Handle downstream MODE messages

downstream.go

@@ -246,6 +246,52 @@ func (c *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 		c.user.forEachUpstream(func(uc *upstreamConn) {
 			uc.messages <- msg
 		})
+	case "MODE":
+		var name string
+		if err := parseMessageParams(msg, &name); err != nil {
+			return err
+		}
+
+		var modeStr string
+		if len(msg.Params) > 1 {
+			modeStr = msg.Params[1]
+		}
+
+		if msg.Prefix.Name != name {
+			ch, err := c.user.getChannel(name)
+			if err != nil {
+				return err
+			}
+
+			if modeStr != "" {
+				ch.conn.messages <- msg
+			} else {
+				c.messages <- &irc.Message{
+					Prefix:  c.srv.prefix(),
+					Command: irc.RPL_CHANNELMODEIS,
+					Params:  []string{ch.Name, string(ch.modes)},
+				}
+			}
+		} else {
+			if name != c.nick {
+				return ircError{&irc.Message{
+					Command: irc.ERR_USERSDONTMATCH,
+					Params:  []string{c.nick, "Cannot change mode for other users"},
+				}}
+			}
+
+			if modeStr != "" {
+				c.user.forEachUpstream(func(uc *upstreamConn) {
+					uc.messages <- msg
+				})
+			} else {
+				c.messages <- &irc.Message{
+					Prefix:  c.srv.prefix(),
+					Command: irc.RPL_UMODEIS,
+					Params:  []string{""}, // TODO
+				}
+			}
+		}
 	default:
 		c.logger.Printf("unhandled message: %v", msg)
 		return newUnknownCommandError(msg.Command)

server.go

@@ -59,6 +59,27 @@ func (u *user) forEachDownstream(f func(dc *downstreamConn)) {
 	u.lock.Unlock()
 }
 
+func (u *user) getChannel(name string) (*upstreamChannel, error) {
+	var channel *upstreamChannel
+	var err error
+	u.forEachUpstream(func(uc *upstreamConn) {
+		if err != nil {
+			return
+		}
+		if ch, ok := uc.channels[name]; ok {
+			if channel != nil {
+				err = fmt.Errorf("ambiguous channel name %q", name)
+			} else {
+				channel = ch
+			}
+		}
+	})
+	if channel == nil {
+		return nil, fmt.Errorf("unknown channel %q", name)
+	}
+	return channel, nil
+}
+
 type Upstream struct {
 	Addr     string
 	Nick     string

upstream.go

@@ -14,6 +14,7 @@ import (
 
 type upstreamChannel struct {
 	Name      string
+	conn      *upstreamConn
 	Topic     string
 	TopicWho  string
 	TopicTime time.Time
@@ -126,11 +127,11 @@ func (c *upstreamConn) handleMessage(msg *irc.Message) error {
 			if err := ch.modes.Apply(modeStr); err != nil {
 				return err
 			}
+		}
 
 		c.user.forEachDownstream(func(dc *downstreamConn) {
 			dc.messages <- msg
 		})
-		}
 	case "NOTICE":
 		c.logger.Print(msg)
 	case irc.RPL_WELCOME:
@@ -182,6 +183,7 @@ func (c *upstreamConn) handleMessage(msg *irc.Message) error {
 				c.logger.Printf("joined channel %q", ch)
 				c.channels[ch] = &upstreamChannel{
 					Name:    ch,
+					conn:    c,
 					Members: make(map[string]membership),
 				}
 			} else {