135 lines
3.7 KiB
Go
135 lines
3.7 KiB
Go
// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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package statelesstoken
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/base64"
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"encoding/json"
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"fmt"
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"strings"
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"time"
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)
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type (
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// Config holds the configuration for tokens
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Config struct {
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// Secret is the secret key used for signing tokens
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Secret string
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// ExpirationTime is the duration after which a token expires
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ExpirationTime time.Duration
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}
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// Payload is a generic token payload that can hold any data
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Payload[T any] struct {
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ExpiresAt time.Time `json:"exp"`
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IssuedAt time.Time `json:"iat"`
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Type string `json:"typ"`
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Data T `json:"data"`
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}
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// ErrInvalidToken is returned when a token is invalid
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ErrInvalidToken struct {
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message string
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}
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// ErrExpiredToken is returned when a token has expired
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ErrExpiredToken struct {
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message string
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}
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)
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var (
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DefaultExpirationTime = 1 * time.Hour
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)
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// Error implementations
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func (e ErrInvalidToken) Error() string {
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return e.message
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}
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func (e ErrExpiredToken) Error() string {
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return e.message
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}
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// NewToken creates a new token with the specified type, data, and expiration time
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func NewToken[T any](secret string, tokenType string, expirationTime time.Duration, data T) (string, error) {
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now := time.Now()
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payload := Payload[T]{
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ExpiresAt: now.Add(expirationTime),
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IssuedAt: now,
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Type: tokenType,
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Data: data,
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}
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payloadBytes, err := json.Marshal(payload)
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if err != nil {
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return "", fmt.Errorf("failed to marshal token payload: %w", err)
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}
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encodedPayload := base64.RawURLEncoding.EncodeToString(payloadBytes)
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h := hmac.New(sha256.New, []byte(secret))
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h.Write([]byte(encodedPayload))
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signature := base64.RawURLEncoding.EncodeToString(h.Sum(nil))
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tokenString := encodedPayload + "." + signature
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return tokenString, nil
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}
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// ValidateToken validates a token and unmarshals the payload
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// It returns an error if the token is invalid or expired
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func ValidateToken[T any](secret string, tokenType string, tokenString string) (*Payload[T], error) {
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parts := strings.Split(tokenString, ".")
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if len(parts) != 2 {
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return nil, &ErrInvalidToken{message: "invalid token format"}
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}
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encodedPayload := parts[0]
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providedSignature := parts[1]
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h := hmac.New(sha256.New, []byte(secret))
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h.Write([]byte(encodedPayload))
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expectedSignature := base64.RawURLEncoding.EncodeToString(h.Sum(nil))
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if providedSignature != expectedSignature {
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return nil, &ErrInvalidToken{message: "invalid token signature"}
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}
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payloadBytes, err := base64.RawURLEncoding.DecodeString(encodedPayload)
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if err != nil {
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return nil, fmt.Errorf("failed to decode token payload: %w", err)
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}
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var payload Payload[T]
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if err := json.Unmarshal(payloadBytes, &payload); err != nil {
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return nil, fmt.Errorf("failed to unmarshal token payload: %w", err)
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}
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if time.Now().After(payload.ExpiresAt) {
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return nil, &ErrExpiredToken{message: "token has expired"}
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}
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if payload.Type != tokenType {
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return nil, &ErrInvalidToken{message: "invalid token type"}
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}
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return &payload, nil
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}
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