def _send(self, data, rpcID, address):
""" Transmit the specified data over UDP, breaking it up into several
packets if necessary
If the data is spread over multiple UDP datagrams, the packets have the
following structure::
| | | | | |||||||||||| 0x00 |
|Transmision|Total number|Sequence number| RPC ID |Header end|
| type ID | of packets |of this packet | | indicator|
| (1 byte) | (2 bytes) | (2 bytes) |(20 bytes)| (1 byte) |
| | | | | |||||||||||| |
@note: The header used for breaking up large data segments will
possibly be moved out of the KademliaProtocol class in the
future, into something similar to a message translator/encoder
class (see C{kademlia.msgformat} and C{kademlia.encoding}).
"""
if len(data) > self.msgSizeLimit:
# We have to spread the data over multiple UDP datagrams, and provide sequencing information
# 1st byte is transmission type id, bytes 2 & 3 are the total number of packets in this transmission, bytes 4 & 5 are the sequence number for this specific packet
totalPackets = len(data) / self.msgSizeLimit
if len(data) % self.msgSizeLimit > 0:
totalPackets += 1
encTotalPackets = chr(totalPackets >> 8) + chr(totalPackets & 0xff)
seqNumber = 0
startPos = 0
while seqNumber < totalPackets:
#reactor.iterate() #IGNORE:E1101
packetData = data[startPos:startPos+self.msgSizeLimit]
encSeqNumber = chr(seqNumber >> 8) + chr(seqNumber & 0xff)
txData = '\x00%s%s%s\x00%s' % (encTotalPackets, encSeqNumber, rpcID, packetData)
reactor.callLater(self.maxToSendDelay*seqNumber+self.minToSendDelay, self.transport.write, txData, address) #IGNORE:E1101
startPos += self.msgSizeLimit
seqNumber += 1
else:
self.transport.write(data, address)
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