fix #2284 (#2317)

Send a configurable NOTICE on first connection that hopm can
detect via target_string

irc/client.go

@@ -414,6 +414,11 @@ func (server *Server) RunClient(conn IRCConn) {
 		session.certfp, session.peerCerts, _ = utils.GetCertFP(wConn.Conn, RegisterTimeout)
 	}
 
+	if config.Server.InitialNotice != "" {
+		// send initial notice for HOPM to recognize
+		client.Send(nil, client.server.name, "NOTICE", "*", config.Server.InitialNotice)
+	}
+
 	if session.isTor {
 		session.rawHostname = config.Server.TorListeners.Vhost
 		client.rawHostname = session.rawHostname

irc/config.go

@@ -580,7 +580,8 @@ type Config struct {
 		CoerceIdent             string `yaml:"coerce-ident"`
 		MOTD                    string
 		motdLines               []string
-		MOTDFormatting          bool `yaml:"motd-formatting"`
+		MOTDFormatting          bool   `yaml:"motd-formatting"`
+		InitialNotice           string `yaml:"initial-notice"`
 		IdleTimeouts            struct {
 			Registration time.Duration
 			Ping         time.Duration