Created new subdirectory for Fall developer day. (#60)

P4D2_2017_Spring/exercises/ipv4_forward/receive.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+import sys
+import struct
+
+from scapy.all import sniff, sendp, hexdump, get_if_list, get_if_hwaddr
+from scapy.all import Packet, IPOption
+from scapy.all import ShortField, IntField, LongField, BitField, FieldListField, FieldLenField
+from scapy.all import IP, UDP, Raw
+from scapy.layers.inet import _IPOption_HDR
+
+def get_if():
+    ifs=get_if_list()
+    iface=None
+    for i in get_if_list():
+        if "eth0" in i:
+            iface=i
+            break;
+    if not iface:
+        print "Cannot find eth0 interface"
+        exit(1)
+    return iface
+
+class IPOption_MRI(IPOption):
+    name = "MRI"
+    option = 31
+    fields_desc = [ _IPOption_HDR,
+                    FieldLenField("length", None, fmt="B",
+                                  length_of="swids",
+                                  adjust=lambda pkt,l:l+4),
+                    ShortField("count", 0),
+                    FieldListField("swids",
+                                   [],
+                                   IntField("", 0),
+                                   length_from=lambda pkt:pkt.count*4) ]
+def handle_pkt(pkt):
+    print "got a packet"
+    pkt.show2()
+#    hexdump(pkt)
+    sys.stdout.flush()
+
+
+def main():
+    iface = 'h2-eth0'
+    print "sniffing on %s" % iface
+    sys.stdout.flush()
+    sniff(filter="udp and port 4321", iface = iface,
+          prn = lambda x: handle_pkt(x))
+
+if __name__ == '__main__':
+    main()