Apple store receipt validation through Twisted server - iphone

Question

I'm trying to validate a transaction receipt from an inApp purchase with the Apple store server from my Twisted server. I have sent the (SKPaymentTransaction *)transaction.transactionReceipt from my app to my server.
But now, sending the JSON object to the Apple server, I keep getting an unhandled error in Deferred from my Agent.request(). I suspect this is because I'm not listening on port 443 for response from Apple store, but I don't want my app to communicate with my Twisted server on port 443 also. Here is my code:
from twisted.application import internet, service
from twisted.internet import protocol, reactor
from zope.interface import implements
from twisted.web.iweb import IBodyProducer
from twisted.internet import defer
from twisted.web.client import Agent
from twisted.web.http_headers import Headers
import json
import base64
class StringProducer(object):
implements(IBodyProducer)
def __init__(self, body):
self.body = body
self.length = len(body)
def startProducing(self, consumer):
consumer.write(self.body)
return succeed(None)
def pauseProducing(self):
pass
def stopProducing(self):
pass
def printResponse(response):
print response # just testing to see what I have
def httpRequest(url, values, headers={}, method='POST'):
agent = Agent(reactor)
d = agent.request(method,
url,
Headers(headers),
StringProducer(values)
)
d.addCallback(printResponse)
class storeServer(protocol.Protocol):
def dataReceived(self, data):
receiptBase64 = base64.standard_b64encode(data)
jsonReceipt = json.dumps({'receipt-data':receiptBase64})
print jsonReceipt # verified that my data is correct
d = httpRequest(
"https://buy.itunes.apple.com/verifyReceipt",
jsonReceipt,
{'Content-Type': ['application/x-www-form-urlencoded']}
)
factory = protocol.Factory()
factory.protocol = storeServer
tcpServer = internet.TCPServer(30000, factory)
tcpServer.setServiceParent(application)
How can I fix this error? Do I have to create another service listening on port 443? If so, how might I have the service connecting to my app communicate with the service connecting through https?

Answer 1

The comment style in your code sample is incorrect. Python uses # for comments, not //.
After fixing that and running the snippet through pyflakes, I see these errors:
program.py:1: 'service' imported but unused
program.py:6: 'defer' imported but unused
program.py:21: undefined name 'succeed'
program.py:48: local variable 'd' is assigned to but never used
program.py:57: undefined name 'application'
It seems likely that the undefined name on line 21 is the cause of the NameError you've encountered. NameError is how Python signals this sort of bug:
x = y
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'y' is not defined