Basic Encapsulation Example (#64)

* Adding initial implementation of basic_encap example

* Updated basic_encap example to count the number of valid packets

* Updated basic_encap example to put encapsulation layer after Ethernet
header.

* Added solution file for basic_encap example

* Changed the name of the basic_encap example to basic_tunnel and called
the new header myTunnel. Also changed the myTunnel field names slightly.

P4D2_2017_Fall/exercises/basic_tunnel/send.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+import argparse
+import sys
+import socket
+import random
+import struct
+
+from scapy.all import sendp, send, get_if_list, get_if_hwaddr, hexdump
+from scapy.all import Packet
+from scapy.all import Ether, IP, UDP, TCP
+from myTunnel_header import MyTunnel
+
+def get_if():
+    ifs=get_if_list()
+    iface=None # "h1-eth0"
+    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
+
+def main():
+
+    if len(sys.argv)<4:
+        print 'pass 2 arguments: <ip_addr> <dst_nid> "<message>"'
+        exit(1)
+
+    addr = socket.gethostbyname(sys.argv[1])
+    dst_id = int(sys.argv[2])
+    iface = get_if()
+
+    print "sending on interface %s to id %s" % (iface, str(dst_id))
+    pkt =  Ether(src=get_if_hwaddr(iface), dst='ff:ff:ff:ff:ff:ff')
+    pkt = pkt / MyTunnel(dst_id=dst_id) / IP(dst=addr) / sys.argv[3]
+    pkt.show2()
+#    hexdump(pkt)
+#    print "len(pkt) = ", len(pkt)
+    sendp(pkt, iface=iface, verbose=False)
+
+
+if __name__ == '__main__':
+    main()