applying relevant github-advanced-security suggestions

Author: lindakladivova

python/grass/workflows/server.py

@@ -48,6 +48,7 @@
 import atexit
 import signal
 import sys
+import shutil
 
 
 class JupyterServerInstance:
@@ -112,7 +113,7 @@ def find_free_port():
         :return: A free port number (int).
         """
         with socket.socket() as sock:
-            sock.bind(("", 0))
+            sock.bind(("127.0.0.1", 0))
             return sock.getsockname()[1]
 
     def is_server_running(self, retries=10, delay=0.2):
@@ -183,6 +184,9 @@ def stop_server(self):
 
         # Check if the process with the given PID is a Jupyter server
         try:
+            ps_cmd = shutil.which("ps")
+            if not ps_cmd:
+                raise RuntimeError(_("Unable to find 'ps' command in PATH."))
             proc_name = (
                 subprocess.check_output(["ps", "-p", str(self.pid), "-o", "args="])
                 .decode()
@@ -200,6 +204,9 @@ def stop_server(self):
         # Attempt to terminate the server process
         if self.is_server_running(self.port):
             try:
+                kill_cmd = shutil.which("kill")
+                if not kill_cmd:
+                    raise RuntimeError(_("Unable to find 'kill' command in PATH."))
                 subprocess.check_call(["kill", str(self.pid)])
             except subprocess.CalledProcessError as e:
                 raise RuntimeError(