func setupVeth(netns string, br *netlink.Bridge, ifName string, mtu int) error {
var hostVethName string
err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) error {
// create the veth pair in the container and move host end into host netns
hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
if err != nil {
return err
}
hostVethName = hostVeth.Attrs().Name
return nil
})
if err != nil {
return err
}
// need to lookup hostVeth again as its index has changed during ns move
hostVeth, err := netlink.LinkByName(hostVethName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", hostVethName, err)
}
// connect host veth end to the bridge
if err = netlink.LinkSetMaster(hostVeth, br); err != nil {
return fmt.Errorf("failed to connect %q to bridge %v: %v", hostVethName, br.Attrs().Name, err)
}
return nil
}
func setupContainerVeth(netns, ifName string, mtu int, pr *types.Result) (string, error) {
// The IPAM result will be something like IP=192.168.3.5/24, GW=192.168.3.1.
// What we want is really a point-to-point link but veth does not support IFF_POINTOPONT.
// Next best thing would be to let it ARP but set interface to 192.168.3.5/32 and
// add a route like "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// Unfortunately that won't work as the GW will be outside the interface's subnet.
// Our solution is to configure the interface with 192.168.3.5/24, then delete the
// "192.168.3.0/24 dev $ifName" route that was automatically added. Then we add
// "192.168.3.1/32 dev $ifName" and "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// In other words we force all traffic to ARP via the gateway except for GW itself.
var hostVethName string
err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) error {
hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
if err != nil {
return err
}
if err = ipam.ConfigureIface(ifName, pr); err != nil {
return err
}
contVeth, err := netlink.LinkByName(ifName)
if err != nil {
return err
}
// Delete the route that was automatically added
route := netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_LINK,
Src: pr.IP4.IP.IP,
}
if err := netlink.RouteDel(&route); err != nil {
return err
}
for _, r := range []netlink.Route{
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.Gateway,
Mask: net.CIDRMask(32, 32),
},
Scope: netlink.SCOPE_LINK,
Src: pr.IP4.IP.IP,
},
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_UNIVERSE,
Gw: pr.IP4.Gateway,
Src: pr.IP4.IP.IP,
},
} {
if err := netlink.RouteAdd(&r); err != nil {
return err
}
}
hostVethName = hostVeth.Attrs().Name
return nil
})
return hostVethName, err
}
