def startTearDown(self, local_current_ack_no, localhostIP, destinationIP, sendSock, receiveSock):
# Sends ACK to server of the received packet content
self.sendAckToServer(local_current_ack_no, localhostIP, destinationIP, sendSock)
self.ip_packet_ID = self.ip_packet_ID + 1
ipheader = self.getIPHeader(localhostIP, destinationIP, self.ip_packet_ID)
tcpobj = TCPHeader()
tcpobj.setValues(self.sourcePortNum, self.destinationPortNum, self.seq_num, local_current_ack_no, 0, 1, 1, "")
tcpheader = tcpobj.build(localhostIP, destinationIP)
packet = ipheader + tcpheader + ""
sendSock.sendto(packet, (destinationIP, 80))
start_time = time.clock()
while True:
try:
receivedPacket = receiveSock.recvfrom(65565)
except:
print "Exception in tear down"
sys.exit(2)
packetData = receivedPacket[0]
received_IPHeader = packetData[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
spent_Time = time.clock() - start_time
# Resend if time exceeds 1min
if spent_Time > 60:
sendSock.sendto(packet, (destinationIP, 80))
start_time = time.clock()
# Checks if the protocol is 6, and checks the source and destination in the IP Packet
if (
ipheader.protocol == 6
and ipheader.sourceIP == destinationIP
and ipheader.destinationIP == localhostIP
and checksum == 0
):
get_TCPHeader = self.getTCPHeaderFromIPHeader(packetData, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
if (
tcpheader.sourcePort == self.destinationPortNum
and tcpheader.destPort == self.sourcePortNum
and tcpheader.ackNo == self.seq_num + 1
):
return
def receiveSYNACKPacket(self, sendSock, SYNPacket, localhostIP, destinationIP):
self.ack_packet = ""
self.cwnd = 1
self.startTime = 0
user_request = ""
receiveSock = self.getReceiveRawSocket()
self.startTime = time.clock()
# Receives packet
while True:
receiveSock.settimeout(180)
try:
receivedPacket = receiveSock.recvfrom(65565)
except:
print "Exception in receiving SYN/ACK packet"
sendSock.close()
receiveSock.close()
sys.exit(2)
packet = receivedPacket[0]
received_IPHeader = packet[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
time_elapsed = time.clock() - self.startTime
if time_elapsed > 60:
sendSock.sendto(SYNPacket, (destinationIP, self.destinationPortNum))
self.startTime = time.clock()
if (ipheader.protocol == 6) and (checksum == 0) and (ipheader.sourceIP == destinationIP) and (ipheader.destinationIP == localhostIP):
get_TCPHeader = self.getTCPHeaderFromIPHeader(packet, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
if (tcpheader.sourcePort == self.destinationPortNum and tcpheader.destPort == self.sourcePortNum and tcpheader.ack_flg == 1 and tcpheader.ackNo == self.seq_num + 1 and not tcpheader.rst_flg):
self.seq_num = tcpheader.ackNo
self.current_ack_no = tcpheader.sequenceNo + 1
self.ip_packet_ID = self.ip_packet_ID + 1
ipheader1 = self.getIPHeader(localhostIP, destinationIP, self.ip_packet_ID)
user_request = self.getHttpGETRequest(self.url, self.urlHostName)
tcp_header1 = self.getTCPHeader(localhostIP, destinationIP, user_request)
self.ack_packet = ipheader1 + tcp_header1 + user_request
sendSock.sendto(self.ack_packet, (destinationIP, 80))
break
# Handshake Completed, start downloading file from the server
self.getMessagesFromServer(time.clock(), user_request, localhostIP, destinationIP, sendSock, receiveSock)
def buildSYNPacket(self, localhostIP, destinationIP):
IPHeaderObj = IPHeader(localhostIP, destinationIP, self.ip_packet_ID)
ipHeader = IPHeaderObj.build()
userData = ""
TCPObj = TCPHeader()
#Set the SYN Flag
TCPObj.setValues(self.sourcePortNum, self.destinationPortNum, self.seq_num, self.current_ack_no, 1, 0, 0, userData)
tcpHeader = TCPObj.build(localhostIP, destinationIP)
SYNPacket = ipHeader + tcpHeader + userData
return SYNPacket
def buildSYNPacket(self, localhostIP, destinationIP):
IPHeaderObj = IPHeader(localhostIP, destinationIP, self.ip_packet_ID)
ipHeader = IPHeaderObj.build()
userData = ""
TCPObj = TCPHeader()
# Set the SYN Flag
TCPObj.setValues(
self.sourcePortNum, self.destinationPortNum, self.seq_num, self.current_ack_no, 1, 0, 0, userData
)
tcpHeader = TCPObj.build(localhostIP, destinationIP)
SYNPacket = ipHeader + tcpHeader + userData
return SYNPacket
def startTearDown(self, local_current_ack_no, localhostIP, destinationIP, sendSock, receiveSock):
# Sends ACK to server of the received packet content
self.sendAckToServer(local_current_ack_no, localhostIP, destinationIP, sendSock)
self.ip_packet_ID = self.ip_packet_ID + 1
ipheader = self.getIPHeader(localhostIP, destinationIP, self.ip_packet_ID)
tcpobj = TCPHeader()
tcpobj.setValues(self.sourcePortNum, self.destinationPortNum, self.seq_num, local_current_ack_no, 0, 1, 1, "")
tcpheader = tcpobj.build(localhostIP, destinationIP)
packet = ipheader + tcpheader + ""
sendSock.sendto(packet, (destinationIP, 80))
start_time = time.clock()
while True:
try:
receivedPacket = receiveSock.recvfrom(65565)
except:
print "Exception in tear down"
sys.exit(2)
packetData = receivedPacket[0]
received_IPHeader = packetData[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
spent_Time = time.clock() - start_time
# Resend if time exceeds 1min
if spent_Time > 60:
sendSock.sendto(packet, (destinationIP, 80))
start_time = time.clock()
# Checks if the protocol is 6, and checks the source and destination in the IP Packet
if ipheader.protocol == 6 and ipheader.sourceIP == destinationIP and ipheader.destinationIP == localhostIP and checksum == 0:
get_TCPHeader = self.getTCPHeaderFromIPHeader(packetData, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
if tcpheader.sourcePort == self.destinationPortNum and tcpheader.destPort == self.sourcePortNum and tcpheader.ackNo == self.seq_num + 1:
return
def getMessagesFromServer(self, start_Time, user_request, localhostIP, destinationIP, sendSock, receiveSock):
self.page_content_dict = {}
roundTripTime = time.clock()
http_ack_flg = False
self.seq_num = self.seq_num + len(user_request)
while True:
receiveSock.settimeout(180)
try:
receivedPacket = receiveSock.recvfrom(65565)
except receiveSock.timeout:
print "Socket timed out. No packet received in 3 minutes"
sendSock.close()
receiveSock.close()
sys.exit(2)
spent_Time = time.clock() - start_Time
# Resend if the packet is not received before 1min
if spent_Time > 60 and not http_ack_flg:
sendSock.sendto(self.ack_packet, (destinationIP, 80))
start_Time = time.clock()
packet = receivedPacket[0]
received_IPHeader = packet[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
# Checks if the protocol is TCP, if the server IP is the source IP in the packet, if the localhostIP is the destination in the packet
if ipheader.protocol == 6 and ipheader.sourceIP == destinationIP and ipheader.destinationIP == localhostIP and checksum == 0:
get_TCPHeader = self.getTCPHeaderFromIPHeader(packet, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
# Strip of header length, and gets the actual data
header_length = (tcpheader.HL_Offset * 4) + (ipheader.ihl * 4)
message_length = ipheader.totalLength - header_length
actual_page_content = packet[header_length:]
self.checkcwnd(tcpheader)
# Checks valid sourcePort,destPort in TCP header
if tcpheader.sourcePort == self.destinationPortNum and tcpheader.destPort == self.sourcePortNum and tcpheader.ackNo == self.seq_num:
time_spent = time.clock() - roundTripTime
if (time_spent > 180):
print "No packet received from server for 3 minutes. Terminating program. "
sendSock.close()
receiveSock.close()
sys.exit(2)
roundTripTime = time.clock()
# Indicates end of data
if tcpheader.fin_flg == 1:
self.current_ack_no += 1
self.page_content_dict[tcpheader.sequenceNo] = actual_page_content
self.startTearDown(self.current_ack_no, localhostIP, destinationIP, sendSock, receiveSock)
break
# Continue to receive data, indicates this is an ACK
if tcpheader.ack_flg == 1 and http_ack_flg == False and tcpheader.ackNo == self.seq_num:
http_ack_flg = True
continue
if tcpheader.syn_flg == 1 and tcpheader.ack_flg == 1:
continue
else:
# Stores Data in the dictionary in sequenceNo:data format
if self.page_content_dict.has_key(tcpheader.sequenceNo):
self.sendAckToServer(message_length + tcpheader.sequenceNo, localhostIP, destinationIP, sendSock)
else:
self.current_ack_no = self.current_ack_no + message_length
self.page_content_dict[tcpheader.sequenceNo] = actual_page_content
self.sendAckToServer(self.current_ack_no, localhostIP, destinationIP, sendSock)
def getIPHeader(self, localhostIP, destinationIP, ip_packet_ID):
ipheader_obj = IPHeader(localhostIP, destinationIP, ip_packet_ID)
ipheader = ipheader_obj.build()
return ipheader
def getMessagesFromServer(self, start_Time, user_request, localhostIP, destinationIP, sendSock, receiveSock):
self.page_content_dict = {}
roundTripTime = time.clock()
http_ack_flg = False
self.seq_num = self.seq_num + len(user_request)
while True:
receiveSock.settimeout(180)
try:
receivedPacket = receiveSock.recvfrom(65565)
except receiveSock.timeout:
print "Socket timed out. No packet received in 3 minutes"
sendSock.close()
receiveSock.close()
sys.exit(2)
spent_Time = time.clock() - start_Time
# Resend if the packet is not received before 1min
if spent_Time > 60 and not http_ack_flg:
sendSock.sendto(self.ack_packet, (destinationIP, 80))
start_Time = time.clock()
packet = receivedPacket[0]
received_IPHeader = packet[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
# Checks if the protocol is TCP, if the server IP is the source IP in the packet, if the localhostIP is the destination in the packet
if (
ipheader.protocol == 6
and ipheader.sourceIP == destinationIP
and ipheader.destinationIP == localhostIP
and checksum == 0
):
get_TCPHeader = self.getTCPHeaderFromIPHeader(packet, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
# Strip of header length, and gets the actual data
header_length = (tcpheader.HL_Offset * 4) + (ipheader.ihl * 4)
message_length = ipheader.totalLength - header_length
actual_page_content = packet[header_length:]
self.checkcwnd(tcpheader)
# Checks valid sourcePort,destPort in TCP header
if (
tcpheader.sourcePort == self.destinationPortNum
and tcpheader.destPort == self.sourcePortNum
and tcpheader.ackNo == self.seq_num
):
time_spent = time.clock() - roundTripTime
if time_spent > 180:
print "No packet received from server for 3 minutes. Terminating program. "
sendSock.close()
receiveSock.close()
sys.exit(2)
roundTripTime = time.clock()
# Indicates end of data
if tcpheader.fin_flg == 1:
self.current_ack_no += 1
self.page_content_dict[tcpheader.sequenceNo] = actual_page_content
self.startTearDown(self.current_ack_no, localhostIP, destinationIP, sendSock, receiveSock)
break
# Continue to receive data, indicates this is an ACK
if tcpheader.ack_flg == 1 and http_ack_flg == False and tcpheader.ackNo == self.seq_num:
http_ack_flg = True
continue
if tcpheader.syn_flg == 1 and tcpheader.ack_flg == 1:
continue
else:
# Stores Data in the dictionary in sequenceNo:data format
if self.page_content_dict.has_key(tcpheader.sequenceNo):
self.sendAckToServer(
message_length + tcpheader.sequenceNo, localhostIP, destinationIP, sendSock
)
else:
self.current_ack_no = self.current_ack_no + message_length
self.page_content_dict[tcpheader.sequenceNo] = actual_page_content
self.sendAckToServer(self.current_ack_no, localhostIP, destinationIP, sendSock)
def getIPHeader(self, localhostIP, destinationIP, ip_packet_ID):
ipheader_obj = IPHeader(localhostIP, destinationIP, ip_packet_ID)
ipheader = ipheader_obj.build()
return ipheader
def receiveSYNACKPacket(self, sendSock, SYNPacket, localhostIP, destinationIP):
self.ack_packet = ""
self.cwnd = 1
self.startTime = 0
user_request = ""
receiveSock = self.getReceiveRawSocket()
self.startTime = time.clock()
# Receives packet
while True:
receiveSock.settimeout(180)
try:
receivedPacket = receiveSock.recvfrom(65565)
except:
print "Exception in receiving SYN/ACK packet"
sendSock.close()
receiveSock.close()
sys.exit(2)
packet = receivedPacket[0]
received_IPHeader = packet[0:20]
ipheader = IPHeader(0, 0, 0)
ipheader.extract(received_IPHeader)
checksum = self.calculateCheckSum(received_IPHeader)
time_elapsed = time.clock() - self.startTime
if time_elapsed > 60:
sendSock.sendto(SYNPacket, (destinationIP, self.destinationPortNum))
self.startTime = time.clock()
if (
(ipheader.protocol == 6)
and (checksum == 0)
and (ipheader.sourceIP == destinationIP)
and (ipheader.destinationIP == localhostIP)
):
get_TCPHeader = self.getTCPHeaderFromIPHeader(packet, ipheader)
tcpheader = TCPHeader()
tcpheader.extract(get_TCPHeader)
if (
tcpheader.sourcePort == self.destinationPortNum
and tcpheader.destPort == self.sourcePortNum
and tcpheader.ack_flg == 1
and tcpheader.ackNo == self.seq_num + 1
and not tcpheader.rst_flg
):
self.seq_num = tcpheader.ackNo
self.current_ack_no = tcpheader.sequenceNo + 1
self.ip_packet_ID = self.ip_packet_ID + 1
ipheader1 = self.getIPHeader(localhostIP, destinationIP, self.ip_packet_ID)
user_request = self.getHttpGETRequest(self.url, self.urlHostName)
tcp_header1 = self.getTCPHeader(localhostIP, destinationIP, user_request)
self.ack_packet = ipheader1 + tcp_header1 + user_request
sendSock.sendto(self.ack_packet, (destinationIP, 80))
break
# Handshake Completed, start downloading file from the server
self.getMessagesFromServer(time.clock(), user_request, localhostIP, destinationIP, sendSock, receiveSock)
