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
|
package codec
import (
"encoding/base64"
)
// likelyBase64Chars is a set of characters that you would expect to find at
// least one of in base64 encoded data. This risks missing about 1% of
// base64 encoded data that doesn't contain these characters, but gives you
// the performance gain of not trying to decode a lot of long symbols in code.
var likelyBase64Chars = make([]bool, 256)
func init() {
for _, c := range `0123456789+/-_` {
likelyBase64Chars[c] = true
}
}
// decodeBase64 decodes base64 encoded printable ASCII characters
func decodeBase64(encodedValue string) string {
// Exit early if it doesn't seem like base64
if !hasByte(encodedValue, likelyBase64Chars) {
return ""
}
// Try standard base64 decoding
decodedValue, err := base64.StdEncoding.DecodeString(encodedValue)
if err == nil && isPrintableASCII(decodedValue) {
return string(decodedValue)
}
// Try base64url decoding
decodedValue, err = base64.RawURLEncoding.DecodeString(encodedValue)
if err == nil && isPrintableASCII(decodedValue) {
return string(decodedValue)
}
return ""
}
|
