Add basic support for TUN/TAP link type and creation.

link.go

@@ -1,6 +1,9 @@
 package netlink
 
-import "net"
+import (
+	"net"
+	"syscall"
+)
 
 // Link represents a link device from netlink. Shared link attributes
 // like name may be retrieved using the Attrs() method. Unique data
@@ -136,6 +139,27 @@ func (macvtap Macvtap) Type() string {
 	return "macvtap"
 }
 
+type TuntapMode uint16
+
+const (
+	TUNTAP_MODE_TUN TuntapMode = syscall.IFF_TUN
+	TUNTAP_MODE_TAP TuntapMode = syscall.IFF_TAP
+)
+
+// Tuntap links created via /dev/tun/tap, but can be destroyed via netlink
+type Tuntap struct {
+	LinkAttrs
+	Mode TuntapMode
+}
+
+func (tuntap *Tuntap) Attrs() *LinkAttrs {
+	return &tuntap.LinkAttrs
+}
+
+func (tuntap *Tuntap) Type() string {
+	return "tuntap"
+}
+
 // Veth devices must specify PeerName on create
 type Veth struct {
 	LinkAttrs

link_linux.go

@@ -5,6 +5,8 @@ import (
 	"encoding/binary"
 	"fmt"
 	"net"
+	"os"
+	"unsafe"
 	"syscall"
 
 	"github.com/vishvananda/netlink/nl"
@@ -285,6 +287,44 @@ func LinkAdd(link Link) error {
 		return fmt.Errorf("LinkAttrs.Name cannot be empty!")
 	}
 
+	if tuntap, ok := link.(*Tuntap); ok {
+		// TODO: support user
+		// TODO: support group
+		// TODO: support non- one_queue
+		// TODO: support pi | vnet_hdr | multi_queue
+		// TODO: support non- exclusive
+		// TODO: support non- persistent
+		if (tuntap.Mode < syscall.IFF_TUN || tuntap.Mode > syscall.IFF_TAP) {
+			return fmt.Errorf("Tuntap.Mode %v unknown!", tuntap.Mode)
+		}
+		file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
+		var req ifReq
+		req.Flags |= syscall.IFF_ONE_QUEUE
+		req.Flags |= syscall.IFF_TUN_EXCL
+		copy(req.Name[:15], base.Name)
+		req.Flags |= uint16(tuntap.Mode)
+		_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), uintptr(syscall.TUNSETIFF), uintptr(unsafe.Pointer(&req)))
+		if errno != 0 {
+			return fmt.Errorf("Tuntap IOCTL TUNSETIFF failed, errno %v", errno)
+		}
+		_, _, errno = syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), uintptr(syscall.TUNSETPERSIST), 1)
+		if errno != 0 {
+			return fmt.Errorf("Tuntap IOCTL TUNSETPERSIST failed, errno %v", errno)
+		}
+		ensureIndex(base)
+
+		// can't set master during create, so set it afterwards
+		if base.MasterIndex != 0 {
+			// TODO: verify MasterIndex is actually a bridge?
+			return LinkSetMasterByIndex(link, base.MasterIndex)
+		}
+		return nil
+	}
+
 	req := nl.NewNetlinkRequest(syscall.RTM_NEWLINK, syscall.NLM_F_CREATE|syscall.NLM_F_EXCL|syscall.NLM_F_ACK)
 
 	msg := nl.NewIfInfomsg(syscall.AF_UNSPEC)

link_tuntap_linux.go

@@ -0,0 +1,17 @@
+package netlink
+
+/*
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+
+#define IFREQ_SIZE sizeof(struct ifreq)
+*/
+import "C"
+
+type ifReq struct {
+	Name [C.IFNAMSIZ]byte
+	Flags uint16
+	pad [C.IFREQ_SIZE-C.IFNAMSIZ-2]byte
+}