diff -r 0eedc17055a0 -r cdf69667593b gameServer2/src/server/handlers/loggingin.rs
--- a/gameServer2/src/server/handlers/loggingin.rs	Thu Jun 14 16:44:27 2018 -0400
+++ b/gameServer2/src/server/handlers/loggingin.rs	Mon Jun 18 09:22:53 2018 -0400
@@ -5,18 +5,47 @@
 use server::actions::Action::*;
 use protocol::messages::HWProtocolMessage;
 use protocol::messages::HWServerMessage::*;
+use utils::is_name_illegal;
 
 pub fn handle(server: & mut HWServer, token: usize, message: HWProtocolMessage) {
     match message {
-        HWProtocolMessage::Nick(nick) =>
-            if server.clients[token].room_id == None {
-                server.react(token, vec![SendMe(Nick(nick.clone()))]);
-                server.clients[token].nick = nick;
-                server.react(token, vec![CheckRegistered]);
-            },
+        HWProtocolMessage::Nick(nick) => {
+            let actions;
+            {
+                let client = &mut server.clients[token];
+                debug!("{} {}", nick, is_name_illegal(&nick));
+                actions = if client.room_id != None {
+                    unreachable!()
+                }
+                else if !client.nick.is_empty() {
+                    vec![ProtocolError("Nickname already provided.".to_string())]
+                }
+                else if     is_name_illegal(&nick) {
+                    vec![ByeClient("Illegal nickname! Nicknames must be between 1-40 characters long, must not have a trailing or leading space and must not have any of these characters: $()*+?[]^{|}".to_string())]
+                }
+                else {
+                    client.nick = nick.clone();
+                    vec![SendMe(Nick(nick)), CheckRegistered]
+                };
+            }
+            server.react(token, actions);
+        },
         HWProtocolMessage::Proto(proto) => {
-            server.clients[token].protocol_number = proto;
-            server.react(token, vec![CheckRegistered]);
+            let actions;
+            {
+                let client = &mut server.clients[token];
+                actions = if client.protocol_number != 0 {
+                    vec![ProtocolError("Protocol already known.".to_string())]
+                }
+                else if proto == 0 {
+                    vec![ProtocolError("Bad number.".to_string())]
+                }
+                else {
+                    client.protocol_number = proto;
+                    vec![SendMe(Proto(proto)), CheckRegistered]
+                };
+            }
+            server.react(token, actions);
         },
         _ => warn!("Incorrect command in logging-in state"),
     }