git-gud-udp

A reliable UDP transfer with fairly low overhead. No dependencies, written in Python 2.7 Includes optional "secure_send" and "secure_recv" for built-in data-in-transit encryption using Diffie-Hellmann + RC4.

The encryption is swappable between stream and block ciphers though. Simply change: GGUdp.encryption = RC4

to point to the encryption class of your choice. That class must have three things though to be compatible:

1. A variable indicating if it is a stream-cipher, ie self.stream = True
2. A make_key as a class-method, that creates the key that will be used. The argument is a Python long, and it can return anything that YourEncryption.init() will accept as a key.
3. A class method crypt. For stream-ciphers, it must accept individual bytes. For block-ciphers, it must accept arbitrarily-sized data that will be between 3 and GGUdp.MAX_DATA_SIZE bytes.

Packet Info

[CHECKSUM]([PACKET_NUMBER][DATA])

Currently, checksum is implemented as an MD5 hash of PACKET_NUMBER+DATA Packets are randomly sized between MIN_DATA_SIZE and MAX_DATA_SIZE. This defaults to data sizes between 500 and 4082

NOTE: The ggudp protocol automatically handle sizes for you, so theres no need to specify size when send()ing or recv()ing. That said, a single send()/recv() gets stored in memory (just like with TCP) so your program should chunk data if youre sending/recieving something exceptionally large.

send() and recv() will return False if data fails to transfer reliably.

Example Usage

Client:

 s = GGUdp("127.0.0.1", 8000)
 data = "hello world"
 s.send(data)

Server:

  s = GGUdp("0.0.0.0", 8000)
  s.bind()
  while True:
      data = s.recv()
      if data:
          print(data)

Timeout Information

Note, TIMEOUT_REREQUEST_SAFETY * TIMEOUT_RECV_REREQUEST is roughly how much time it takes to TIMEOUT a rerequest loop If absolutely no packets get received. Each time a successful rerequest comes through though, TIMEOUT_REREQUEST_SAFETY gets reset I feel 5 seconds total is generous, but for less reliable networks you might tweak these values

Example setup:

For a network with roughly 5 second latency between points, this might be more appropriate: TIMEOUT_REREQUEST_SAFETY = 10 TIMEOUT_SYNC = 6 TIMEOUT_RECV_LOOP = 8 TIMEOUT_NO_WAIT = 0.05 TIMEOUT_SEND_REREQUEST = 15 TIMEOUT_RECV_REREQUEST = 3.5