fix tcp options for trace data packet (#35)

* fix tcp options for trace data packet

* only ask for tcp handshake if flag is psh,ack

* fix tcp options for trace single packet

* timestamp correction: convert to milliseconds

* fix packet trace mistake

utils/packet_input.py

@@ -31,32 +31,36 @@ def copy_input_packets(os_name: str, trace_retransmission: bool):
         " ********************************************************************** ")
     print(
         " paste here the first packet hex dump start with the IP layer and then enter :")
+    print(" . . . - .     . . . - .     . . . - .     . . . - . ")
     copy_packet_1 = IP(import_hexcap())
     print(" . . . - .     . . . - .     . . . - .     . . . - . ")
     print(" . . . - . developed view of this packet:")
     copy_packet_1.show()
     print(" . . . - .     . . . - .     . . . - .     . . . - . ")
     if not trace_retransmission:
         if copy_packet_1.haslayer(TCP):
-            if os_name == "Linux":
-                do_tcph1 = yesno_second_packet(
-                    "Would you like to do a TCP Handshake before sending this packet?"
-                    + firewall_commands_help)
-            else:
-                do_tcph1 = yesno_second_packet(
-                    "Would you like to do a TCP Handshake before sending this packet?")
-            print(" · - · - ·     · - · - ·     · - · - ·     · - · - · ")
+            if copy_packet_1[TCP].flags == "PA":
+                if os_name == "Linux":
+                    do_tcph1 = yesno_second_packet(
+                        "Would you like to do a TCP Handshake before sending this packet?"
+                        + firewall_commands_help)
+                else:
+                    do_tcph1 = yesno_second_packet(
+                        "Would you like to do a TCP Handshake before sending this packet?")
+                print(" · - · - ·     · - · - ·     · - · - ·     · - · - · ")
         if yesno_second_packet("Would you like to add a second packet"):
             print(
                 " paste here the second packet hex dump start with the IP layer and then enter (optional) :")
+            print(" . . . - .     . . . - .     . . . - .     . . . - . ")
             copy_packet_2 = IP(import_hexcap())
             print(" . . . - .     . . . - .     . . . - .     . . . - . ")
             print(" . . . - . developed view of this packet:")
             copy_packet_2.show()
             print(" . . . - .     . . . - .     . . . - .     . . . - . ")
-            if copy_packet_1.haslayer(TCP):
-                do_tcph2 = yesno_second_packet(
-                    "Would you like to do a TCP Handshake before sending this packet?")
+            if copy_packet_2.haslayer(TCP):
+                if copy_packet_2[TCP].flags == "PA":
+                    do_tcph2 = yesno_second_packet(
+                        "Would you like to do a TCP Handshake before sending this packet?")
     print(
         " ********************************************************************** ")
     return copy_packet_1, copy_packet_2, do_tcph1, do_tcph2

utils/trace.py

@@ -3,6 +3,7 @@
 
 import contextlib
 import json
+import platform
 import socket
 import sys
 import time
@@ -22,6 +23,7 @@
 SLEEP_TIME = 1
 have_2_packet = False
 measurement_data = [[], []]
+OS_NAME = platform.system()
 
 
 def parse_packet(request_and_answer, current_ttl, elapsed_ms):
@@ -83,9 +85,61 @@ def ephemeral_port_reserve(proto: str = "tcp"):
                 return sockname[1]
 
 
+def tcp_options_correction(tcp_options, new_timestamp, syn_ack_timestamp):
+    new_options = []
+    default_timestamp = ('Timestamp', (new_timestamp, syn_ack_timestamp))
+    for attr in tcp_options:
+        if 'Timestamp' == str(attr[0]):
+            new_options.append(default_timestamp)
+        else:
+            new_options.append(attr)
+    return new_options
+
+
+def generate_syn_tcp_options(new_timestamp):
+    if OS_NAME == "Linux":
+        tcp_options = [('MSS', 1460), ('SAckOK', b''),
+                       ('Timestamp', (new_timestamp, 0)), ('NOP', None), ('WScale', 7)]
+        return tcp_options
+    elif OS_NAME == "Windows":
+        tcp_options = [('MSS', 1460), ('NOP', None),
+                       ('NOP', None), ('SAckOK', b'')]
+        return tcp_options
+    elif OS_NAME == "Darwin":
+        tcp_options = [('MSS', 1460), ('NOP', None), ('WScale', 6), ('NOP', None),
+                       ('NOP', None), ('Timestamp', (new_timestamp, 0)), ('SAckOK', b''), ('EOL', None)]
+        return tcp_options
+    else:
+        return []
+
+
+def generate_ack_tcp_options(new_timestamp, syn_ack_timestamp):
+    if OS_NAME == "Linux" or OS_NAME == "Darwin":
+        tcp_options = [('NOP', None), ('NOP', None),
+                       ('Timestamp', (new_timestamp, syn_ack_timestamp))]
+        return tcp_options
+    else:
+        return []
+
+
+def get_timestamp(tcp_options):
+    default_timestamp = 0
+    for attr in tcp_options:
+        if 'Timestamp' == str(attr[0]):
+            default_timestamp = attr[1][0]
+    return default_timestamp
+
+
+def get_new_timestamp():
+    timestamp_now = time.time()
+    return timestamp_now, (int(timestamp_now) ^ int(RandInt()))
+
+
 def send_packet_with_tcphandshake(this_request, timeout):
+    timestamp_start, new_timestamp = get_new_timestamp()
     ip_address = this_request[IP].dst
     destination_port = this_request[TCP].dport
+    syn_tcp_options = generate_syn_tcp_options(new_timestamp)
     ans = []
     max_repeat = 0
     # here we are trying to do a new TCP handshake every time because
@@ -95,7 +149,7 @@ def send_packet_with_tcphandshake(this_request, timeout):
         source_port = ephemeral_port_reserve("tcp")
         send_syn = IP(
             dst=ip_address, id=RandShort())/TCP(
-            sport=source_port, dport=destination_port, seq=RandInt(), flags="S")
+            sport=source_port, dport=destination_port, seq=RandInt(), flags="S", options=syn_tcp_options)
         tcp_handshake_timeout = timeout + max_repeat
         ans, unans = sr(send_syn, verbose=0, timeout=tcp_handshake_timeout)
         if len(ans) == 0:
@@ -109,17 +163,24 @@ def send_packet_with_tcphandshake(this_request, timeout):
         return ans, unans
     else:
         timeout += 2  # we should wait more for data packets.
+        syn_ack_timestamp = get_timestamp(ans[0][1][TCP].options)
+        new_timestamp = new_timestamp + \
+            int((time.time() - timestamp_start) * 1000)
+        ack_tcp_options = generate_ack_tcp_options(
+            new_timestamp, syn_ack_timestamp)
         send_ack = IP(
             dst=ip_address, id=(ans[0][0][IP].id + 1))/TCP(
             sport=source_port, dport=destination_port, seq=ans[0][1][TCP].ack,
-            ack=ans[0][1][TCP].seq + 1, flags="A")
+            ack=ans[0][1][TCP].seq + 1, flags="A", options=ack_tcp_options)
         send(send_ack, verbose=0)
         send_data = this_request
         del(send_data[IP].src)
         send_data[IP].id = ans[0][0][IP].id + 2
         send_data[TCP].sport = source_port
         send_data[TCP].seq = ans[0][1][TCP].ack
         send_data[TCP].ack = ans[0][1][TCP].seq + 1
+        send_data[TCP].options = tcp_options_correction(
+            send_data[TCP].options, new_timestamp, syn_ack_timestamp)
         del(send_data[TCP].chksum)
         del(send_data[IP].len)
         del(send_data[IP].chksum)
@@ -142,6 +203,9 @@ def send_single_packet(this_request, timeout):
         this_request[TCP].sport = ephemeral_port_reserve("tcp")
         if this_request[TCP].flags == "S":
             this_request[TCP].seq = RandInt()
+        timestamp_start, new_timestamp = get_new_timestamp()
+        this_request[TCP].options = tcp_options_correction(
+            this_request[TCP].options, new_timestamp, int(timestamp_start))
         del(this_request[TCP].chksum)
     elif this_request.haslayer(UDP):
         this_request[UDP].sport = ephemeral_port_reserve("udp")