def sendACK(rxp_socket): print "Sending ACK!" header = RxPPacketHeader() header.src_port = rxp_socket.source_address[1] header.dst_port = rxp_socket.destination_address[1] header.ack_flag = 1 header.ack_number = rxp_socket.ack_number packet = RxPPacket(header) rxp_socket.sendPacket(packet)
def sendSYN(rxp_socket):
print "Sending SYN! from socket", rxp_socket
header = RxPPacketHeader()
header.src_port = rxp_socket.source_address[1]
header.dst_port = rxp_socket.destination_address[1]
header.syn_flag = 1
packet = RxPPacket(header)
number_of_resends = RxPPacket.MAX_RESEND_LIMIT
while number_of_resends > 0:
print "Attempt #", (RxPPacket.MAX_RESEND_LIMIT - number_of_resends) + 1
rxp_socket.sendPacket(packet)
try:
address, packet = rxp_socket.receivePacket(RxPPacket.MAX_PACKET_SIZE)
print "Verifying packet"
if not packet.verifyPacket(): #invalid checksum
print("Incorrect checksum for sent data ack. Discarding packet")
number_of_resends -= 1
elif packet.header.syn_flag == 0 or packet.header.ack_flag == 0:
print("Not a SYN ACK! Discarding")
number_of_resends -= 1
else:
print("Received succesful SYN ACK")
return packet
except Exception as e:
if str(e) == "timed out":
print("Sending SYN timed out. " + str(number_of_resends - 1) + " attempts remaining")
number_of_resends -= 1
elif str(e).find("EOFError"):
print("Packet was mangled! resending!")
number_of_resends -= 1
else:
print "Grr"
print str(e)
raise e
raise RxPException("Sending SYN failed!")
return None
def sendSYNACK(rxp_socket):
print "Sending SYNACK!"
header = RxPPacketHeader()
header.src_port = rxp_socket.source_address[1]
header.dst_port = rxp_socket.destination_address[1]
header.syn_flag = 1
header.ack_flag = 1
packet = RxPPacket(header)
number_of_resends = RxPPacket.MAX_RESEND_LIMIT
while number_of_resends > 0:
rxp_socket.sendPacket(packet)
try:
address, packet = rxp_socket.receivePacket(RxPPacket.MAX_PACKET_SIZE)
if not packet.verifyPacket(): #invalid checksum
print("Incorrect checksum for sent data ack. Discarding packet")
number_of_resends -= 1
elif packet.header.syn_flag == 1 or packet.header.ack_flag == 0:
print("Not a ACK! Discarding")
number_of_resends -= 1
else:
print("Received succesful ACK to our SYNACK")
return packet
except Exception as e:
if str(e) == "timed out":
print("Sending SYN timed out. " + str(number_of_resends) + " resends remaining")
number_of_resends -= 1
else:
raise e
return None
def sendData(rxp_socket, data):
if not rxp_socket.state == SocketState.CONNECTED:
raise RxPException("sendData: Socket not connected!")
# break data into chunks
data_chunks = deque()
packet_payload_length = RxPPacket.MAX_PAYLOAD_LENGTH
numberOfPackets = int(len(data) / packet_payload_length)
if len(data) % packet_payload_length > 0:
numberOfPackets += 1
print("Preparing " + str(numberOfPackets) + " packets to send")
for i in range(numberOfPackets):
start_index = int(packet_payload_length * i)
end_index = int(start_index + packet_payload_length)
if i + 1 == numberOfPackets:
data_chunks.append(data[start_index:])
else:
data_chunks.append(data[start_index:end_index])
# these are the acual packets that we need to send
packets_to_send = deque()
for data_item in data_chunks:
is_last_packet = (data_item == data_chunks[-1])
header = RxPPacketHeader()
header.src_port = rxp_socket.source_address[1]
header.dst_port = rxp_socket.destination_address[1]
header.rcv_window = rxp_socket.receive_window_size
if is_last_packet:
header.lst_flag = 1
header.seq_number = rxp_socket.seq_number
rxp_socket.seq_number += 1 # todo wrap sequence number if needed
packet = RxPPacket(header, data_item)
packets_to_send.append(packet)
# these are the packets that we know are sent but haven't been acked yet
packets_to_be_acked = deque()
window_size = rxp_socket.receive_window_size
cur_seq_number = packets_to_send[0].header.seq_number
print ("Sending packets for data: ", data)
while len(packets_to_send) > 0:
while window_size > 0 and len(packets_to_send) > 0:
packet = packets_to_send.popleft()
rxp_socket.sendPacket(packet)
window_size -= 1
packets_to_be_acked.append(packet)
# collect acks
try:
address, packet = rxp_socket.receivePacket(RxPPacket.MAX_PACKET_SIZE)
if not packet.verifyPacket: #invalid checksum
print("Incorrect checksum for sent data ack. Discarding packet")
window_size += 1
else:
# valid packet
print("Validating packet!")
if packet.header.ack_number == cur_seq_number and packet.header.ack_flag > 0:
print("Received desired ack: ", cur_seq_number)
if len(packets_to_be_acked) > 0:
break
packets_to_be_acked.popleft()
cur_seq_number += 1
window_size += 1
window_size *= 2
else:
print("Received sent packet ack but not one we were looking for")
print(str(packet.header.ack_number) + " vs " + str(cur_seq_number))
if packet.header.seq_number > cur_seq_number:
print("Sequence number is greater than looking for")
window_size += 1
else:
packets_to_send.extendleft(packets_to_be_acked)
packets_to_be_acked.clear()
print ("Receive duplicate packet. Discarding")
except Exception as e:
if str(e) == "timed out":
print("Socket timeout for sent ack receive--resending")
# need to send packet
window_size = 3
