From 077081076cb6a92fe5583aa4c0dd8b08530cbe73 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Tue, 3 May 2022 12:46:12 -0400
Subject: [PATCH] fix #1941

KLINE'd clients would produce a QUIT snotice without a corresponding
CONNECT snotice; explicitly suppress the QUIT snotice.
---
 irc/client.go  | 8 ++++++--
 irc/getters.go | 6 ++++++
 irc/server.go  | 2 ++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index d0deb063..62ce70c3 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -80,6 +80,7 @@ type Client struct {
 	hostname           string
 	invitedTo          map[string]channelInvite
 	isSTSOnly          bool
+	isKlined           bool // #1941: k-line kills are special-cased to suppress some triggered notices/events
 	languages          []string
 	lastActive         time.Time            // last time they sent a command that wasn't PONG or similar
 	lastSeen           map[string]time.Time // maps device ID (including "") to time of last received command
@@ -1181,6 +1182,7 @@ func (client *Client) destroy(session *Session) {
 	details := client.detailsNoMutex()
 	sessionRemoved := false
 	registered := client.registered
+	isKlined := client.isKlined
 	// XXX a temporary (reattaching) client can be marked alwaysOn when it logs in,
 	// but then the session attaches to another client and we need to clean it up here
 	alwaysOn := registered && client.alwaysOn
@@ -1341,8 +1343,10 @@ func (client *Client) destroy(session *Session) {
 	}
 
 	if registered {
-		client.server.snomasks.Send(sno.LocalQuits, fmt.Sprintf(ircfmt.Unescape("%s$r exited the network"), details.nick))
-		client.server.logger.Info("quit", fmt.Sprintf("%s is no longer on the server", details.nick))
+		if !isKlined {
+			client.server.snomasks.Send(sno.LocalQuits, fmt.Sprintf(ircfmt.Unescape("%s$r exited the network"), details.nick))
+			client.server.logger.Info("quit", fmt.Sprintf("%s is no longer on the server", details.nick))
+		}
 	}
 }
 
diff --git a/irc/getters.go b/irc/getters.go
index 761ece18..c50d8ab4 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -550,6 +550,12 @@ func (client *Client) shouldFlushTimestamps() (result bool) {
 	return
 }
 
+func (client *Client) setKlined() {
+	client.stateMutex.Lock()
+	client.isKlined = true
+	client.stateMutex.Unlock()
+}
+
 func (channel *Channel) Name() string {
 	channel.stateMutex.RLock()
 	defer channel.stateMutex.RUnlock()
diff --git a/irc/server.go b/irc/server.go
index 955a9337..c2c63161 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -373,7 +373,9 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 	if !session.IP().IsLoopback() || session.isTor {
 		isBanned, info := server.klines.CheckMasks(c.AllNickmasks()...)
 		if isBanned {
+			c.setKlined()
 			c.Quit(info.BanMessage(c.t("You are banned from this server (%s)")), nil)
+			server.logger.Info("connect", "Client rejected by k-line", c.NickMaskString())
 			return true
 		}
 	}