ducky/devices
2015-11-12
ducky/devices/vendor/code.google.com/p/go-uuid/uuid/node.go
Initial attempt. Create the basic types (Device, DeviceType, DeviceChange) that we'll be using in the service. Also, create our Storer interface, and the helper methods to store, retrieve, and update information in the datastore. Also, we're using Godep, so check in our Godeps folder and the vendor folder. Note that this only works on Go 1.5 and later, with the GO15VENDOREXPERIMENT environment variable set to 1.
1 // Copyright 2011 Google Inc. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 package uuid
7 import "net"
9 var (
10 interfaces []net.Interface // cached list of interfaces
11 ifname string // name of interface being used
12 nodeID []byte // hardware for version 1 UUIDs
13 )
15 // NodeInterface returns the name of the interface from which the NodeID was
16 // derived. The interface "user" is returned if the NodeID was set by
17 // SetNodeID.
18 func NodeInterface() string {
19 return ifname
20 }
22 // SetNodeInterface selects the hardware address to be used for Version 1 UUIDs.
23 // If name is "" then the first usable interface found will be used or a random
24 // Node ID will be generated. If a named interface cannot be found then false
25 // is returned.
26 //
27 // SetNodeInterface never fails when name is "".
28 func SetNodeInterface(name string) bool {
29 if interfaces == nil {
30 var err error
31 interfaces, err = net.Interfaces()
32 if err != nil && name != "" {
33 return false
34 }
35 }
37 for _, ifs := range interfaces {
38 if len(ifs.HardwareAddr) >= 6 && (name == "" || name == ifs.Name) {
39 if setNodeID(ifs.HardwareAddr) {
40 ifname = ifs.Name
41 return true
42 }
43 }
44 }
46 // We found no interfaces with a valid hardware address. If name
47 // does not specify a specific interface generate a random Node ID
48 // (section 4.1.6)
49 if name == "" {
50 if nodeID == nil {
51 nodeID = make([]byte, 6)
52 }
53 randomBits(nodeID)
54 return true
55 }
56 return false
57 }
59 // NodeID returns a slice of a copy of the current Node ID, setting the Node ID
60 // if not already set.
61 func NodeID() []byte {
62 if nodeID == nil {
63 SetNodeInterface("")
64 }
65 nid := make([]byte, 6)
66 copy(nid, nodeID)
67 return nid
68 }
70 // SetNodeID sets the Node ID to be used for Version 1 UUIDs. The first 6 bytes
71 // of id are used. If id is less than 6 bytes then false is returned and the
72 // Node ID is not set.
73 func SetNodeID(id []byte) bool {
74 if setNodeID(id) {
75 ifname = "user"
76 return true
77 }
78 return false
79 }
81 func setNodeID(id []byte) bool {
82 if len(id) < 6 {
83 return false
84 }
85 if nodeID == nil {
86 nodeID = make([]byte, 6)
87 }
88 copy(nodeID, id)
89 return true
90 }
92 // NodeID returns the 6 byte node id encoded in uuid. It returns nil if uuid is
93 // not valid. The NodeID is only well defined for version 1 and 2 UUIDs.
94 func (uuid UUID) NodeID() []byte {
95 if len(uuid) != 16 {
96 return nil
97 }
98 node := make([]byte, 6)
99 copy(node, uuid[10:])
100 return node
101 }