Fix checksum comparison in traffic scripts

[csit.git] / resources / libraries / python / PacketVerifier.py

diff --git a/resources/libraries/python/PacketVerifier.py b/resources/libraries/python/PacketVerifier.py
index 54f719f..45fab6a 100644 (file)
--- a/resources/libraries/python/PacketVerifier.py
+++ b/resources/libraries/python/PacketVerifier.py
@@ -60,11 +60,11 @@
       seq       = 0x0
     ###[ Padding ]###
       load = 'RT\x00\xca]\x0b\xaa\xbb\xcc\xdd\xee\xff\x08\x06\x00\x01\x08\x00'
-    >>> rxq._proc.terminate()
 """
 
 
 import socket
+import select
 import os
 import time
 from multiprocessing import Queue, Process
@@ -73,7 +73,7 @@ from scapy.all import Ether, ARP, Packet
 from scapy.layers.inet6 import IPv6
 
 __all__ = ['RxQueue', 'TxQueue', 'Interface', 'create_gratuitous_arp_request',
-           'auto_pad']
+           'auto_pad', 'checksum_equal']
 
 # TODO: http://stackoverflow.com/questions/320232/ensuring-subprocesses-are-dead-on-exiting-python-program
 
@@ -86,6 +86,7 @@ class PacketVerifier(object):
         self._sock = socket.socket(socket.AF_PACKET, socket.SOCK_RAW,
                                    ETH_P_ALL)
         self._sock.bind((interface_name, ETH_P_ALL))
+        self._ifname = interface_name
 
 
 def extract_one_packet(buf):
@@ -186,18 +187,9 @@ def packet_reader(interface_name, queue):
     sock = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, ETH_P_ALL)
     sock.bind((interface_name, ETH_P_ALL))
 
-    buf = ""
     while True:
-        recvd = sock.recv(1514)
-        buf = buf + recvd
-
-        pkt = extract_one_packet(buf)
-        while pkt is not None:
-            if pkt is None:
-                break
-            queue.put(pkt)
-            buf = buf[len(pkt):]
-            pkt = extract_one_packet(buf)
+        pkt = sock.recv(0x7fff)
+        queue.put(pkt)
 
 
 class RxQueue(PacketVerifier):
@@ -213,12 +205,12 @@ class RxQueue(PacketVerifier):
     def __init__(self, interface_name):
         PacketVerifier.__init__(self, interface_name)
 
-        self._queue = Queue()
-        self._proc = Process(target=packet_reader, args=(interface_name,
-                                                         self._queue))
-        self._proc.daemon = True
-        self._proc.start()
-        time.sleep(2)
+        #self._queue = Queue()
+        #self._proc = Process(target=packet_reader, args=(interface_name,
+        #                                                 self._queue))
+        #self._proc.daemon = True
+        #self._proc.start()
+        #time.sleep(2)
 
     def recv(self, timeout=3, ignore=None):
         """Read next received packet.
@@ -234,14 +226,23 @@ class RxQueue(PacketVerifier):
         :rtype: scapy.Ether
         """
 
-        pkt = self._queue.get(True, timeout=timeout)
+        #pkt = self._queue.get(True, timeout=timeout)
+        (rlist, _, _) = select.select([self._sock], [], [], timeout)
+        if self._sock not in rlist:
+            return None
+
+        pkt = self._sock.recv(0x7fff)
+        pkt_pad = auto_pad(pkt)
+        print 'Received packet on {0} of len {1}'.format(self._ifname, len(pkt))
+        Ether(pkt).show2()
+        print
 
         if ignore is not None:
             for i, ig_pkt in enumerate(ignore):
                 # Auto pad all packets in ignore list
                 ignore[i] = auto_pad(ig_pkt)
             for ig_pkt in ignore:
-                if ig_pkt == pkt:
+                if ig_pkt == pkt_pad:
                     # Found the packet in ignore list, get another one
                     # TODO: subtract timeout - time_spent in here
                     ignore.remove(ig_pkt)
@@ -267,9 +268,12 @@ class TxQueue(PacketVerifier):
         :param pkt: Packet to send.
         :type pkt: string or scapy Packet derivative.
         """
-        if isinstance(pkt, Packet):
-            pkt = str(pkt)
-        pkt = auto_pad(pkt)
+        print 'Sending packet out of {0} of len {1}'.format(self._ifname,
+                                                            len(pkt))
+        Ether(str(pkt)).show2()
+        print
+
+        pkt = auto_pad(str(pkt))
         self._sock.send(pkt)
 
 
@@ -277,8 +281,8 @@ class Interface(object):
     def __init__(self, if_name):
         self.if_name = if_name
         self.sent_packets = []
-        self.txq = TxQueue(if_name)
         self.rxq = RxQueue(if_name)
+        self.txq = TxQueue(if_name)
 
     def send_pkt(self, pkt):
         self.sent_packets.append(pkt)
@@ -287,9 +291,6 @@ class Interface(object):
     def recv_pkt(self, timeout=3):
         return self.rxq.recv(timeout, self.sent_packets)
 
-    def close(self):
-        self.rxq._proc.terminate()
-
 
 def create_gratuitous_arp_request(src_mac, src_ip):
     """Creates scapy representation of gratuitous ARP request"""
@@ -304,3 +305,25 @@ def auto_pad(packet):
         padded += ('\0' * (60 - len(padded)))
     return padded
 
+
+def checksum_equal(chksum1, chksum2):
+    """Compares two checksums in one's complement notation.
+
+    Checksums to be compared are calculated as 16 bit one's complement of the
+    one's complement sum of 16 bit words of some buffer.
+    In one's complement notation 0x0000 (positive zero) and 0xFFFF
+    (negative zero) are equivalent.
+
+    :param chksum1: First checksum.
+    :param chksum2: Second checksum.
+    :type chksum1: uint16
+    :type chksum2: uint16
+
+    :return: True if checksums are equivalent, False otherwise.
+    :rtype: boolean
+    """
+    if chksum1 == 0xFFFF:
+        chksum1 = 0
+    if chksum2 == 0xFFFF:
+        chksum2 = 0
+    return chksum1 == chksum2