Add chunking for messeages over 512 bytes (#15)

Hologram/Network/Modem/Modem.py

@@ -289,7 +289,6 @@ def connect_socket(self, host, port):
             self.logger.info('Connect socket is successful')
 
     def listen_socket(self, port):
-
         at_command_val = "%d,%s" % (self.socket_identifier, port)
         self.listen_socket_identifier = self.socket_identifier
         ok, _ = self.set('+USOLI', at_command_val, timeout=5)
@@ -298,17 +297,25 @@ def listen_socket(self, port):
             raise NetworkError('Failed to listen socket')
 
     def write_socket(self, data):
-
         self.enable_hex_mode()
-        value = b'%d,%d,\"%s\"' % (self.socket_identifier,
-                len(data),
-                binascii.hexlify(data))
-        ok, _ = self.set('+USOWR', value, timeout=10)
-        if ok != ModemResult.OK:
-            self.logger.error('Failed to write to socket')
-            raise NetworkError('Failed to write socket')
+        hexdata = binascii.hexlify(data)
+        # We have to do it in chunks of 510 since 512 is actually too long (CMEE error)
+        # and we need 2n chars for hexified data
+        for chunk in self._chunks(hexdata, 510):
+            value = b'%d,%d,\"%s\"' % (self.socket_identifier,
+                    len(binascii.unhexlify(chunk)),
+                    chunk)
+            ok, _ = self.set('+USOWR', value, timeout=10)
+            if ok != ModemResult.OK:
+                self.logger.error('Failed to write to socket')
+                raise NetworkError('Failed to write socket')
         self.disable_hex_mode()
 
+    def _chunks(self, data, n):
+        """Yield successive n-sized chunks from lst."""
+        for i in range(0, len(data), n):
+            yield data[i:i + n]
+
     def read_socket(self, socket_identifier=None, payload_length=None):
 
         if socket_identifier is None:

tests/Modem/test_Modem.py

@@ -32,6 +32,9 @@ def mock_open_serial_port(modem, device_name=None):
 def mock_close_serial_port(modem):
     return True
 
+def mock_result(modem):
+    return (ModemResult.OK, None)
+
 def mock_detect_usable_serial_port(modem, stop_on_first=True):
     return '/dev/ttyUSB0'
 
@@ -54,9 +57,14 @@ def no_serial_port(monkeypatch):
 def get_sms(monkeypatch):
     monkeypatch.setattr(Modem, 'command', mock_command_sms)
     monkeypatch.setattr(Modem, 'set', mock_set_sms)
+def override_command_result(monkeypatch):
+    monkeypatch.setattr(Modem, '_command_result', mock_result)
 
-# CONSTRUCTOR
+@pytest.fixture
+def override_command_result(monkeypatch):
+    monkeypatch.setattr(Modem, '_command_result', mock_result)
 
+# CONSTRUCTOR
 
 def test_init_modem_no_args(no_serial_port):
     modem = Modem()
@@ -80,10 +88,8 @@ def test_get_result_string(no_serial_port):
     assert(modem.getResultString(-3) == 'Modem response doesn\'t match expected return value')
     assert(modem.getResultString(-99) == 'Unknown response code')
 
-
 # PROPERTIES
 
-
 def test_get_location(no_serial_port):
     modem = Modem()
     with pytest.raises(NotImplementedError) as e:
@@ -99,8 +105,19 @@ def test_get_sms(no_serial_port, get_sms):
     assert(res.timestamp == datetime.utcfromtimestamp(1498264009))
     assert(res.message == 'Test 123')
 
-# DEBUGWRITE
+# WRITE SOCKET
+
+def test_socket_write_under_512(no_serial_port, override_command_result):
+    modem = Modem()
+    data = '{message:{fill}{align}{width}}'.format(message='Test-', fill='@', align='<', width=64)
+    modem.write_socket(data.encode())
+
+def test_socket_write_over_512(no_serial_port, override_command_result):
+    modem = Modem()
+    data = '{message:{fill}{align}{width}}'.format(message='Test-', fill='@', align='<', width=600)
+    modem.write_socket(data.encode())
 
+# DEBUGWRITE
 
 def test_debugwrite(no_serial_port):
     modem = Modem()
@@ -111,10 +128,8 @@ def test_debugwrite(no_serial_port):
     modem.debugwrite('test222', hide=True)
     assert(modem.debug_out == 'test') # debug_out shouldn't change since hide is enabled.
 
-
 # MODEMWRITE
 
-
 def test_modemwrite(no_serial_port):
     modem = Modem()
     assert(modem.debug_out == '')
@@ -136,7 +151,6 @@ def test_modemwrite(no_serial_port):
     modem.modemwrite('test5', start=True, at=True, seteq=True, read=True, end=True)
     assert(modem.debug_out == '[ATtest5=?]')
 
-
 # COMMAND_RESULT
 
 def test_command_result(no_serial_port):
@@ -193,7 +207,6 @@ def test_command_result(no_serial_port):
 
 # HANDLEURC
 
-
 # These are static methods that can be tested independently.
 # We decided to wrap it all here under this test object
 class TestModemProtectedStaticMethods():