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Copy pathinterface-ips.go
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69 lines (64 loc) · 2.23 KB
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/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"fmt"
"net"
"sort"
)
// byLastOctetValue implements sort.Interface used in sorting a list
// of ip address by their last octet value.
type byLastOctetValue []net.IP
func (n byLastOctetValue) Len() int { return len(n) }
func (n byLastOctetValue) Swap(i, j int) { n[i], n[j] = n[j], n[i] }
func (n byLastOctetValue) Less(i, j int) bool {
return []byte(n[i].To4())[3] < []byte(n[j].To4())[3]
}
// getInterfaceIPv4s is synonymous to net.InterfaceAddrs()
// returns net.IP IPv4 only representation of the net.Addr.
// Additionally the returned list is sorted by their last
// octet value.
//
// [The logic to sort by last octet is implemented to
// prefer CIDRs with higher octects, this in-turn skips the
// localhost/loopback address to be not preferred as the
// first ip on the list. Subsequently this list helps us print
// a user friendly message with appropriate values].
func getInterfaceIPv4s() ([]net.IP, error) {
addrs, err := net.InterfaceAddrs()
if err != nil {
return nil, fmt.Errorf("Unable to determine network interface address. %s", err)
}
// Go through each return network address and collate IPv4 addresses.
var nips []net.IP
for _, addr := range addrs {
if addr.Network() == "ip+net" {
var nip net.IP
// Attempt to parse the addr through CIDR.
nip, _, err = net.ParseCIDR(addr.String())
if err != nil {
return nil, fmt.Errorf("Unable to parse addrss %s, error %s", addr, err)
}
// Collect only IPv4 addrs.
if nip.To4() != nil {
nips = append(nips, nip)
}
}
}
// Sort the list of IPs by their last octet value.
sort.Sort(sort.Reverse(byLastOctetValue(nips)))
return nips, nil
}