def __sendCnct(self):
#create packet
self.log("Creating init packet......\n")
try:
self.log("Setting flags...\n")
flags = (True, False, False, False, False, False)
except Exception as e:
self.log("Exception: " + str(e))
sys.exit(0)
self.log("Flags created...\n")
try:
cnctPacket = RxPacket.getCnct(
srcPort = self.srcRxPPort,
desPort = self.desRxPPort,
seqNum = self.seqNum,
ackNum = self.ackNum,
winSize = self.recvWindowSize,
)
except Exception as e:
self.log("Exception: " + str(e))
sys.exit(0)
#increment seq num
self.log("Incrementing sequence number......\n")
self.seqNum = self.seqNum + 1 #increment by number of bytes (20 byte header only)
if self.seqNum > RxPacket.maxSeqNum():
self.seqNum = 0
#transfer packet
resetsLeft = self.resetLimit
self.log("Entering send loop for CNCT packet......\n")
while resetsLeft:
self.log("Sending init to IP: " + self.desAddr + " and Port:" + str(self.desUDPPort) +"...\n")
try:
self.sendto(cnctPacket.toByteArray(), (self.desAddr, self.desUDPPort))
except Exception as e:
self.log("Exception while calling sendto: " + str(e) + "\n")
self.log("SENT INIT PACKET!\n")
try:
self.log("Waiting for ack......\n")
data, address = self.recvfrom(self.recvWindowSize)
log("Packet received successfully, calling reconstructPacket from _sendCNCT...\n")
packet = self.__reconstructPacket(data = bytearray(data))
log("Packet successfully reconstructed inside _sendCNCT...\n")
if not packet:
self.log("Checksum failed......\n")
resetsLeft -= 1
continue
except socket.timeout:
resetsLeft -= 1
except Exception:
resetsLeft -= 1
else:
if packet.isAck() and packet.header['ackNum'] == self.seqNum:
self.log("init has been acked......\n")
break
else:
self.log("Wrong packet recieved, restarting cnct loop......\n")
resetsLeft -= 1
if not resetsLeft:
self.log("socket timeout......\n")
raise Exception('socket timeout')
return packet
