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
|
package coding
import (
"fmt"
"io"
)
// base64CleanerTable notes byte values that should be stripped (-2), stripped w/ error (-1).
var base64CleanerTable = []int8{
-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
-1, 0, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
}
// Base64Cleaner improves the tolerance of in Go's built-in base64 decoder by stripping out
// characters that would cause decoding to fail.
type Base64Cleaner struct {
// Report of non-whitespace characters detected while cleaning base64 data.
Errors []error
r io.Reader
buffer [1024]byte
}
// Enforce io.Reader interface.
var _ io.Reader = &Base64Cleaner{}
// NewBase64Cleaner returns a Base64Cleaner object for the specified reader. Base64Cleaner
// implements the io.Reader interface.
func NewBase64Cleaner(r io.Reader) *Base64Cleaner {
return &Base64Cleaner{
Errors: make([]error, 0),
r: r,
}
}
// Read method for io.Reader interface.
func (bc *Base64Cleaner) Read(p []byte) (n int, err error) {
// Size our buf to smallest of len(p) or len(bc.buffer).
size := len(bc.buffer)
if size > len(p) {
size = len(p)
}
buf := bc.buffer[:size]
bn, err := bc.r.Read(buf)
for i := 0; i < bn; i++ {
switch base64CleanerTable[buf[i]&0x7f] {
case -2:
// Strip these silently: tab, \n, \r, space, equals sign.
case -1:
// Strip these, but warn the client.
bc.Errors = append(bc.Errors, fmt.Errorf("unexpected %q in base64 stream", buf[i]))
default:
p[n] = buf[i]
n++
}
}
return
}
|
