fix default server randomness, introducing group support (#140)

config.go

@@ -49,6 +49,7 @@ type Config struct {
 	NoTelnet         bool
 	TelnetAddr       string
 	BindAddr         string
+	DefaultSrv       string
 	Servers          map[string]Server
 	ForceDefaultSrv  bool
 	KickOnNewPool    bool
@@ -200,12 +201,17 @@ func copyMapSlice[K comparable, V any](in map[K][]V) map[K][]V {
 // and information about it. The return values are uninitialized
 // if no servers exist.
 func (cnf Config) DefaultServerInfo() (string, Server) {
-	for name, srv := range Conf().Servers {
-		return name, srv
+	name, ok := cnf.RandomGroupServer(cnf.DefaultSrv)
+	if !ok {
+		return "", Server{}
+	}
+
+	srv, ok := cnf.Servers[name]
+	if !ok {
+		return "", Server{}
 	}
 
-	// No servers are configured.
-	return "", Server{}
+	return name, srv
 }
 
 // DefaultServerName returns the name of the default server.

doc/config.md

@@ -93,6 +93,13 @@ Default: ":40000"
 Description: The proxy will listen for new clients on this address.
 ```
 
+> `DefaultSrv`
+```
+Type: string
+Default: ""
+Description: The default server to connect new clients to. May be a group.
+```
+
 > `Servers`
 ```
 Type: map[string]Server

run.go

@@ -117,6 +117,11 @@ func runFunc() {
 				cc.Kick("No servers are configured.")
 				return
 			}
+			if _, ok := conf.Servers[""]; !ok && conf.DefaultServerName() == "" {
+				cc.Log("<-", "no default server")
+				cc.Kick("No valid default server is configured.")
+				return
+			}
 
 			srvName, srv := conf.DefaultServerInfo()
 			lastSrv, err := authIface.LastSrv(cc.Name())