File size: 3,109 Bytes
1e92f2d |
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 |
package authtoken
import (
"encoding/base64"
"encoding/binary"
"time"
"github.com/google/uuid"
"github.com/target/goalert/validation"
)
// A VerifyFunc will verify that the signature is valid for the given type and payload. Additionally,
// if supported, it indicates if an old-but-still-valid key (since been rotated) was used
// to generate the signature.
type VerifyFunc func(t Type, payload, signature []byte) (isValid, isOldKey bool)
func alwaysValid(Type, []byte, []byte) (bool, bool) { return true, false }
// Parse will parse a token string, optionally verifying it's signature.
// If verifyFn is nil, the signature is ignored.
func Parse(s string, verifyFn VerifyFunc) (*Token, bool, error) {
if len(s) == 0 {
return nil, false, validation.NewGenericError("invalid length")
}
if len(s) == 36 {
// integration key type is the only one with possible length 36. Session keys, even if
// we switched to a 128-bit signature would be a minimum of 38 base64-encoded chars.
id, err := uuid.Parse(s)
if err != nil {
return nil, false, validation.NewGenericError(err.Error())
}
return &Token{ID: id}, false, nil
}
if verifyFn == nil {
verifyFn = alwaysValid
}
enc := b64Encoding
if s[0] == 'U' { // always 'U' if it's an encoded session token (first encoded byte is 'S')
// session tokens were/are encoded with padding enabled
enc = base64.URLEncoding
}
data, err := enc.DecodeString(s)
if err != nil {
return nil, false, validation.NewGenericError(err.Error())
}
if len(data) < 2 {
return nil, false, validation.NewGenericError("invalid length")
}
headerFormat := data[0]
if headerFormat == 'S' {
// session token (version: 1)
if len(data) < 17 {
return nil, false, validation.NewGenericError("invalid length")
}
valid, isOldKey := verifyFn(TypeSession, data[:17], data[17:])
if !valid {
return nil, false, validation.NewGenericError("invalid signature")
}
t := &Token{
Version: 1,
Type: TypeSession,
}
copy(t.ID[:], data[1:])
return t, isOldKey, nil
}
// Ensure we're using the new "versioned" token format
if headerFormat != 'V' {
return nil, false, validation.NewGenericError("invalid token header format")
}
switch data[1] {
case 3:
if len(data) < 19 {
return nil, false, validation.NewGenericError("invalid length")
}
t := &Token{
Version: 3,
Type: Type(data[2]),
}
valid, isOldKey := verifyFn(t.Type, data[:19], data[19:])
if !valid {
return nil, false, validation.NewGenericError("invalid signature")
}
copy(t.ID[:], data[3:])
return t, isOldKey, nil
case 2:
if len(data) < 27 {
return nil, false, validation.NewGenericError("invalid length")
}
t := &Token{
Version: 2,
Type: Type(data[2]),
}
valid, isOldKey := verifyFn(t.Type, data[:27], data[27:])
if !valid {
return nil, false, validation.NewGenericError("invalid signature")
}
copy(t.ID[:], data[3:])
t.CreatedAt = time.Unix(int64(binary.BigEndian.Uint64(data[19:])), 0)
return t, isOldKey, nil
}
return nil, false, validation.NewGenericError("unsupported token version")
}
|