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Merged
merged 2 commits into from
Jul 24, 2016
Merged

Update #2

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f6ccf05
Refactoring and better error checking
PouuleT Jul 24, 2016
c7b74b5
Add the possibility to specify the nsPath
PouuleT Jul 24, 2016
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84 changes: 53 additions & 31 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ import (
"github.com/vishvananda/netns"
)

var ip, command, gateway, intf, logLevel string
var ip, command, gateway, intf, logLevel, nsPath string
var log = logrus.New()

func init() {
Expand All @@ -26,6 +26,12 @@ func init() {
flag.StringVar(&command, "command", "ip route", "command to be executed")
flag.StringVar(&gateway, "gw", "", "gateway of the request")
flag.StringVar(&logLevel, "log-level", "info", "min level of logs to print")
flag.StringVar(
&nsPath,
"ns-path",
fmt.Sprintf("/var/run/netns/w000t%d", os.Getpid()),
"path of the temporary namespace to be created, default will be /var/run/netns/w000t$PID",
)
flag.Parse()
}

Expand Down Expand Up @@ -58,18 +64,17 @@ func main() {
// Check the /run/netns mount
err = setupNetnsDir()
if err != nil {
log.Warn("Error setting up netns", err)
log.Warn("Error setting up netns: ", err)
return
}

eth, err := netlink.LinkByName(intf)
if err != nil {
log.Warnf("error while getting %s : %s", intf, err)
log.Warnf("Error while getting %s : %s", intf, err)
return
}
log.Debugf("%s : %+v", intf, eth.Attrs().Flags)

// askAndPrint()
// ============================== Create the macVLAN

log.Debug("Create a new macVlan")
Expand All @@ -96,26 +101,27 @@ func main() {

link, err := netlink.LinkByName("peth0")
if err != nil {
log.Warn("error while getting macVlan :", err)
log.Warn("Error while getting macVlan: ", err)
return
}
log.Debugf("MacVlan created : %+v", link)

// askAndPrint()
// ============================== Create the new Namespace

newns, err := newNS()
if err != nil {
log.Warn("error while creating new NS :", err)
log.Warn("error while creating new NS: ", err)
return
}
defer delNS(newns)
defer deleteNS(newns)

log.Debug("Go back to original NS")

netns.Set(origns)

// askAndPrint()
err = netns.Set(origns)
if err != nil {
log.Warn("Failed to change the namespace: ", err)
return
}

// ============================== Add the MacVlan in the new Namespace

Expand All @@ -129,46 +135,62 @@ func main() {

log.Debug("Enter the namespace")

netns.Set(*newns)
err = netns.Set(*newns)
if err != nil {
log.Warn("Failed to enter the namespace: ", err)
return
}

// ============================= Configure the new namespace to configure it

addr, err := netlink.ParseAddr(ip)
if err != nil {
log.Warn("Failed to parse ip", err)
log.Warn("Failed to parse the given IP: ", err)
return
}

log.Debugf("Add the addr to the macVlan: %+v", addr)
netlink.AddrAdd(link, addr)
// ============================= Set the address in the namespace
err = netlink.AddrAdd(link, addr)
if err != nil {
log.Warn("Failed to add the IP to the macVlan: ", err)
return
}
gwaddr := net.ParseIP(gateway)

log.Debug("Set the macVlan interface UP")
// ============================= Set the link up in the namespace
err = netlink.LinkSetUp(link)
if err != nil {
log.Warn("Error while setting up the interface peth0", err)
log.Warn("Error while setting up the interface peth0: ", err)
return
}

log.Debugf("Set %s as the route", gwaddr)
// ============================= Set the default route in the namespace
err = netlink.RouteAdd(&netlink.Route{
Scope: netlink.SCOPE_UNIVERSE,
LinkIndex: link.Attrs().Index,
Gw: gwaddr,
})
if err != nil {
log.Warn("Error while setting up route on interface peth0", err)
log.Warn("Error while setting up route on interface peth0 :", err)
return
}

// ============================= Execute the command in the namespace
err = execCmd(command)
if err != nil {
log.Warn("error while checking IP", err)
log.Warn("Error while running command : ", err)
}

log.Debug("Go back to orignal namspace")

netns.Set(origns)
err = netns.Set(origns)
if err != nil {
log.Warn("Error while going back to the original namespace: ", err)
return
}

log.Debug("Cleaning ...")
}
Expand Down Expand Up @@ -238,7 +260,7 @@ func newNS() (*netns.NsHandle, error) {
}

src := fmt.Sprintf("/proc/%d/ns/net", pid)
target := getNsName()
target := nsPath

log.Debugf("Create file %s", target)
// Create an empty file
Expand All @@ -248,9 +270,14 @@ func newNS() (*netns.NsHandle, error) {
return nil, err
}
// And close it
file.Close()
err = file.Close()
if err != nil {
log.Warn(err)
return nil, err
}

log.Debugf("Mount %s", target)

// Mount the namespace in /var/run/netns so it becomes a named namespace
if err := syscall.Mount(src, target, "proc", syscall.MS_BIND|syscall.MS_NOEXEC|syscall.MS_NOSUID|syscall.MS_NODEV, ""); err != nil {
return nil, err
Expand All @@ -259,33 +286,28 @@ func newNS() (*netns.NsHandle, error) {
return &newns, nil
}

// getNsName gets the default namespace name : w000t$PID$
func getNsName() string {
pid := os.Getpid()
return fmt.Sprintf("/var/run/netns/w000t%d", pid)
}

func delNS(ns *netns.NsHandle) error {
// deleteNS will delete the given namespace
func deleteNS(ns *netns.NsHandle) error {
// Close the nsHandler
err := ns.Close()
if err != nil {
log.Warn("Error while closing", err)
log.Warn("Error while closing the namespace: ", err)
return err
}

// Unmount the named namespace
target := getNsName()
target := nsPath

log.Debugf("Unmounting %s", target)
if err := syscall.Unmount(target, 0); err != nil {
log.Warn("Error while unmounting", err)
log.Warnf("Error while unmounting %s : %s", target, err)
return err
}

// Delete the namespace file
log.Debugf("Deleting %s", target)
if err := os.Remove(target); err != nil {
log.Warn(err)
log.Warn("Error while deleting %s : %s", target, err)
return err
}

Expand Down