Make an IRC listener connection follow its session's nick (closes #184)

When the session's nick was changed from another client, such as the
web client over the HTTP API, the IRC listener connection kept the old
nick and sent its messages, joins and later NICK changes under it. The
relay now gives the connection the new nick when it delivers a NICK
change whose old nick is the connection's own: nicks are unique, so its
own session made that change. As the relay goroutine can now change the
nick, the command handlers read it under the connection's lock, through
currentNick, as the relay already did.

Model: opus-5-5

internal/db/queries.go

@@ -264,25 +264,6 @@ func (database *Database) GetSessionByNick(
 	return sessionID, nil
 }
 
-// GetSessionNick returns the nick a session holds.
-func (database *Database) GetSessionNick(
-	ctx context.Context,
-	sessionID int64,
-) (string, error) {
-	var nick string
-
-	err := database.conn.QueryRowContext(
-		ctx,
-		"SELECT nick FROM sessions WHERE id = ?",
-		sessionID,
-	).Scan(&nick)
-	if err != nil {
-		return "", fmt.Errorf("get session nick: %w", err)
-	}
-
-	return nick, nil
-}
-
 // SessionHostInfo holds the username, hostname, and IP
 // for a session.
 type SessionHostInfo struct {

internal/ircserver/commands.go

@@ -92,10 +92,9 @@ func (c *Conn) handleNick(
 		return
 	}
 
-	// Take the nick the session holds, not newNick: another
-	// client of the session may have changed it again since
-	// ChangeNick stored newNick.
-	c.loadSessionNick(ctx)
+	c.mu.Lock()
+	c.nick = newNick
+	c.mu.Unlock()
 
 	// Echo NICK change to the client on wire.
 	c.send(FormatMessage(oldMask, "NICK", newNick))

internal/ircserver/conn.go

@@ -313,22 +313,6 @@ func (c *Conn) currentNick() string {
 	return c.nick
 }
 
-// loadSessionNick sets c.nick to the nick the connection's
-// session holds in the database, read by session ID. The
-// connection's own NICK and the relay passing on a NICK line
-// both call it, and it reads and sets the nick under c.mu, so
-// whichever runs last leaves the connection on its session's
-// nick. If the read fails, c.nick is left as it is.
-func (c *Conn) loadSessionNick(ctx context.Context) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	nick, err := c.database.GetSessionNick(ctx, c.sessionID)
-	if err == nil {
-		c.nick = nick
-	}
-}
-
 // send writes a formatted IRC line to the connection.
 func (c *Conn) send(line string) {
 	c.sendWithin(writeTimeout, line)

internal/ircserver/relay.go

@@ -92,7 +92,7 @@ func (c *Conn) drainQueue(ctx context.Context) bool {
 //
 //nolint:cyclop // dispatch table
 func (c *Conn) deliverIRCMessage(
-	ctx context.Context,
+	_ context.Context,
 	msg *db.IRCMessage,
 ) {
 	command := msg.Command
@@ -120,7 +120,7 @@ func (c *Conn) deliverIRCMessage(
 	case command == irc.CmdPart:
 		c.deliverPart(msg, text)
 	case command == irc.CmdNick:
-		c.deliverNickChange(ctx, msg, text)
+		c.deliverNickChange(msg, text)
 	case command == irc.CmdQuit:
 		c.deliverQuitMsg(msg, text)
 	case command == irc.CmdTopic:
@@ -230,17 +230,21 @@ func (c *Conn) deliverPart(msg *db.IRCMessage, text string) {
 	}
 }
 
-// deliverNickChange sends a NICK change notification. The
-// change may be its own session's, made from another client,
-// so the connection first takes the nick its session holds
-// now. It does not go by the line's old nick: the connection
-// may have taken that nick after another user gave it up.
+// deliverNickChange sends a NICK change notification. When
+// the old nick is the connection's own, the change was made
+// from another client of its session, as nicks are unique,
+// and the connection takes the new nick too.
 func (c *Conn) deliverNickChange(
-	ctx context.Context,
 	msg *db.IRCMessage,
 	newNick string,
 ) {
-	c.loadSessionNick(ctx)
+	c.mu.Lock()
+
+	if msg.From == c.nick {
+		c.nick = newNick
+	}
+
+	c.mu.Unlock()
 
 	prefix := msg.From + "!" + msg.From + "@*"
 

internal/ircserver/relay_test.go

@@ -655,43 +655,3 @@ func TestRelayNickChangeFromHTTPAPI(t *testing.T) {
 		}
 	}
 }
-
-// TestRelayNickChangeKeepsTakenNick checks that an IRC
-// listener connection which takes a nick another user has
-// given up keeps it when that user's change reaches it
-// afterwards: what it then sends goes out under the nick its
-// session holds.
-func TestRelayNickChangeKeepsTakenNick(t *testing.T) {
-	t.Parallel()
-
-	env := newTestEnv(t)
-
-	bob := env.dial(t)
-	bob.register("bob")
-	bob.sendAndExpect("NICK bob2", " NICK bob2")
-
-	alice := env.dial(t)
-	alice.register("alice")
-	alice.sendAndExpect("NICK bob", " NICK bob")
-	alice.joinAndDrain("#chan")
-
-	bob.joinAndDrain("#chan")
-
-	// Bob's change reaches alice only now, as it does when she
-	// takes his old nick before her connection has passed the
-	// change on. She holds bob now, so it is queued to bob.
-	env.queueMessage(t, "bob", "NICK", "bob", "", []string{"bob2"})
-
-	alice.readUntil(func(l string) bool {
-		return l == ":bob!bob@* NICK bob2"
-	})
-
-	alice.send("PRIVMSG #chan :hi there")
-
-	const want = ":bob!bob@* PRIVMSG #chan :hi there"
-
-	got := bob.readLine()
-	if got != want {
-		t.Errorf("got %q, want %q", got, want)
-	}
-}