From 8f1bc93cca17fdef4eff574e0cbcd053f11c03d7 Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Fri, 28 Apr 2023 16:51:17 +0200
Subject: [PATCH] Protect against clients with an empty id.

---
 group/group.go | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/group/group.go b/group/group.go
index 42c5763..3fa0f36 100644
--- a/group/group.go
+++ b/group/group.go
@@ -609,17 +609,18 @@ func AddClient(group string, c Client, creds ClientCredentials) (*Group, error)
 			}
 		}
 	}
-
-	if g.clients[c.Id()] != nil {
+	id := c.Id()
+	if id == "" {
+		return nil, errors.New("client has empty id")
+	}
+	if g.clients[id] != nil {
 		return nil, ProtocolError("duplicate client id")
 	}
-
-	g.clients[c.Id()] = c
+	g.clients[id] = c
 	g.timestamp = time.Now()
 
 	c.Joined(g.Name(), "join")
 
-	id := c.Id()
 	u := c.Username()
 	p := c.Permissions()
 	s := c.Data()