81 lines
2.2 KiB
Go
81 lines
2.2 KiB
Go
// Package netns allows ultra-simple network namespace handling. NsHandles
|
|
// can be retrieved and set. Note that the current namespace is thread
|
|
// local so actions that set and reset namespaces should use LockOSThread
|
|
// to make sure the namespace doesn't change due to a goroutine switch.
|
|
// It is best to close NsHandles when you are done with them. This can be
|
|
// accomplished via a `defer ns.Close()` on the handle. Changing namespaces
|
|
// requires elevated privileges, so in most cases this code needs to be run
|
|
// as root.
|
|
package netns
|
|
|
|
import (
|
|
"fmt"
|
|
"syscall"
|
|
)
|
|
|
|
// NsHandle is a handle to a network namespace. It can be cast directly
|
|
// to an int and used as a file descriptor.
|
|
type NsHandle int
|
|
|
|
// Equal determines if two network handles refer to the same network
|
|
// namespace. This is done by comparing the device and inode that the
|
|
// file descriptors point to.
|
|
func (ns NsHandle) Equal(other NsHandle) bool {
|
|
if ns == other {
|
|
return true
|
|
}
|
|
var s1, s2 syscall.Stat_t
|
|
if err := syscall.Fstat(int(ns), &s1); err != nil {
|
|
return false
|
|
}
|
|
if err := syscall.Fstat(int(other), &s2); err != nil {
|
|
return false
|
|
}
|
|
return (s1.Dev == s2.Dev) && (s1.Ino == s2.Ino)
|
|
}
|
|
|
|
// String shows the file descriptor number and its dev and inode.
|
|
func (ns NsHandle) String() string {
|
|
var s syscall.Stat_t
|
|
if ns == -1 {
|
|
return "NS(None)"
|
|
}
|
|
if err := syscall.Fstat(int(ns), &s); err != nil {
|
|
return fmt.Sprintf("NS(%d: unknown)", ns)
|
|
}
|
|
return fmt.Sprintf("NS(%d: %d, %d)", ns, s.Dev, s.Ino)
|
|
}
|
|
|
|
// UniqueId returns a string which uniquely identifies the namespace
|
|
// associated with the network handle.
|
|
func (ns NsHandle) UniqueId() string {
|
|
var s syscall.Stat_t
|
|
if ns == -1 {
|
|
return "NS(none)"
|
|
}
|
|
if err := syscall.Fstat(int(ns), &s); err != nil {
|
|
return "NS(unknown)"
|
|
}
|
|
return fmt.Sprintf("NS(%d:%d)", s.Dev, s.Ino)
|
|
}
|
|
|
|
// IsOpen returns true if Close() has not been called.
|
|
func (ns NsHandle) IsOpen() bool {
|
|
return ns != -1
|
|
}
|
|
|
|
// Close closes the NsHandle and resets its file descriptor to -1.
|
|
// It is not safe to use an NsHandle after Close() is called.
|
|
func (ns *NsHandle) Close() error {
|
|
if err := syscall.Close(int(*ns)); err != nil {
|
|
return err
|
|
}
|
|
(*ns) = -1
|
|
return nil
|
|
}
|
|
|
|
// None gets an empty (closed) NsHandle.
|
|
func None() NsHandle {
|
|
return NsHandle(-1)
|
|
}
|