setstatus.py: add check if certs readable

setstatus.py

@@ -12,11 +12,12 @@ import argparse
 import socket
 import ssl
 import sys
+import os
 
 
 def main():
-    parser = argparse.ArgumentParser(description="Set door status of 
-                                     Krautspace.")
+    description = "Set door status of Krautspace"
+    parser = argparse.ArgumentParser(description=description)
     parser.add_argument("status_code", help="status to set", type=int,
                         choices=(0, 1))
     args = parser.parse_args()
@@ -31,12 +32,21 @@ def main():
     STATUS = None
     RESPONSE = None
 
+    print('Check certs')
+    for certfile in (CLIENT_CERT, CLIENT_KEY, SERVER_CERT):
+        if os.access(certfile, os.R_OK) is False:
+            print('Failed to read cert: {}'.format(certfile))
+            sys.exit(1)
+    try:
         context = ssl.create_default_context(ssl.Purpose.SERVER_AUTH,
                                          cafile=SERVER_CERT)
+        context.load_cert_chain(certfile=CLIENT_CERT, keyfile=CLIENT_KEY)
         context.set_ciphers('EECDH+AESGCM')   # only ciphers for tls 1.2 and 1.3
         context.options |= getattr(ssl._ssl, 'OP_NO_COMPRESSION', 0)
-    context.load_cert_chain(certfile=CLIENT_CERT, keyfile=CLIENT_KEY)
         print('SSL context created')
+    except Exception as e:
+        print('Failed to create ssl context: {}'.format(e))
+        sys.exit(2)
 
     with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as mySocket:
         print('Socket created')
@@ -54,14 +64,14 @@ def main():
             print('Connection timeout')
         except Exception as e:
             print('Connection failed: {}'.format(e))
-            sys.exit(1)
+            sys.exit(3)
 
         try:
             print('Send new status: {}'.format(STATUS))
             conn.send(STATUS)
         except Exception as e:
             print('Error: {}'.format(e))
-            sys.exit(2)
+            sys.exit(4)
 
         try:
             RESPONSE = conn.recv(1)
@@ -73,7 +83,7 @@ def main():
             print('Disconnect from server')
         except Exception as e:
             print('Error: {}'.format(e))
-            sys.exit(3)
+            sys.exit(5)
 
 
 if __name__ == '__main__':