lnd.xprv/lntypes/preimage.go

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package lntypes
import (
"crypto/sha256"
"encoding/hex"
"fmt"
)
// PreimageSize of array used to store preimagees.
const PreimageSize = 32
// Preimage is used in several of the lightning messages and common structures.
// It represents a payment preimage.
type Preimage [PreimageSize]byte
// String returns the Preimage as a hexadecimal string.
func (p Preimage) String() string {
return hex.EncodeToString(p[:])
}
// MakePreimage returns a new Preimage from a bytes slice. An error is returned
// if the number of bytes passed in is not PreimageSize.
func MakePreimage(newPreimage []byte) (Preimage, error) {
nhlen := len(newPreimage)
if nhlen != PreimageSize {
return Preimage{}, fmt.Errorf("invalid preimage length of %v, "+
"want %v", nhlen, PreimageSize)
}
var preimage Preimage
copy(preimage[:], newPreimage)
return preimage, nil
}
// MakePreimageFromStr creates a Preimage from a hex preimage string.
func MakePreimageFromStr(newPreimage string) (Preimage, error) {
// Return error if preimage string is of incorrect length.
if len(newPreimage) != PreimageSize*2 {
return Preimage{}, fmt.Errorf("invalid preimage string length "+
"of %v, want %v", len(newPreimage), PreimageSize*2)
}
preimage, err := hex.DecodeString(newPreimage)
if err != nil {
return Preimage{}, err
}
return MakePreimage(preimage)
}
// Hash returns the sha256 hash of the preimage.
func (p *Preimage) Hash() Hash {
return Hash(sha256.Sum256(p[:]))
}
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// Matches returns whether this preimage is the preimage of the given hash.
func (p *Preimage) Matches(h Hash) bool {
return h == p.Hash()
}