forked from gitea/gitea
129 lines
3.2 KiB
Go
129 lines
3.2 KiB
Go
// Copyright 2023 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package token
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import (
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"context"
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crypto_hmac "crypto/hmac"
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"crypto/sha256"
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"encoding/base32"
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"fmt"
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"time"
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user_model "code.gitea.io/gitea/models/user"
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"code.gitea.io/gitea/modules/util"
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)
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// A token is a verifiable container describing an action.
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//
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// A token has a dynamic length depending on the contained data and has the following structure:
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// | Token Version | User ID | HMAC | Payload |
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//
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// The payload is verifiable by the generated HMAC using the user secret. It contains:
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// | Timestamp | Action/Handler Type | Action/Handler Data |
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const (
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tokenVersion1 byte = 1
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tokenLifetimeInYears int = 1
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)
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type HandlerType byte
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const (
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UnknownHandlerType HandlerType = iota
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ReplyHandlerType
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UnsubscribeHandlerType
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)
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var encodingWithoutPadding = base32.StdEncoding.WithPadding(base32.NoPadding)
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type ErrToken struct {
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context string
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}
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func (err *ErrToken) Error() string {
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return "invalid email token: " + err.context
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}
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func (err *ErrToken) Unwrap() error {
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return util.ErrInvalidArgument
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}
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// CreateToken creates a token for the action/user tuple
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func CreateToken(ht HandlerType, user *user_model.User, data []byte) (string, error) {
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payload, err := util.PackData(
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time.Now().AddDate(tokenLifetimeInYears, 0, 0).Unix(),
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ht,
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data,
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)
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if err != nil {
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return "", err
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}
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packagedData, err := util.PackData(
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user.ID,
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generateHmac([]byte(user.Rands), payload),
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payload,
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)
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if err != nil {
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return "", err
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}
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return encodingWithoutPadding.EncodeToString(append([]byte{tokenVersion1}, packagedData...)), nil
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}
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// ExtractToken extracts the action/user tuple from the token and verifies the content
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func ExtractToken(ctx context.Context, token string) (HandlerType, *user_model.User, []byte, error) {
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data, err := encodingWithoutPadding.DecodeString(token)
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if err != nil {
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return UnknownHandlerType, nil, nil, err
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}
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if len(data) < 1 {
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return UnknownHandlerType, nil, nil, &ErrToken{"no data"}
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}
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if data[0] != tokenVersion1 {
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return UnknownHandlerType, nil, nil, &ErrToken{fmt.Sprintf("unsupported token version: %v", data[0])}
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}
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var userID int64
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var hmac []byte
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var payload []byte
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if err := util.UnpackData(data[1:], &userID, &hmac, &payload); err != nil {
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return UnknownHandlerType, nil, nil, err
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}
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user, err := user_model.GetUserByID(ctx, userID)
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if err != nil {
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return UnknownHandlerType, nil, nil, err
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}
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if !crypto_hmac.Equal(hmac, generateHmac([]byte(user.Rands), payload)) {
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return UnknownHandlerType, nil, nil, &ErrToken{"verification failed"}
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}
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var expiresUnix int64
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var handlerType HandlerType
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var innerPayload []byte
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if err := util.UnpackData(payload, &expiresUnix, &handlerType, &innerPayload); err != nil {
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return UnknownHandlerType, nil, nil, err
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}
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if time.Unix(expiresUnix, 0).Before(time.Now()) {
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return UnknownHandlerType, nil, nil, &ErrToken{"token expired"}
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}
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return handlerType, user, innerPayload, nil
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}
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// generateHmac creates a trunkated HMAC for the given payload
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func generateHmac(secret, payload []byte) []byte {
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mac := crypto_hmac.New(sha256.New, secret)
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mac.Write(payload)
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hmac := mac.Sum(nil)
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return hmac[:10] // RFC2104 recommends not using less then 80 bits
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}
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