From 2b240faa9090db71419b6e9f30a64d8fb7cc0265 Mon Sep 17 00:00:00 2001
From: Daniel Oaks <daniel@danieloaks.net>
Date: Sat, 14 Jan 2017 02:32:15 +1000
Subject: [PATCH] strings: Fix nick bugs, use UsernameCaseMapped

---
 irc/client.go            |  2 +-
 irc/client_lookup_set.go |  9 ++++-----
 irc/server.go            |  2 +-
 irc/strings.go           | 10 +++++++---
 4 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index dd30f8ce..0f457b08 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -397,11 +397,11 @@ func (client *Client) SetNickname(nickname string) error {
 // ChangeNickname changes the existing nickname of the client.
 func (client *Client) ChangeNickname(nickname string) error {
 	origNickMask := client.nickMaskString
-	client.updateNickMask()
 	err := client.server.clients.Replace(client.nick, nickname, client)
 	if err == nil {
 		client.server.whoWas.Append(client)
 		client.nick = nickname
+		client.updateNickMask()
 		for friend := range client.Friends() {
 			friend.Send(nil, origNickMask, "NICK", nickname)
 		}
diff --git a/irc/client_lookup_set.go b/irc/client_lookup_set.go
index 1437624f..d2f97ced 100644
--- a/irc/client_lookup_set.go
+++ b/irc/client_lookup_set.go
@@ -128,13 +128,12 @@ func (clients *ClientLookupSet) Replace(oldNick, newNick string, client *Client)
 	clients.ByNickMutex.Lock()
 	defer clients.ByNickMutex.Unlock()
 
-	oldClient := clients.getNoMutex(newNick)
-	if oldClient != nil {
+	oldClient := clients.ByNick[newNick]
+	if oldClient == nil || oldClient == client {
+		// whoo
+	} else {
 		return ErrNicknameInUse
 	}
-	if oldClient != client {
-		return ErrNicknameMismatch
-	}
 
 	if oldNick == newNick {
 		// if they're only changing case, don't need to remove+re-add them
diff --git a/irc/server.go b/irc/server.go
index 37bdffe3..08b4bc9e 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -305,7 +305,7 @@ func (server *Server) setISupport() {
 	// add RPL_ISUPPORT tokens
 	server.isupport = NewISupportList()
 	server.isupport.Add("AWAYLEN", strconv.Itoa(server.limits.AwayLen))
-	server.isupport.Add("CASEMAPPING", "rfc7700")
+	server.isupport.Add("CASEMAPPING", casemappingName)
 	server.isupport.Add("CHANMODES", strings.Join([]string{ChannelModes{BanMask, ExceptMask, InviteMask}.String(), "", ChannelModes{UserLimit, Key}.String(), ChannelModes{InviteOnly, Moderated, NoOutside, OpOnlyTopic, ChanRoleplaying, Secret}.String()}, ","))
 	server.isupport.Add("CHANNELLEN", strconv.Itoa(server.limits.ChannelLen))
 	server.isupport.Add("CHANTYPES", "#")
diff --git a/irc/strings.go b/irc/strings.go
index 072bac18..ed37333d 100644
--- a/irc/strings.go
+++ b/irc/strings.go
@@ -12,18 +12,22 @@ import (
 	"golang.org/x/text/secure/precis"
 )
 
+const (
+	casemappingName = "rfc7613"
+)
+
 var (
 	errInvalidCharacter = errors.New("Invalid character")
 )
 
 // Casefold returns a casefolded string, without doing any name or channel character checks.
 func Casefold(str string) (string, error) {
-	return precis.Nickname.CompareKey(str)
+	return precis.UsernameCaseMapped.CompareKey(str)
 }
 
 // CasefoldChannel returns a casefolded version of a channel name.
 func CasefoldChannel(name string) (string, error) {
-	lowered, err := precis.Nickname.CompareKey(name)
+	lowered, err := Casefold(name)
 
 	if err != nil {
 		return "", err
@@ -47,7 +51,7 @@ func CasefoldChannel(name string) (string, error) {
 
 // CasefoldName returns a casefolded version of a nick/user name.
 func CasefoldName(name string) (string, error) {
-	lowered, err := precis.Nickname.CompareKey(name)
+	lowered, err := Casefold(name)
 
 	if err != nil {
 		return "", err