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Independently of this, ClientLookupSet.Resume ensures that at most one resume can succeed, so this doesn't actually change the behavior. But ResumeManager should be a standalone example of how to implement resume without race conditions.
91 lines
2.1 KiB
Go
91 lines
2.1 KiB
Go
// Copyright (c) 2019 Shivaram Lingamneni <slingamn@cs.stanford.edu>
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// released under the MIT license
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package irc
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import (
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"sync"
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"github.com/oragono/oragono/irc/utils"
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)
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// implements draft/resume-0.3, in particular the issuing, management, and verification
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// of resume tokens with two components: a unique ID and a secret key
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type resumeTokenPair struct {
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client *Client
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secret string
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}
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type ResumeManager struct {
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sync.RWMutex // level 2
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resumeIDtoCreds map[string]resumeTokenPair
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server *Server
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}
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func (rm *ResumeManager) Initialize(server *Server) {
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rm.resumeIDtoCreds = make(map[string]resumeTokenPair)
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rm.server = server
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}
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// GenerateToken generates a resume token for a client. If the client has
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// already been assigned one, it returns "".
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func (rm *ResumeManager) GenerateToken(client *Client) (token string) {
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id := utils.GenerateSecretToken()
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secret := utils.GenerateSecretToken()
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rm.Lock()
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defer rm.Unlock()
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if client.ResumeID() != "" {
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return
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}
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client.SetResumeID(id)
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rm.resumeIDtoCreds[id] = resumeTokenPair{
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client: client,
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secret: secret,
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}
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return id + secret
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}
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// VerifyToken looks up the client corresponding to a resume token, returning
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// nil if there is no such client or the token is invalid. If successful,
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// the token is consumed and cannot be used to resume again.
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func (rm *ResumeManager) VerifyToken(token string) (client *Client) {
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if len(token) != 2*utils.SecretTokenLength {
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return
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}
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rm.RLock()
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defer rm.RUnlock()
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id := token[:utils.SecretTokenLength]
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pair, ok := rm.resumeIDtoCreds[id]
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if ok {
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if utils.SecretTokensMatch(pair.secret, token[utils.SecretTokenLength:]) {
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// disallow resume of an unregistered client; this prevents the use of
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// resume as an auth bypass
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if pair.client.Registered() {
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// consume the token, ensuring that at most one resume can succeed
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delete(rm.resumeIDtoCreds, id)
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return pair.client
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}
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}
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}
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return
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}
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// Delete stops tracking a client's resume token.
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func (rm *ResumeManager) Delete(client *Client) {
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rm.Lock()
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defer rm.Unlock()
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currentID := client.ResumeID()
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if currentID != "" {
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delete(rm.resumeIDtoCreds, currentID)
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}
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}
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