diff options
Diffstat (limited to 'src/tun_linux.go')
| -rw-r--r-- | src/tun_linux.go | 159 |
1 files changed, 147 insertions, 12 deletions
diff --git a/src/tun_linux.go b/src/tun_linux.go index 34f746a..476a43f 100644 --- a/src/tun_linux.go +++ b/src/tun_linux.go @@ -6,6 +6,7 @@ package main import ( "encoding/binary" "errors" + "fmt" "golang.org/x/sys/unix" "net" "os" @@ -13,12 +14,93 @@ import ( "unsafe" ) -const CloneDevicePath = "/dev/net/tun" +// #include <string.h> +// #include <unistd.h> +// #include <net/if.h> +// #include <netinet/in.h> +// #include <linux/netlink.h> +// #include <linux/rtnetlink.h> +// +// /* Creates a netlink socket +// * listening to the RTMGRP_LINK multicast group +// */ +// +// int bind_rtmgrp() { +// int nl_sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); +// if (nl_sock < 0) +// return -1; +// +// struct sockaddr_nl addr; +// memset ((void *) &addr, 0, sizeof (addr)); +// addr.nl_family = AF_NETLINK; +// addr.nl_pid = getpid (); +// addr.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR; +// +// if (bind(nl_sock, (struct sockaddr *) &addr, sizeof (addr)) < 0) +// return -1; +// +// return nl_sock; +// } +import "C" + +const ( + CloneDevicePath = "/dev/net/tun" + IFReqSize = unix.IFNAMSIZ + 64 +) type NativeTun struct { fd *os.File + index int name string - events chan TUNEvent + errors chan error // async error handling + events chan TUNEvent // +} + +func (tun *NativeTun) RoutineNetlinkListener() { + sock := int(C.bind_rtmgrp()) + if sock < 0 { + tun.errors <- errors.New("Failed to create netlink event listener") + return + } + + for msg := make([]byte, 1<<16); ; { + + msgn, _, _, _, err := unix.Recvmsg(sock, msg[:], nil, 0) + if err != nil { + tun.errors <- fmt.Errorf("Failed to receive netlink message: %s", err.Error()) + return + } + + for remain := msg[:msgn]; len(remain) >= unix.SizeofNlMsghdr; { + + hdr := *(*unix.NlMsghdr)(unsafe.Pointer(&remain[0])) + + if int(hdr.Len) > len(remain) { + break + } + + switch hdr.Type { + case unix.NLMSG_DONE: + remain = []byte{} + + case unix.RTM_NEWLINK: + info := *(*unix.IfInfomsg)(unsafe.Pointer(&remain[unix.SizeofNlMsghdr])) + + if info.Flags&unix.IFF_RUNNING != 0 { + tun.events <- TUNEventUp + } + + if info.Flags&unix.IFF_RUNNING == 0 { + tun.events <- TUNEventDown + } + + remain = remain[hdr.Len:] + + default: + remain = remain[hdr.Len:] + } + } + } } func (tun *NativeTun) isUp() (bool, error) { @@ -30,6 +112,46 @@ func (tun *NativeTun) Name() string { return tun.name } +func toInt32(val []byte) int { + n := binary.LittleEndian.Uint32(val[:4]) + if n >= (1 << 31) { + return int(n-(1<<31)) - (1 << 31) + } + return int(n) +} + +func getDummySock() (int, error) { + return unix.Socket( + unix.AF_INET, + unix.SOCK_DGRAM, + 0, + ) +} + +func getIFIndex(name string) (int, error) { + fd, err := getDummySock() + if err != nil { + return 0, err + } + + defer unix.Close(fd) + + var ifr [IFReqSize]byte + copy(ifr[:], name) + _, _, errno := unix.Syscall( + unix.SYS_IOCTL, + uintptr(fd), + uintptr(unix.SIOCGIFINDEX), + uintptr(unsafe.Pointer(&ifr[0])), + ) + + if errno != 0 { + return 0, errno + } + + return toInt32(ifr[unix.IFNAMSIZ:]), nil +} + func (tun *NativeTun) setMTU(n int) error { // open datagram socket @@ -48,7 +170,7 @@ func (tun *NativeTun) setMTU(n int) error { // do ioctl call - var ifr [64]byte + var ifr [IFReqSize]byte copy(ifr[:], tun.name) binary.LittleEndian.PutUint32(ifr[16:20], uint32(n)) _, _, errno := unix.Syscall( @@ -83,7 +205,7 @@ func (tun *NativeTun) MTU() (int, error) { // do ioctl call - var ifr [64]byte + var ifr [IFReqSize]byte copy(ifr[:], tun.name) _, _, errno := unix.Syscall( unix.SYS_IOCTL, @@ -109,7 +231,12 @@ func (tun *NativeTun) Write(d []byte) (int, error) { } func (tun *NativeTun) Read(d []byte) (int, error) { - return tun.fd.Read(d) + select { + case err := <-tun.errors: + return 0, err + default: + return tun.fd.Read(d) + } } func (tun *NativeTun) Events() chan TUNEvent { @@ -131,11 +258,11 @@ func CreateTUN(name string) (TUNDevice, error) { // create new device - var ifr [64]byte + var ifr [IFReqSize]byte var flags uint16 = unix.IFF_TUN | unix.IFF_NO_PI nameBytes := []byte(name) if len(nameBytes) >= unix.IFNAMSIZ { - return nil, errors.New("Name size too long") + return nil, errors.New("Interface name too long") } copy(ifr[:], nameBytes) binary.LittleEndian.PutUint16(ifr[16:], flags) @@ -147,7 +274,7 @@ func CreateTUN(name string) (TUNDevice, error) { uintptr(unsafe.Pointer(&ifr[0])), ) if errno != 0 { - return nil, errors.New("Failed to create tun, ioctl call failed") + return nil, errno } // read (new) name of interface @@ -158,13 +285,21 @@ func CreateTUN(name string) (TUNDevice, error) { fd: fd, name: newName, events: make(chan TUNEvent, 5), + errors: make(chan error, 5), } - // TODO: Wait for device to be upped - device.events <- TUNEventUp + // fetch IF index + + device.index, err = getIFIndex(device.name) + if err != nil { + return nil, err + } + + go device.RoutineNetlinkListener() // set default MTU - err = device.setMTU(DefaultMTU) - return device, err + fmt.Println(device) + + return device, device.setMTU(DefaultMTU) } |