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