#!/usr/bin/env python
# Pytella, a Gnutella servant written in Python, Copyright (C) 2000 Tom Goulet
# This program is protected under the terms of the GNU General Public
# License version 2, see the file COPYING in this directory.

# Stuff we need.
import sys			# For argv[] and exit()
from socket import *		# Socket stuff
import time			# for sleeping
import whrandom			# Random stuff

def sendping():			# Send a ping out
        guid = ''		# random identifier
	flag = '\000'		# ping
        ttl = '\004'		# default ttl of 4
        hops = '\000'		# default hops of 0
        payloadsize = '\000\000\000\000'	# pings have precisely 0 payload
        for i in range(16): guid = guid + chr(whrandom.randint(0, 255))	# Generated random GUID.
        sendstring = guid + flag + ttl + hops + payloadsize  # make a sendstring
        s.send(sendstring) # send it
	print "Sent ping:", `sendstring`
	return()		# Done, now.

def processpong(payload):		# Process a pong
        port = 0			# port is an integer
        ipaddress = ''			# ipaddress is a string
        port = ord(payload[0]) + ord(payload[1]) * 256	# sucking the port out of the payload
        ipaddress = str(ord(payload[2])) + "." + str(ord(payload[3])) + "." + str(ord(payload[4])) + "." + str(ord(payload[5]))		# sucking the ip address out of the payload
#	print "Pong processed."
	return(ipaddress, port)		# bring home the bacon

def connect(HOST, PORT):			# connect to a gnutellanet node
        s.connect(HOST, PORT)			# connect socket
        s.send('GNUTELLA CONNECT/0.4\n\n')	# handshake string
        if s.recv(64) != 'GNUTELLA OK\n\n':	# countersign
		print "Connection failed, exiting."
		sys.exit(1)# barf if countersign bad
	print "Connected to "+HOST+':'+str(PORT)+"."
        return()	# done, go home

def processheader(header):
	ipaddress = ''
	port = 0
	payload = ''
	payloadlength = processheaderpayload(header[19:23])
        if header[16] == '\001':		# header signifies pong
		print "Pong header: ", `header`
		payload = s.recv(payloadlength) # try to receive what the header says
                ipaddress, port = processpong(payload)  # Process the pong.
#                print "Got Pong", `payload`, "Pong shows host at "+ipaddress+":"+str(port)+"."
	elif header[16] == '\000':
#		print "Got a ping.  Don't care."
		payload = s.recv(payloadlength)
#		print "Ping payload: "+`payload`
	else:
#		print "Got some packet.  Don't care."
		payload = s.recv(payloadlength)
#		print "Unkown payload: "+`payload`
	return()	# return happily

def processheaderpayload(headerpayload): #takes bytes 19 to 22 from the header
#	print "Header length bytes: "+`headerpayload`
	pll = 0	# I've broken this up into a bunch of lines so it'll look nicer
	pll = pll + ord(headerpayload[0]) # least significant
	pll = pll + ord(headerpayload[1]) * 256
	pll = pll + ord(headerpayload[2]) * 65536
	pll = pll + ord(headerpayload[3]) * 16777216 # most significant
#	print "payloadlength is: "+`pll`
	return(pll) # returns payload length according to header

def main():
#        s = socket(AF_INET, SOCK_STREAM)# Make a socket
	# This should move to command line parameters, and then to reading from a file.
	HOST = '192.168.0.254'		# Host to connect to
	PORT = 6346			# Port to connect to
	connect(HOST, PORT)		# Connect to a gnutellanet node.
	sendping()			# Send a ping out.
	while 1:			# main loop
		header = s.recv(23)	# The first 23 bytes are always header
#		print "got: "+`header`# diagnostic
		processheader(header)	# process the header
	#	time.sleep(1)		# sleep  *snore*

	s.close() 			# Close it up

s = socket(AF_INET, SOCK_STREAM)# Make a socket
main()		# Run the program

# EOF