mirror of
https://github.com/netbirdio/netbird.git
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95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
package hmac
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import (
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"bytes"
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"crypto/hmac"
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"encoding/base64"
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"encoding/gob"
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"fmt"
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"hash"
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"strconv"
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"time"
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log "github.com/sirupsen/logrus"
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)
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type Token struct {
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Payload string
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Signature string
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}
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func unmarshalToken(payload []byte) (Token, error) {
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var creds Token
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buffer := bytes.NewBuffer(payload)
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decoder := gob.NewDecoder(buffer)
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err := decoder.Decode(&creds)
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return creds, err
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}
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// TimedHMAC generates a token with TTL and uses a pre-shared secret known to the relay server
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type TimedHMAC struct {
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secret string
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timeToLive time.Duration
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}
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// NewTimedHMAC creates a new TimedHMAC instance
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func NewTimedHMAC(secret string, timeToLive time.Duration) *TimedHMAC {
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return &TimedHMAC{
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secret: secret,
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timeToLive: timeToLive,
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}
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}
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// GenerateToken generates new time-based secret token - basically Payload is a unix timestamp and Signature is a HMAC
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// hash of a timestamp with a preshared TURN secret
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func (m *TimedHMAC) GenerateToken(algo func() hash.Hash) (*Token, error) {
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timeAuth := time.Now().Add(m.timeToLive).Unix()
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timeStamp := strconv.FormatInt(timeAuth, 10)
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checksum, err := m.generate(algo, timeStamp)
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if err != nil {
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return nil, err
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}
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return &Token{
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Payload: timeStamp,
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Signature: base64.StdEncoding.EncodeToString(checksum),
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}, nil
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}
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// Validate checks if the token is valid
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func (m *TimedHMAC) Validate(algo func() hash.Hash, token Token) error {
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expectedMAC, err := m.generate(algo, token.Payload)
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if err != nil {
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return err
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}
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expectedSignature := base64.StdEncoding.EncodeToString(expectedMAC)
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if !hmac.Equal([]byte(expectedSignature), []byte(token.Signature)) {
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return fmt.Errorf("signature mismatch")
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}
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timeAuthInt, err := strconv.ParseInt(token.Payload, 10, 64)
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if err != nil {
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return fmt.Errorf("invalid payload: %w", err)
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}
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if time.Now().Unix() > timeAuthInt {
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return fmt.Errorf("expired token")
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}
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return nil
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}
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func (m *TimedHMAC) generate(algo func() hash.Hash, payload string) ([]byte, error) {
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mac := hmac.New(algo, []byte(m.secret))
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_, err := mac.Write([]byte(payload))
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if err != nil {
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log.Debugf("failed to generate token: %s", err)
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return nil, fmt.Errorf("failed to generate token: %w", err)
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}
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return mac.Sum(nil), nil
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}
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