PyBitmessage/bitmessagemain.py

# Copyright (c) 2012 Jonathan Warren
# Copyright (c) 2012 The Bitmessage developers
# Distributed under the MIT/X11 software license. See the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.

#Right now, PyBitmessage only support connecting to stream 1. It doesn't yet contain logic to expand into further streams.

softwareVersion = '0.1.5'
verbose = 2
maximumAgeOfAnObjectThatIAmWillingToAccept = 216000 #Equals two days and 12 hours.
lengthOfTimeToLeaveObjectsInInventory = 237600 #Equals two days and 18 hours. This should be longer than maximumAgeOfAnObjectThatIAmWillingToAccept so that we don't process messages twice.
maximumAgeOfObjectsThatIAdvertiseToOthers = 216000 #Equals two days and 12 hours
maximumAgeOfNodesThatIAdvertiseToOthers = 10800 #Equals three hours


import sys
try:
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *
except Exception, err:
    print 'PyBitmessage requires PyQt. You can download it from http://www.riverbankcomputing.com/software/pyqt/download   or by searching Google for \'PyQt Download\' (without quotes).'
    print 'Error message:', err
    sys.exit()
import ConfigParser
from bitmessageui import *
from newaddressdialog import *
from newsubscriptiondialog import *
from settings import *
from about import *
from help import *
from iconglossary import *
from addresses import *
import Queue
from defaultKnownNodes import *
import time
import socket
import threading
import rsa
from rsa.bigfile import *
import hashlib
from struct import *
import pickle
import random
import sqlite3
import threading #used for the locks, not for the threads
import cStringIO
from time import strftime, localtime
import os
import string
import socks

#For each stream to which we connect, one outgoingSynSender thread will exist and will create 8 connections with peers.
class outgoingSynSender(QThread):
    def __init__(self, parent = None):
        QThread.__init__(self, parent)
        self.selfInitiatedConnectionList = [] #This is a list of current connections (the thread pointers at least)
        self.alreadyAttemptedConnectionsList = [] #This is a list of nodes to which we have already attempted a connection

    def setup(self,streamNumber):
        self.streamNumber = streamNumber


    def run(self):
        time.sleep(1)
        resetTime = int(time.time()) #used below to clear out the alreadyAttemptedConnectionsList periodically so that we will retry connecting to hosts to which we have already tried to connect.
        while True:
            #time.sleep(999999)#I'm using this to prevent connections for testing.
            if len(self.selfInitiatedConnectionList) < 8: #maximum number of outgoing connections = 8
                random.seed()
                HOST, = random.sample(knownNodes[self.streamNumber],  1)
                while HOST in self.alreadyAttemptedConnectionsList or HOST in connectedHostsList:
                    #print 'choosing new sample'
                    random.seed()
                    HOST, = random.sample(knownNodes[self.streamNumber],  1)
                    time.sleep(1)
                    #Clear out the alreadyAttemptedConnectionsList every half hour so that this program will again attempt a connection to any nodes, even ones it has already tried.
                    if (int(time.time()) - resetTime) > 1800:
                        self.alreadyAttemptedConnectionsList = []
                        resetTime = int(time.time())
                self.alreadyAttemptedConnectionsList.append(HOST)
                PORT, timeNodeLastSeen = knownNodes[self.streamNumber][HOST]
                sock = socks.socksocket(socket.AF_INET, socket.SOCK_STREAM)
                sock.settimeout(20)
                if config.get('bitmessagesettings', 'socksproxytype') == 'none':
                    printLock.acquire()
                    print 'Trying an outgoing connection to', HOST, ':', PORT
                    printLock.release()
                    #sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                elif config.get('bitmessagesettings', 'socksproxytype') == 'SOCKS4a':
                    printLock.acquire()
                    print '(Using SOCKS4a) Trying an outgoing connection to', HOST, ':', PORT
                    printLock.release()
                    proxytype = socks.PROXY_TYPE_SOCKS4
                    sockshostname = config.get('bitmessagesettings', 'sockshostname')
                    socksport = config.getint('bitmessagesettings', 'socksport')
                    rdns = True #Do domain name lookups through the proxy; though this setting doesn't really matter since we won't be doing any domain name lookups anyway.
                    if config.getboolean('bitmessagesettings', 'socksauthentication'):
                        socksusername = config.get('bitmessagesettings', 'socksusername')
                        sockspassword = config.get('bitmessagesettings', 'sockspassword')
                        sock.setproxy(proxytype, sockshostname, socksport, rdns, socksusername, sockspassword)
                    else:
                        sock.setproxy(proxytype, sockshostname, socksport, rdns)
                elif config.get('bitmessagesettings', 'socksproxytype') == 'SOCKS5':
                    printLock.acquire()
                    print '(Using SOCKS5) Trying an outgoing connection to', HOST, ':', PORT
                    printLock.release()
                    proxytype = socks.PROXY_TYPE_SOCKS5
                    sockshostname = config.get('bitmessagesettings', 'sockshostname')
                    socksport = config.getint('bitmessagesettings', 'socksport')
                    rdns = True #Do domain name lookups through the proxy; though this setting doesn't really matter since we won't be doing any domain name lookups anyway.
                    if config.getboolean('bitmessagesettings', 'socksauthentication'):
                        socksusername = config.get('bitmessagesettings', 'socksusername')
                        sockspassword = config.get('bitmessagesettings', 'sockspassword')
                        sock.setproxy(proxytype, sockshostname, socksport, rdns, socksusername, sockspassword)
                    else:
                        sock.setproxy(proxytype, sockshostname, socksport, rdns)

                try:
                    sock.connect((HOST, PORT))
                    rd = receiveDataThread()
                    self.emit(SIGNAL("passObjectThrough(PyQt_PyObject)"),rd)
                    rd.setup(sock,HOST,PORT,self.streamNumber,self.selfInitiatedConnectionList)
                    rd.start()
                    printLock.acquire()
                    print self, 'connected to', HOST, 'during outgoing attempt.'
                    printLock.release()
                    
                    sd = sendDataThread()
                    sd.setup(sock,HOST,PORT,self.streamNumber)
                    sd.start()
                    sd.sendVersionMessage()

                except socks.GeneralProxyError, err:
                    print 'Could NOT connect to', HOST, 'during outgoing attempt.', err
                    PORT, timeLastSeen = knownNodes[self.streamNumber][HOST]
                    if (int(time.time())-timeLastSeen) > 172800 and len(knownNodes[self.streamNumber]) > 1000: # for nodes older than 48 hours old if we have more than 1000 hosts in our list, delete from the knownNodes data-structure.
                        del knownNodes[self.streamNumber][HOST]
                        print 'deleting ', HOST, 'from knownNodes because it is more than 48 hours old and we could not connect to it.'
                except socks.Socks5AuthError, err:
                    self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),"SOCKS5 Authentication problem: "+str(err))
                except socks.Socks5Error, err:
                    pass
                    print 'SOCKS5 error. (It is possible that the server wants authentication).)' ,str(err)
                    #self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),"SOCKS5 error. Server might require authentication. "+str(err))
                except socks.Socks4Error, err:
                    print 'Socks4Error:', err
                    #self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),"SOCKS4 error: "+str(err))
                except socket.error, err:
                    if config.get('bitmessagesettings', 'socksproxytype')[0:5] == 'SOCKS':
                        print 'Bitmessage MIGHT be having trouble connecting to the SOCKS server. '+str(err)
                        #self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),"Problem: Bitmessage can not connect to the SOCKS server. "+str(err))
                    else:
                        print 'Could NOT connect to', HOST, 'during outgoing attempt.', err
                        PORT, timeLastSeen = knownNodes[self.streamNumber][HOST]
                        if (int(time.time())-timeLastSeen) > 172800 and len(knownNodes[self.streamNumber]) > 1000: # for nodes older than 48 hours old if we have more than 1000 hosts in our list, delete from the knownNodes data-structure.
                            del knownNodes[self.streamNumber][HOST]
                            print 'deleting ', HOST, 'from knownNodes because it is more than 48 hours old and we could not connect to it.'
                except Exception, err:
                    print 'An exception has occurred in the outgoingSynSender thread that was not caught by other exception types:', err
            time.sleep(1)

#Only one singleListener thread will ever exist. It creates the receiveDataThread and sendDataThread for each incoming connection. Note that it cannot set the stream number because it is not known yet- the other node will have to tell us its stream number in a version message. If we don't care about their stream, we will close the connection (within the recversion function of the recieveData thread)
class singleListener(QThread):
    def __init__(self, parent = None):
        QThread.__init__(self, parent)
        

    def run(self):
        #We don't want to accept incoming connections if the user is using a SOCKS proxy. If they eventually select proxy 'none' then this will start listening for connections.
        while config.get('bitmessagesettings', 'socksproxytype')[0:5] == 'SOCKS':
            time.sleep(300)

        print 'bitmessage listener running'
        HOST = '' # Symbolic name meaning all available interfaces
        PORT = config.getint('bitmessagesettings', 'port')
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        #This option apparently avoids the TIME_WAIT state so that we can rebind faster
        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        sock.bind((HOST, PORT))
        sock.listen(2)
        self.incomingConnectionList = [] #This list isn't used for anything. The reason it exists is because receiveData threads expect that a list be passed to them. They expect this because the outgoingSynSender thread DOES use a similar list to keep track of the number of outgoing connections it has created.


        while True:
            #We don't want to accept incoming connections if the user is using a SOCKS proxy. If they eventually select proxy 'none' then this will start listening for connections.
            while config.get('bitmessagesettings', 'socksproxytype')[0:5] == 'SOCKS':
                time.sleep(10)
            a,(HOST,PORT) = sock.accept()
            #Users are finding that if they run more than one node in the same network (thus with the same public IP), they can not connect with the second node. This is because this section of code won't accept the connection from the same IP. This problem will go away when the Bitmessage network grows behond being tiny but in the mean time, I'll comment out this code section.
            """while HOST in connectedHostsList:
                print 'incoming connection is from a host in connectedHostsList (we are already connected to it). Ignoring it.'
                a.close()
                a,(HOST,PORT) = sock.accept()"""
            rd = receiveDataThread()
            self.emit(SIGNAL("passObjectThrough(PyQt_PyObject)"),rd)
            rd.setup(a,HOST,PORT,-1,self.incomingConnectionList)
            printLock.acquire()
            print self, 'connected to', HOST,'during INCOMING request.'
            printLock.release()
            rd.start()

            sd = sendDataThread()
            sd.setup(a,HOST,PORT,-1)
            sd.start()


#This thread is created either by the synSenderThread(for outgoing connections) or the singleListenerThread(for incoming connectiosn).
class receiveDataThread(QThread):
    def __init__(self, parent = None):
        QThread.__init__(self, parent)
        self.data = ''
        self.verackSent = False
        self.verackReceived = False

    def setup(self,sock,HOST,port,streamNumber,selfInitiatedConnectionList):
        self.sock = sock
        self.HOST = HOST
        self.PORT = port
        self.sock.settimeout(600) #We'll send out a pong every 5 minutes to make sure the connection stays alive if there has been no other traffic to send lately.
        self.streamNumber = streamNumber
        self.selfInitiatedConnectionList = selfInitiatedConnectionList
        self.selfInitiatedConnectionList.append(self)
        self.payloadLength = 0
        self.receivedgetbiginv = False
        self.objectsThatWeHaveYetToGet = {}
        connectedHostsList[self.HOST] = 0
        self.connectionIsOrWasFullyEstablished = False #set to true after the remote node and I accept each other's version messages. This is needed to allow the user interface to accurately reflect the current number of connections.
        if self.streamNumber == -1: #This was an incoming connection. Send out a version message if we accept the other node's version message.
            self.initiatedConnection = False
        else:
            self.initiatedConnection = True
        self.ackDataThatWeHaveYetToSend = [] #When we receive a message bound for us, we store the acknowledgement that we need to send (the ackdata) here until we are done processing all other data received from this peer.


    def run(self):

        while True:
            try:
                self.data = self.data + self.sock.recv(65536)
            except socket.timeout:
                printLock.acquire()
                print 'Timeout occurred waiting for data. Closing thread.'
                printLock.release()
                break
            except Exception, err:
                printLock.acquire()
                print 'sock.recv error. Closing receiveData thread.', err
                printLock.release()
                break
            #print 'Received', repr(self.data)
            if self.data == "":
                printLock.acquire()
                print 'Connection closed.'
                printLock.release()
                break
            else:
                self.processData()
                
                

        try:
            self.sock.close()
        except Exception, err:
            print 'Within receiveDataThread run(), self.sock.close() failed.', err
        
        try:
            self.selfInitiatedConnectionList.remove(self)
            print 'removed self from ConnectionList'
        except:
            pass
        broadcastToSendDataQueues((self.streamNumber, 'shutdown', self.HOST))
        if self.connectionIsOrWasFullyEstablished: #We don't want to decrement the number of connections and show the result if we never incremented it in the first place (which we only do if the connection is fully established- meaning that both nodes accepted each other's version packets.)
            connectionsCountLock.acquire()
            connectionsCount[self.streamNumber] -= 1
            self.emit(SIGNAL("updateNetworkStatusTab(PyQt_PyObject,PyQt_PyObject)"),self.streamNumber,connectionsCount[self.streamNumber])
            connectionsCountLock.release()
        try:
            del connectedHostsList[self.HOST]
        except Exception, err:
            print 'Could not delete', self.HOST, 'from connectedHostsList.', err
       
    def processData(self):
        global verbose
        #if verbose >= 2:
            #printLock.acquire()
            #print 'self.data is currently ', repr(self.data)
            #printLock.release()
        if self.data == "":
            pass
        elif self.data[0:4] != '\xe9\xbe\xb4\xd9':
            self.data = ""
            if verbose >= 2:
                printLock.acquire()
                sys.stderr.write('The magic bytes were not correct.\n')
                printLock.release()
        elif len(self.data) < 20: #if so little of the data has arrived that we can't even unpack the payload length
            pass
        else:
            self.payloadLength, = unpack('>L',self.data[16:20])
            if len(self.data) >= self.payloadLength: #check if the whole message has arrived yet. If it has,...
                if self.data[20:24] == hashlib.sha512(self.data[24:self.payloadLength+24]).digest()[0:4]:#test the checksum in the message. If it is correct...
                    #print 'message checksum is correct'
                    #The time we've last seen this node is obviously right now since we just received valid data from it. So update the knownNodes list so that other peers can be made aware of its existance.
                    if self.initiatedConnection: #The remote port is only something we should share with others if it is the remote node's incoming port (rather than some random operating-system-assigned outgoing port).
                        knownNodes[self.streamNumber][self.HOST] = (self.PORT,int(time.time()))
                    remoteCommand = self.data[4:16]
                    if verbose >= 2:
                        printLock.acquire()
                        print 'remoteCommand ', remoteCommand, 'from', self.HOST
                        printLock.release()
                    if remoteCommand == 'version\x00\x00\x00\x00\x00':
                        self.recversion()
                    elif remoteCommand == 'verack\x00\x00\x00\x00\x00\x00':
                        self.recverack()
                    elif remoteCommand == 'addr\x00\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recaddr()
                    elif remoteCommand == 'getpubkey\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recgetpubkey()
                    elif remoteCommand == 'pubkey\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recpubkey()
                    elif remoteCommand == 'inv\x00\x00\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recinv()
                    elif remoteCommand == 'getdata\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recgetdata()
                    elif remoteCommand == 'getbiginv\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.sendBigInv()
                    elif remoteCommand == 'msg\x00\x00\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recmsg()
                    elif remoteCommand == 'broadcast\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.recbroadcast()
                    elif remoteCommand == 'getaddr\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.sendaddr()
                    elif remoteCommand == 'ping\x00\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        self.sendpong()
                    elif remoteCommand == 'pong\x00\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        pass
                    elif remoteCommand == 'alert\x00\x00\x00\x00\x00\x00\x00' and self.connectionIsOrWasFullyEstablished:
                        pass

                    self.data = self.data[self.payloadLength+24:]#take this message out and then process the next message
                    if self.data == '':
                        while len(self.objectsThatWeHaveYetToGet) > 0:
                            random.seed()
                            objectHash, = random.sample(self.objectsThatWeHaveYetToGet,  1)
                            if objectHash in inventory:
                                print 'Inventory (in memory) already has object listed in inv message.'
                                del self.objectsThatWeHaveYetToGet[objectHash]
                            elif isInSqlInventory(objectHash):
                                print 'Inventory (SQL on disk) already has object listed in inv message.'
                                del self.objectsThatWeHaveYetToGet[objectHash]
                            else:
                                print 'processData function making request for object:', repr(objectHash)
                                self.sendgetdata(objectHash)
                                del self.objectsThatWeHaveYetToGet[objectHash] #It is possible that the remote node doesn't respond with the object. In that case, we'll very likely get it from someone else anyway.
                                break
                        if len(self.objectsThatWeHaveYetToGet) > 0:
                            printLock.acquire()
                            print 'within processData, number of objectsThatWeHaveYetToGet is now', len(self.objectsThatWeHaveYetToGet)
                            printLock.release()
                        if len(self.ackDataThatWeHaveYetToSend) > 0:
                            self.data = self.ackDataThatWeHaveYetToSend.pop()
                    self.processData()
                else:
                    print 'Checksum incorrect. Clearing this message.'
                    self.data = self.data[self.payloadLength+24:]

    def isProofOfWorkSufficient(self):
        POW, = unpack('>Q',hashlib.sha512(hashlib.sha512(self.data[24:32]+ hashlib.sha512(self.data[32:24+self.payloadLength]).digest()).digest()).digest()[0:8])
        #print 'POW:', POW
        #Notice that I have divided the averageProofOfWorkNonceTrialsPerByte by two. This makes the POW requirement easier. This gives us wiggle-room: if we decide that we want to make the POW easier, the change won't obsolete old clients because they already expect a lower POW. If we decide that the current work done by clients feels approperate then we can remove this division by 2 and make the requirement match what is actually done by a sending node. If we want to raise the POW requirement then old nodes will HAVE to upgrade no matter what.
        return POW < 2**64 / ((self.payloadLength+payloadLengthExtraBytes) * (averageProofOfWorkNonceTrialsPerByte/2))

    def sendpong(self):
        print 'Sending pong'
        self.sock.sendall('\xE9\xBE\xB4\xD9\x70\x6F\x6E\x67\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xcf\x83\xe1\x35')

    def recverack(self):
        print 'verack received'
        self.verackReceived = True
        if self.verackSent == True:
            #We have thus both sent and received a verack.
            self.connectionFullyEstablished()

    def connectionFullyEstablished(self):
        self.connectionIsOrWasFullyEstablished = True
        if not self.initiatedConnection:
            self.emit(SIGNAL("setStatusIcon(PyQt_PyObject)"),'green')
        #Update the 'Network Status' tab
        connectionsCountLock.acquire()
        connectionsCount[self.streamNumber] += 1
        self.emit(SIGNAL("updateNetworkStatusTab(PyQt_PyObject,PyQt_PyObject)"),self.streamNumber,connectionsCount[self.streamNumber])
        connectionsCountLock.release()
        remoteNodeIncomingPort, remoteNodeSeenTime = knownNodes[self.streamNumber][self.HOST]
        printLock.acquire()
        print 'Connection fully established with', self.HOST, remoteNodeIncomingPort
        print 'broadcasting addr from within connectionFullyEstablished function.'
        printLock.release()
        self.broadcastaddr([(int(time.time()), self.streamNumber, 1, self.HOST, remoteNodeIncomingPort)]) #This lets all of our peers know about this new node.
        self.sendaddr() #This is one addr message to this one peer.
        if connectionsCount[self.streamNumber] > 150:
            print 'We are connected to too many people. Closing connection.'
            self.sock.close()
            return
        self.sendBigInv()

    def sendBigInv(self): #I used capitals in for this function name because there is no such Bitmessage command as 'biginv'.
        if self.receivedgetbiginv:
            print 'We have already sent a big inv message to this peer. Ignoring request.'
            return
        else:
            self.receivedgetbiginv = True
            sqlLock.acquire()
            #Select all hashes which are younger than two days old and in this stream.
            t = (int(time.time())-maximumAgeOfObjectsThatIAdvertiseToOthers,self.streamNumber)
            sqlSubmitQueue.put('''SELECT hash FROM inventory WHERE receivedtime>? and streamnumber=?''')
            sqlSubmitQueue.put(t)
            queryreturn = sqlReturnQueue.get()
            sqlLock.release()      
            print 'sendBigInv pulled', len(queryreturn), 'items from SQL inventory.'
            bigInvList = {}
            for row in queryreturn:
                hash, = row
                bigInvList[hash] = 0
            #print 'bigInvList:', bigInvList
            for hash, storedValue in inventory.items():
                objectType, streamNumber, payload, receivedTime = storedValue
                if streamNumber == self.streamNumber and receivedTime > int(time.time())-maximumAgeOfObjectsThatIAdvertiseToOthers:
                    bigInvList[hash] = 0
            numberOfObjectsInInvMessage = 0
            payload = ''
            for hash, storedValue in bigInvList.items():
                payload += hash
                numberOfObjectsInInvMessage += 1
                if numberOfObjectsInInvMessage >= 50000: #We can only send a max of 50000 items per inv message but we may have more objects to advertise. They must be split up into multiple inv messages.
                    sendinvMessageToJustThisOnePeer(numberOfObjectsInInvMessage,payload)
                    payload = ''
                    numberOfObjectsInInvMessage = 0
            if numberOfObjectsInInvMessage > 0:
                self.sendinvMessageToJustThisOnePeer(numberOfObjectsInInvMessage,payload)
                
    #Self explanatory. Notice that there is also a broadcastinv function for broadcasting invs to everyone in our stream.
    def sendinvMessageToJustThisOnePeer(self,numberOfObjects,payload):
        payload = encodeVarint(numberOfObjects) + payload
        headerData = '\xe9\xbe\xb4\xd9' #magic bits, slighly different from Bitcoin's magic bits.
        headerData = headerData + 'inv\x00\x00\x00\x00\x00\x00\x00\x00\x00'
        headerData = headerData + pack('>L',len(payload))
        headerData = headerData + hashlib.sha512(payload).digest()[:4]
        print 'Sending inv message to just this one peer'
        self.sock.send(headerData + payload)

    #We have received a broadcast message
    def recbroadcast(self):
        #First we must check to make sure the proof of work is sufficient.
        if not self.isProofOfWorkSufficient():
            print 'Proof of work in broadcast message insufficient.'
            return
        embeddedTime, = unpack('>I',self.data[32:36])
        if embeddedTime > (int(time.time())+10800): #prevent funny business
            print 'The embedded time in this broadcast message is more than three hours in the future. That doesn\'t make sense. Ignoring message.'
            return
        if embeddedTime < (int(time.time())-maximumAgeOfAnObjectThatIAmWillingToAccept):
            print 'The embedded time in this broadcast message is too old. Ignoring message.'
            return
        if self.payloadLength < 66:
            print 'The payload length of this broadcast packet is unreasonably low. Someone is probably trying funny business. Ignoring message.'
            return
        inventoryLock.acquire()
        inventoryHash = calculateInventoryHash(self.data[24:self.payloadLength+24])
        if inventoryHash in inventory:
            print 'We have already received this broadcast object. Ignoring.'
            inventoryLock.release()
            return
        elif isInSqlInventory(inventoryHash):
            print 'We have already received this broadcast object (it is stored on disk in the SQL inventory). Ignoring it.'
            inventoryLock.release()
            return
        #It is valid so far. Let's let our peers know about it.
        objectType = 'broadcast'
        inventory[inventoryHash] = (objectType, self.streamNumber, self.data[24:self.payloadLength+24], embeddedTime)
        inventoryLock.release()
        self.broadcastinv(inventoryHash)
        self.emit(SIGNAL("incrementNumberOfBroadcastsProcessed()"))
        
        readPosition = 36
        broadcastVersion, broadcastVersionLength = decodeVarint(self.data[readPosition:readPosition+9])
        if broadcastVersion <> 1:
            #Cannot decode incoming broadcast versions higher than 1. Assuming the sender isn\' being silly, you should upgrade Bitmessage because this message shall be ignored.
            return
        readPosition += broadcastVersionLength
        sendersAddressVersion, sendersAddressVersionLength = decodeVarint(self.data[readPosition:readPosition+9])
        if sendersAddressVersion <> 1:
            #Cannot decode senderAddressVersion higher than 1. Assuming the sender isn\' being silly, you should upgrade Bitmessage because this message shall be ignored.
            return
        readPosition += sendersAddressVersionLength
        sendersStream, sendersStreamLength = decodeVarint(self.data[readPosition:readPosition+9])
        if sendersStream <= 0:
            return
        readPosition += sendersStreamLength
        sendersHash = self.data[readPosition:readPosition+20]
        if sendersHash not in broadcastSendersForWhichImWatching:
            return
        #At this point, this message claims to be from sendersHash and we are interested in it. We still have to hash the public key to make sure it is truly the key that matches the hash, and also check the signiture.
        readPosition += 20
        nLength, nLengthLength = decodeVarint(self.data[readPosition:readPosition+9])
        if nLength < 1:
            return
        readPosition += nLengthLength
        nString = self.data[readPosition:readPosition+nLength]
        readPosition += nLength
        eLength, eLengthLength = decodeVarint(self.data[readPosition:readPosition+9])
        if eLength < 1:
            return
        readPosition += eLengthLength
        eString = self.data[readPosition:readPosition+eLength]
        #We are now ready to hash the public key and verify that its hash matches the hash claimed in the message
        readPosition += eLength
        sha = hashlib.new('sha512')
        sha.update(nString+eString)
        ripe = hashlib.new('ripemd160')
        ripe.update(sha.digest())
        if ripe.digest() != sendersHash:
            #The sender of this message lied.
            return

        readPositionAtBeginningOfMessageEncodingType = readPosition
        messageEncodingType, messageEncodingTypeLength = decodeVarint(self.data[readPosition:readPosition+9])
        if messageEncodingType == 0:
            return
        readPosition += messageEncodingTypeLength
        messageLength, messageLengthLength = decodeVarint(self.data[readPosition:readPosition+9])
        readPosition += messageLengthLength
        message = self.data[readPosition:readPosition+messageLength]
        readPosition += messageLength
        signature = self.data[readPosition:readPosition+nLength]
        print 'signature', repr(signature)
        sendersPubkey = rsa.PublicKey(convertStringToInt(nString),convertStringToInt(eString))
        #print 'senders Pubkey', sendersPubkey
        try:
            #You may notice that this signature doesn't cover any information that identifies the RECEIVER of the message. This makes it vulnerable to a malicious receiver Bob forwarding the message from Alice to Charlie, making it look like Alice sent the message to Charlie. This will be fixed in the next version.
                #See http://world.std.com/~dtd/sign_encrypt/sign_encrypt7.html
            rsa.verify(self.data[readPositionAtBeginningOfMessageEncodingType:readPositionAtBeginningOfMessageEncodingType+messageEncodingTypeLength+messageLengthLength+messageLength],signature,sendersPubkey)
            print 'verify passed'
        except Exception, err:
            print 'verify failed', err
            return
        #verify passed
        fromAddress = encodeAddress(sendersAddressVersion,sendersStream,ripe.digest())
        print 'fromAddress:', fromAddress

        if messageEncodingType == 2:
            bodyPositionIndex = string.find(message,'\nBody:')
            if bodyPositionIndex > 1:
                subject = message[8:bodyPositionIndex]
                body = message[bodyPositionIndex+6:]
            else:
                subject = ''
                body = message
        elif messageEncodingType == 1:
            body = message
            subject = ''
        elif messageEncodingType == 0:
            print 'messageEncodingType == 0. Doing nothing with the message.'
        else:
            body = 'Unknown encoding type.\n\n' + repr(message)
            subject = ''

        toAddress = '[Broadcast subscribers]'
        if messageEncodingType <> 0:
            sqlLock.acquire()
            t = (inventoryHash,toAddress,fromAddress,subject,int(time.time()),body,'inbox')
            sqlSubmitQueue.put('''INSERT INTO inbox VALUES (?,?,?,?,?,?,?)''')
            sqlSubmitQueue.put(t)
            sqlReturnQueue.get()
            sqlLock.release()
            self.emit(SIGNAL("displayNewMessage(PyQt_PyObject,PyQt_PyObject,PyQt_PyObject,PyQt_PyObject,PyQt_PyObject)"),inventoryHash,toAddress,fromAddress,subject,body)

    #We have received a msg message.
    def recmsg(self):
        #First we must check to make sure the proof of work is sufficient.
        if not self.isProofOfWorkSufficient():
            print 'Proof of work in msg message insufficient.'
            return
        initialDecryptionSuccessful = False
        readPosition = 32
        embeddedTime, = unpack('>I',self.data[readPosition:readPosition+4])
        if embeddedTime > int(time.time())+10800:
            print 'The time in the msg message is too new. Ignoring it. Time:', embeddedTime
            return
        if embeddedTime < int(time.time())-maximumAgeOfAnObjectThatIAmWillingToAccept:
            print 'The time in the msg message is too old. Ignoring it. Time:', embeddedTime
            return
        readPosition += 4
        inventoryHash = calculateInventoryHash(self.data[24:self.payloadLength+24])

        streamNumberAsClaimedByMsg, streamNumberAsClaimedByMsgLength = decodeVarint(self.data[readPosition:readPosition+9])
        if streamNumberAsClaimedByMsg != self.streamNumber:
            print 'The stream number encoded in this msg (' + streamNumberAsClaimedByMsg + ') message does not match the stream number on which it was received. Ignoring it.'
            return
        readPosition += streamNumberAsClaimedByMsgLength
        inventoryLock.acquire()
        if inventoryHash in inventory:
            print 'We have already received this msg message. Ignoring.'
            inventoryLock.release()
            return
        elif isInSqlInventory(inventoryHash):
            print 'We have already received this msg message (it is stored on disk in the SQL inventory). Ignoring it.'
            inventoryLock.release()
            return
        #This msg message is valid. Let's let our peers know about it.
        objectType = 'msg'
        inventory[inventoryHash] = (objectType, self.streamNumber, self.data[24:self.payloadLength+24], embeddedTime)
        inventoryLock.release()
        self.broadcastinv(inventoryHash)
        self.emit(SIGNAL("incrementNumberOfMessagesProcessed()"))

        #Let's check whether this is a message acknowledgement bound for us.
        if self.data[readPosition:24+self.payloadLength] in ackdataForWhichImWatching:
            printLock.acquire()
            print 'This msg IS an acknowledgement bound for me.'
            printLock.release()
            del ackdataForWhichImWatching[self.data[readPosition:24+self.payloadLength]]
            t = ('ackreceived',self.data[readPosition:24+self.payloadLength])
            sqlLock.acquire()
            sqlSubmitQueue.put('UPDATE sent SET status=? WHERE ackdata=?')
            sqlSubmitQueue.put(t)
            sqlReturnQueue.get()
            sqlLock.release()
            self.emit(SIGNAL("updateSentItemStatusByAckdata(PyQt_PyObject,PyQt_PyObject)"),self.data[readPosition:24+self.payloadLength],'Acknowledgement of the message received just now.')
            flushInventory() #so that we won't accidentially receive this message twice if the user restarts Bitmessage soon.
            return
        else:
            printLock.acquire()
            print 'This was NOT an acknowledgement bound for me.' #Msg potential ack data:', repr(self.data[readPosition:24+self.payloadLength])
            #print 'ackdataForWhichImWatching', ackdataForWhichImWatching
            printLock.release()

        #This is not an acknowledgement bound for me. See if it is a message bound for me by trying to decrypt it with my private keys.
        infile = cStringIO.StringIO(self.data[readPosition:self.payloadLength+24])
        outfile = cStringIO.StringIO()
        #print 'len(myAddressHashes.items()):', len(myAddressHashes.items())
        for key, value in myAddressHashes.items():
            try:
                decrypt_bigfile(infile, outfile, value)
                #The initial decryption passed though there is a small chance that the message isn't actually for me. We'll need to check that the 20 zeros are present.
                #print 'initial decryption successful using key', repr(key)
                initialDecryptionSuccessful = True
                printLock.acquire()
                print 'Initial decryption passed'
                printLock.release()
                break
            except Exception, err:
                infile.seek(0)
                #print 'Exception:', err
                #print 'outfile len is:', len(outfile.getvalue()),'data is:', repr(outfile.getvalue())
                #print 'Initial decryption failed using key', value
                #decryption failed for this key. The message is for someone else (or for a different key of mine).
        if initialDecryptionSuccessful and outfile.getvalue()[:20] == '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00': #this run of 0s allows the true message receiver to identify his message
            #This is clearly a message bound for me.
            flushInventory() #so that we won't accidentially receive this message twice if the user restarts Bitmessage soon.
            outfile.seek(0)
            data = outfile.getvalue()
            readPosition = 20 #To start reading past the 20 zero bytes
            messageVersion, messageVersionLength = decodeVarint(data[readPosition:readPosition+10])
            readPosition += messageVersionLength
            if messageVersion == 1:
                bitfieldBehavior = data[readPosition:readPosition+4]
                readPosition += 4
                sendersAddressVersionNumber, sendersAddressVersionNumberLength = decodeVarint(data[readPosition:readPosition+10])
                if sendersAddressVersionNumber == 1:
                    readPosition += sendersAddressVersionNumberLength
                    sendersStreamNumber, sendersStreamNumberLength = decodeVarint(data[readPosition:readPosition+10])
                    readPosition += sendersStreamNumberLength

                    sendersNLength, sendersNLengthLength = decodeVarint(data[readPosition:readPosition+10])
                    readPosition += sendersNLengthLength
                    sendersN = data[readPosition:readPosition+sendersNLength]
                    readPosition += sendersNLength
                    sendersELength, sendersELengthLength = decodeVarint(data[readPosition:readPosition+10])
                    readPosition += sendersELengthLength
                    sendersE = data[readPosition:readPosition+sendersELength]
                    readPosition += sendersELength
                    endOfThePublicKeyPosition = readPosition


                    messageEncodingType, messageEncodingTypeLength = decodeVarint(data[readPosition:readPosition+10])
                    readPosition += messageEncodingTypeLength
                    print 'Message Encoding Type:', messageEncodingType
                    messageLength, messageLengthLength = decodeVarint(data[readPosition:readPosition+10])
                    print 'message length:', messageLength
                    readPosition += messageLengthLength
                    message = data[readPosition:readPosition+messageLength]
                    #print 'First 150 characters of message:', repr(message[:150])
                    readPosition += messageLength
                    ackLength, ackLengthLength = decodeVarint(data[readPosition:readPosition+10])
                    #print 'ackLength:', ackLength
                    readPosition += ackLengthLength
                    ackData = data[readPosition:readPosition+ackLength]
                    readPosition += ackLength
                    payloadSigniture = data[readPosition:readPosition+sendersNLength] #We're using the length of the sender's n because it should match the signiture size.
                    sendersPubkey = rsa.PublicKey(convertStringToInt(sendersN),convertStringToInt(sendersE))
                    print 'sender\'s Pubkey', sendersPubkey
                    
                    #Check the cryptographic signiture
                    verifyPassed = False
                    try:
                        rsa.verify(data[:-len(payloadSigniture)],payloadSigniture, sendersPubkey)
                        print 'verify passed'
                        verifyPassed = True
                    except Exception, err:
                        print 'verify failed', err
                    if verifyPassed:
                        #Let's calculate the fromAddress.
                        sha = hashlib.new('sha512')
                        sha.update(sendersN+sendersE)
                        ripe = hashlib.new('ripemd160')
                        ripe.update(sha.digest())

                        #Let's store the public key in case we want to reply to this person.
                        #We don't have the correct nonce in order to send out a pubkey message so we'll just fill it with 1's. We won't be able to send this pubkey to others (without doing the proof of work ourselves, which this program is programmed to not do.)
                        t = (ripe.digest(),False,'\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF'+data[20+messageVersionLength:endOfThePublicKeyPosition],int(time.time())+2419200) #after one month we may remove this pub key from our database. (2419200 = a month)
                        sqlLock.acquire()
                        sqlSubmitQueue.put('''INSERT INTO pubkeys VALUES (?,?,?,?)''')
                        sqlSubmitQueue.put(t)
                        sqlReturnQueue.get()
                        sqlLock.release()

                        blockMessage = False #Gets set to True if the user shouldn't see the message according to black or white lists.
                        fromAddress = encodeAddress(sendersAddressVersionNumber,sendersStreamNumber,ripe.digest())
                        if config.get('bitmessagesettings', 'blackwhitelist') == 'black': #If we are using a blacklist
                            t = (fromAddress,) 
                            sqlLock.acquire()
                            sqlSubmitQueue.put('''SELECT label, enabled FROM blacklist where address=?''')
                            sqlSubmitQueue.put(t)
                            queryreturn = sqlReturnQueue.get()
                            sqlLock.release()           
                            for row in queryreturn:
                                label, enabled = row
                                if enabled:
                                    print 'Message ignored because address is in blacklist.'
                                    blockMessage = True
                        else: #We're using a whitelist
                            t = (fromAddress,) 
                            sqlLock.acquire()
                            sqlSubmitQueue.put('''SELECT label, enabled FROM whitelist where address=?''')
                            sqlSubmitQueue.put(t)
                            queryreturn = sqlReturnQueue.get()
                            sqlLock.release()           
                            if queryreturn == []:
                                print 'Message ignored because address not in whitelist.'
                                blockMessage = True
                            for row in queryreturn: #It could be in the whitelist but disabled. Let's check.
                                label, enabled = row
                                if not enabled:
                                    print 'Message ignored because address in whitelist but not enabled.'
                                    blockMessage = True

                        if not blockMessage:
                            print 'fromAddress:', fromAddress
                            print 'First 150 characters of message:', repr(message[:150])

                            #Look up the destination address (my address) based on the destination ripe hash.
                            #I realize that I could have a data structure devoted to this task, or maintain an indexed table
                            #in the sql database, but I would prefer to minimize the number of data structures this program
                            #uses. Searching linearly through the user's short list of addresses doesn't take very long anyway.
                            configSections = config.sections()
                            for addressInKeysFile in configSections:
                                if addressInKeysFile <> 'bitmessagesettings':
                                    status,addressVersionNumber,streamNumber,hash = decodeAddress(addressInKeysFile)
                                    if hash == key:
                                        toAddress = addressInKeysFile
                                        toLabel = config.get(addressInKeysFile, 'label')
                                        if toLabel == '':
                                            toLabel = addressInKeysFile

                            if messageEncodingType == 2:
                                bodyPositionIndex = string.find(message,'\nBody:')
                                if bodyPositionIndex > 1:
                                    subject = message[8:bodyPositionIndex]
                                    body = message[bodyPositionIndex+6:]
                                else:
                                    subject = ''
                                    body = message
                            elif messageEncodingType == 1:
                                body = message
                                subject = ''
                            elif messageEncodingType == 0:
                                print 'messageEncodingType == 0. Doing nothing with the message. They probably just sent it so that we would store their public key or send their ack data for them.'
                            else:
                                body = 'Unknown encoding type.\n\n' + repr(message)
                                subject = ''
                            print 'within recmsg, inventoryHash is', repr(inventoryHash)
                            if messageEncodingType <> 0:
                                sqlLock.acquire()
                                t = (inventoryHash,toAddress,fromAddress,subject,int(time.time()),body,'inbox')
                                sqlSubmitQueue.put('''INSERT INTO inbox VALUES (?,?,?,?,?,?,?)''')
                                sqlSubmitQueue.put(t)
                                sqlReturnQueue.get()
                                sqlLock.release()
                                self.emit(SIGNAL("displayNewMessage(PyQt_PyObject,PyQt_PyObject,PyQt_PyObject,PyQt_PyObject,PyQt_PyObject)"),inventoryHash,toAddress,fromAddress,subject,body)
                        #Now let's send the acknowledgement
                        #POW, = unpack('>Q',hashlib.sha512(hashlib.sha512(ackData[24:]).digest()).digest()[4:12])
                        #if POW <= 2**64 / ((len(ackData[24:])+payloadLengthExtraBytes) * averageProofOfWorkNonceTrialsPerByte):
                            #print 'The POW is strong enough that this ackdataPayload will be accepted by the Bitmessage network.'
                            #Currently PyBitmessage only supports sending a message with the acknowledgement in the form of a msg message. But future versions, and other clients, could send any object and this software will relay them. This can be used to relay identifying information, like your public key, through another Bitmessage host in case you believe that your Internet connection is being individually watched. You may pick a random address, hope its owner is online, and send a message with encoding type 0 so that they ignore the message but send your acknowledgement data over the network. If you send and receive many messages, it would also be clever to take someone else's acknowledgement data and use it for your own. Assuming that your message is delivered successfully, both will be acknowledged simultaneously (though if it is not delivered successfully, you will be in a pickle.)
                            #print 'self.data before:', repr(self.data)
                        #We'll need to make sure that our client will properly process the ackData; if the packet is malformed, we could clear out self.data and an attacker could use that behavior to determine that we were capable of decoding this message.
                        ackDataValidThusFar = True
                        if len(ackData) < 24:
                            print 'The length of ackData is unreasonably short. Not sending ackData.'
                            ackDataValidThusFar = False
                        if ackData[0:4] != '\xe9\xbe\xb4\xd9':
                            print 'Ackdata magic bytes were wrong. Not sending ackData.'
                            ackDataValidThusFar = False
                        if ackDataValidThusFar:
                            ackDataPayloadLength, = unpack('>L',ackData[16:20])
                            if len(ackData)-24 != ackDataPayloadLength:
                                print 'ackData payload length doesn\'t match the payload length specified in the header. Not sending ackdata.'
                                ackDataValidThusFar = False
                        if ackDataValidThusFar:
                            print 'ackData is valid. Will process it.'
                            #self.data = self.data[:self.payloadLength+24] + ackData + self.data[self.payloadLength+24:]
                            self.ackDataThatWeHaveYetToSend.append(ackData) #When we have processed all data, the processData function will pop the ackData out and process it as if it is a message received from our peer.
                            #print 'self.data after:', repr(self.data)
                        '''if ackData[4:16] == 'msg\x00\x00\x00\x00\x00\x00\x00\x00\x00':
                            inventoryHash = calculateInventoryHash(ackData[24:])
                            #objectType = 'msg'
                            #inventory[inventoryHash] = (objectType, self.streamNumber, ackData[24:], embeddedTime) #We should probably be storing the embeddedTime of the ackData, not the embeddedTime of the original incoming msg message, but this is probably close enough.
                            #print 'sending the inv for the msg which is actually an acknowledgement (within sendmsg function)'
                            #self.broadcastinv(inventoryHash)
                            self.data[:payloadLength+24] + ackData + self.data[payloadLength+24:]
                        elif ackData[4:16] == 'getpubkey\x00\x00\x00':
                            #objectType = 'getpubkey'
                            #inventory[inventoryHash] = (objectType, self.streamNumber, ackData[24:], embeddedTime) #We should probably be storing the embeddedTime of the ackData, not the embeddedTime of the original incoming msg message, but this is probably close enough.
                            #print 'sending the inv for the getpubkey which is actually an acknowledgement (within sendmsg function)'
                            self.data[:payloadLength+24] + ackData + self.data[payloadLength+24:]
                        elif ackData[4:16] == 'pubkey\x00\x00\x00\x00\x00\x00':
                            #objectType = 'pubkey'
                            #inventory[inventoryHash] = (objectType, self.streamNumber, ackData[24:], embeddedTime) #We should probably be storing the embeddedTime of the ackData, not the embeddedTime of the original incoming msg message, but this is probably close enough.
                            #print 'sending the inv for a pubkey which is actually an acknowledgement (within sendmsg function)'
                            self.data[:payloadLength+24] + ackData + self.data[payloadLength+24:]
                        elif ackData[4:16] == 'broadcast\x00\x00\x00':
                            #objectType = 'broadcast'
                            #inventory[inventoryHash] = (objectType, self.streamNumber, ackData[24:], embeddedTime) #We should probably be storing the embeddedTime of the ackData, not the embeddedTime of the original incoming msg message, but this is probably close enough.
                            #print 'sending the inv for a broadcast which is actually an acknowledgement (within sendmsg function)'
                            self.data[:payloadLength+24] + ackData + self.data[payloadLength+24:]'''
                        #else:
                            #print 'ACK POW not strong enough to be accepted by the Bitmessage network.'

                else:
                    print 'This program cannot decode messages from addresses with versions higher than 1. Ignoring.'
                    statusbar = 'This program cannot decode messages from addresses with versions higher than 1. Ignoring it.'
                    self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),statusbar)
            else:
                print 'Error: Cannot decode incoming msg versions higher than 1. Assuming the sender isn\' being silly, you should upgrade Bitmessage because this message shall be ignored.'
                statusbar = 'Error: Cannot decode incoming msg versions higher than 1. Assuming the sender isn\' being silly, you should upgrade Bitmessage because this message shall be ignored.'
                self.emit(SIGNAL("updateStatusBar(PyQt_PyObject)"),statusbar)
        else:
            printLock.acquire()
            print 'Decryption unsuccessful.'
            printLock.release()
        infile.close()
        outfile.close()

    #We have received a pubkey
    def recpubkey(self):
        #We must check to make sure the proof of work is sufficient.
        if not self.isProofOfWorkSufficient():
            print 'Proof of work in pubkey message insufficient.'
            return

        inventoryHash = calculateInventoryHash(self.data[24:self.payloadLength+24])
        inventoryLock.acquire()
        if inventoryHash in inventory:
            print 'We have already received this pubkey. Ignoring it.'
            inventoryLock.release()
            return
        elif isInSqlInventory(inventoryHash):
            print 'We have already received this pubkey (it is stored on disk in the SQL inventory). Ignoring it.'
            inventoryLock.release()
            return

        objectType = 'pubkey'
        inventory[inventoryHash] = (objectType, self.streamNumber, self.data[24:self.payloadLength+24], int(time.time()))
        inventoryLock.release()
        self.broadcastinv(inventoryHash)
        self.emit(SIGNAL("incrementNumberOfPubkeysProcessed()"))

        readPosition = 24 #for the message header