1// Copyright 2011 The Go Authors. All rights reserved.
 2// Use of this source code is governed by a BSD-style
 3// license that can be found in the LICENSE file.
 4
 5package openpgp
 6
 7import (
 8	"hash"
 9	"io"
10)
11
12// NewCanonicalTextHash reformats text written to it into the canonical
13// form and then applies the hash h.  See RFC 4880, section 5.2.1.
14func NewCanonicalTextHash(h hash.Hash) hash.Hash {
15	return &canonicalTextHash{h, 0}
16}
17
18type canonicalTextHash struct {
19	h hash.Hash
20	s int
21}
22
23var newline = []byte{'\r', '\n'}
24
25func writeCanonical(cw io.Writer, buf []byte, s *int) (int, error) {
26	start := 0
27	for i, c := range buf {
28		switch *s {
29		case 0:
30			if c == '\r' {
31				*s = 1
32			} else if c == '\n' {
33				if _, err := cw.Write(buf[start:i]); err != nil {
34					return 0, err
35				}
36				if _, err := cw.Write(newline); err != nil {
37					return 0, err
38				}
39				start = i + 1
40			}
41		case 1:
42			*s = 0
43		}
44	}
45
46	if _, err := cw.Write(buf[start:]); err != nil {
47		return 0, err
48	}
49	return len(buf), nil
50}
51
52func (cth *canonicalTextHash) Write(buf []byte) (int, error) {
53	return writeCanonical(cth.h, buf, &cth.s)
54}
55
56func (cth *canonicalTextHash) Sum(in []byte) []byte {
57	return cth.h.Sum(in)
58}
59
60func (cth *canonicalTextHash) Reset() {
61	cth.h.Reset()
62	cth.s = 0
63}
64
65func (cth *canonicalTextHash) Size() int {
66	return cth.h.Size()
67}
68
69func (cth *canonicalTextHash) BlockSize() int {
70	return cth.h.BlockSize()
71}