faasd/pkg/weave/weave.go
Alex Ellis (OpenFaaS Ltd) 5c43b4c802 Bind DNS names through /etc/hosts
Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>
2019-12-21 12:44:01 +00:00

132 lines
3.2 KiB
Go

// Copyright Weaveworks
// github.com/weaveworks/weave/net
package weave
import (
"fmt"
"net"
"os"
"github.com/vishvananda/netlink"
"github.com/vishvananda/netns"
)
type Dev struct {
Name string `json:"Name,omitempty"`
MAC net.HardwareAddr `json:"MAC,omitempty"`
CIDRs []*net.IPNet `json:"CIDRs,omitempty"`
}
func linkToNetDev(link netlink.Link) (Dev, error) {
addrs, err := netlink.AddrList(link, netlink.FAMILY_V4)
if err != nil {
return Dev{}, err
}
netDev := Dev{Name: link.Attrs().Name, MAC: link.Attrs().HardwareAddr}
for _, addr := range addrs {
netDev.CIDRs = append(netDev.CIDRs, addr.IPNet)
}
return netDev, nil
}
// ConnectedToBridgeVethPeerIds returns peer indexes of veth links connected to
// the given bridge. The peer index is used to query from a container netns
// whether the container is connected to the bridge.
func ConnectedToBridgeVethPeerIds(bridgeName string) ([]int, error) {
var ids []int
br, err := netlink.LinkByName(bridgeName)
if err != nil {
return nil, err
}
links, err := netlink.LinkList()
if err != nil {
return nil, err
}
for _, link := range links {
if _, isveth := link.(*netlink.Veth); isveth && link.Attrs().MasterIndex == br.Attrs().Index {
peerID := link.Attrs().ParentIndex
if peerID == 0 {
// perhaps running on an older kernel where ParentIndex doesn't work.
// as fall-back, assume the peers are consecutive
peerID = link.Attrs().Index - 1
}
ids = append(ids, peerID)
}
}
return ids, nil
}
// Lookup the weave interface of a container
func GetWeaveNetDevs(processID int) ([]Dev, error) {
peerIDs, err := ConnectedToBridgeVethPeerIds("weave")
if err != nil {
return nil, err
}
return GetNetDevsByVethPeerIds(processID, peerIDs)
}
func GetNetDevsByVethPeerIds(processID int, peerIDs []int) ([]Dev, error) {
// Bail out if this container is running in the root namespace
netnsRoot, err := netns.GetFromPid(1)
if err != nil {
return nil, fmt.Errorf("unable to open root namespace: %s", err)
}
defer netnsRoot.Close()
netnsContainer, err := netns.GetFromPid(processID)
if err != nil {
// Unable to find a namespace for this process - just return nothing
if os.IsNotExist(err) {
return nil, nil
}
return nil, fmt.Errorf("unable to open process %d namespace: %s", processID, err)
}
defer netnsContainer.Close()
if netnsRoot.Equal(netnsContainer) {
return nil, nil
}
// convert list of peerIDs into a map for faster lookup
indexes := make(map[int]struct{})
for _, id := range peerIDs {
indexes[id] = struct{}{}
}
var netdevs []Dev
err = WithNetNS(netnsContainer, func() error {
links, err := netlink.LinkList()
if err != nil {
return err
}
for _, link := range links {
if _, found := indexes[link.Attrs().Index]; found {
netdev, err := linkToNetDev(link)
if err != nil {
return err
}
netdevs = append(netdevs, netdev)
}
}
return nil
})
return netdevs, err
}
// Get the weave bridge interface.
// NB: Should be called from the root network namespace.
func GetBridgeNetDev(bridgeName string) (Dev, error) {
link, err := netlink.LinkByName(bridgeName)
if err != nil {
return Dev{}, err
}
return linkToNetDev(link)
}