autotest: make hlrauc.py able to run standalone

For testing purposes, it is useful to run hlrauc.py by itself
not including it from another python script like autotests do.

Better error checking was also added as testing can result in
badly formatted data.

autotests/util/hlrauc.py

@@ -1,6 +1,8 @@
 import socket
 import os
 import threading
+import sys
+import signal
 from Crypto.Cipher import AES
 
 class AuthCenter:
@@ -13,7 +15,7 @@ class AuthCenter:
         self._read_config(config_file)
         self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
         self._socket.setblocking(0)
-        if os.path.isfile(sock_path):
+        if os.path.exists(sock_path):
             os.unlink(sock_path)
         self._socket.bind(sock_path)
 
@@ -48,7 +50,12 @@ class AuthCenter:
         if data[:12] == "SIM-REQ-AUTH":
             # SIM requests just return the stored values for the IMSI
             imsi, num_chals = data[13:].split(' ')
-            data = self._database[imsi]
+            if not imsi or not num_chals:
+                return "ERROR"
+
+            data = self._database.get(imsi, None)
+            if not data:
+                return "ERROR"
 
             response = "SIM-RESP-AUTH %s" % imsi
             response += (' ' + data)*int(num_chals)
@@ -57,7 +64,13 @@ class AuthCenter:
         elif data[:12] == "AKA-REQ-AUTH":
             # AKA requests must compute the milenage parameters for the IMSI
             imsi = data.split(' ')[1]
-            data = self._database[imsi]
+            data = self._database.get(imsi, None)
+            if not data:
+                return "ERROR"
+
+            # make sure this is an AKA entry
+            if len(data.split(':')) < 4:
+                return "ERROR"
 
             k, opc, amf, sqn = data.split(':')
 
@@ -172,3 +185,22 @@ class AuthCenter:
         self._rxhandle.shutdown = True
         self._rxhandle.join()
         self._socket.close()
+
+if __name__ == '__main__':
+    '''
+        This will run in a stand-alone mode for testing
+    '''
+    if len(sys.argv) < 3:
+        print('Usage: ./hlrauc.py <sock_path> <config>')
+        sys.exit()
+
+    hlrauc = AuthCenter(sys.argv[1], sys.argv[2])
+
+    def signal_handler(signal, frame):
+        print('Exiting...')
+        hlrauc.stop()
+        sys.exit()
+
+    signal.signal(signal.SIGINT, signal_handler)
+
+    signal.pause()