-
Notifications
You must be signed in to change notification settings - Fork 7.7k
/
jwtutil.go
150 lines (127 loc) · 3.75 KB
/
jwtutil.go
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
140
141
142
143
144
145
146
147
148
149
150
// Copyright Istio Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package util
import (
"bytes"
"encoding/base64"
"encoding/json"
"fmt"
"strings"
"time"
)
// GetExp returns token expiration time, or error on failures.
func GetExp(token string) (time.Time, error) {
claims, err := parseJwtClaims(token)
if err != nil {
return time.Time{}, err
}
if claims["exp"] == nil {
// The JWT doesn't have "exp", so it's always valid. E.g., the K8s first party JWT.
return time.Time{}, nil
}
var expiration time.Time
switch exp := claims["exp"].(type) {
case float64:
expiration = time.Unix(int64(exp), 0)
case json.Number:
v, _ := exp.Int64()
expiration = time.Unix(v, 0)
}
return expiration, nil
}
// GetAud returns the claim `aud` from the token. Returns nil if not found.
func GetAud(token string) ([]string, error) {
claims, err := parseJwtClaims(token)
if err != nil {
return nil, err
}
rawAud := claims["aud"]
if rawAud == nil {
return nil, fmt.Errorf("no aud in the token claims")
}
data, err := json.Marshal(rawAud)
if err != nil {
return nil, err
}
var singleAud string
if err = json.Unmarshal(data, &singleAud); err == nil {
return []string{singleAud}, nil
}
var listAud []string
if err = json.Unmarshal(data, &listAud); err == nil {
return listAud, nil
}
return nil, err
}
type jwtPayload struct {
// Aud is JWT token audience - used to identify 3p tokens.
// It is empty for the default K8S tokens.
Aud []string `json:"aud"`
}
// IsK8SUnbound detects if the token is a K8S unbound token.
// It is a regular JWT with no audience and expiration, which can
// be exchanged with bound tokens with audience.
//
// This is used to determine if we check audience in the token.
// Clients should not use unbound tokens except in cases where
// bound tokens are not possible.
func IsK8SUnbound(jwt string) bool {
aud, f := ExtractJwtAud(jwt)
if !f {
return false // unbound tokens are valid JWT
}
return len(aud) == 0
}
// ExtractJwtAud extracts the audiences from a JWT token. If aud cannot be parse, the bool will be set
// to false. This distinguishes aud=[] from not parsed.
func ExtractJwtAud(jwt string) ([]string, bool) {
jwtSplit := strings.Split(jwt, ".")
if len(jwtSplit) != 3 {
return nil, false
}
payload := jwtSplit[1]
payloadBytes, err := base64.RawStdEncoding.DecodeString(payload)
if err != nil {
return nil, false
}
structuredPayload := &jwtPayload{}
err = json.Unmarshal(payloadBytes, &structuredPayload)
if err != nil {
return nil, false
}
return structuredPayload.Aud, true
}
func parseJwtClaims(token string) (map[string]interface{}, error) {
parts := strings.Split(token, ".")
if len(parts) != 3 {
return nil, fmt.Errorf("token contains an invalid number of segments: %d, expected: 3", len(parts))
}
// Decode the second part.
claimBytes, err := decodeSegment(parts[1])
if err != nil {
return nil, err
}
dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
claims := make(map[string]interface{})
if err := dec.Decode(&claims); err != nil {
return nil, fmt.Errorf("failed to decode the JWT claims")
}
return claims, nil
}
func decodeSegment(seg string) ([]byte, error) {
if l := len(seg) % 4; l > 0 {
seg += strings.Repeat("=", 4-l)
}
return base64.URLEncoding.DecodeString(seg)
}