metadata-2 (#2273)

Initial implementation of draft/metadata-2

irc/channel.go

@@ -55,6 +55,7 @@ type Channel struct {
 	dirtyBits         uint
 	settings          ChannelSettings
 	uuid              utils.UUID
+	metadata          map[string]string
 	// these caches are paired to allow iteration over channel members without holding the lock
 	membersCache    []*Client
 	memberDataCache []*memberData
@@ -126,6 +127,7 @@ func (channel *Channel) applyRegInfo(chanReg RegisteredChannel) {
 	channel.userLimit = chanReg.UserLimit
 	channel.settings = chanReg.Settings
 	channel.forward = chanReg.Forward
+	channel.metadata = chanReg.Metadata
 
 	for _, mode := range chanReg.Modes {
 		channel.flags.SetMode(mode, true)
@@ -163,6 +165,7 @@ func (channel *Channel) ExportRegistration() (info RegisteredChannel) {
 	info.AccountToUMode = maps.Clone(channel.accountToUMode)
 
 	info.Settings = channel.settings
+	info.Metadata = channel.metadata
 
 	return
 }
@@ -892,6 +895,10 @@ func (channel *Channel) Join(client *Client, key string, isSajoin bool, rb *Resp
 		rb.Add(nil, client.server.name, "MARKREAD", chname, client.GetReadMarker(chcfname))
 	}
 
+	if rb.session.capabilities.Has(caps.Metadata) {
+		syncChannelMetadata(client.server, rb, channel)
+	}
+
 	if rb.session.client == client {
 		// don't send topic and names for a SAJOIN of a different client
 		channel.SendTopic(client, rb, false)