101 lines
2.6 KiB
Go
101 lines
2.6 KiB
Go
package net
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import (
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"fmt"
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"net"
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"syscall"
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"github.com/vishvananda/netlink/nl"
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)
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// Wait for an interface to come up.
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func EnsureInterface(ifaceName string) (*net.Interface, error) {
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s, err := nl.Subscribe(syscall.NETLINK_ROUTE, syscall.RTNLGRP_LINK)
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if err != nil {
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return nil, err
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}
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defer s.Close()
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iface, err := ensureInterface(s, ifaceName)
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if err != nil {
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return nil, err
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}
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return iface, err
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}
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func ensureInterface(s *nl.NetlinkSocket, ifaceName string) (*net.Interface, error) {
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if iface, err := findInterface(ifaceName); err == nil {
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return iface, nil
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}
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netlinkReceiveUntil(s, matchIfName(ifaceName))
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iface, err := findInterface(ifaceName)
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return iface, err
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}
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// Wait for an interface to come up and have a route added to the multicast subnet.
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// This matches the behaviour in 'weave attach', which is the only context in which
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// we expect this to be called. If you change one, change the other to match.
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func EnsureInterfaceAndMcastRoute(ifaceName string) (*net.Interface, error) {
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s, err := nl.Subscribe(syscall.NETLINK_ROUTE, syscall.RTNLGRP_LINK, syscall.RTNLGRP_IPV4_ROUTE)
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if err != nil {
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return nil, err
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}
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defer s.Close()
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iface, err := ensureInterface(s, ifaceName)
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if err != nil {
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return nil, err
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}
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dest := net.IPv4(224, 0, 0, 0)
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if CheckRouteExists(ifaceName, dest) {
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return iface, err
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}
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netlinkReceiveUntil(s, matchRoute(ifaceName, dest))
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return iface, err
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}
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func findInterface(ifaceName string) (iface *net.Interface, err error) {
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if iface, err = net.InterfaceByName(ifaceName); err != nil {
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return iface, fmt.Errorf("Unable to find interface %s", ifaceName)
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}
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if 0 == (net.FlagUp & iface.Flags) {
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return iface, fmt.Errorf("Interface %s is not up", ifaceName)
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}
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return
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}
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func netlinkReceiveUntil(s *nl.NetlinkSocket, f func(syscall.NetlinkMessage) (bool, error)) error {
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for {
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msgs, err := s.Receive()
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if err != nil {
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return err
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}
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for _, m := range msgs {
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if done, err := f(m); done {
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return err
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}
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}
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}
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}
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func matchIfName(ifaceName string) func(m syscall.NetlinkMessage) (bool, error) {
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return func(m syscall.NetlinkMessage) (bool, error) {
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switch m.Header.Type {
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case syscall.RTM_NEWLINK: // receive this type for link 'up'
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ifmsg := nl.DeserializeIfInfomsg(m.Data)
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attrs, err := syscall.ParseNetlinkRouteAttr(&m)
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if err != nil {
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return true, err
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}
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name := ""
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for _, attr := range attrs {
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if attr.Attr.Type == syscall.IFA_LABEL {
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name = string(attr.Value[:len(attr.Value)-1])
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}
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}
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if ifaceName == name && ifmsg.Flags&syscall.IFF_UP != 0 {
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return true, nil
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}
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}
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return false, nil
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}
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}
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