public const int RESPONSE_CRC = -0x0002; // UInt16BE
// returns the dycrypted response payload only
protected byte[] Decode(MedtronicCnlSession pumpSession, byte[] payload)
{
if (payload.Length < MM_PAYLOAD + NGP_PAYLOAD + NGP55_PAYLOAD + RESPONSE_PAYLOAD ||
payload[MM_COMMAND] == (byte)CommandType.READ_INFO ||
payload[MM_COMMAND] == (byte)CommandType.REQUEST_LINK_KEY_RESPONSE)
{
throw new EncryptionException("Message received for decryption wrong type/size");
}
byte encryptedPayloadSize = payload[MM_PAYLOAD + NGP_PAYLOAD + NGP55_ENCRYPTED_SIZE];
if (encryptedPayloadSize == 0)
{
throw new EncryptionException("Could not decrypt Medtronic Message (encryptedPayloadSize == 0)");
}
var encryptedPayload = new MedtronicMessageBuffer(encryptedPayloadSize);
encryptedPayload.Put(payload, MM_PAYLOAD + NGP_PAYLOAD + NGP55_PAYLOAD, encryptedPayloadSize);
var decryptedPayload = Decrypt(pumpSession.getKey(), pumpSession.getIV(), encryptedPayload);
if (decryptedPayload == null)
{
throw new EncryptionException("Could not decrypt Medtronic Message (decryptedPayload == null)");
}
#if DEBUG
string outputstring = HexDump.DumpHexstring(decryptedPayload);
Log.d(TAG, "DECRYPTED: " + outputstring);
#endif
return(decryptedPayload);
}
protected async Task <byte[]> ReadMessage(UsbHidDriver mDevice, int timeout = READ_TIMEOUT_MS)
{
ByteArrayOutputStream responseMessage = new ByteArrayOutputStream();
int messageSize = 0;
int bytesRead;
do
{
var rawBytes = await mDevice.Read(timeout);
bytesRead = rawBytes?.Length ?? -1;
if (bytesRead == -1)
{
throw new TimeoutException("Timeout waiting for response from pump");
}
else if (bytesRead > 0)
{
// Validate the header
var responseBuffer = new MedtronicMessageBuffer(bytesRead);
ValidateHeader(responseBuffer);
messageSize = responseBuffer.MessageLength;
responseMessage.write(responseBuffer, 4, messageSize);
}
else
{
Log.w(TAG, "readMessage: got a zero-sized response.");
}
} while (bytesRead > 0 && messageSize == USB_MAX_MESSAGE_SIZE);
string responsestring = HexDump.DumpHexstring(responseMessage.toByteArray());
Log.d(TAG, "READ: " + responsestring);
return(responseMessage.toByteArray());
}
protected void SendMessage(UsbHidDriver mDevice)
{
int pos = 0;
var message = Encode();
// chop into pieces and send each individual piece
while (message.Length > pos)
{
var outputBuffer = new MedtronicMessageBuffer(USB_BLOCKSIZE);
int sendLength = (pos + USB_MAX_MESSAGE_SIZE > message.Length)
? message.Length - pos
: USB_MAX_MESSAGE_SIZE;
outputBuffer.Put(HeaderBytes);
outputBuffer.Put((byte)sendLength);
outputBuffer.Put(message, pos, sendLength);
// separate the send concern
mDevice.Write(outputBuffer, WRITE_TIMEOUT_MS);
pos += sendLength;
string outputstring = HexDump.DumpHexstring(outputBuffer);
Log.d(TAG, "WRITE: " + outputstring);
}
}
protected async Task <byte[]> ReadFromPump(UsbHidDriver mDevice, MedtronicCnlSession pumpSession, string tag)
{
tag = " (" + tag + ")";
MultipacketSession multipacketSession = null;
byte[] tupple;
byte[] payload = null;
byte[] decrypted = null;
bool fetchMoreData = true;
int retry = 0;
int expectedSegments = 0;
int cmd;
while (fetchMoreData)
{
if (multipacketSession != null)
{
do
{
if (expectedSegments < 1)
{
tupple = multipacketSession.MissingSegments();
new MultipacketResendPacketsMessage(pumpSession, tupple).send(mDevice);
expectedSegments = read16BEtoUInt(tupple, 0x02);
}
try
{
payload = await ReadMessage(mDevice, MULTIPACKET_TIMEOUT_MS);
break;
}
catch (TimeoutException e)
{
if (++retry >= SEGMENT_RETRY)
{
throw new TimeoutException("Timeout waiting for response from pump (multipacket)" + tag);
}
Log.d(TAG, "*** Multisession timeout, expecting:" + expectedSegments + " retry: " + retry);
expectedSegments = 0;
}
} while (retry > 0);
}
else
{
try
{
payload = await ReadMessage(mDevice, READ_TIMEOUT_MS);
}
catch (TimeoutException e)
{
throw new TimeoutException("Timeout waiting for response from pump" + tag);
}
}
if (payload.Length < 0x0039)
{
Log.d(TAG, "*** bad response" + HexDump.DumpHexstring(payload, 0x12, payload.Length - 0x14));
fetchMoreData = true;
}
else
{
decrypted = Decode(pumpSession, payload);
cmd = read16BEtoUInt(decrypted, RESPONSE_COMMAND);
Log.d(TAG, "CMD: " + HexDump.ToHexstring(cmd));
if (MedtronicSendMessageRequestMessage.MessageType.EHSM_SESSION.response(cmd))
{
// EHSM_SESSION(0)
Log.d(TAG, "*** EHSM response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = true;
}
else if (MedtronicSendMessageRequestMessage.MessageType.NAK_COMMAND.response(cmd))
{
Log.d(TAG, "*** NAK response" + HexDump.DumpHexstring(decrypted));
ClearMessage(mDevice, ERROR_CLEAR_TIMEOUT_MS);
// if multipacket was in progress we may need to clear 2 EHSM_SESSION(1) messages from pump
short nakcmd = read16BEtoShort(decrypted, 3);
byte nakcode = decrypted[5];
throw new UnexpectedMessageException("Pump sent a NAK(" + string.Format("%02X", nakcmd) + ":" + string.Format("%02X", nakcode) + ") response" + tag);
}
else if (MedtronicSendMessageRequestMessage.MessageType.INITIATE_MULTIPACKET_TRANSFER.response(cmd))
{
multipacketSession = new MultipacketSession(decrypted);
new AckMessage(pumpSession, MedtronicSendMessageRequestMessage.MessageType.INITIATE_MULTIPACKET_TRANSFER.response()).send(mDevice);
expectedSegments = multipacketSession.PacketsToFetch;
fetchMoreData = true;
}
else if (MedtronicSendMessageRequestMessage.MessageType.MULTIPACKET_SEGMENT_TRANSMISSION.response(cmd))
{
if (multipacketSession == null)
{
throw new UnexpectedMessageException("multipacketSession not initiated before segment received" + tag);
}
multipacketSession.AddSegment(decrypted);
expectedSegments--;
if (multipacketSession.PayloadComplete)
{
Log.d(TAG, "*** Multisession Complete");
new AckMessage(pumpSession, MedtronicSendMessageRequestMessage.MessageType.MULTIPACKET_SEGMENT_TRANSMISSION.response()).send(mDevice);
// read 0412 = EHSM_SESSION(1)
payload = await ReadMessage(mDevice, READ_TIMEOUT_MS);
decrypted = Decode(pumpSession, payload);
Log.d(TAG, "*** response" + HexDump.DumpHexstring(decrypted));
return(multipacketSession.Response);
}
else
{
fetchMoreData = true;
}
}
else if (MedtronicSendMessageRequestMessage.MessageType.END_HISTORY_TRANSMISSION.response(cmd))
{
Log.d(TAG, "*** END_HISTORY_TRANSMISSION response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_PUMP_TIME.response(cmd))
{
Log.d(TAG, "*** READ_PUMP_TIME response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_PUMP_STATUS.response(cmd))
{
Log.d(TAG, "*** READ_PUMP_STATUS response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_HISTORY_INFO.response(cmd))
{
Log.d(TAG, "*** READ_HISTORY_INFO response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_BASAL_PATTERN.response(cmd))
{
Log.d(TAG, "*** READ_BASAL_PATTERN response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_BOLUS_WIZARD_CARB_RATIOS.response(cmd))
{
Log.d(TAG, "*** READ_BOLUS_WIZARD_CARB_RATIOS response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_BOLUS_WIZARD_SENSITIVITY_FACTORS.response(cmd))
{
Log.d(TAG, "*** READ_BOLUS_WIZARD_SENSITIVITY_FACTORS response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else if (MedtronicSendMessageRequestMessage.MessageType.READ_BOLUS_WIZARD_BG_TARGETS.response(cmd))
{
Log.d(TAG, "*** READ_BOLUS_WIZARD_BG_TARGETS response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = false;
}
else
{
Log.d(TAG, "*** ??? response" + HexDump.DumpHexstring(decrypted));
fetchMoreData = true;
}
}
}
// when returning non-multipacket decrypted data, we need to trim the 2 byte checksum
if (decrypted == null)
{
return(payload);
}
return(decrypted.Partial(0, decrypted.Length - 2));
}
