/usr/share/gocode/src/github.com/opencontainers/runc/libcontainer/network_linux.go is in golang-github-opencontainers-runc-dev 1.0.0~rc4+dfsg1-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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package libcontainer
import (
"fmt"
"io/ioutil"
"net"
"path/filepath"
"strconv"
"strings"
"github.com/opencontainers/runc/libcontainer/configs"
"github.com/opencontainers/runc/libcontainer/utils"
"github.com/vishvananda/netlink"
)
var strategies = map[string]networkStrategy{
"veth": &veth{},
"loopback": &loopback{},
}
// networkStrategy represents a specific network configuration for
// a container's networking stack
type networkStrategy interface {
create(*network, int) error
initialize(*network) error
detach(*configs.Network) error
attach(*configs.Network) error
}
// getStrategy returns the specific network strategy for the
// provided type.
func getStrategy(tpe string) (networkStrategy, error) {
s, exists := strategies[tpe]
if !exists {
return nil, fmt.Errorf("unknown strategy type %q", tpe)
}
return s, nil
}
// Returns the network statistics for the network interfaces represented by the NetworkRuntimeInfo.
func getNetworkInterfaceStats(interfaceName string) (*NetworkInterface, error) {
out := &NetworkInterface{Name: interfaceName}
// This can happen if the network runtime information is missing - possible if the
// container was created by an old version of libcontainer.
if interfaceName == "" {
return out, nil
}
type netStatsPair struct {
// Where to write the output.
Out *uint64
// The network stats file to read.
File string
}
// Ingress for host veth is from the container. Hence tx_bytes stat on the host veth is actually number of bytes received by the container.
netStats := []netStatsPair{
{Out: &out.RxBytes, File: "tx_bytes"},
{Out: &out.RxPackets, File: "tx_packets"},
{Out: &out.RxErrors, File: "tx_errors"},
{Out: &out.RxDropped, File: "tx_dropped"},
{Out: &out.TxBytes, File: "rx_bytes"},
{Out: &out.TxPackets, File: "rx_packets"},
{Out: &out.TxErrors, File: "rx_errors"},
{Out: &out.TxDropped, File: "rx_dropped"},
}
for _, netStat := range netStats {
data, err := readSysfsNetworkStats(interfaceName, netStat.File)
if err != nil {
return nil, err
}
*(netStat.Out) = data
}
return out, nil
}
// Reads the specified statistics available under /sys/class/net/<EthInterface>/statistics
func readSysfsNetworkStats(ethInterface, statsFile string) (uint64, error) {
data, err := ioutil.ReadFile(filepath.Join("/sys/class/net", ethInterface, "statistics", statsFile))
if err != nil {
return 0, err
}
return strconv.ParseUint(strings.TrimSpace(string(data)), 10, 64)
}
// loopback is a network strategy that provides a basic loopback device
type loopback struct {
}
func (l *loopback) create(n *network, nspid int) error {
return nil
}
func (l *loopback) initialize(config *network) error {
return netlink.LinkSetUp(&netlink.Device{LinkAttrs: netlink.LinkAttrs{Name: "lo"}})
}
func (l *loopback) attach(n *configs.Network) (err error) {
return nil
}
func (l *loopback) detach(n *configs.Network) (err error) {
return nil
}
// veth is a network strategy that uses a bridge and creates
// a veth pair, one that is attached to the bridge on the host and the other
// is placed inside the container's namespace
type veth struct {
}
func (v *veth) detach(n *configs.Network) (err error) {
return netlink.LinkSetMaster(&netlink.Device{LinkAttrs: netlink.LinkAttrs{Name: n.HostInterfaceName}}, nil)
}
// attach a container network interface to an external network
func (v *veth) attach(n *configs.Network) (err error) {
brl, err := netlink.LinkByName(n.Bridge)
if err != nil {
return err
}
br, ok := brl.(*netlink.Bridge)
if !ok {
return fmt.Errorf("Wrong device type %T", brl)
}
host, err := netlink.LinkByName(n.HostInterfaceName)
if err != nil {
return err
}
if err := netlink.LinkSetMaster(host, br); err != nil {
return err
}
if err := netlink.LinkSetMTU(host, n.Mtu); err != nil {
return err
}
if n.HairpinMode {
if err := netlink.LinkSetHairpin(host, true); err != nil {
return err
}
}
if err := netlink.LinkSetUp(host); err != nil {
return err
}
return nil
}
func (v *veth) create(n *network, nspid int) (err error) {
tmpName, err := v.generateTempPeerName()
if err != nil {
return err
}
n.TempVethPeerName = tmpName
if n.Bridge == "" {
return fmt.Errorf("bridge is not specified")
}
veth := &netlink.Veth{
LinkAttrs: netlink.LinkAttrs{
Name: n.HostInterfaceName,
TxQLen: n.TxQueueLen,
},
PeerName: n.TempVethPeerName,
}
if err := netlink.LinkAdd(veth); err != nil {
return err
}
defer func() {
if err != nil {
netlink.LinkDel(veth)
}
}()
if err := v.attach(&n.Network); err != nil {
return err
}
child, err := netlink.LinkByName(n.TempVethPeerName)
if err != nil {
return err
}
return netlink.LinkSetNsPid(child, nspid)
}
func (v *veth) generateTempPeerName() (string, error) {
return utils.GenerateRandomName("veth", 7)
}
func (v *veth) initialize(config *network) error {
peer := config.TempVethPeerName
if peer == "" {
return fmt.Errorf("peer is not specified")
}
child, err := netlink.LinkByName(peer)
if err != nil {
return err
}
if err := netlink.LinkSetDown(child); err != nil {
return err
}
if err := netlink.LinkSetName(child, config.Name); err != nil {
return err
}
// get the interface again after we changed the name as the index also changes.
if child, err = netlink.LinkByName(config.Name); err != nil {
return err
}
if config.MacAddress != "" {
mac, err := net.ParseMAC(config.MacAddress)
if err != nil {
return err
}
if err := netlink.LinkSetHardwareAddr(child, mac); err != nil {
return err
}
}
ip, err := netlink.ParseAddr(config.Address)
if err != nil {
return err
}
if err := netlink.AddrAdd(child, ip); err != nil {
return err
}
if config.IPv6Address != "" {
ip6, err := netlink.ParseAddr(config.IPv6Address)
if err != nil {
return err
}
if err := netlink.AddrAdd(child, ip6); err != nil {
return err
}
}
if err := netlink.LinkSetMTU(child, config.Mtu); err != nil {
return err
}
if err := netlink.LinkSetUp(child); err != nil {
return err
}
if config.Gateway != "" {
gw := net.ParseIP(config.Gateway)
if err := netlink.RouteAdd(&netlink.Route{
Scope: netlink.SCOPE_UNIVERSE,
LinkIndex: child.Attrs().Index,
Gw: gw,
}); err != nil {
return err
}
}
if config.IPv6Gateway != "" {
gw := net.ParseIP(config.IPv6Gateway)
if err := netlink.RouteAdd(&netlink.Route{
Scope: netlink.SCOPE_UNIVERSE,
LinkIndex: child.Attrs().Index,
Gw: gw,
}); err != nil {
return err
}
}
return nil
}
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