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ergo/irc/resume.go
2019-05-21 22:36:37 -04:00

105 lines
2.6 KiB
Go

// Copyright (c) 2019 Shivaram Lingamneni <slingamn@cs.stanford.edu>
// released under the MIT license
package irc
import (
"sync"
"github.com/oragono/oragono/irc/utils"
)
// implements draft/resume, in particular the issuing, management, and verification
// of resume tokens with two components: a unique ID and a secret key
type resumeTokenPair struct {
client *Client
secret string
}
type ResumeManager struct {
sync.Mutex // level 2
resumeIDtoCreds map[string]resumeTokenPair
server *Server
}
func (rm *ResumeManager) Initialize(server *Server) {
rm.resumeIDtoCreds = make(map[string]resumeTokenPair)
rm.server = server
}
// GenerateToken generates a resume token for a client. If the client has
// already been assigned one, it returns "".
func (rm *ResumeManager) GenerateToken(client *Client) (token string, id string) {
id = utils.GenerateSecretToken()
secret := utils.GenerateSecretToken()
rm.Lock()
defer rm.Unlock()
if client.ResumeID() != "" {
return
}
client.SetResumeID(id)
rm.resumeIDtoCreds[id] = resumeTokenPair{
client: client,
secret: secret,
}
return id + secret, id
}
// VerifyToken looks up the client corresponding to a resume token, returning
// nil if there is no such client or the token is invalid. If successful,
// the token is consumed and cannot be used to resume again.
func (rm *ResumeManager) VerifyToken(newClient *Client, token string) (oldClient *Client, id string) {
if len(token) != 2*utils.SecretTokenLength {
return
}
rm.Lock()
defer rm.Unlock()
id = token[:utils.SecretTokenLength]
pair, ok := rm.resumeIDtoCreds[id]
if !ok {
return
}
// disallow resume of an unregistered client; this prevents the use of
// resume as an auth bypass
if !pair.client.Registered() {
return
}
if utils.SecretTokensMatch(pair.secret, token[utils.SecretTokenLength:]) {
oldClient = pair.client // success!
// consume the token, ensuring that at most one resume can succeed
delete(rm.resumeIDtoCreds, id)
// old client is henceforth resumeable under new client's creds (possibly empty)
newResumeID := newClient.ResumeID()
oldClient.SetResumeID(newResumeID)
if newResumeID != "" {
if newResumeCreds, ok := rm.resumeIDtoCreds[newResumeID]; ok {
newResumeCreds.client = oldClient
rm.resumeIDtoCreds[newResumeID] = newResumeCreds
}
}
// new client no longer "owns" newResumeID, remove the association
newClient.SetResumeID("")
}
return
}
// Delete stops tracking a client's resume token.
func (rm *ResumeManager) Delete(client *Client) {
rm.Lock()
defer rm.Unlock()
currentID := client.ResumeID()
if currentID != "" {
delete(rm.resumeIDtoCreds, currentID)
}
}