Fix IRC listener relay of bodies and modes, and JOIN names (closes #127)

The IRC listener relayed only the first line of a PRIVMSG or NOTICE
body; it now sends one line per body line. A MODE change reached IRC
listener members without its key, limit or mask, and "+o bob" went out
as one trailing parameter; each value is now its own parameter, in the
relay and in the echo to the IRC listener user who made the change.
Every line written to an IRC listener connection now has CR, LF and NUL
removed, so a stored body line, key or mask cannot start a line of its
own. The channel name check moved from the HTTP handler into
service.JoinChannel, so the IRC listener's JOIN refuses the same names
with 403.

Model: opus-5-5

internal/ircserver/relay.go

@@ -3,6 +3,7 @@ package ircserver
 import (
 	"context"
 	"encoding/json"
+	"slices"
 	"strings"
 	"time"
 
@@ -105,7 +106,7 @@ func (c *Conn) deliverIRCMessage(
 	case isNumeric(command):
 		c.deliverNumeric(msg, text)
 	case command == irc.CmdPrivmsg || command == irc.CmdNotice:
-		c.deliverTextMessage(msg, command, text)
+		c.deliverTextMessage(msg, command, bodyLines)
 	case command == irc.CmdJoin:
 		c.deliverJoin(msg)
 	case command == irc.CmdPart:
@@ -123,7 +124,7 @@ func (c *Conn) deliverIRCMessage(
 	case command == irc.CmdWallops:
 		c.deliverWallops(msg, text)
 	case command == irc.CmdMode:
-		c.deliverMode(msg, text)
+		c.deliverMode(msg, bodyLines)
 	case command == irc.CmdPing:
 		// Server-originated PING — reply with PONG.
 		c.sendFromServer("PING", c.serverSfx)
@@ -179,10 +180,12 @@ func (c *Conn) deliverNumeric(
 	c.send(FormatMessage(from, msg.Command, allParams...))
 }
 
-// deliverTextMessage sends PRIVMSG or NOTICE.
+// deliverTextMessage sends PRIVMSG or NOTICE, one line for
+// each line of the body.
 func (c *Conn) deliverTextMessage(
 	msg *db.IRCMessage,
-	command, text string,
+	command string,
+	bodyLines []string,
 ) {
 	from := msg.From
 	target := msg.To
@@ -201,7 +204,9 @@ func (c *Conn) deliverTextMessage(
 		prefix = from + "!" + from + "@*"
 	}
 
-	c.send(FormatMessage(prefix, command, target, text))
+	for _, line := range bodyLines {
+		c.send(FormatMessage(prefix, command, target, line))
+	}
 }
 
 // deliverJoin sends a JOIN notification.
@@ -351,15 +356,26 @@ func (c *Conn) deliverWallops(
 	))
 }
 
-// deliverMode sends a MODE change notification.
+// deliverMode sends a MODE change notification. The first
+// body line is the change, possibly followed by its values
+// separated by spaces ("+o bob"); any further lines are
+// values ("+k", "secret"). Each goes out as its own
+// parameter, as IRC sends them.
 func (c *Conn) deliverMode(
 	msg *db.IRCMessage,
-	text string,
+	bodyLines []string,
 ) {
-	prefix := msg.From + "!" + msg.From + "@*"
-	target := msg.To
-
-	if text != "" {
-		c.send(FormatMessage(prefix, "MODE", target, text))
+	if len(bodyLines) == 0 || bodyLines[0] == "" {
+		return
 	}
+
+	prefix := msg.From + "!" + msg.From + "@*"
+
+	params := slices.Concat(
+		[]string{msg.To},
+		strings.Fields(bodyLines[0]),
+		bodyLines[1:],
+	)
+
+	c.send(FormatMessage(prefix, "MODE", params...))
 }