From 2265d4da88af76d553f8b0e74071b8d237bb175b Mon Sep 17 00:00:00 2001
From: Alexander Kissinger <akissing@ucsd.edu>
Date: Sun, 20 Apr 2014 08:29:31 -0700
Subject: [PATCH] Added basic classes and functionality to make and send IP
 packets

---
 network.py | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 network.py

diff --git a/network.py b/network.py
new file mode 100644
index 0000000..4e22516
--- /dev/null
+++ b/network.py
@@ -0,0 +1,106 @@
+import sys
+import socket
+from struct import *
+
+class OutPipe:
+  socket = None
+
+  #def __init__(self):
+
+  def start(self):
+    try:
+      self.socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
+    except socket.error , msg:
+      print('There was an issue with OutPipe. Error Code : ' + str(msg[0]) + ' Message ' + msg[1])
+      sys.exit()
+
+  def transmit(self, data, addr):
+    if(self.socket != None):
+      self.socket.sendto(data, addr)
+    else:
+      print('OutPipe is not initialized')
+
+  #Replace Later.. Maybe Cython Implementation
+  def checksum(self, msg):
+    s = 0
+    for i in range(0, len(msg), 2):
+      w = ord(msg[i]) + (ord(msg[i+1]) << 8 )
+      s = s + w
+    s = (s>>16) + (s & 0xffff);
+    s = s + (s >> 16);
+    s = ~s & 0xffff
+    return s
+
+  #Simple IP Test 
+  def ip_packet_test(self):
+    # tell kernel not to put in headers, since we are providing it, when using IPPROTO_RAW this is not necessary
+    # s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
+         
+    # now start constructing the packet
+    packet = '';
+     
+    source_ip = '192.168.1.101'
+    dest_ip = '192.168.1.114' # or socket.gethostbyname('www.google.com')
+     
+    # ip header fields
+    ip_ihl = 5
+    ip_ver = 4
+    ip_tos = 0
+    ip_tot_len = 0  # kernel will fill the correct total length
+    ip_id = 54321   #Id of this packet
+    ip_frag_off = 0
+    ip_ttl = 255
+    ip_proto = socket.IPPROTO_TCP
+    ip_check = 0    # kernel will fill the correct checksum
+    ip_saddr = socket.inet_aton ( source_ip )   #Spoof the source ip address if you want to
+    ip_daddr = socket.inet_aton ( dest_ip )
+     
+    ip_ihl_ver = (ip_ver << 4) + ip_ihl
+     
+    # the ! in the pack format string means network order
+    ip_header = pack('!BBHHHBBH4s4s' , ip_ihl_ver, ip_tos, ip_tot_len, ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr)
+     
+    # tcp header fields
+    tcp_source = 1234   # source port
+    tcp_dest = 80   # destination port
+    tcp_seq = 454
+    tcp_ack_seq = 0
+    tcp_doff = 5    #4 bit field, size of tcp header, 5 * 4 = 20 bytes
+    #tcp flags
+    tcp_fin = 0
+    tcp_syn = 1
+    tcp_rst = 0
+    tcp_psh = 0
+    tcp_ack = 0
+    tcp_urg = 0
+    tcp_window = socket.htons (5840)    #   maximum allowed window size
+    tcp_check = 0
+    tcp_urg_ptr = 0
+     
+    tcp_offset_res = (tcp_doff << 4) + 0
+    tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh <<3) + (tcp_ack << 4) + (tcp_urg << 5)
+     
+    # the ! in the pack format string means network order
+    tcp_header = pack('!HHLLBBHHH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags,  tcp_window, tcp_check, tcp_urg_ptr)
+     
+    user_data = 'Hello, how are you'
+     
+    # pseudo header fields
+    source_address = socket.inet_aton( source_ip )
+    dest_address = socket.inet_aton(dest_ip)
+    placeholder = 0
+    protocol = socket.IPPROTO_TCP
+    tcp_length = len(tcp_header) + len(user_data)
+     
+    psh = pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
+    psh = psh + tcp_header + user_data;
+     
+    tcp_check = self.checksum(psh)
+    #print tcp_checksum
+     
+    # make the tcp header again and fill the correct checksum - remember checksum is NOT in network byte order
+    tcp_header = pack('!HHLLBBH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags,  tcp_window) + pack('H' , tcp_check) + pack('!H' , tcp_urg_ptr)
+     
+    # final full packet - syn packets dont have any data
+    packet = ip_header + tcp_header + user_data
+    return packet
-- 
1.9.1