1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package quotedprintable implements quoted-printable encoding as specified by
// RFC 2045.
package quotedprintable
import (
"bufio"
"bytes"
"fmt"
"io"
)
// Reader is a quoted-printable decoder.
type Reader struct {
br *bufio.Reader
rerr error // last read error
line []byte // to be consumed before more of br
}
// NewReader returns a quoted-printable reader, decoding from r.
func NewReader(r io.Reader) *Reader {
return &Reader{
br: bufio.NewReader(r),
}
}
func fromHex(b byte) (byte, error) {
switch {
case b >= '0' && b <= '9':
return b - '0', nil
case b >= 'A' && b <= 'F':
return b - 'A' + 10, nil
// Accept badly encoded bytes.
case b >= 'a' && b <= 'f':
return b - 'a' + 10, nil
}
return 0, fmt.Errorf("quotedprintable: invalid hex byte 0x%02x", b)
}
func readHexByte(v []byte) (b byte, err error) {
if len(v) < 2 {
return 0, io.ErrUnexpectedEOF
}
var hb, lb byte
if hb, err = fromHex(v[0]); err != nil {
return 0, err
}
if lb, err = fromHex(v[1]); err != nil {
return 0, err
}
return hb<<4 | lb, nil
}
func isQPDiscardWhitespace(r rune) bool {
switch r {
case '\n', '\r', ' ', '\t':
return true
}
return false
}
var (
crlf = []byte("\r\n")
lf = []byte("\n")
softSuffix = []byte("=")
)
// Read reads and decodes quoted-printable data from the underlying reader.
func (r *Reader) Read(p []byte) (n int, err error) {
// Deviations from RFC 2045:
// 1. in addition to "=\r\n", "=\n" is also treated as soft line break.
// 2. it will pass through a '\r' or '\n' not preceded by '=', consistent
// with other broken QP encoders & decoders.
// 3. it accepts soft line-break (=) at end of message (issue 15486); i.e.
// the final byte read from the underlying reader is allowed to be '=',
// and it will be silently ignored.
// 4. it takes = as literal = if not followed by two hex digits
// but not at end of line (issue 13219).
for len(p) > 0 {
if len(r.line) == 0 {
if r.rerr != nil {
return n, r.rerr
}
r.line, r.rerr = r.br.ReadSlice('\n')
// Does the line end in CRLF instead of just LF?
hasLF := bytes.HasSuffix(r.line, lf)
hasCR := bytes.HasSuffix(r.line, crlf)
wholeLine := r.line
r.line = bytes.TrimRightFunc(wholeLine, isQPDiscardWhitespace)
if bytes.HasSuffix(r.line, softSuffix) {
rightStripped := wholeLine[len(r.line):]
r.line = r.line[:len(r.line)-1]
if !bytes.HasPrefix(rightStripped, lf) && !bytes.HasPrefix(rightStripped, crlf) &&
!(len(rightStripped) == 0 && len(r.line) > 0 && r.rerr == io.EOF) {
r.rerr = fmt.Errorf("quotedprintable: invalid bytes after =: %q", rightStripped)
}
} else if hasLF {
if hasCR {
r.line = append(r.line, '\r', '\n')
} else {
r.line = append(r.line, '\n')
}
}
continue
}
b := r.line[0]
switch {
case b == '=':
b, err = readHexByte(r.line[1:])
if err != nil {
if len(r.line) >= 2 && r.line[1] != '\r' && r.line[1] != '\n' {
// Take the = as a literal =.
b = '='
break
}
return n, err
}
r.line = r.line[2:] // 2 of the 3; other 1 is done below
case b == '\t' || b == '\r' || b == '\n':
break
case b >= 0x80:
// As an extension to RFC 2045, we accept
// values >= 0x80 without complaint. Issue 22597.
break
case b < ' ' || b > '~':
return n, fmt.Errorf("quotedprintable: invalid unescaped byte 0x%02x in body", b)
}
p[0] = b
p = p[1:]
r.line = r.line[1:]
n++
}
return n, nil
}
|
