Allow configuring relay

conventional.yaml

@@ -134,6 +134,19 @@ server:
     # if this is true, the motd is escaped using formatting codes like $c, $b, and $i
     motd-formatting: true
 
+    # relaying using the RELAYMSG command
+    relaying:
+        # is relaying enabled at all?
+        enabled: true
+
+        # which character(s) are reserved for relayed nicks?
+        separators: "/"
+
+        # can channel operators use RELAYMSG in their channels?
+        # our implementation of RELAYMSG makes it safe for chanops to use without the
+        # possibility of real users being silently spoofed
+        available-to-chanops: true
+
     # addresses/CIDRs the PROXY command can be used from
     # this should be restricted to localhost (127.0.0.1/8, ::1/128, and unix sockets),
     # unless you have a good reason. you should also add these addresses to the

irc/client_lookup_set.go

@@ -173,9 +173,14 @@ func (clients *ClientManager) SetNick(client *Client, session *Session, newNick
 			return "", errNicknameInvalid, false
 		}
 
-		if strings.Contains(newCfNick, "/") {
+		config := client.server.Config()
+		if config.Server.Relaying.Enabled {
+			for _, char := range config.Server.Relaying.Separators {
+				if strings.ContainsRune(newCfNick, char) {
 					return "", errNicknameInvalid, false
 				}
+			}
+		}
 
 		if restrictedCasefoldedNicks[newCfNick] || restrictedSkeletons[newSkeleton] {
 			return "", errNicknameInvalid, false

irc/config.go

@@ -500,6 +500,11 @@ type Config struct {
 		MOTD                    string
 		motdLines               []string
 		MOTDFormatting          bool `yaml:"motd-formatting"`
+		Relaying                struct {
+			Enabled            bool
+			Separators         string
+			AvailableToChanops bool `yaml:"available-to-chanops"`
+		}
 		ProxyAllowedFrom     []string `yaml:"proxy-allowed-from"`
 		proxyAllowedFromNets []net.IPNet
 		WebIRC               []webircConfig `yaml:"webirc"`
@@ -1068,8 +1073,16 @@ func LoadConfig(filename string) (config *Config, err error) {
 	}
 	config.Server.capValues[caps.Languages] = config.languageManager.CapValue()
 
-	// intentionally not configurable
-	config.Server.capValues[caps.Relaymsg] = "/"
+	if config.Server.Relaying.Enabled {
+		for _, char := range protocolBreakingNameCharacters {
+			if strings.ContainsRune(config.Server.Relaying.Separators, char) {
+				return nil, fmt.Errorf("Relaying separators cannot include the characters %s", protocolBreakingNameCharacters)
+			}
+		}
+		config.Server.capValues[caps.Relaymsg] = config.Server.Relaying.Separators
+	} else {
+		config.Server.supportedCaps.Disable(caps.Relaymsg)
+	}
 
 	config.Debug.recoverFromErrors = utils.BoolDefaultTrue(config.Debug.RecoverFromErrors)
 

irc/handlers.go

@@ -1888,13 +1888,23 @@ func messageHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *R
 			break
 		}
 
-		if strings.Contains(targetString, "/") {
+		config := server.Config()
+		if config.Server.Relaying.Enabled {
+			var isForRelayClient bool
+			for _, char := range config.Server.Relaying.Separators {
+				if strings.ContainsRune(targetString, char) {
+					isForRelayClient = true
+					break
+				}
+			}
+			if isForRelayClient {
 				if histType == history.Privmsg {
 					rb.Add(nil, server.name, ERR_NOSUCHNICK, client.Nick(), targetString, client.t("Relayed users cannot be sent private messages"))
 				}
 				// TAGMSG/NOTICEs are intentionally silently dropped
 				continue
 			}
+		}
 
 		// each target gets distinct msgids
 		splitMsg := utils.MakeMessage(message)
@@ -2281,14 +2291,21 @@ func rehashHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 
 // RELAYMSG <channel> <spoofed nick> :<message>
 func relaymsgHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *ResponseBuffer) (result bool) {
+	config := server.Config()
+	if !config.Server.Relaying.Enabled {
+		rb.Add(nil, server.name, "FAIL", "RELAYMSG", "NOT_ENABLED", client.t("Relaying has been disabled"))
+		return false
+	}
+
 	channel := server.channels.Get(msg.Params[0])
 	if channel == nil {
 		rb.Add(nil, server.name, ERR_NOSUCHCHANNEL, client.Nick(), utils.SafeErrorParam(msg.Params[0]), client.t("No such channel"))
 		return false
 	}
 
-	if !(channel.ClientIsAtLeast(client, modes.ChannelOperator) || client.HasRoleCapabs("relaymsg-anywhere")) {
-		rb.Add(nil, server.name, "FAIL", "RELAYMSG", "NOT_PRIVED", client.t("Only channel operators or ircops with the 'relaymsg-anywhere' role can relay messages"))
+	allowedToRelay := client.HasRoleCapabs("relaymsg-anywhere") || (config.Server.Relaying.AvailableToChanops && channel.ClientIsAtLeast(client, modes.ChannelOperator))
+	if !allowedToRelay {
+		rb.Add(nil, server.name, "FAIL", "RELAYMSG", "NOT_PRIVED", client.t("You cannot relay messages to this channel"))
 		return false
 	}
 

irc/server.go

@@ -497,6 +497,10 @@ func (server *Server) applyConfig(config *Config) (err error) {
 			return fmt.Errorf("Casemapping cannot be changed after launching the server, rehash aborted")
 		} else if oldConfig.Accounts.Multiclient.AlwaysOn != config.Accounts.Multiclient.AlwaysOn {
 			return fmt.Errorf("Default always-on setting cannot be changed after launching the server, rehash aborted")
+		} else if oldConfig.Server.Relaying.Enabled != config.Server.Relaying.Enabled {
+			return fmt.Errorf("Cannot enable or disable relaying after launching the server, rehash aborted")
+		} else if oldConfig.Server.Relaying.Separators != config.Server.Relaying.Separators {
+			return fmt.Errorf("Cannot change relaying separators after launching the server, rehash aborted")
 		}
 	}
 

irc/strings.go

@@ -19,6 +19,16 @@ import (
 
 const (
 	precisUTF8MappingToken = "rfc8265"
+
+	// space can't be used
+	// , is used as a separator
+	// * is used in mask matching
+	// ? is used in mask matching
+	// . denotes a server name
+	// ! separates nickname from username
+	// @ separates username from hostname
+	// : means trailing
+	protocolBreakingNameCharacters = " ,*?.!@:"
 )
 
 var (
@@ -132,18 +142,10 @@ func CasefoldName(name string) (string, error) {
 		return "", errStringIsEmpty
 	}
 
-	// space can't be used
-	// , is used as a separator
-	// * is used in mask matching
-	// ? is used in mask matching
-	// . denotes a server name
-	// ! separates nickname from username
-	// @ separates username from hostname
-	// : means trailing
 	// # is a channel prefix
 	// ~&@%+ are channel membership prefixes
 	// - I feel like disallowing
-	if strings.ContainsAny(lowered, " ,*?.!@:") || strings.ContainsAny(string(lowered[0]), "#~&@%+-") {
+	if strings.ContainsAny(lowered, protocolBreakingNameCharacters) || strings.ContainsAny(string(lowered[0]), "#~&@%+-") {
 		return "", errInvalidCharacter
 	}
 

oragono.yaml

@@ -160,6 +160,19 @@ server:
     # if this is true, the motd is escaped using formatting codes like $c, $b, and $i
     motd-formatting: true
 
+    # relaying using the RELAYMSG command
+    relaying:
+        # is relaying enabled at all?
+        enabled: true
+
+        # which character(s) are reserved for relayed nicks?
+        separators: "/"
+
+        # can channel operators use RELAYMSG in their channels?
+        # our implementation of RELAYMSG makes it safe for chanops to use without the
+        # possibility of real users being silently spoofed
+        available-to-chanops: true
+
     # addresses/CIDRs the PROXY command can be used from
     # this should be restricted to localhost (127.0.0.1/8, ::1/128, and unix sockets),
     # unless you have a good reason. you should also add these addresses to the