def MakePacketChecksum():
global i
global j
pt = 0
sumOfBites = 0
sumOfBites = bin(sumOfBites)
checksum = 0
checksum = bin(checksum)
while (pt <= 510): #loop for checksum calculation
data1 = buffer[i:j]
p1 = ''.join(format(x, 'b').zfill(8) for x in bytearray(data1))
i = i + 2
j = j + 2
data2 = buffer[i:j]
p2 = ''.join(format(y, 'b').zfill(8) for y in bytearray(data2))
q = add(p1, p2)
i = i + 2
j = j + 2
pt = pt + 2
sumOfBites = add(q, sumOfBites)
checksum = ''.join(
[bin(~0)[3:] if x == '0' else bin(~1)[4:] for x in sumOfBites])
return checksum
def datasum(data): #Calculating sum all th data that we reecived in a packet
buffer = bytearray(data) #typecasting all the data into array
length = len(buffer)
first_index = 0 #initializing all the varaible
second_index = 2
iteration = 0
sum_all_Bites = 0
sum_all_Bites = bin(sum_all_Bites)
checksum = 0
checksum = bin(checksum)
while (
iteration <= 510
): # looping it 512 times ,we are fetching 1024 bytes of data in this loop in 50%in data1 and 50 % in data2,2 extra becasue of all the header in it
data1 = buffer[first_index:second_index] #fetches 16 bits at a time
two_bytes = ''.join(format(x, 'b').zfill(8)
for x in bytearray(data1)) #joining all the bytes
first_index = first_index + 2 #incrementing it by 2 position two fecth next 16 bits
second_index = second_index + 2
data2 = buffer[first_index:second_index]
two_bytes_2 = ''.join(
format(y, 'b').zfill(8) for y in bytearray(data2))
sum_one_bites = add(two_bytes, two_bytes_2)
first_index = first_index + 2 #incrementing it by 2 position two fecth next 16 bits
second_index = second_index + 2
sum_all_Bites = add(sum_one_bites, sum_all_Bites) #Sum of data only
iteration = iteration + 2
return sum_all_Bites
def checksum_Packets():
global first_index
global second_index
global buf
global packets_state
global checksum
iteration=0
sum_all_Bites=0
sum_all_Bites=bin(sum_all_Bites) #typecasting it to binary
checksum=0
checksum=bin(checksum) #typecasting it to binary
while(iteration<=510): # looping it 510 times ,we are fetching 1024 bytes of data in this loop in 50%in data1 and 50 % in data2
data_1=buffer[first_index:second_index] #fetches 16 bits at a time
two_bytes=''.join(format(x,'b').zfill(8) for x in bytearray(data_1))
buf=buf+1
#print'index'
first_index=first_index+2 #incrementing it by 2 position two fecth next 16 bits
second_index=second_index+2
data_2=buffer[first_index:second_index]
two_bytes_2=''.join(format(x,'b').zfill(8) for x in bytearray(data_2))
sum_one_iteration=add(two_bytes,two_bytes_2)
first_index=first_index+2 #incrementing it by 2 position two fecth next 16 bits
second_index=second_index+2
iteration=iteration+2
#print ""+str(iteration)
sum_all_Bites=add(sum_one_iteration,sum_all_Bites)
checksum=''.join([bin(~0)[3:] if x == '0' else bin(~1)[4:] for x in sum_all_Bites])
if(checksum=='111'): #Ending the transmission of the packet if there is no data to transmit
print"All data have been sent "
print"closing the socket"
flag_1=1
flag_2=1
flag_3=1
flag_4=1
flag_5=1
#print ''
fle.close
ClientSocket.close()
return checksum
def SumOfData(data):
buffer = bytearray(data)
length = len(buffer)
i = 0
j = 2
pt = 0
sumOfBites = 0
sumOfBites = bin(sumOfBites)
checksum = 0
checksum = bin(checksum)
while (pt <= 510): # loop for an data part
data1 = buffer[i:j]
p1 = ''.join(format(x, 'b').zfill(8) for x in bytearray(data1))
i = i + 2
j = j + 2
data2 = buffer[i:j]
p2 = ''.join(format(y, 'b').zfill(8) for y in bytearray(data2))
q = add(p1, p2)
i = i + 2
j = j + 2
sumOfBites = add(q, sumOfBites) #Sum of data only
pt = pt + 2
return sumOfBites
def ExtractPacket():
global numPacks
global ACK
global ExSeqNo
global packetdata
packetdata, clientAddress = ServerSocket.recvfrom(packet_size)
print("")
data = packetdata[0:1024]
Check = packetdata[1024:1040]
ExpectedSeqNo = packetdata[1040:1042]
print("CHECKSUM = " + Check)
print("ExpectedSeqNo" + ExpectedSeqNo)
datasumval = SumOfData(data)
q = add(Check, datasumval)
q = str(q)
print("Sum of CHK and LOCAL and this hould be all 1 = " + q)
ExSeqNo = str(ExSeqNo)
if ((ExpectedSeqNo == ExSeqNo) & (q == '1111111111111111')):
print("PACKET RECIEVED")
myfile.write(data)
ACK = int(ACK)
ExSeqNo = int(ExSeqNo)
print(ACK)
print(ExSeqNo)
backpacket = AckPacket(ACK, ExSeqNo)
ACK = ACK + 1
ExSeqNo = ExSeqNo + 1
ServerSocket.sendto(backpacket, clientAddress)
print("ACK packet send ")
else:
print("Packet Not recieved")
ACK = int(ACK)
ExSeqNo = int(ExSeqNo)
ACK = ACK - 1
ExSeqNo = ExSeqNo - 1
def extracting():
global packetdata #telling the compiler that these varibale as been defined in global section
global FSM_r
global Refrence
global No_of_kilobytes
global selection
global err
global start
global err_1
packetdata, clientAddress = ServerSocket.recvfrom(
packet_size) #waitng for the packet from the sender end
#print clientAddress
data = packetdata[0:1024] #pasring the data of 1 KB
Chk = packetdata[1024:1040] #parsing the checksum
Refrence = Refrence + 1
print ""
print Refrence
#data loss error
if (Refrence == err_1 < 101):
err_1 = err_1 + 1
data = packetdata[0:1022]
print "data loss error"
datasumvalue = datasum(
data
) #sending it to the function to calculate all the sum of the data that we received
received_packet = add(
Chk, datasumvalue
) #adding the checksum we received and sum of all data to get "1111111111111111"
received_packet = str(received_packet)
SeqNo = packetdata[1040:1041] #parsing the seqno
#data bit error
if (Refrence == err and err < 2):
err = err + 1
SeqNo = 3
print "data bit error"
if (FSM_r == 1): #checking whether we recieved packet 1
if ((SeqNo == '1') & (received_packet == '1111111111111111')):
print "PACKET [1] is RECIEVED"
print "CHECKSUM = " + Chk
print "LOCAL SUM OF DATA= " + datasumvalue
print "Sum of CHK and LOCAL = " + received_packet
fle.write(data) #writting the data to the file
backpacket = [
'1', '1', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
FSM_r = 2 #telling the FSM to jump to next level FSM 2
print "Sending ACK 1"
ServerSocket.sendto(backpacket,
clientAddress) #send the packet to client
return
else: #if our selction is non recovery, jump to next state ignoring missing packets
if (selection == 2):
FSM_r = 2
backpacket = [
'1', '1', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Im ignoring errors "
ServerSocket.sendto(backpacket, clientAddress)
return
if (SeqNo == '2' or SeqNo == '3'
): #correcting its FSM, go back to the beginning of the window
FSM_r = 1
elif (SeqNo == '5'):
FSM_r = 5
elif (
SeqNo == '4'
): #go back to the right FSM and wait for the right packet ot arrive
FSM_r = 4
else:
FSM_r = 1 #stay in FSM 1
print "received_packet" + str(received_packet)
#telling the FSM to stay in same level of FSM1
No_of_kilobytes = No_of_kilobytes + 1 #since we asking the client to send the data again ,we are incrementing the No_of Kilobytes
print "Im here because of wrong ACK 1 bit recived by Sender "
backpacket = [
'5', '1', Chk
] #telling client we recived a seq 1 instead of seq 0
backpacket = ''.join(backpacket)
ServerSocket.sendto(backpacket, clientAddress)
return
elif (FSM_r == 2): #checking whether we recieved packet 1
print received_packet
if ((SeqNo == '2') & (received_packet == '1111111111111111')):
print "PACKET [2] is RECIEVED"
print "CHECKSUM = " + Chk
print "LOCAL SUM OF DATA=" + datasumvalue
print "Sum of CHK and LOCAL = " + received_packet
fle.write(data) #writting the data to the file
backpacket = [
'2', '2', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Sending ACK 2"
FSM_r = 3 #telling the FSM to jump to next level FSM 1
ServerSocket.sendto(backpacket, clientAddress)
return
else:
if (
selection == 2
): #if our selction is non recovery, jump to next state ignoring missing packets
FSM_r = 3
backpacket = [
'2', '2', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Im ignoring errors "
ServerSocket.sendto(backpacket, clientAddress)
return
if (SeqNo == '3' or SeqNo == '4'
): #correcting its FSM, go back to the beginning of the window
FSM_r = 2
elif (SeqNo == '1'):
FSM_r = 1
elif (
SeqNo == '5'
): #go back to the right FSM and wait for the right packet ot arrive
FMS_r = 5
else:
FSM_r = 2 #stay in FSM 2
print "received_packet" + str(received_packet)
#telling the FSM to stay in same level of FSM1
No_of_kilobytes = No_of_kilobytes + 1 #since we asking the client to send the data again ,we are incrementing the No_of Kilobytes
print "Im sending duplicate ACK 2 bit recived by Sender "
backpacket = [
'1', '2', Chk
] #telling client we recived a seq 1 instead of seq 0
backpacket = ''.join(backpacket)
ServerSocket.sendto(backpacket, clientAddress)
return
elif (FSM_r == 3): #checking whether we recieved packet
if ((SeqNo == '3') & (received_packet == '1111111111111111')):
print "PACKET [3] is RECIEVED"
print "CHECKSUM = " + Chk
print "LOCAL SUM OF DATA=" + datasumvalue
print "Sum of CHK and LOCAL = " + received_packet
fle.write(data) #writting the data to the file
backpacket = [
'3', '3', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Sending ACK 3"
FSM_r = 4 #telling the FSM to jump to next level FSM 1
ServerSocket.sendto(backpacket, clientAddress)
return
else:
if (
selection == 2
): #if our selction is non recovery, jump to next state ignoring missing packets
FSM_r = 4
backpacket = [
'3', '3', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Im ignoring errors "
ServerSocket.sendto(backpacket, clientAddress)
return
if (SeqNo == '4' or SeqNo == '5'
): #correcting its FSM, go back to the beginning of the window
FSM_r = 3
elif (SeqNo == '2'):
FSM_r = 2
elif (
SeqNo == '1'
): #go back to the right FSM and wait for the right packet ot arrive
FSM_r = 1
else:
FSM_r = 3 #stay in FSM 3
print "received_packet" + str(received_packet)
#telling the FSM to stay in same level of FSM1
No_of_kilobytes = No_of_kilobytes + 1 #since we asking the client to send the data again ,we are incrementing the No_of Kilobytes
print "Im sending duplicate ACk 3 bit recived by Sender "
backpacket = [
'2', '3', Chk
] #telling client we recived a seq 1 instead of seq 0
backpacket = ''.join(backpacket)
ServerSocket.sendto(backpacket, clientAddress)
return
elif (FSM_r == 4): #checking whether we recieved packet
print "received_packet" + str(received_packet)
if ((SeqNo == '4') & (received_packet == '1111111111111111')):
print "PACKET [4] is RECIEVED"
print "CHECKSUM = " + Chk
print "LOCAL SUM OF DATA=" + datasumvalue
print "Sum of CHK and LOCAL = " + received_packet
fle.write(data) #writting the data to the file
backpacket = [
'4', '4', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Sending ACK 4"
FSM_r = 5 #telling the FSM to jump to next level FSM 1
ServerSocket.sendto(backpacket, clientAddress)
return
else:
if (
selection == 2
): #if our selction is non recovery, jump to next state ignoring missing packets
FSM_r = 5
backpacket = [
'4', '4', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Im ignoring errors "
ServerSocket.sendto(backpacket, clientAddress)
return
if (SeqNo == '5' or SeqNo == '1'
): #correcting its FSM, go back to the beginning of the window
FSM_r = 4
elif (SeqNo == '3'):
FSM_r = 3
elif (
SeqNo == '2'
): #go back to the right FSM and wait for the right packet ot arrive
FSM_r = 2
else:
FSM_r = 4 #telling the FSM to stay in same level of FSM4
No_of_kilobytes = No_of_kilobytes + 1
print "CHECKSUM = " + Chk
print "Im here because of wrong ACK 4 bit recived by Sender "
backpacket = [
'3', '4', Chk
] #telling client we recived a seq 1 instead of seq 0
backpacket = ''.join(backpacket)
ServerSocket.sendto(backpacket, clientAddress)
return
elif (FSM_r == 5): #checking whether we recieved packet
if ((SeqNo == '5') & (received_packet == '1111111111111111')):
print "PACKET [5] is RECIEVED"
print "CHECKSUM = " + Chk
print "LOCAL SUM OF DATA=" + datasumvalue
print "Sum of CHK and LOCAL = " + received_packet
fle.write(data) #writting the data to the file
backpacket = [
'5', '5', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Sending ACK 5"
FSM_r = 1 #telling the FSM to jump to next level FSM 1
ServerSocket.sendto(backpacket, clientAddress)
return
else:
if (
selection == 2
): #if our selction is non recovery, jump to next state ignoring missing packets
FSM_r = 1
backpacket = [
'5', '5', Chk
] #telling the client we received right data which had seq 0,and cheksum you sent
backpacket = ''.join(backpacket)
print "Im ignoring errors "
ServerSocket.sendto(backpacket, clientAddress)
return
if (SeqNo == '1' or SeqNo == '2'
): #correcting its FSM, go back to the beginning of the window
FSM_r = 5
elif (SeqNo == '4'):
FSM_r = 4
elif (
SeqNo == '3'
): #go back to the right FSM and wait for the right packet ot arrive
FSM_r = 3
else:
FSM_r = 5 #telling the FSM to stay in same level of FSM
No_of_kilobytes = No_of_kilobytes + 1 #since we asking the client to send the data again ,we are incrementing the No_of Kilobytes
print "Im here because of wrong ACK 5 bit recived by Sender "
backpacket = [
'4', '5', Chk
] #telling client we recived a seq 1 instead of seq 0
backpacket = ''.join(backpacket)
ServerSocket.sendto(backpacket, clientAddress)
return