100 lines
2.1 KiB
Go
100 lines
2.1 KiB
Go
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package netns
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// inspired from https://github.com/vishvananda/netns/blob/master/nshandle_linux.go#L11
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import (
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"fmt"
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"golang.org/x/sys/unix"
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"os"
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"path"
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)
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const bindMountPath = "/run/netns"
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// NsHandle is a handle to a network namespace. It can be cast directly
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// to an int and used as a file descriptor.
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type NsHandle struct {
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fd int
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name string
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}
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// persist and bind mount net namespace to `/run/netns`
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func (ns NsHandle) persist() error {
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if _, err := os.Stat(bindMountPath); os.IsNotExist(err) {
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err = os.MkdirAll(bindMountPath, 0o755)
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if err != nil {
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return err
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}
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}
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namedPath := path.Join(bindMountPath, ns.name)
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f, err := os.OpenFile(namedPath, os.O_CREATE|os.O_EXCL, 0o444)
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if err != nil {
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return err
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}
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err = f.Close()
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if err != nil {
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return err
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}
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nsPath := GetPath()
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err = unix.Mount(nsPath, namedPath, "bind", unix.MS_BIND, "")
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if err != nil {
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return err
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}
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return nil
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}
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// Equal determines if two network handles refer to the same network
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// namespace. This is done by comparing the device and inode that the
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// file descriptors point to.
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func (ns NsHandle) Equal(other NsHandle) bool {
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if ns == other {
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return true
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}
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var s1, s2 unix.Stat_t
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if err := unix.Fstat(ns.fd, &s1); err != nil {
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return false
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}
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if err := unix.Fstat(other.fd, &s2); err != nil {
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return false
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}
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return (s1.Dev == s2.Dev) && (s1.Ino == s2.Ino)
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}
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// String shows the file descriptor number and its dev and inode.
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func (ns NsHandle) String() string {
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if ns.fd == -1 {
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return "NS(none)"
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}
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var s unix.Stat_t
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if err := unix.Fstat(ns.fd, &s); err != nil {
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return fmt.Sprintf("NS(%d: unknown)", ns)
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}
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return fmt.Sprintf("NS(%d: %d, %d)", ns, s.Dev, s.Ino)
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}
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// IsOpen returns true if Close() has not been called.
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func (ns NsHandle) IsOpen() bool {
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return ns.fd != -1
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}
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// Close closes the NsHandle and resets its file descriptor to -1.
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// It is not safe to use an NsHandle after Close() is called.
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func (ns NsHandle) Close() error {
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if err := unix.Close(ns.fd); err != nil {
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return err
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}
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ns.fd = -1
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return nil
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}
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// None gets an empty (closed) NsHandle.
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func None() NsHandle {
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return NsHandle{
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fd: -1,
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}
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}
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