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netutil.go
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netutil.go
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// Copyright 2015 PLUMgrid
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// vim: set ts=8:sts=8:sw=8:noet
package hover
import (
"runtime"
"github.com/vishvananda/netlink"
"github.com/vishvananda/netns"
)
var (
initNs netns.NsHandle
)
func nsContext() func() {
runtime.LockOSThread()
return func() {
if err := netns.Set(initNs); err != nil {
panic(err)
}
runtime.UnlockOSThread()
}
}
func init() {
initNs, _ = netns.Get()
}
func RunInNs(fd netns.NsHandle, fn func() error) error {
defer nsContext()()
if err := netns.Set(fd); err != nil {
return err
}
if err := fn(); err != nil {
return err
}
return nil
}
// NewVeth creates a veth pair with the given name, moves the peer into the
// namespace n, then renames the peer to dstName and assigns the provided ip.
// If insideFn is not nil, also executes that function in the context of the
// given namespace.
func NewVeth(n netns.NsHandle, name, dstName, ip string, insideFn func(netlink.Link) error) (link *netlink.Veth, err error) {
l := &netlink.Veth{
LinkAttrs: netlink.LinkAttrs{
Name: name,
},
PeerName: name + "_",
}
if err = netlink.LinkAdd(l); err != nil {
return
}
defer func() {
if err != nil {
netlink.LinkDel(l)
}
}()
otherL, err := netlink.LinkByName(l.PeerName)
if err != nil {
return
}
if err = netlink.LinkSetNsFd(otherL, int(n)); err != nil {
return
}
err = RunInNs(n, func() error {
lo, err := netlink.LinkByName("lo")
if err != nil {
return err
}
err = netlink.LinkSetUp(lo)
if err != nil {
return err
}
l, err := netlink.LinkByName(name + "_")
if err != nil {
return err
}
if err = netlink.LinkSetName(l, dstName); err != nil {
return err
}
l.Attrs().Name = dstName
a, err := netlink.ParseIPNet(ip)
if err != nil {
return err
}
if err := netlink.AddrAdd(l, &netlink.Addr{IPNet: a}); err != nil {
return err
}
if insideFn != nil {
if err := insideFn(l); err != nil {
return err
}
}
if err = netlink.LinkSetUp(l); err != nil {
return err
}
return nil
})
if err != nil {
return
}
if err = netlink.LinkSetUp(l); err != nil {
return
}
link = l
return
}
// NewNs creates a new network namespace and returns a handle to it. The caller
// is responsible for calling Close on the handle when done with it.
func NewNs() netns.NsHandle {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
origns, err := netns.Get()
if err != nil {
panic(err)
}
n, err := netns.New()
if err != nil {
panic(err)
}
if err := netns.Set(origns); err != nil {
panic(err)
}
return n
}