import hmac

import json

import cryptotools

# generate_nodeid() uses SHA256 so this will prevent replay-attacks,

# because every message will have a different nonce.

# It's not nessecary to compare the nonce, HMAC already gives message

# integrety.

nonce = lambda: cryptotools.generate_nodeid()

incr_nonce = lambda env: format(int(env["nonce"], 16) + 1, 'x')

class InvalidSignatureError(Exception):

pass

class InvalidNonceError(Exception):

pass

def make_envelope(msgtype, msg, nodeid):

return json.dumps(envelope)

def envelope_decorator(nodeid, func):

return inner

# ------

def create_ackhello(nodeid):

msg = {}

return make_envelope("ackhello", msg, nodeid)

def create_hello(nodeid, version):

msg = {'version': version}

return make_envelope("hello", msg, nodeid)

def create_ping(nodeid):

msg = {}

return make_envelope("ping", msg, nodeid)

def create_pong(nodeid):

msg = {}

return make_envelope("pong", msg, nodeid)

def create_getaddr(nodeid):

msg = {}

return make_envelope("getaddr", msg, nodeid)

def create_addr(nodeid, nodes):

msg = {'nodes': nodes}

return make_envelope("addr", msg, nodeid)

# -------

def read_envelope(message):

return json.loads(message)

def read_message(message):

raise InvalidSignatureError