Hello,
we have two applications, one written in Java and one in Python. They are
exchanging network packets via UDP using protobuf.
We ran into the following error:
We build a packet in python, then serialize it by calling
SerializeToString():
def serialize(self):
# create outer packet message
packetMessage = protoPackets_pb2.PacketMessage()
packetMessage.type = protoPackets_pb2.PacketMessage.ADVERT
packetMessage.transactionID = self.transactionID
# add advert-specific content
packetMessage.advertMessage.finalDestinationIP =
self.finalDestinationIP
packetMessage.advertMessage.ceil = self.ceil
packetMessage.advertMessage.deadline = self.deadline
packetMessage.advertMessage.fine = self.fine
packetMessage.advertMessage.initialBudget = self.initialBudget
return packetMessage.SerializeToString()
This returns us a serialized version of our object as a string. We can
successfully deserialize it in the python client (we did that to test if
the serializiation might be the problem).
We now send this string via Ad-hoc UDP to another device, where the Java
software runs. Out of the received DatagramPacket we take the byte array
and use PacketMessage.parseFrom(byte[]) to deserialize it.
The problem is the following:
Calling parseFrom causes a InvalidProtocolBufferException, specifically
because the parser does not seem to recognize when the meaningful input in
the byte array is "done" and just keeps reading the rest of it (which is
garbage, filled with 0's). We found a temporary workaround by altering this
method in CodeInputStream.java:
public boolean isAtEnd() throws IOException {
// EVIL HACK: ToDo: Change BACK!
return bufferPos == bufferSize && !refillBuffer(false) ||
buffer[bufferPos] == 0;
// return bufferPos == bufferSize && !refillBuffer(false);
}
Obviously this is not a good solution and while it solves the problem with
one of our package types, the same problem occurs with another type with
the difference that the buffer is not filled with 0's but numbers, so our
hack doesn't work and the parser doesn't stop reading and eventually causes
the same exception.
Its late so I hope this was not too unclear,
any help would be very much appreciated.
Cheers
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