74 lines
1.5 KiB
Go
74 lines
1.5 KiB
Go
package main
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import (
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"crypto/cipher"
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"errors"
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"github.com/aead/chacha20poly1305" // Needed for XChaCha20Poly1305, TODO:
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"golang.org/x/crypto/blake2s"
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"sync"
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"time"
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)
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type MacStatePeer struct {
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mutex sync.RWMutex
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cookieSet time.Time
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cookie [blake2s.Size128]byte
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lastMac1 [blake2s.Size128]byte
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keyMac1 [blake2s.Size]byte
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xaead cipher.AEAD
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}
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func (state *MacStatePeer) Init(pk NoisePublicKey) {
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state.mutex.Lock()
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defer state.mutex.Unlock()
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func() {
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hsh, _ := blake2s.New256(nil)
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hsh.Write([]byte(WGLabelMAC1))
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hsh.Write(pk[:])
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hsh.Sum(state.keyMac1[:0])
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}()
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state.xaead, _ = chacha20poly1305.NewXCipher(state.keyMac1[:])
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state.cookieSet = time.Time{} // never
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}
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func (state *MacStatePeer) AddMacs(msg []byte) {
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size := len(msg)
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if size < blake2s.Size128*2 {
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panic(errors.New("bug: message too short"))
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}
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startMac1 := size - (blake2s.Size128 * 2)
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startMac2 := size - blake2s.Size128
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mac1 := msg[startMac1 : startMac1+blake2s.Size128]
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mac2 := msg[startMac2 : startMac2+blake2s.Size128]
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state.mutex.Lock()
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defer state.mutex.Unlock()
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// set mac1
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func() {
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mac, _ := blake2s.New128(state.keyMac1[:])
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mac.Write(msg[:startMac1])
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mac.Sum(state.lastMac1[:0])
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}()
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copy(mac1, state.lastMac1[:])
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// set mac2
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if state.cookieSet.IsZero() {
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return
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}
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if time.Now().Sub(state.cookieSet) > CookieRefreshTime {
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state.cookieSet = time.Time{}
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return
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}
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func() {
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mac, _ := blake2s.New128(state.cookie[:])
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mac.Write(msg[:startMac2])
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mac.Sum(mac2[:0])
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}()
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}
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