fix: gsm_simulator doesn't need to be restarted every time

protocol_prototype/DryBox/simulator/gsm_simulator.py

@@ -1,4 +1,3 @@
-#gsm_simulator.py
 import socket
 import threading
 import time
@@ -9,13 +8,19 @@ FRAME_SIZE = 1000
 FRAME_DELAY = 0.02
 
 clients = []
+clients_lock = threading.Lock()
 
 def handle_client(client_sock, client_id):
     print(f"Starting handle_client for Client {client_id}")
-    while True:
     try:
-            other_client = clients[1 - client_id] if len(clients) == 2 else None
+        while True:
+            other_client = None
+            with clients_lock:
+                if len(clients) == 2 and client_id < len(clients):
+                    other_client = clients[1 - client_id]
             print(f"Client {client_id} waiting for data, other_client exists: {other_client is not None}")
+            
+            try:
                 data = client_sock.recv(1024)
                 if not data:
                     print(f"Client {client_id} disconnected or no data received")
@@ -26,33 +31,54 @@ def handle_client(client_sock, client_id):
                         other_client.send(frame)
                         time.sleep(FRAME_DELAY)
                     print(f"Forwarded {len(data)} bytes from Client {client_id} to Client {1 - client_id}")
-        except Exception as e:
+            except socket.error as e:
-            print(f"Error with Client {client_id}: {e}")
+                print(f"Socket error with Client {client_id}: {e}")
                 break
+    finally:
         print(f"Closing connection for Client {client_id}")
+        with clients_lock:
+            if client_id < len(clients) and clients[client_id] == client_sock:
+                clients.pop(client_id)
+                print(f"Removed Client {client_id} from clients list")
         client_sock.close()
 
 def start_simulator():
     server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     server.bind((HOST, PORT))
     server.listen(2)
     print(f"GSM Simulator listening on {HOST}:{PORT}...")
 
-    while len(clients) < 2:
-        client_sock, addr = server.accept()
-        client_sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)  # Keep connection alive
-        clients.append(client_sock)
-        client_id = len(clients) - 1
-        print(f"Client {client_id} connected from {addr}")
-        threading.Thread(target=handle_client, args=(client_sock, client_id), daemon=True).start()
-
     try:
         while True:
-            time.sleep(1)
+            client_sock, addr = server.accept()
+            client_sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)  # Keep connection alive
+            with clients_lock:
+                if len(clients) < 2:
+                    clients.append(client_sock)
+                    client_id = len(clients) - 1
+                else:
+                    # Replace a closed socket or reject if both slots are active
+                    replaced = False
+                    for i in range(len(clients)):
+                        if clients[i].fileno() == -1:  # Check if socket is closed
+                            clients[i] = client_sock
+                            client_id = i
+                            replaced = True
+                            break
+                    if not replaced:
+                        print(f"Rejecting new client from {addr}: max clients (2) reached")
+                        client_sock.close()
+                        continue
+            print(f"Client {client_id} connected from {addr}")
+            threading.Thread(target=handle_client, args=(client_sock, client_id), daemon=True).start()
     except KeyboardInterrupt:
         print("Shutting down simulator...")
+    finally:
+        with clients_lock:
             for client in clients:
                 client.close()
+            clients.clear()
         server.close()
 
 if __name__ == "__main__":