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r.py
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/
r.py
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import socket
import sys
import os
import struct
from binascii import hexlify
import random
client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_address = ('localhost', 20660)
packet_size = 1024
buff = 1060
send_Packet = 1024
option_Selected = 0
packet_Count = -1
sq_previous = '0000000000000000'
print >> sys.stderr, '\n********* Starting Receiver *********'
def GBN():
print >> sys.stderr," inside GBN"
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
data, server = client_socket.recvfrom(buff)
i = 0
while(data):
if(data == 'EOF'):
data = 0
file.close()
else:
file_data = data[0:1024] #extract file data
sum_calulated = cal_Checksum_for_received_data(file_data)#calculate sum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, sum_calulated)
sq_receive = data[1040:1055]
sq_decimal = int(sq_receive, 2)
print >> sys.stderr, "sq_decimal = %s" %sq_decimal
if(packet_Count + 1 == sq_decimal):
send_ack = sq_receive
sq_previous = send_ack
else:
sq_previous = sq_previous
send_ack = sq_previous
if(is_Success == '1'):
print >> sys.stderr , "checksum matched"
file.write(file_data)
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
print >> sys.stderr, "packet %s is received correctly before timeout" %i
data, server = client_socket.recvfrom(buff)
else:
print >> sys.stderr, "packet %s lost hecne ack won't be send" %i
i = i + 1
def manage_FileNames():
f_name = "C:\\Users\\sayal\\Downloads\\new_test.jpg"
base_name = os.path.basename(f_name)
d = os.path.splitext(base_name)
path = "C:\\Users\\sayal\\Downloads\\"
k = 0
dupFlag = 0
while(os.path.isfile(f_name)):
k = k + 1
new_fname = d[0]+'_'+str(k)+d[1]
name = path+new_fname
f_name = name
return f_name
def corrupt_Pack_no(n):
packet_samples = [0]
for i in range(1, No_Of_Packets, 1):
packet_samples.insert(i,i)
m = (No_Of_Packets * n ) / 100
arr = random.sample(packet_samples, m)
return arr
def detect_Data_PKT_Loss():
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
data, server = client_socket.recvfrom(buff)
i = 0
while(data):
i = i + 1
if(data == 'EOF'):
data = 0
file.close()
else:
file_data = data[0:1024] #extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, chksum_calulated)
sq_receive = data[1040:1041]
send_ack = 0
if(sq_receive == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
if(is_Success == '1'):
file.write(file_data)
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
print >> sys.stderr, "packet %s is received correctly before timeout" %i
data, server = client_socket.recvfrom(buff)
else:
print >> sys.stderr, "packet %s lost hecne ack won't be send" %i
def detect_ACK_PKT_Loss():
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
arr = corrupt_Pack_no(10)
print >> sys.stderr , "arr = %s" %arr
data, server = client_socket.recvfrom(buff)
i = 0
while(data):
if(data == 'EOF'):
data = 0
file.close()
else:
if(i in arr):
print >> sys.stderr, " ************ drop ack for packet %s" %i
else:
file_data = data[0:1024] # extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, chksum_calulated)
sq_receive = data[1040:1041]
send_ack = 0
if(sq_receive == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
if(is_Success == '1'):
file.write(file_data)
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
'''print >> sys.stderr, "packet %s is received without any errors" %i'''
data, server = client_socket.recvfrom(buff)
i = i + 1
def get_bit(byteval, index):
if((byteval&(1<<index))!=0):
return 1
else:
return 0
def get_op1_ready(byteval):
h = hexlify(byteval)
num = int(h, 16)
num1 = bin(num)
num1 = str(num1)[2:]
num1 = num1.zfill(16)
return num1
def cal_Checksum_for_received_data(data):
sum = bin(0)
sum = str(sum)[2:].zfill(16)
k = 0
m = 1
for i in range (0, 1023, 2):
byte = data[k:m]
num1 = get_op1_ready(byte)
sum = bin(int(sum,2) + int(num1,2))
sum = str(sum)[2:].zfill(16)
chk = get_bit(int(sum,2), 16)
if(chk == 1):
carry = bin(1)
carry = str(carry)[2:].zfill(16)
sum = bin(int(sum,2) + int(carry,2))
offset = '0b10000000000000000'
sum = bin(int(sum,2) - int(offset,2))
sum = str(sum)[2:].zfill(16)
k = k + 2
m = m + 2
return sum
def cal_Local_Checksum(a):
a = [str(a)]
a = ''.join(a)
Local_checksum =''.join([bin(~0)[3:] if x == '0' else bin(~1)[4:] for x in a])
return Local_checksum
def add_Checksum(c1, c2): # Function to perform bit wise addition on 16 bits
c3 = bin(int(c1,2) + int(c2,2))
c4 = hex(int(c3,2))
if (c4 == '0xffff'):
c5 = '1'
else:
c5 = '0'
return c5
def detect_Bit_Errors():# This function is called when receiver selects Option = 2
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
data, server = client_socket.recvfrom(buff)
i = 0
while(data):
if(data == 'EOF'):
data = 0
file.close()
else:
file_data = data[0:1024] # extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
sq_received = data[1040:1041]
is_Success = add_Checksum(chksum_received, chksum_calulated)
print >> sys.stderr ,"chksum_received = %s" %chksum_received
print >> sys.stderr ,"chksum_calulated = %s" %chksum_calulated
if(is_Success == '1'):
file.write(file_data)
dupFlag = 0
if(sq_received == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
print >> sys.stderr, "packet %s is received without any errors" %i
else:
dupFlag = 1
if(sq_received == '0'):
send_ack = '1111111111111111'
else:
send_ack = '0000000000000000'
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack, chksum_received]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
if(dupFlag != 1):
i = i + 1
data, server = client_socket.recvfrom(buff)
def N0_Errors():# This function is called when receiver selects Option = 1
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
data, server = client_socket.recvfrom(buff)
i = 0
while(data):
i = i + 1
if(data == 'EOF'):
data = 0
file.close()
else:
file_data = data[0:1024] # extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, chksum_calulated)
sq_receive = data[1040:1041]
send_ack = 0
if(sq_receive == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
if(is_Success == '1'):
file.write(file_data)
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
print >> sys.stderr, "packet %s is received without any errors" %i
data, server = client_socket.recvfrom(buff)
def error_ack():# This function is called when receiver selects Option = 3
f_name = manage_FileNames()
print >> sys.stderr ,"f_name = %s" %f_name
file = open(f_name, 'wb')
data, server = client_socket.recvfrom(buff)
i = 0
m = 0
prev_sq = 0
arr = corrupt_Pack_no(10)
print >> sys.stderr, "arr = %s" %arr
while(data):
if(data == 'EOF'):
data = 0
file.close()
else:
file_data = data[0:1024] # extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, chksum_calulated)
sq_received = data[1040:1041]
if(is_Success == '1'):
if( (m in arr) & (dupFlag != 1)):
if(sq_received == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
print >> sys.stderr, "send_ack = %s" %send_ack
c1 = chksum_ack[1:4] # select 1st 3 bits
c2 =''.join([bin(~0)[3:] if x == '0' else bin(~1)[4:] for x in c1])#corrupt 3 bits
c3 = chksum_ack[3:17]
c4 = [c2,c3]
c4 = ''.join(c4)
send_packet = [send_ack,c4]
send_packet = ''.join(send_packet)
print >> sys.stderr ," %s has corrupted ACK" %m
sent = client_socket.sendto(send_packet, server_address)
dupFlag = 1
i = i -1
m = m -1
else:
file_data = data[0:1024] # extract file data
chksum_calulated = cal_Checksum_for_received_data(file_data)#calculate checksum of received data
chksum_received = data[1024:1040]# checksum received from sender
is_Success = add_Checksum(chksum_received, chksum_calulated)
if(is_Success == '1'):
file.write(file_data)
if(sq_received == '0'):
send_ack = '0000000000000000'
else:
send_ack = '1111111111111111'
print >> sys.stderr, "send_ack = %s" %send_ack
chksum_ack = cal_Local_Checksum(send_ack)
chksum_ack = str(chksum_ack)
send_packet = [send_ack,chksum_ack]
send_packet = ''.join(send_packet)
sent = client_socket.sendto(send_packet, server_address)
print >> sys.stderr, "packet %s is received without any errors" %i
dupFlag = 0
i = i + 1
m = m + 1
data, server = client_socket.recvfrom(buff)
bClose = 0
bExit = 1
while (bClose != 1 & bExit == 1):
message = raw_input("Receiver tries to ping server : ")
sent = client_socket.sendto(message, server_address)
print >>sys.stderr, 'Receiver waiting for reply'
data, server = client_socket.recvfrom(1041)
print >>sys.stderr, 'Sender Says: "%s"' % data
if(data == 'Option 1 Selected by receiver'):
N0_Errors()
elif(data == 'Option 2 Selected by receiver'):
detect_Bit_Errors()
elif(data == 'Option 3 Selected by receiver'):
error_ack()
elif(data == 'Option 4 Selected by receiver'):
detect_ACK_PKT_Loss()
elif(data == 'Option 5 Selected by receiver'):
detect_Data_PKT_Loss()
elif(data == 'Option 6 Selected by receiver'):
bClose = 1
elif(data == 'Option 7 Selected by receiver'):
GBN()
client_socket.close()
print >> sys.stderr, 'Receiver connection is closed'