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
package oauthclient
import (
"cmp"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"net/url"
"strings"
"time"
"github.com/bluesky-social/indigo/atproto/atcrypto"
)
const (
DPoPLifetime = 30 * time.Second
ReplyLimit = 1 << 20
)
type DPoPHeader struct {
Typ string `json:"typ"`
Alg string `json:"alg"`
JWK *atcrypto.JWK `json:"jwk"`
}
type DPoPClaims struct {
JTI string `json:"jti"`
HTM string `json:"htm"`
HTU string `json:"htu"`
IAT int64 `json:"iat"`
EXP int64 `json:"exp"`
ATH string `json:"ath,omitempty"`
Nonce string `json:"nonce,omitempty"`
}
func DPoPProof(key atcrypto.PrivateKeyExportable, method, target, accessToken, nonce string) (string, error) {
if key == nil {
return "", errors.New("oauthclient: no DPoP key")
}
public, err := key.PublicKey()
if err != nil {
return "", err
}
jwk, err := public.JWK()
if err != nil {
return "", err
}
htu, ok := DPoPHTU(target)
if !ok {
return "", fmt.Errorf("oauthclient: the request url %q is not absolute", target)
}
jtiRaw := make([]byte, 16)
if _, err := rand.Read(jtiRaw); err != nil {
return "", err
}
now := time.Now()
claims := DPoPClaims{
JTI: base64.RawURLEncoding.EncodeToString(jtiRaw),
HTM: strings.ToUpper(method),
HTU: htu,
IAT: now.Unix(),
EXP: now.Add(DPoPLifetime).Unix(),
Nonce: nonce,
}
if accessToken != "" {
sum := sha256.Sum256([]byte(accessToken))
claims.ATH = base64.RawURLEncoding.EncodeToString(sum[:])
}
headerJSON, err := json.Marshal(DPoPHeader{Typ: "dpop+jwt", Alg: "ES256", JWK: jwk})
if err != nil {
return "", err
}
claimsJSON, err := json.Marshal(claims)
if err != nil {
return "", err
}
signingInput := base64.RawURLEncoding.EncodeToString(headerJSON) + "." + base64.RawURLEncoding.EncodeToString(claimsJSON)
signature, err := key.HashAndSign([]byte(signingInput))
if err != nil {
return "", err
}
return signingInput + "." + base64.RawURLEncoding.EncodeToString(signature), nil
}
func DPoPHTU(raw string) (string, bool) {
parsed, err := url.Parse(raw)
if err != nil || parsed.Scheme == "" || parsed.Host == "" {
return "", false
}
scheme := strings.ToLower(parsed.Scheme)
host := strings.ToLower(parsed.Hostname())
port := parsed.Port()
if (scheme == "https" && port == "443") || (scheme == "http" && port == "80") {
port = ""
}
if strings.Contains(host, ":") {
host = "[" + host + "]"
}
if port != "" {
host += ":" + port
}
path := parsed.EscapedPath()
path = cmp.Or(path, "/")
return scheme + "://" + host + path, true
}
