mirror of
https://github.com/tim-beatham/smegmesh.git
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126 lines
2.3 KiB
Go
126 lines
2.3 KiB
Go
package ip
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/*
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* Use a WireGuard public key to generate a unique interface ID
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*/
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import (
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"crypto/rand"
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"crypto/sha1"
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"net"
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"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
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)
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const (
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ModifierLength = 16
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ZeroLength = 9
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hash2Length = 57
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hash1Length = 58
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Hash2Prefix = 14
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Hash1Prefix = 8
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InterfaceIdLen = 8
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)
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/*
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* Cga parameters used to generate an IPV6 interface ID
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*/
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type CgaParameters struct {
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Modifier [ModifierLength]byte
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SubnetPrefix [2 * InterfaceIdLen]byte
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CollisionCount uint8
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PublicKey wgtypes.Key
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interfaceId [2 * InterfaceIdLen]byte
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flag byte
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}
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func NewCga(key wgtypes.Key, subnetPrefix [2 * InterfaceIdLen]byte) (*CgaParameters, error) {
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var params CgaParameters
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_, err := rand.Read(params.Modifier[:])
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if err != nil {
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return nil, err
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}
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params.PublicKey = key
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params.SubnetPrefix = subnetPrefix
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return ¶ms, nil
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}
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func (c *CgaParameters) generateHash2() []byte {
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var byteVal [hash2Length]byte
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for i := 0; i < ModifierLength; i++ {
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byteVal[i] = c.Modifier[i]
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}
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for i := 0; i < wgtypes.KeyLen; i++ {
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byteVal[ModifierLength+ZeroLength+i] = c.PublicKey[i]
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}
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hash := sha1.Sum(byteVal[:])
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return hash[:Hash2Prefix]
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}
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func (c *CgaParameters) generateHash1() []byte {
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var byteVal [hash1Length]byte
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for i := 0; i < ModifierLength; i++ {
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byteVal[i] = c.Modifier[i]
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}
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for i := 0; i < wgtypes.KeyLen; i++ {
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byteVal[ModifierLength+ZeroLength+i] = c.PublicKey[i]
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}
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byteVal[hash1Length-1] = c.CollisionCount
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hash := sha1.Sum(byteVal[:])
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return hash[:Hash1Prefix]
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}
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func clearBit(num, pos int) byte {
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mask := ^(1 << pos)
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result := num & mask
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return byte(result)
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}
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func (c *CgaParameters) generateInterface() []byte {
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// TODO: On duplicate address detection increment collision.
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// Also incorporate SEC
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hash1 := c.generateHash1()
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var interfaceId []byte = make([]byte, InterfaceIdLen)
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copy(interfaceId[:], hash1)
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interfaceId[0] = clearBit(int(interfaceId[0]), 6)
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interfaceId[0] = clearBit(int(interfaceId[1]), 7)
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return interfaceId
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}
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func (c *CgaParameters) GetIP() net.IP {
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if c.flag == 1 {
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return c.interfaceId[:]
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}
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bytes := c.generateInterface()
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for i := 0; i < InterfaceIdLen; i++ {
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c.interfaceId[i] = c.SubnetPrefix[i]
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}
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for i := InterfaceIdLen; i < 2*InterfaceIdLen; i++ {
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c.interfaceId[i] = bytes[i-8]
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}
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c.flag = 1
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return c.interfaceId[:]
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}
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