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moby--moby/libnetwork/ipamutils/utils_linux.go

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