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105 lines
2.6 KiB
Go
105 lines
2.6 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/ergochat/ergo/irc/utils"
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)
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// implements draft/resume, 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.Mutex // 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, id 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, id
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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(newClient *Client, token string) (oldClient *Client, id string) {
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if len(token) != 2*utils.SecretTokenLength {
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return
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}
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rm.Lock()
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defer rm.Unlock()
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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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return
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}
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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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return
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}
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if utils.SecretTokensMatch(pair.secret, token[utils.SecretTokenLength:]) {
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oldClient = pair.client // success!
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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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// old client is henceforth resumeable under new client's creds (possibly empty)
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newResumeID := newClient.ResumeID()
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oldClient.SetResumeID(newResumeID)
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if newResumeID != "" {
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if newResumeCreds, ok := rm.resumeIDtoCreds[newResumeID]; ok {
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newResumeCreds.client = oldClient
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rm.resumeIDtoCreds[newResumeID] = newResumeCreds
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}
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}
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// new client no longer "owns" newResumeID, remove the association
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newClient.SetResumeID("")
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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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