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122 lines
2.6 KiB
Go
122 lines
2.6 KiB
Go
package bridge
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import (
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"fmt"
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"net"
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"syscall"
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"unsafe"
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)
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const (
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ifNameSize = 16
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ioctlBrAdd = 0x89a0
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ioctlBrAddIf = 0x89a2
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)
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type ifreqIndex struct {
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IfrnName [ifNameSize]byte
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IfruIndex int32
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}
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type ifreqHwaddr struct {
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IfrnName [ifNameSize]byte
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IfruHwaddr syscall.RawSockaddr
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}
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// THIS CODE DOES NOT COMMUNICATE WITH KERNEL VIA RTNETLINK INTERFACE
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// IT IS HERE FOR BACKWARDS COMPATIBILITY WITH OLDER LINUX KERNELS
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// WHICH SHIP WITH OLDER NOT ENTIRELY FUNCTIONAL VERSION OF NETLINK
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func getIfSocket() (fd int, err error) {
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for _, socket := range []int{
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syscall.AF_INET,
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syscall.AF_PACKET,
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syscall.AF_INET6,
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} {
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if fd, err = syscall.Socket(socket, syscall.SOCK_DGRAM, 0); err == nil {
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break
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}
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}
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if err == nil {
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return fd, nil
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}
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return -1, err
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}
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func ifIoctBridge(iface, master *net.Interface, op uintptr) error {
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if len(master.Name) >= ifNameSize {
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return fmt.Errorf("Interface name %s too long", master.Name)
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}
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s, err := getIfSocket()
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if err != nil {
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return err
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}
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defer syscall.Close(s)
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ifr := ifreqIndex{}
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copy(ifr.IfrnName[:len(ifr.IfrnName)-1], master.Name)
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ifr.IfruIndex = int32(iface.Index)
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if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(s), op, uintptr(unsafe.Pointer(&ifr))); err != 0 {
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return err
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}
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return nil
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}
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// Add a slave to a bridge device. This is more backward-compatible than
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// netlink.NetworkSetMaster and works on RHEL 6.
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func ioctlAddToBridge(iface, master *net.Interface) error {
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return ifIoctBridge(iface, master, ioctlBrAddIf)
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}
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func ioctlSetMacAddress(name, addr string) error {
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if len(name) >= ifNameSize {
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return fmt.Errorf("Interface name %s too long", name)
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}
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hw, err := net.ParseMAC(addr)
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if err != nil {
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return err
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}
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s, err := getIfSocket()
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if err != nil {
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return err
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}
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defer syscall.Close(s)
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ifr := ifreqHwaddr{}
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ifr.IfruHwaddr.Family = syscall.ARPHRD_ETHER
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copy(ifr.IfrnName[:len(ifr.IfrnName)-1], name)
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for i := 0; i < 6; i++ {
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ifr.IfruHwaddr.Data[i] = ifrDataByte(hw[i])
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}
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if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(s), syscall.SIOCSIFHWADDR, uintptr(unsafe.Pointer(&ifr))); err != 0 {
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return err
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}
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return nil
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}
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func ioctlCreateBridge(name, macAddr string) error {
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if len(name) >= ifNameSize {
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return fmt.Errorf("Interface name %s too long", name)
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}
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s, err := getIfSocket()
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if err != nil {
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return err
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}
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defer syscall.Close(s)
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nameBytePtr, err := syscall.BytePtrFromString(name)
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if err != nil {
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return err
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}
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if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(s), ioctlBrAdd, uintptr(unsafe.Pointer(nameBytePtr))); err != 0 {
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return err
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}
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return ioctlSetMacAddress(name, macAddr)
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}
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