modes: Limit length of beI mode lists

CHANGELOG.md

@@ -12,6 +12,7 @@ New release of Oragono!
 ### Added
 * Added operator classes, allowing for more finely-grained permissions for operators.
 * Added automatic client connection limiting, similar to other IRCds.
+* Length of channel mode lists (ban / ban-except / invite-except) is now restricted to the limit in config.
 * Added support for IRCv3 capability [`chghost`](http://ircv3.net/specs/extensions/chghost-3.2.html).
 
 ### Changed

irc/config.go

@@ -136,6 +136,7 @@ type Config struct {
 		TopicLen       uint `yaml:"topiclen"`
 		WhowasEntries  uint `yaml:"whowas-entries"`
 		MonitorEntries uint `yaml:"monitor-entries"`
+		ChanListModes  uint `yaml:"chan-list-modes"`
 	}
 }
 

irc/modes.go

@@ -404,6 +404,9 @@ func cmodeHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 			changes = append(changes, &change)
 		}
 
+		// so we only output one warning for each list type when full
+		listFullWarned := make(map[ChannelMode]bool)
+
 		for _, change := range changes {
 			switch change.mode {
 			case BanMask, ExceptMask, InviteMask:
@@ -428,6 +431,14 @@ func cmodeHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 
 				switch change.op {
 				case Add:
+					if len(list.masks) >= server.limits.ChanListModes {
+						if !listFullWarned[change.mode] {
+							client.Send(nil, server.name, ERR_BANLISTFULL, client.nick, channel.name, change.mode.String(), "Channel list is full")
+							listFullWarned[change.mode] = true
+						}
+						continue
+					}
+
 					list.Add(mask)
 					applied = append(applied, change)
 

irc/server.go

@@ -39,6 +39,7 @@ type Limits struct {
 	MonitorEntries int
 	NickLen        int
 	TopicLen       int
+	ChanListModes  int
 }
 
 // ListenerInterface represents an interface for a listener.
@@ -166,6 +167,7 @@ func NewServer(configFilename string, config *Config) *Server {
 			MonitorEntries: int(config.Limits.MonitorEntries),
 			NickLen:        int(config.Limits.NickLen),
 			TopicLen:       int(config.Limits.TopicLen),
+			ChanListModes:  int(config.Limits.ChanListModes),
 		},
 		listeners:      make(map[string]ListenerInterface),
 		monitoring:     make(map[string][]Client),
@@ -266,7 +268,7 @@ func (server *Server) setISupport() {
 	server.isupport.Add("EXCEPTS", "")
 	server.isupport.Add("INVEX", "")
 	server.isupport.Add("KICKLEN", strconv.Itoa(server.limits.KickLen))
-	// server.isupport.Add("MAXLIST", "") //TODO(dan): Support max list length?
+	server.isupport.Add("MAXLIST", fmt.Sprintf("beI:%s", strconv.Itoa(server.limits.ChanListModes)))
 	// server.isupport.Add("MODES", "")   //TODO(dan): Support max modes?
 	server.isupport.Add("MONITOR", strconv.Itoa(server.limits.MonitorEntries))
 	server.isupport.Add("NETWORK", server.networkName)
@@ -1056,6 +1058,7 @@ func (server *Server) rehash() error {
 		MonitorEntries: int(config.Limits.MonitorEntries),
 		NickLen:        int(config.Limits.NickLen),
 		TopicLen:       int(config.Limits.TopicLen),
+		ChanListModes:  int(config.Limits.ChanListModes),
 	}
 	server.operclasses = *operclasses
 	server.operators = opers

oragono.yaml

@@ -160,3 +160,6 @@ limits:
 
     # whowas entries to store
     whowas-entries: 100
+
+    # maximum length of channel lists (beI modes)
+    chan-list-modes: 60