k3s/pkg/netutil/iface.go

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package netutil
import (
"fmt"
"net"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
func GetIPFromInterface(ifaceName string) string {
ip, err := getIPFromInterface(ifaceName)
if err != nil {
logrus.Warn(errors.Wrap(err, "unable to get global unicast ip from interface name"))
} else {
logrus.Infof("Found ip %s from iface %s", ip, ifaceName)
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}
return ip
}
func getIPFromInterface(ifaceName string) (string, error) {
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return "", err
}
addrs, err := iface.Addrs()
if err != nil {
return "", err
}
if iface.Flags&net.FlagUp == 0 {
return "", fmt.Errorf("the interface %s is not up", ifaceName)
}
globalUnicasts := []string{}
globalUnicastsIPv6 := []string{}
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for _, addr := range addrs {
ip, _, err := net.ParseCIDR(addr.String())
if err != nil {
return "", errors.Wrapf(err, "unable to parse CIDR for interface %s", iface.Name)
}
// if not IPv4 adding it on IPv6 list
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if ip.To4() == nil {
if ip.IsGlobalUnicast() {
globalUnicastsIPv6 = append(globalUnicastsIPv6, ip.String())
}
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continue
}
if ip.IsGlobalUnicast() {
globalUnicasts = append(globalUnicasts, ip.String())
}
}
if len(globalUnicasts) > 1 {
return "", fmt.Errorf("multiple global unicast addresses defined for %s, please set ip from one of %v", ifaceName, globalUnicasts)
}
if len(globalUnicasts) == 1 && len(globalUnicastsIPv6) == 0 {
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return globalUnicasts[0], nil
} else if len(globalUnicastsIPv6) > 0 && len(globalUnicasts) == 1 {
return globalUnicasts[0] + "," + globalUnicastsIPv6[0], nil
} else if len(globalUnicastsIPv6) > 0 {
return globalUnicastsIPv6[0], nil
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}
return "", fmt.Errorf("can't find ip for interface %s", ifaceName)
}