Martynas Pumputis
fd0a7efa23
The #2418 has changed a behaviour of "weave ps" which outputs "Link not found" in the case of weave not running. The previous behaviour was to output an empty line.
66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
package net
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import (
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"errors"
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"runtime"
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"github.com/vishvananda/netlink"
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"github.com/vishvananda/netns"
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)
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var ErrLinkNotFound = errors.New("Link not found")
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// NB: The following function is unsafe, because:
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// - It changes a network namespace (netns) of an OS thread which runs
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// the function. During execution, the Go runtime might clone a new OS thread
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// for scheduling other go-routines, thus they might end up running in
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// a "wrong" netns.
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// - runtime.LockOSThread does not guarantee that a spawned go-routine on
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// the locked thread will be run by it. Thus, the work function is
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// not allowed to spawn any go-routine which is dependent on the given netns.
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// Please see https://github.com/weaveworks/weave/issues/2388#issuecomment-228365069
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// for more details and make sure that you understand the implications before
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// using the function!
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func WithNetNSUnsafe(ns netns.NsHandle, work func() error) error {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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oldNs, err := netns.Get()
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if err == nil {
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defer oldNs.Close()
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err = netns.Set(ns)
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if err == nil {
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defer netns.Set(oldNs)
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err = work()
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}
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}
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return err
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}
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func WithNetNSLinkUnsafe(ns netns.NsHandle, ifName string, work func(link netlink.Link) error) error {
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return WithNetNSUnsafe(ns, func() error {
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link, err := netlink.LinkByName(ifName)
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if err != nil {
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if err.Error() == errors.New("Link not found").Error() {
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return ErrLinkNotFound
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}
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return err
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}
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return work(link)
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})
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}
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func WithNetNSLinkByPidUnsafe(pid int, ifName string, work func(link netlink.Link) error) error {
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ns, err := netns.GetFromPid(pid)
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if err != nil {
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return err
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}
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defer ns.Close()
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return WithNetNSLinkUnsafe(ns, ifName, work)
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}
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