mirror of
https://github.com/impact-eintr/netstack.git
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71 lines
1.5 KiB
Go
71 lines
1.5 KiB
Go
package hash
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import (
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"crypto/rand"
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"encoding/binary"
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"netstack/tcpip/header"
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)
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var hashIV = RandN32(1)[0]
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// RandN32 生成 n 个加密随机 32 位数字的切片
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func RandN32(n int) []uint32 {
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b := make([]byte, 4*n)
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if _, err := rand.Read(b); err != nil {
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panic("unable to get random numbers: " + err.Error())
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}
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r := make([]uint32, n)
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for i := range r {
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r[i] = binary.LittleEndian.Uint32(b[4*i : (4*i + 4)])
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}
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return r
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}
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func Hash3Words(a, b, c, initval uint32) uint32 {
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const iv = 0xdeadbeef + (3 << 2)
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initval += iv
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a += initval
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b += initval
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c += initval
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c ^= b
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c -= rol32(b, 14)
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a ^= c
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a -= rol32(c, 11)
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b ^= a
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b -= rol32(a, 25)
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c ^= b
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c -= rol32(b, 16)
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a ^= c
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a -= rol32(c, 4)
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b ^= a
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b -= rol32(a, 14)
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c ^= b
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c -= rol32(b, 24)
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return c
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}
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// 根据id，源ip，目的ip和协议类型得到hash值
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func IPv4FragmentHash(h header.IPv4) uint32 {
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x := uint32(h.ID())<<16 | uint32(h.Protocol())
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t := h.SourceAddress()
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y := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
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t = h.DestinationAddress()
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z := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
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return Hash3Words(x, y, z, hashIV)
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}
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func IPv6FragmentHash(h header.IPv6, f header.IPv6Fragment) uint32 {
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t := h.SourceAddress()
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y := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
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t = h.DestinationAddress()
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z := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
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return Hash3Words(f.ID(), y, z, hashIV)
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}
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func rol32(v, shift uint32) uint32 {
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return (v << shift) | (v >> ((-shift) & 31))
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}
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