108 lines
3 KiB
Go
108 lines
3 KiB
Go
// Copyright (c) 2013-2014 Conformal Systems LLC.
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package btcwire
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import (
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"bytes"
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"encoding/hex"
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"fmt"
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)
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// Size of array used to store sha hashes. See ShaHash.
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const HashSize = 32
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// MaxHashStringSize is the maximum length of a ShaHash hash string.
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const MaxHashStringSize = HashSize * 2
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// ErrHashStrSize describes an error that indicates the caller specified a hash
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// string that has too many characters.
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var ErrHashStrSize = fmt.Errorf("max hash string length is %v bytes", MaxHashStringSize)
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// ShaHash is used in several of the bitcoin messages and common structures. It
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// typically represents the double sha256 of data.
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type ShaHash [HashSize]byte
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// String returns the ShaHash as the hexadecimal string of the byte-reversed
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// hash.
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func (hash ShaHash) String() string {
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for i := 0; i < HashSize/2; i++ {
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hash[i], hash[HashSize-1-i] = hash[HashSize-1-i], hash[i]
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}
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return hex.EncodeToString(hash[:])
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}
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// Bytes returns the bytes which represent the hash as a byte slice.
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func (hash *ShaHash) Bytes() []byte {
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newHash := make([]byte, HashSize)
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copy(newHash, hash[:])
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return newHash
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}
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// SetBytes sets the bytes which represent the hash. An error is returned if
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// the number of bytes passed in is not HashSize.
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func (hash *ShaHash) SetBytes(newHash []byte) error {
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nhlen := len(newHash)
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if nhlen != HashSize {
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return fmt.Errorf("invalid sha length of %v, want %v", nhlen,
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HashSize)
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}
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copy(hash[:], newHash[0:HashSize])
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return nil
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}
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// IsEqual returns true if target is the same as hash.
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func (hash *ShaHash) IsEqual(target *ShaHash) bool {
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return bytes.Equal(hash[:], target[:])
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}
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// NewShaHash returns a new ShaHash from a byte slice. An error is returned if
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// the number of bytes passed in is not HashSize.
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func NewShaHash(newHash []byte) (*ShaHash, error) {
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var sh ShaHash
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err := sh.SetBytes(newHash)
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if err != nil {
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return nil, err
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}
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return &sh, err
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}
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// NewShaHashFromStr creates a ShaHash from a hash string. The string should be
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// the hexadecimal string of a byte-reversed hash, but any missing characters
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// result in zero padding at the end of the ShaHash.
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func NewShaHashFromStr(hash string) (*ShaHash, error) {
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// Return error if hash string is too long.
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if len(hash) > MaxHashStringSize {
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return nil, ErrHashStrSize
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}
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// Hex decoder expects the hash to be a multiple of two.
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if len(hash)%2 != 0 {
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hash = "0" + hash
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}
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// Convert string hash to bytes.
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buf, err := hex.DecodeString(hash)
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if err != nil {
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return nil, err
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}
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// Un-reverse the decoded bytes, copying into in leading bytes of a
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// ShaHash. There is no need to explicitly pad the result as any
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// missing (when len(buf) < HashSize) bytes from the decoded hex string
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// will remain zeros at the end of the ShaHash.
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var ret ShaHash
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blen := len(buf)
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mid := blen / 2
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if blen%2 != 0 {
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mid++
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}
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blen--
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for i, b := range buf[:mid] {
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ret[i], ret[blen-i] = buf[blen-i], b
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}
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return &ret, nil
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}
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