even need to call shutdown, or use a rwcancel. TODO: CONFIRM THIS CLAIM. IT WAS TRUE ON DARWIN BUT...
+		err4 = unix.Close(tun.routeSocket)
+		tun.routeSocket = -1
+	} else if tun.events != nil {
+		close(tun.events)
+	}
 	if err1 != nil {
 		return err1
 	}
 	if err2 != nil {
 		return err2
 	}
-	return err3
+	if err3 != nil {
+		return err3
+	}
+	return err4
 }
 
 func (tun *NativeTun) setMTU(n int) error {
@@ -462,7 +491,7 @@ func (tun *NativeTun) setMTU(n int) error {
 	)
 
 	if errno != 0 {
-		return fmt.Errorf("Failed to set MTU on %s", tun.name)
+		return fmt.Errorf("failed to set MTU on %s", tun.name)
 	}
 
 	return nil
@@ -494,7 +523,7 @@ func (tun *NativeTun) MTU() (int, error) {
 		uintptr(unsafe.Pointer(&ifr)),
 	)
 	if errno != 0 {
-		return 0, fmt.Errorf("Failed to get MTU on %s", tun.name)
+		return 0, fmt.Errorf("failed to get MTU on %s", tun.name)
 	}
 
 	// convert result to signed 32-bit int