fix: add validation to prevent duplicated local ports

main.go

@@ -14,6 +14,7 @@ import (
 
 	chclient "github.com/jpillora/chisel/client"
 	"github.com/jpillora/chisel/share/cos"
+	"github.com/jpillora/chisel/share/settings"
 )
 
 var (
@@ -140,7 +141,13 @@ func client(args []string) {
 		log.Fatalf("A server and least one remote is required")
 	}
 	config.Server = args[0]
-	config.Remotes = args[1:]
+
+	if err := validateRemotes(args[1:]); err != nil {
+		log.Fatal(err)
+	} else {
+		config.Remotes = args[1:]
+	}
+
 	//default auth
 	if config.Auth == "" {
 		config.Auth = os.Getenv("AUTH")
@@ -167,3 +174,35 @@ func client(args []string) {
 		log.Fatal(err)
 	}
 }
+
+// validate the provided Remotes configuration is valid
+func validateRemotes(remotes []string) error {
+	uniqueRemotes := []string{}
+
+	for _, newRemote := range remotes {
+		// iterate all remotes already in the unique list, if duplicate is found return error
+		for _, unique := range uniqueRemotes {
+			firstRemote, err := settings.DecodeRemote(unique)
+			if err != nil {
+				return fmt.Errorf("failed to decode remote '%s': %s", unique, err)
+			}
+
+			secondRemote, err := settings.DecodeRemote(newRemote)
+			if err != nil {
+				return fmt.Errorf("failed to decode remote '%s': %s", newRemote, err)
+			}
+
+			if isDuplicatedRemote(firstRemote, secondRemote) {
+				return fmt.Errorf("invalid Remote configuration: remote port '%s' is duplicated", secondRemote.RemotePort)
+			}
+		}
+
+		uniqueRemotes = append(uniqueRemotes, newRemote)
+	}
+
+	return nil
+}
+
+func isDuplicatedRemote(first, second *settings.Remote) bool {
+	return first.RemotePort == second.RemotePort
+}