75 lines
2.1 KiB
Go
75 lines
2.1 KiB
Go
// Package ipamutils provides utililty functions for ipam management
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package ipamutils
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import (
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"fmt"
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"net"
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"github.com/docker/libnetwork/netutils"
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"github.com/docker/libnetwork/osl"
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"github.com/docker/libnetwork/resolvconf"
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"github.com/vishvananda/netlink"
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)
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// ElectInterfaceAddresses looks for an interface on the OS with the specified name
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// and returns its IPv4 and IPv6 addresses in CIDR form. If the interface does not exist,
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// it chooses from a predifined list the first IPv4 address which does not conflict
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// with other interfaces on the system.
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func ElectInterfaceAddresses(name string) (*net.IPNet, []*net.IPNet, error) {
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var (
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v4Net *net.IPNet
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v6Nets []*net.IPNet
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err error
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)
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defer osl.InitOSContext()()
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link, _ := netlink.LinkByName(name)
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if link != nil {
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v4addr, err := netlink.AddrList(link, netlink.FAMILY_V4)
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if err != nil {
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return nil, nil, err
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}
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v6addr, err := netlink.AddrList(link, netlink.FAMILY_V6)
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if err != nil {
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return nil, nil, err
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}
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if len(v4addr) > 0 {
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v4Net = v4addr[0].IPNet
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}
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for _, nlAddr := range v6addr {
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v6Nets = append(v6Nets, nlAddr.IPNet)
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}
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}
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if link == nil || v4Net == nil {
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// Choose from predifined broad networks
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v4Net, err = FindAvailableNetwork(PredefinedBroadNetworks)
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if err != nil {
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return nil, nil, err
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}
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}
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return v4Net, v6Nets, nil
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}
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// FindAvailableNetwork returns a network from the passed list which does not
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// overlap with existing interfaces in the system
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func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
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// We don't check for an error here, because we don't really care if we
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// can't read /etc/resolv.conf. So instead we skip the append if resolvConf
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// is nil. It either doesn't exist, or we can't read it for some reason.
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var nameservers []string
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if rc, err := resolvconf.Get(); err == nil {
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nameservers = resolvconf.GetNameserversAsCIDR(rc.Content)
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}
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for _, nw := range list {
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if err := netutils.CheckNameserverOverlaps(nameservers, nw); err == nil {
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if err := netutils.CheckRouteOverlaps(nw); err == nil {
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return nw, nil
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}
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}
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}
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return nil, fmt.Errorf("no available network")
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}
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