From 06882a9b895fa55afe4bb926d6390a6b51736b91 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Thu, 6 Aug 2020 03:16:58 -0400
Subject: [PATCH] fix #1225

---
 irc/client.go            | 11 +++++++++--
 irc/client_lookup_set.go |  4 +++-
 irc/getters.go           | 15 +++++----------
 irc/nickname.go          | 12 +++++-------
 irc/server.go            |  4 ----
 5 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index ad3009c0..3f4c1e8b 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -1124,14 +1124,21 @@ func (client *Client) SetVHost(vhost string) (updated bool) {
 	return
 }
 
-// updateNick updates `nick` and `nickCasefolded`.
-func (client *Client) updateNick(nick, nickCasefolded, skeleton string) {
+// SetNick gives the client a nickname and marks it as registered, if necessary
+func (client *Client) SetNick(nick, nickCasefolded, skeleton string) (success bool) {
 	client.stateMutex.Lock()
 	defer client.stateMutex.Unlock()
+	if client.destroyed {
+		return false
+	} else if !client.registered {
+		// XXX test this before setting it to avoid annoying the race detector
+		client.registered = true
+	}
 	client.nick = nick
 	client.nickCasefolded = nickCasefolded
 	client.skeleton = skeleton
 	client.updateNickMaskNoMutex()
+	return true
 }
 
 // updateNickMaskNoMutex updates the casefolded nickname and nickmask, not acquiring any mutexes.
diff --git a/irc/client_lookup_set.go b/irc/client_lookup_set.go
index 45737b90..1f4fbe82 100644
--- a/irc/client_lookup_set.go
+++ b/irc/client_lookup_set.go
@@ -243,10 +243,12 @@ func (clients *ClientManager) SetNick(client *Client, session *Session, newNick
 		return "", errNicknameInUse, false
 	}
 
+	if changeSuccess := client.SetNick(newNick, newCfNick, newSkeleton); !changeSuccess {
+		return "", errClientDestroyed, false
+	}
 	clients.removeInternal(client)
 	clients.byNick[newCfNick] = client
 	clients.bySkeleton[newSkeleton] = client
-	client.updateNick(newNick, newCfNick, newSkeleton)
 	return newNick, nil, false
 }
 
diff --git a/irc/getters.go b/irc/getters.go
index dd619a32..8b2386f0 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -235,20 +235,15 @@ func (client *Client) Oper() *Oper {
 	return client.oper
 }
 
-func (client *Client) Registered() bool {
-	client.stateMutex.RLock()
-	defer client.stateMutex.RUnlock()
-	return client.registered
-}
-
-func (client *Client) SetRegistered() {
+func (client *Client) Registered() (result bool) {
 	// `registered` is only written from the client's own goroutine, but may be
 	// read from other goroutines; therefore, the client's own goroutine may read
 	// the value without synchronization, but must write it with synchronization,
 	// and other goroutines must read it with synchronization
-	client.stateMutex.Lock()
-	client.registered = true
-	client.stateMutex.Unlock()
+	client.stateMutex.RLock()
+	result = client.registered
+	client.stateMutex.RUnlock()
+	return
 }
 
 func (client *Client) RawHostname() (result string) {
diff --git a/irc/nickname.go b/irc/nickname.go
index 7bf80e3d..c44d7635 100644
--- a/irc/nickname.go
+++ b/irc/nickname.go
@@ -91,13 +91,11 @@ func performNickChange(server *Server, client *Client, target *Client, session *
 		channel.AddHistoryItem(histItem, details.account)
 	}
 
-	if target.Registered() {
-		newCfnick := target.NickCasefolded()
-		if newCfnick != details.nickCasefolded {
-			client.server.monitorManager.AlertAbout(details.nick, details.nickCasefolded, false)
-			client.server.monitorManager.AlertAbout(assignedNickname, newCfnick, true)
-		}
-	} // else: these will be deferred to the end of registration (see #572)
+	newCfnick := target.NickCasefolded()
+	if newCfnick != details.nickCasefolded {
+		client.server.monitorManager.AlertAbout(details.nick, details.nickCasefolded, false)
+		client.server.monitorManager.AlertAbout(assignedNickname, newCfnick, true)
+	}
 	return nil
 }
 
diff --git a/irc/server.go b/irc/server.go
index d12460da..40368fe2 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -283,12 +283,8 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 		c.SetMode(defaultMode, true)
 	}
 
-	// registration has succeeded:
-	c.SetRegistered()
-
 	// count new user in statistics
 	server.stats.Register(c.HasMode(modes.Invisible))
-	server.monitorManager.AlertAbout(c.Nick(), c.NickCasefolded(), true)
 
 	server.playRegistrationBurst(session)
 	return false