Add chainhash package, TxIDChainHash() and IsExtended() to TX.

chainhash/hash.go

@@ -0,0 +1,193 @@
+// Copyright (c) 2013-2016 The btcsuite developers
+// Copyright (c) 2015 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package chainhash
+
+import (
+	"bytes"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+)
+
+// HashSize of array used to store hashes.  See Hash.
+const HashSize = 32
+
+// MaxHashStringSize is the maximum length of a Hash hash string.
+const MaxHashStringSize = HashSize * 2
+
+// ErrHashStrSize describes an error that indicates the caller specified a hash
+// string that has too many characters.
+var ErrHashStrSize = fmt.Errorf("max hash string length is %v bytes", MaxHashStringSize)
+
+// Hash is used in several of the bitcoin messages and common structures.  It
+// typically represents the double sha256 of data.
+type Hash [HashSize]byte
+
+// String returns the Hash as the hexadecimal string of the byte-reversed
+// hash.
+func (hash Hash) String() string {
+	for i := 0; i < HashSize/2; i++ {
+		hash[i], hash[HashSize-1-i] = hash[HashSize-1-i], hash[i]
+	}
+	return hex.EncodeToString(hash[:])
+}
+
+// CloneBytes returns a copy of the bytes which represent the hash as a byte
+// slice.
+//
+// NOTE: It is generally cheaper to just slice the hash directly thereby reusing
+// the same bytes rather than calling this method.
+func (hash *Hash) CloneBytes() []byte {
+	newHash := make([]byte, HashSize)
+	copy(newHash, hash[:])
+
+	return newHash
+}
+
+// SetBytes sets the bytes which represent the hash.  An error is returned if
+// the number of bytes passed in is not HashSize.
+func (hash *Hash) SetBytes(newHash []byte) error {
+	nhLen := len(newHash)
+	if nhLen != HashSize {
+		return fmt.Errorf("invalid hash length of %v, want %v", nhLen,
+			HashSize)
+	}
+	copy(hash[:], newHash)
+
+	return nil
+}
+
+// IsEqual returns true if target is the same as hash.
+func (hash *Hash) IsEqual(target *Hash) bool {
+	if hash == nil && target == nil {
+		return true
+	}
+	if hash == nil || target == nil {
+		return false
+	}
+	return *hash == *target
+}
+
+func (hash *Hash) MarshalJSON() ([]byte, error) {
+	return json.Marshal(hash.String())
+}
+
+func (hash *Hash) UnmarshalJSON(data []byte) error {
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+	h, err := NewHashFromStr(s)
+	if err != nil {
+		return err
+	}
+	*hash = *h
+	return nil
+}
+
+// NewHash returns a new Hash from a byte slice.  An error is returned if
+// the number of bytes passed in is not HashSize.
+func NewHash(newHash []byte) (*Hash, error) {
+	var sh Hash
+	err := sh.SetBytes(newHash)
+	if err != nil {
+		return nil, err
+	}
+	return &sh, err
+}
+
+// func NewHashNoError(newHash []byte) *Hash {
+// 	sh, _ := NewHash(newHash)
+// 	return sh
+// }
+
+// NewHashFromStr creates a Hash from a hash string.  The string should be
+// the hexadecimal string of a byte-reversed hash, but any missing characters
+// result in zero padding at the end of the Hash.
+func NewHashFromStr(hash string) (*Hash, error) {
+	ret := new(Hash)
+	err := Decode(ret, hash)
+	if err != nil {
+		return nil, err
+	}
+	return ret, nil
+}
+
+// func NewHashFromStrNoError(hash string) *Hash {
+// 	sh, _ := NewHashFromStr(hash)
+// 	return sh
+// }
+
+// Decode decodes the byte-reversed hexadecimal string encoding of a Hash to a
+// destination.
+func Decode(dst *Hash, src string) error {
+	// Return error if hash string is too long.
+	if len(src) > MaxHashStringSize {
+		return ErrHashStrSize
+	}
+
+	// Hex decoder expects the hash to be a multiple of two.  When not, pad
+	// with a leading zero.
+	var srcBytes []byte
+	if len(src)%2 == 0 {
+		srcBytes = []byte(src)
+	} else {
+		srcBytes = make([]byte, 1+len(src))
+		srcBytes[0] = '0'
+		copy(srcBytes[1:], src)
+	}
+
+	// Hex decode the source bytes to a temporary destination.
+	var reversedHash Hash
+	_, err := hex.Decode(reversedHash[HashSize-hex.DecodedLen(len(srcBytes)):], srcBytes)
+	if err != nil {
+		return err
+	}
+
+	// Reverse copy from the temporary hash to destination.  Because the
+	// temporary was zeroed, the written result will be correctly padded.
+	for i, b := range reversedHash[:HashSize/2] {
+		dst[i], dst[HashSize-1-i] = reversedHash[HashSize-1-i], b
+	}
+
+	return nil
+}
+func (hash Hash) Marshal() ([]byte, error) {
+	if len(hash) == 0 {
+		return nil, nil
+	}
+	return hash.CloneBytes(), nil
+}
+
+func (hash Hash) MarshalTo(data []byte) (n int, err error) {
+	if len(hash) == 0 {
+		return 0, nil
+	}
+	copy(data, hash.CloneBytes())
+	return 16, nil
+}
+
+func (hash *Hash) Unmarshal(data []byte) error {
+	if len(data) == 0 {
+		return nil
+	}
+	id := &Hash{}
+	copy(id[:], data)
+	*hash = *id
+	return nil
+}
+
+func (hash Hash) Equal(other Hash) bool {
+	return bytes.Equal(hash[0:], other[0:])
+}
+
+func (hash *Hash) Size() int {
+	if hash == nil {
+		return 0
+	}
+
+	return len(*hash)
+}