forked from kubernetes/kubernetes
-
-
Notifications
You must be signed in to change notification settings - Fork 0
/
interface.go
278 lines (253 loc) · 6.75 KB
/
interface.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/*
Copyright 2016 The Kubernetes Authors All rights reserved.
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 net
import (
"bufio"
"encoding/hex"
"fmt"
"io"
"net"
"os"
"strings"
"github.com/golang/glog"
)
type Route struct {
Interface string
Destination net.IP
Gateway net.IP
// TODO: add more fields here if needed
}
func getRoutes(input io.Reader) ([]Route, error) {
routes := []Route{}
if input == nil {
return nil, fmt.Errorf("input is nil")
}
scanner := bufio.NewReader(input)
for {
line, err := scanner.ReadString('\n')
if err == io.EOF {
break
}
//ignore the headers in the route info
if strings.HasPrefix(line, "Iface") {
continue
}
fields := strings.Fields(line)
routes = append(routes, Route{})
route := &routes[len(routes)-1]
route.Interface = fields[0]
ip, err := parseIP(fields[1])
if err != nil {
return nil, err
}
route.Destination = ip
ip, err = parseIP(fields[2])
if err != nil {
return nil, err
}
route.Gateway = ip
}
return routes, nil
}
func parseIP(str string) (net.IP, error) {
if str == "" {
return nil, fmt.Errorf("input is nil")
}
bytes, err := hex.DecodeString(str)
if err != nil {
return nil, err
}
//TODO add ipv6 support
if len(bytes) != net.IPv4len {
return nil, fmt.Errorf("only IPv4 is supported")
}
bytes[0], bytes[1], bytes[2], bytes[3] = bytes[3], bytes[2], bytes[1], bytes[0]
return net.IP(bytes), nil
}
func isInterfaceUp(intf *net.Interface) bool {
if intf == nil {
return false
}
if intf.Flags&net.FlagUp != 0 {
glog.V(4).Infof("Interface %v is up", intf.Name)
return true
}
return false
}
//getFinalIP method receives all the IP addrs of a Interface
//and returns a nil if the address is Loopback, Ipv6, link-local or nil.
//It returns a valid IPv4 if an Ipv4 address is found in the array.
func getFinalIP(addrs []net.Addr) (net.IP, error) {
if len(addrs) > 0 {
for i := range addrs {
glog.V(4).Infof("Checking addr %s.", addrs[i].String())
ip, _, err := net.ParseCIDR(addrs[i].String())
if err != nil {
return nil, err
}
//Only IPv4
//TODO : add IPv6 support
if ip.To4() != nil {
if !ip.IsLoopback() && !ip.IsLinkLocalMulticast() && !ip.IsLinkLocalUnicast() {
glog.V(4).Infof("IP found %v", ip)
return ip, nil
} else {
glog.V(4).Infof("Loopback/link-local found %v", ip)
}
} else {
glog.V(4).Infof("%v is not a valid IPv4 address", ip)
}
}
}
return nil, nil
}
func getIPFromInterface(intfName string, nw networkInterfacer) (net.IP, error) {
intf, err := nw.InterfaceByName(intfName)
if err != nil {
return nil, err
}
if isInterfaceUp(intf) {
addrs, err := nw.Addrs(intf)
if err != nil {
return nil, err
}
glog.V(4).Infof("Interface %q has %d addresses :%v.", intfName, len(addrs), addrs)
finalIP, err := getFinalIP(addrs)
if err != nil {
return nil, err
}
if finalIP != nil {
glog.V(4).Infof("valid IPv4 address for interface %q found as %v.", intfName, finalIP)
return finalIP, nil
}
}
return nil, nil
}
func flagsSet(flags net.Flags, test net.Flags) bool {
return flags&test != 0
}
func flagsClear(flags net.Flags, test net.Flags) bool {
return flags&test == 0
}
func chooseHostInterfaceNativeGo() (net.IP, error) {
intfs, err := net.Interfaces()
if err != nil {
return nil, err
}
i := 0
var ip net.IP
for i = range intfs {
if flagsSet(intfs[i].Flags, net.FlagUp) && flagsClear(intfs[i].Flags, net.FlagLoopback|net.FlagPointToPoint) {
addrs, err := intfs[i].Addrs()
if err != nil {
return nil, err
}
if len(addrs) > 0 {
for _, addr := range addrs {
if addrIP, _, err := net.ParseCIDR(addr.String()); err == nil {
if addrIP.To4() != nil {
ip = addrIP.To4()
if !ip.IsLinkLocalMulticast() && !ip.IsLinkLocalUnicast() {
break
}
}
}
}
if ip != nil {
// This interface should suffice.
break
}
}
}
}
if ip == nil {
return nil, fmt.Errorf("no acceptable interface from host")
}
glog.V(4).Infof("Choosing interface %s (IP %v) as default", intfs[i].Name, ip)
return ip, nil
}
//ChooseHostInterface is a method used fetch an IP for a daemon.
//It uses data from /proc/net/route file.
//For a node with no internet connection ,it returns error
//For a multi n/w interface node it returns the IP of the interface with gateway on it.
func ChooseHostInterface() (net.IP, error) {
inFile, err := os.Open("/proc/net/route")
if err != nil {
if os.IsNotExist(err) {
return chooseHostInterfaceNativeGo()
}
return nil, err
}
defer inFile.Close()
var nw networkInterfacer = networkInterface{}
return chooseHostInterfaceFromRoute(inFile, nw)
}
type networkInterfacer interface {
InterfaceByName(intfName string) (*net.Interface, error)
Addrs(intf *net.Interface) ([]net.Addr, error)
}
type networkInterface struct{}
func (_ networkInterface) InterfaceByName(intfName string) (*net.Interface, error) {
intf, err := net.InterfaceByName(intfName)
if err != nil {
return nil, err
}
return intf, nil
}
func (_ networkInterface) Addrs(intf *net.Interface) ([]net.Addr, error) {
addrs, err := intf.Addrs()
if err != nil {
return nil, err
}
return addrs, nil
}
func chooseHostInterfaceFromRoute(inFile io.Reader, nw networkInterfacer) (net.IP, error) {
routes, err := getRoutes(inFile)
if err != nil {
return nil, err
}
zero := net.IP{0, 0, 0, 0}
var finalIP net.IP
for i := range routes {
//find interface with gateway
if routes[i].Destination.Equal(zero) {
glog.V(4).Infof("Default route transits interface %q", routes[i].Interface)
finalIP, err := getIPFromInterface(routes[i].Interface, nw)
if err != nil {
return nil, err
}
if finalIP != nil {
glog.V(4).Infof("Choosing IP %v ", finalIP)
return finalIP, nil
}
}
}
glog.V(4).Infof("No valid IP found")
if finalIP == nil {
return nil, fmt.Errorf("Unable to select an IP.")
}
return nil, nil
}
// If bind-address is usable, return it directly
// If bind-address is not usable (unset, 0.0.0.0, or loopback), we will use the host's default
// interface.
func ChooseBindAddress(bindAddress net.IP) (net.IP, error) {
if bindAddress == nil || bindAddress.IsUnspecified() || bindAddress.IsLoopback() {
hostIP, err := ChooseHostInterface()
if err != nil {
return nil, err
}
bindAddress = hostIP
}
return bindAddress, nil
}