def reset(self):
self.rxpWindow = RxPWindow()
self.rxpTimer = RxPTimer()
self.cntBit = 0
self.getBit = 0
self.postBit = 0
self.buffer = deque()
self.recvFileIndex = 0
self.output = None
def __init__(self, hostAddress, emuPort, hostPort, destPort, filename):
self.netEmuPort = emuPort
self.hostAddress = hostAddress
self.hostPort = hostPort
self.destPort = destPort
self.socket = socket(AF_INET, SOCK_DGRAM)
self.socket.bind((self.hostAddress, self.hostPort))
self.header = RxPHeader(hostPort, destPort, 0, 0)
self.cntBit = 0 # stands for connection state(3 way handshake)
self.getBit = 0 # get file
self.postBit = 0 # post file
self.rxpWindow = RxPWindow()
self.rxpTimer = RxPTimer()
self.buffer = deque() # buffer to store data
self.output = None # output file
self.recvFileIndex = 0 # current index of receiving file
self.threads = [] # supports multiple get request
class RxP:
dataMax = 255 # total bytes in a packet
# refer to rxpHeader class for more info
def __init__(self, hostAddress, emuPort, hostPort, destPort, filename):
self.netEmuPort = emuPort
self.hostAddress = hostAddress
self.hostPort = hostPort
self.destPort = destPort
self.socket = socket(AF_INET, SOCK_DGRAM)
self.socket.bind((self.hostAddress, self.hostPort))
self.header = RxPHeader(hostPort, destPort, 0, 0)
self.cntBit = 0 # stands for connection state(3 way handshake)
self.getBit = 0 # get file
self.postBit = 0 # post file
self.rxpWindow = RxPWindow()
self.rxpTimer = RxPTimer()
self.buffer = deque() # buffer to store data
self.output = None # output file
self.recvFileIndex = 0 # current index of receiving file
self.threads = [] # supports multiple get request
# When user type in "connect" command Establish handshake connection with
# host by sending SYN messages. Handling the time out situation
# cntBit = 0 : listening for connection
# cntBit = 1 : received first SYN = 1 packet
def connect(self):
print 'Start to connect'
self.header.cnt = True
self.header.syn = True
self.header.seqNum = 0
self.send(None)
self.rxpTimer.start()
print 'Send first SYN segment with SYN = 1'
while self.cntBit == 0:
if self.rxpTimer.isTimeout():
self.header.syn = True
self.header.seqNum = 0
self.send(None)
print 'Resend first SYN segment with SYN = 1'
self.rxpTimer.start()
while self.cntBit == 1:
if self.rxpTimer.isTimeout():
self.header.syn = False
self.header.seqNum = 1
self.send(None)
print 'Resend segment with SYN = 0'
self.rxpTimer.start()
self.header.cnt = False
print '>>>>>>>>>>>Connection established<<<<<<<<<<<<<'
# When receive "disconnect" command,it will close connection.
# cntBit = 2 : connection established.
# cntBit = 3 : closing wait
def close(self):
self.header.cnt = True
self.header.fin = True
self.header.seqNum = 0
self.send(None)
print 'Send first FIN segment with FIN = 1'
self.rxpTimer.start()
while self.cntBit == 2:
if self.rxpTimer.isTimeout():
self.header.fin = True
self.header.seqNum = 0
self.send(None)
print 'Resend first FIN segment with FIN = 1'
self.rxpTimer.start()
while self.cntBit == 3:
if self.rxpTimer.isTimeout():
self.header.fin = False
self.header.seqNum = 1
self.send(None)
print 'Resend first FIN segment with FIN = 0'
self.rxpTimer.start()
self.header.cnt = False
print '>>>>>>>>>Connection Closed<<<<<<<<<<<<'
self.reset()
# Listening the incoming request including connect request, get, post, and
# data action by checking the received packet contents
def listen(self, event):
print 'start to listen'
while True and not event.stopped():
self.socket.settimeout(1)
try:
recvPacket, address = self.socket.recvfrom(1024)
except IOError:
continue
packet = bytearray(recvPacket)
if self.validateChecksum(packet):
tempHeader = self.getHeader(packet)
if tempHeader.cnt:
print 'Received control packet'
self.recvCntPkt(packet)
elif tempHeader.get:
print 'Received get packet'
self.recvGetPkt(packet)
elif tempHeader.post:
print 'Received post packet'
self.recvPostPkt(packet)
elif tempHeader.dat:
print 'Received data packet'
self.recvDataPkt(packet)
else:
print 'Received corrupted data, packet dropped.'
# reset all setting
def reset(self):
self.rxpWindow = RxPWindow()
self.rxpTimer = RxPTimer()
self.cntBit = 0
self.getBit = 0
self.postBit = 0
self.buffer = deque()
self.recvFileIndex = 0
self.output = None
# client uses getFile method to get a file from server side protocol sends
# the requested file to client side
def getFile(self, filename):
if self.cntBit == 2:
nameBytes = bytearray(filename)
self.header.get = True
self.header.seqNum = 0
self.send(nameBytes)
self.header.get = False
print 'Sending Get request'
self.rxpTimer.start()
while self.getBit == 0:
if self.rxpTimer.isTimeout():
self.header.get = True
self.header.seqNum = 0
self.send(nameBytes)
self.header.get = False
print 'Resend Get request'
self.rxpTimer.start()
print 'Start to receive file'
else:
print 'No connection found'
# Protocol send incoming data into Datagrams through UDP socket the data
# need to be add check sum before sending
def send(self, data):
print 'sending seq#: %d' % self.header.seqNum
self.header.ack = False
datagram = self.pack(self.header.getHeader(), data)
datagram = self.addChecksum(datagram)
self.socket.sendto(datagram, (self.hostAddress, self.netEmuPort))
# Getting header's ack number and add check sum to this ack number then
# send new ACK through UDP socket
def sendAck(self):
print 'acking num: %d' % self.header.ackNum
self.header.ack = True
datagram = self.addChecksum(self.header.getHeader())
self.socket.sendto(datagram, (self.hostAddress, self.netEmuPort))
# Getting the header information from received data
def getHeader(self, datagram):
tmpHeader = RxPHeader()
tmpHeader.headerFromBytes(datagram)
return tmpHeader
# Packing header array and data array into a new array, so that we can send
# this new data to the UDP socket
def pack(self,header, data):
if data:
result = header + data
return result
else:
return header
# Sending file to the server.
def postFile(self, filename, event):
if self.cntBit == 2:
nameBytes = bytearray(filename)
self.header.post = True
self.header.seqNum = 0
self.send(nameBytes)
self.header.post = False
print 'Sending Post request'
self.rxpTimer.start()
while self.postBit == 0 and not event.stopped():
if self.rxpTimer.isTimeout():
self.header.post = True
self.header.seqNum = 0
self.send(nameBytes)
self.header.post = False
print 'Resend Post request'
self.rxpTimer.start()
if event.stopped():
print 'Post file interrupted'
return
try:
readFile = open(filename, "rb")
except:
print ("file not found. Please type in correct filename")
sys.exit()
fileBytes = bytearray(readFile.read())
bufferSize = RxP.dataMax - RxPHeader.headerLen
fileSize = len(fileBytes)
fileIndex = 0
self.rxpTimer.start()
while (fileIndex < fileSize or len(self.buffer) > 0) and not event.stopped():
if self.rxpTimer.isTimeout():
self.rxpWindow.nextToSend = self.rxpWindow.startWindow
self.rxpTimer.start()
for i in range(len(self.buffer)):
if fileIndex >= fileSize:
if i == len(self.buffer) - 1:
self.header.end = True
seq = self.rxpWindow.nextToSend
self.header.seqNum = seq
self.header.dat = True
try:
self.send(self.buffer[i])
except:
print ("Corruption or Reodring rate too high, connection fails")
sys.exit()
self.header.dat = False
self.header.end = False
self.rxpWindow.nextToSend = seq + 1
if self.rxpWindow.nextToSend <= self.rxpWindow.endWindow and fileIndex < fileSize:
data = []
if fileIndex + bufferSize > fileSize:
data = fileBytes[fileIndex:fileSize]
else:
data = fileBytes[fileIndex:fileIndex + bufferSize]
fileIndex += bufferSize
if fileIndex >= fileSize:
self.header.end = True
seq = self.rxpWindow.nextToSend
self.header.seqNum = seq
self.header.dat = True
self.send(data)
self.header.dat = False
self.header.end = False
self.rxpWindow.nextToSend = seq + 1
self.buffer.append(data)
readFile.close()
self.postBit = 0
self.getBit = 0
self.header.end = False
print '>>>>>>>>>>>File transfer completed<<<<<<<<<<<<'
if event.stopped():
print 'Post file interrupted'
else:
print 'No connection found'
# Handle received data transmission packet.
def recvDataPkt(self, packet):
tmpHeader = self.getHeader(packet)
if tmpHeader.ack:
print 'Received Data ACK Num: %d' % tmpHeader.ackNum
if tmpHeader.ackNum == self.rxpWindow.startWindow:
self.rxpTimer.start()
self.rxpWindow.startWindow += 1
self.rxpWindow.endWindow += 1
self.buffer.popleft()
else:
if self.output == None:
print 'Output is not ready'
else:
if self.recvFileIndex == tmpHeader.seqNum:
content = packet[RxPHeader.headerLen:]
self.output.write(content)
self.recvFileIndex += 1
self.output.flush()
if tmpHeader.end:
self.output.close()
print '>>>>>>>>>>>>File transfer completed<<<<<<<<<<<<<'
seq = tmpHeader.seqNum
if self.recvFileIndex > seq:
self.header.ackNum = seq
elif self.recvFileIndex < seq:
if self.recvFileIndex != 0:
self.header.ackNum = self.recvFileIndex - 1
else:
self.header.ackNum = 0
self.header.dat = True
self.sendAck()
self.header.dat = False
# Handle get file packet
def recvGetPkt(self, packet):
tmpHeader = self.getHeader(packet)
seq = tmpHeader.seqNum
self.header.ackNum = seq
if tmpHeader.ack:
self.getBit = 1
else:
if self.getBit == 0:
content = packet[RxPHeader.headerLen:]
uniFilename = self.bytesToString(content)
filename = unicodedata.normalize('NFKD', uniFilename).encode('utf-8','ignore')
self.getBit = 1
sendTread = SendThread(self, filename)
self.threads.append(sendTread)
sendTread.start()
self.header.get = True
self.sendAck()
self.header.get = False
# Handle post file packet
def recvPostPkt(self, packet):
tmpHeader = self.getHeader(packet)
seq = tmpHeader.seqNum
self.header.ackNum = seq
if self.postBit == 0:
if tmpHeader.ack:
self.postBit = 1
else:
content = packet[RxPHeader.headerLen:]
filename = self.bytesToString(content)
try:
self.output = open("./down/" + filename, "ab")
except:
print ("file not found. Please type in correct filename")
sys.exit()
self.header.post = True
print 'sending post ack'
self.sendAck()
self.header.post = False
# receive connection establishment packet
# 3 way handshake
# closing wait
def recvCntPkt(self, packet):
tmpHeader = self.getHeader(packet)
seq = tmpHeader.seqNum
self.header.ackNum = seq
if self.cntBit == 0:
if tmpHeader.syn:
print 'Received connection request SYN segment with SYN = 1'
self.header.cnt = True
self.sendAck()
self.cntBit = 1
elif self.header.syn and tmpHeader.ack:
self.header.syn = False
self.header.seqNum = 1
self.send(None)
print 'Received first SYN ack, sending second msg[SYN=0]'
self.cntBit = 1
elif not tmpHeader.fin and not tmpHeader.ack:
print 'server received SYN from client, and sent back ACK to client'
self.header.cnt = True
self.sendAck()
self.header.cnt = False
elif self.cntBit == 1:
if not tmpHeader.ack and not tmpHeader.syn:
self.cntBit = 2
self.sendAck()
self.header.cnt = False
print '>>>>>>>>>>>>Connection established<<<<<<<<<<<<<'
if tmpHeader.seqNum == 0 and tmpHeader.syn:
print 'Second SYN initialization'
self.header.cnt = True
self.sendAck()
self.header.cnt = False
if tmpHeader.ack:
self.cntBit = 2
elif self.cntBit == 2:
if tmpHeader.fin:
print 'Received connection closing request with FIN = 1'
self.header.cnt = True
self.sendAck()
self.cntBit = 3
elif self.header.fin and tmpHeader.ack:
self.header.fin = False
self.header.seqNum = 1
self.send(None)
print 'Received first FIN ack, sending second packet with FIN = 0'
self.cntBit = 3
elif not tmpHeader.ack and not tmpHeader.syn:
self.header.cnt = True
self.sendAck()
self.header.cnt = False
elif self.cntBit == 3:
if not tmpHeader.ack and not tmpHeader.fin:
self.cntBit = 0
self.sendAck()
self.header.cnt = False
self.reset()
print '>>>>>>>>>Connection Close<<<<<<<<<<<'
elif not tmpHeader.seqNum and tmpHeader.fin:
self.header.cnt = True
self.sendAck()
self.header.cnt = False
elif tmpHeader.ack:
self.cntBit = 0
# set the window size for protocol
def setWindowSize(self, windowSize):
if self.cntBit == 2:
self.rxpWindow.windowSize = windowSize
print 'The window size is set to: %d' % windowSize
else:
print 'Please initialize connection.'
# Convert the ASCII byte[] data into String
def bytesToString(self, data):
return data.decode('utf-8')
# Before sending the packet, we have to add a check sum field into each
# packet to make sure the correction of data
def addChecksum(self, packet):
data = ''
packet[14] = 0
packet[15] = 0
for byte in packet:
data += str(byte)
checksum = crc16xmodem(data)
packet[14] = checksum >> 8
packet[15] = checksum & 0xFF
return packet
# Using this check sum function to check every received packet's corruption
def validateChecksum(self, packet):
correct = False
data = ''
firstB = packet[14]
secondB = packet[15]
packet[14] = 0
packet[15] = 0
for byte in packet:
data += str(byte)
checksum = crc16xmodem(data)
msb = checksum >> 8
lsb = checksum & 0xFF
if msb == firstB and lsb == secondB:
correct = True
return correct