limit the number of channels a client can join

irc/config.go

@@ -296,6 +296,7 @@ type Config struct {
 	Channels struct {
 		DefaultModes         *string `yaml:"default-modes"`
 		defaultModes         modes.Modes
+		MaxChannelsPerClient int `yaml:"max-channels-per-client"`
 		Registration         ChannelRegistrationConfig
 	}
 
@@ -790,6 +791,9 @@ func LoadConfig(filename string) (config *Config, err error) {
 		config.Accounts.Registration.BcryptCost = passwd.DefaultCost
 	}
 
+	if config.Channels.MaxChannelsPerClient == 0 {
+		config.Channels.MaxChannelsPerClient = 100
+	}
 	if config.Channels.Registration.MaxChannelsPerAccount == 0 {
 		config.Channels.Registration.MaxChannelsPerAccount = 10
 	}

irc/getters.go

@@ -184,6 +184,12 @@ func (client *Client) Channels() (result []*Channel) {
 	return
 }
 
+func (client *Client) NumChannels() int {
+	client.stateMutex.RLock()
+	defer client.stateMutex.RUnlock()
+	return len(client.channels)
+}
+
 func (client *Client) WhoWas() (result WhoWas) {
 	return client.Details().WhoWas
 }

irc/handlers.go

@@ -1148,7 +1148,13 @@ func joinHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 		keys = strings.Split(msg.Params[1], ",")
 	}
 
+	config := server.Config()
+	oper := client.Oper()
 	for i, name := range channels {
+		if config.Channels.MaxChannelsPerClient <= client.NumChannels() && oper == nil {
+			rb.Add(nil, server.name, ERR_UNKNOWNERROR, client.Nick(), name, client.t("You have joined too many channels already"))
+			return false
+		}
 		var key string
 		if len(keys) > i {
 			key = keys[i]

oragono.yaml

@@ -275,6 +275,9 @@ channels:
     # see  /QUOTE HELP cmodes  for more channel modes
     default-modes: +nt
 
+    # how many channels can a client be in at once?
+    max-channels-per-client: 100
+
     # channel registration - requires an account
     registration:
         # can users register new channels?