#!/usr/bin/env python

#
# Standard imports
#
import string
import struct, socket, select

#
# Default variables
#
BOOTP_PORT = 67
BOOTP_PORT_MVP = 16867  # For MediaMVP

BOOTREQUEST = 1
BOOTREPLY = 2

BOOTPFormat = "!4bIHH4s4s4s4s16s64s128s64s"
BOOTPFormatSize = struct.calcsize(BOOTPFormat)
DHCPFormat = "!4bIHH4s4s4s4s16s64s128s4s"
DHCPFormatSize = struct.calcsize(DHCPFormat)

COOKIE='\0x63\0x82\0x53\0x63'

#
# Errors
#
class BOOTPError(Exception):
    pass


def getOutAddr(addr):
    """Return local IP address as decimal dotted string to send data to target
    addr (which is tuple)
    TODO: Cache the result."""
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.connect(addr)
    result = s.getsockname()[0]
    s.close()
    return result

#
# Simple BootP Server
# 
class BOOTPServer:
    """BOOTP Server
    Implements bootstrap protocol
    """

    def __init__(self):
        self.sock = []
    # end __init__

    def bind(self, host, port):
        print "binding to", port
        if not host and port==BOOTP_PORT:
            host = '10.0.0.153'
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self.sock.append(sock)
        sock.bind((host, port))
    # end start

    def forever(self):
        while 1:
            r,w,e = select.select(self.sock, [], self.sock)
            for sock in r:
                data, addr = sock.recvfrom(556)
                self.handle(sock, addr, data)   
    # end serve_forever

    def handle(self, sock, addr, data):
        print "Sender:", addr, " on socket ", sock.getsockname()
        if len(data) < DHCPFormatSize:
            print "Cannot be a DHCP or BOOTP request - too small!"
        tail = data[DHCPFormatSize:]
        buf = list(struct.unpack(DHCPFormat, data[:DHCPFormatSize]))
        if buf[0] == BOOTREQUEST:
            print "  data:", buf
            # construct reply
            buf[0] = BOOTREPLY
            # "your" address
            print "Client IP ", socket.inet_ntoa(buf[7])
            if buf[7] == '\x00\x00\x00\x00':
                #print "Cannot serve this client, it does not have an IP yet"
                #return
                # client needs its address?
                buf[8] = socket.inet_aton('10.0.0.155')
                addr = ('10.0.0.155', addr[1])
            else:
                buf[8] = buf[7] # 0x0A00009BL # 10.0.0.155
            # siaddr
            siaddr = socket.inet_aton(getOutAddr(addr))
            buf[9] = siaddr # 10.0.0.153
            
            buf[10] = siaddr
            # sname
            buf[12] = "milo.lan"
            # file
            buf[13] = "dongle.bin.mvpmc" # -1.2.0"
            #buf[13] = "dongle.bin"
            # Extras (DHCP options?)
            buf[14] = ''
            print "Sending reply:", buf
            pkt = struct.pack(BOOTPFormat, *buf)
            sock.sendto(pkt, addr)
        
    # end handle

# end class TFTPServer


if __name__ == "__main__":
    import sys
    if sys.argv[1:]:
        port = string.atoi(sys.argv[1])
    try:
        serv = BOOTPServer()
        serv.bind("", BOOTP_PORT)
        serv.bind("", BOOTP_PORT_MVP)
        serv.forever()
    except KeyboardInterrupt, SystemExit:
        pass