forked from yl2chen/cidranger
-
Notifications
You must be signed in to change notification settings - Fork 0
/
ip.go
300 lines (264 loc) · 7.55 KB
/
ip.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
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
/*
Package net provides utility functions for working with IPs (net.IP).
*/
package net
import (
"encoding/binary"
"fmt"
"math"
"net/netip"
)
// IPVersion is version of IP address.
type IPVersion string
// Helper constants.
const (
IPv4Uint32Count = 1
IPv6Uint32Count = 4
BitsPerUint32 = 32
BytePerUint32 = 4
IPv4 IPVersion = "IPv4"
IPv6 IPVersion = "IPv6"
)
// ErrInvalidBitPosition is returned when bits requested is not valid.
var ErrInvalidBitPosition = fmt.Errorf("bit position not valid")
// ErrVersionMismatch is returned upon mismatch in network input versions.
var ErrVersionMismatch = fmt.Errorf("Network input version mismatch")
// ErrNoGreatestCommonBit is an error returned when no greatest common bit
// exists for the cidr ranges.
var ErrNoGreatestCommonBit = fmt.Errorf("no greatest common bit")
// NetworkNumber represents an IP address using uint32 as internal storage.
// IPv4 usings 1 uint32, while IPv6 uses 4 uint32.
type NetworkNumber []uint32
// NewNetworkNumber returns a equivalent NetworkNumber to given IP address,
// return nil if ip is neither IPv4 nor IPv6.
func NewNetworkNumber(ip netip.Addr) NetworkNumber {
var parts int
if ip.Is4() {
parts = 1
} else if ip.Is6() {
parts = 4
} else {
return nil
}
nn := make(NetworkNumber, parts)
sl := ip.AsSlice()
for i := 0; i < parts; i++ {
nn[i] = binary.BigEndian.Uint32(sl[i*4 : (i+1)*4])
}
return nn
}
// ToV4 returns ip address if ip is IPv4, returns nil otherwise.
func (n NetworkNumber) ToV4() NetworkNumber {
if len(n) != IPv4Uint32Count {
return nil
}
return n
}
// ToV6 returns ip address if ip is IPv6, returns nil otherwise.
func (n NetworkNumber) ToV6() NetworkNumber {
if len(n) != IPv6Uint32Count {
return nil
}
return n
}
// ToIP returns equivalent net.IP.
func (n NetworkNumber) ToIP() netip.Addr {
sl := make([]byte, len(n)*BytePerUint32)
for i := 0; i < len(n); i++ {
binary.BigEndian.PutUint32(sl[i*4:(i+1)*4], n[i])
}
ip, _ := netip.AddrFromSlice(sl)
return ip
}
// Equal is the equality test for 2 network numbers.
func (n NetworkNumber) Equal(n1 NetworkNumber) bool {
if len(n) != len(n1) {
return false
}
if n[0] != n1[0] {
return false
}
if len(n) == IPv6Uint32Count {
return n[1] == n1[1] && n[2] == n1[2] && n[3] == n1[3]
}
return true
}
// Next returns the next logical network number.
func (n NetworkNumber) Next() NetworkNumber {
newIP := make(NetworkNumber, len(n))
copy(newIP, n)
for i := len(newIP) - 1; i >= 0; i-- {
newIP[i]++
if newIP[i] > 0 {
break
}
}
return newIP
}
// Previous returns the previous logical network number.
func (n NetworkNumber) Previous() NetworkNumber {
newIP := make(NetworkNumber, len(n))
copy(newIP, n)
for i := len(newIP) - 1; i >= 0; i-- {
newIP[i]--
if newIP[i] < math.MaxUint32 {
break
}
}
return newIP
}
// Bit returns uint32 representing the bit value at given position, e.g.,
// "128.0.0.0" has bit value of 1 at position 31, and 0 for positions 30 to 0.
func (n NetworkNumber) Bit(position uint) (uint32, error) {
if int(position) > len(n)*BitsPerUint32-1 {
return 0, ErrInvalidBitPosition
}
idx := len(n) - 1 - int(position/BitsPerUint32)
// Mod 31 to get array index.
rShift := position & (BitsPerUint32 - 1)
return (n[idx] >> rShift) & 1, nil
}
// FlipNthBit reverses the bit value at position. Position numbering is LSB 0.
func (n *NetworkNumber) FlipNthBit(position uint) error {
if int(position) > len(*n)*BitsPerUint32-1 {
return ErrInvalidBitPosition
}
idx := len(*n) - 1 - int(position/BitsPerUint32)
bitUintPosition := position % 32
XORMask := 1 << bitUintPosition
//byteNum := net.IPv6len - (position / 8) - 1
// getByteIndexOfBit(bitNum)
(*n)[idx] ^= uint32(XORMask)
return nil
}
// LeastCommonBitPosition returns the smallest position of the preceding common
// bits of the 2 network numbers, and returns an error ErrNoGreatestCommonBit
// if the two network number diverges from the first bit.
// e.g., if the network number diverges after the 1st bit, it returns 131 for
// IPv6 and 31 for IPv4 .
func (n NetworkNumber) LeastCommonBitPosition(n1 NetworkNumber) (uint, error) {
if len(n) != len(n1) {
return 0, ErrVersionMismatch
}
for i := 0; i < len(n); i++ {
mask := uint32(1) << 31
pos := uint(31)
for ; mask > 0; mask >>= 1 {
if n[i]&mask != n1[i]&mask {
if i == 0 && pos == 31 {
return 0, ErrNoGreatestCommonBit
}
return (pos + 1) + uint(BitsPerUint32)*uint(len(n)-i-1), nil
}
pos--
}
}
return 0, nil
}
// Network represents a block of network numbers, also known as CIDR.
type Network struct {
IPNet netip.Prefix
Number NetworkNumber
Mask NetworkNumberMask
}
// NewNetwork returns Network built using given net.IPNet.
func NewNetwork(ipNet netip.Prefix) Network {
return Network{
IPNet: ipNet, //.Masked(),
Number: NewNetworkNumber(ipNet.Addr()),
Mask: bitsToMask(ipNet.Bits(), ipNet.Addr().BitLen()),
}
}
func bitsToMask(ones, bits int) NetworkNumberMask {
parts := bits / BitsPerUint32
sl := make([]uint32, parts)
for i := 0; i < parts; i++ {
if ones == 0 {
break
}
var maskBits uint32
if ones >= 32 {
maskBits = 0xffff_ffff
ones -= 32
} else {
maskBits = ((1 << ones) - 1) << (32 - ones)
ones = 0
}
sl[i] = maskBits
}
return NetworkNumberMask(sl)
}
// Masked returns a new network conforming to new mask.
func (n Network) Masked(ones int) Network {
return NewNetwork(netip.PrefixFrom(n.IPNet.Addr(), ones).Masked())
}
// Contains returns true if NetworkNumber is in range of Network, false
// otherwise.
func (n Network) Contains(nn NetworkNumber) bool {
if len(n.Mask) != len(nn) {
return false
}
if nn[0]&n.Mask[0] != n.Number[0] {
return false
}
if len(nn) == IPv6Uint32Count {
return nn[1]&n.Mask[1] == n.Number[1] && nn[2]&n.Mask[2] == n.Number[2] && nn[3]&n.Mask[3] == n.Number[3]
}
return true
}
// Covers returns true if Network covers o, false otherwise
func (n Network) Covers(o Network) bool {
if len(n.Number) != len(o.Number) {
return false
}
nMaskSize := n.IPNet.Bits()
oMaskSize := o.IPNet.Bits()
return n.Contains(o.Number) && nMaskSize <= oMaskSize
}
// LeastCommonBitPosition returns the smallest position of the preceding common
// bits of the 2 networks, and returns an error ErrNoGreatestCommonBit
// if the two network number diverges from the first bit.
func (n Network) LeastCommonBitPosition(n1 Network) (max uint, err error) {
maskSize := n.IPNet.Bits()
if maskSize1 := n1.IPNet.Bits(); maskSize1 < maskSize {
maskSize = maskSize1
}
if max, err = n.Number.LeastCommonBitPosition(n1.Number); err != nil {
return 0, err
}
if maskPosition := uint(len(n1.Number)*BitsPerUint32 - maskSize); maskPosition > max {
max = maskPosition
}
return max, nil
}
// Equal is the equality test for 2 networks.
func (n Network) Equal(n1 Network) bool {
return n.IPNet == n1.IPNet
}
func (n Network) String() string {
return n.IPNet.String()
}
// NetworkNumberMask is an IP address.
type NetworkNumberMask NetworkNumber
// Mask returns a new masked NetworkNumber from given NetworkNumber.
func (m NetworkNumberMask) Mask(n NetworkNumber) (NetworkNumber, error) {
if len(m) != len(n) {
return nil, ErrVersionMismatch
}
result := make(NetworkNumber, len(m))
result[0] = m[0] & n[0]
if len(m) == IPv6Uint32Count {
result[1] = m[1] & n[1]
result[2] = m[2] & n[2]
result[3] = m[3] & n[3]
}
return result, nil
}
// NextIP returns the next sequential ip.
func NextIP(ip netip.Addr) netip.Addr {
return NewNetworkNumber(ip).Next().ToIP()
}
// PreviousIP returns the previous sequential ip.
func PreviousIP(ip netip.Addr) netip.Addr {
return NewNetworkNumber(ip).Previous().ToIP()
}