Add upstream RPL_CREATIONTIME support

downstream.go

@@ -1031,6 +1031,13 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 				Command: irc.RPL_CHANNELMODEIS,
 				Params:  params,
 			})
+			if ch.creationTime != "" {
+				dc.SendMessage(&irc.Message{
+					Prefix:  dc.srv.prefix(),
+					Command: rpl_creationtime,
+					Params:  []string{dc.nick, name, ch.creationTime},
+				})
+			}
 		}
 	case "TOPIC":
 		var channel string

irc.go

@@ -11,6 +11,7 @@ const (
 	rpl_statsping     = "246"
 	rpl_localusers    = "265"
 	rpl_globalusers   = "266"
+	rpl_creationtime  = "329"
 	rpl_topicwhotime  = "333"
 	err_invalidcapcmd = "410"
 )

upstream.go

@@ -23,6 +23,7 @@ type upstreamChannel struct {
 	TopicTime    time.Time
 	Status       channelStatus
 	modes        channelModes
+	creationTime string
 	Members      map[string]*membership
 	complete     bool
 }
@@ -763,6 +764,28 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 				})
 			})
 		}
+	case rpl_creationtime:
+		var channel, creationTime string
+		if err := parseMessageParams(msg, nil, &channel, &creationTime); err != nil {
+			return err
+		}
+
+		ch, err := uc.getChannel(channel)
+		if err != nil {
+			return err
+		}
+
+		firstCreationTime := ch.creationTime == ""
+		ch.creationTime = creationTime
+		if firstCreationTime {
+			uc.forEachDownstream(func(dc *downstreamConn) {
+				dc.SendMessage(&irc.Message{
+					Prefix:  dc.srv.prefix(),
+					Command: rpl_creationtime,
+					Params:  []string{dc.nick, channel, creationTime},
+				})
+			})
+		}
 	case rpl_topicwhotime:
 		var name, who, timeStr string
 		if err := parseMessageParams(msg, nil, &name, &who, &timeStr); err != nil {