MRAB
3/16/2010 3:08:00 AM
Jordan Apgar wrote:
> Hi all,
>
> I'm trying to transfer a binary file over xmlrpclib. My test file is
> a .jpeg file. I can transfer all the data over but when I go to open
> the .jpeg I get "Error interpreting JPEG image file (Invalid JPEG file
> structure: SOS before SOF)"
>
> here's the code:
>
> ===========Various Shared Functions========
> #EncodeAES takes a Cipher c and encrypts a String s
> EncodeAES = lambda c, s: base64.b64encode(c.encrypt(pad(s)))
>
> #DecodeAES takes a Cipher C and decrypts the cyphertext e
> #then removes the padding from the decrypted string
> DecodeAES = lambda c, e:
> c.decrypt(base64.b64decode(e)).rstrip(PADDING)
>
>
> CIPHER = AES.new("KEY")
>
>
> # method to change strings back into tuples
> def stringToTuple(string):
> if string[0] + string[-1] == "()":
> items = string[1:-1]
> items = items.split(',')
> return items
> else:
> raise ValueError("Badly formatted string (missing brackets).")
>
> ======client=================
> def Download(self, FileName, Data_Size=1024):
> ErrorCount = 0
> Pkt_Num = -1
> OldPkt_Num = Pkt_Num
> localFile = open("files/"+FileName, "wb")
> print
> print "Requesting First Packet"
> packet = self.client.download(EncodeAES(CIPHER, str(Pkt_Num)))
> if packet[0] == "False":
> print packet[1]
> return False
> packet = stringToTuple(DecodeAES(CIPHER, packet))
> if int(packet[0]) == -3:
> print "Received Error Packet"
> else:
> print "Received Packet: ", int(packet[0])
>
> print "packet[1], ", packet[2:-1]
>
> Pkt_Num = int(packet[0])
>
> while Pkt_Num >= 0 and ErrorCount <= 10:
> if (OldPkt_Num +1) == Pkt_Num:
> OldPkt_Num = OldPkt_Num +1
> localFile.write(binascii.
> a2b_base64(packet[1][2:-1]))
> #<<<<!!!!!<<< writing to the file on the client
> ErrorCount == 0
> else:
> ErrorCount = ErrorCount +1
> Pkt_Num = OldPkt_Num
>
> print "Requesting Packet: ", Pkt_Num +1
> packet = self.client.download(EncodeAES(CIPHER,
> str(Pkt_Num)))
> packet = stringToTuple(DecodeAES(CIPHER, packet))
> Pkt_Num = int(packet[0])
> if int(packet[0]) == -3:
> print "Received Error Packet"
> elif int(packet[0]) == -2:
> print "Received EOF"
> else:
> print "Received Packet: ", int(packet[0])
>
> localFile.close()
>
> if Pkt_Num == -2:
> print packet[1][2:-1]
> return True
> elif Pkt_Num == -3:
> os.remove("files/"+FileName)
> print packet[1][2:-1]
> return False
> else:
> os.remove("files/"+FileName)
> print "Unexpected Packet: File Transfer Stopped"
> return False
>
>
> ==========Server Method=============
> def download(self, Pkt_Num):
>
> Old_Pkt_Num = self.PKT
> DataRate = self.DATA
> Pkt_Num = int(DecodeAES(CIPHER,Pkt_Num))
> if Pkt_Num == -1 and Old_Pkt_Num == -1:
> Pkt_Num = 0
> try:
> f = open("files/"+self.usr_dict[client][FILENAME],
> "rb")
> except IOError:
> return EncodeAES(CIPHER,
> str((-3, "File Could Not be
> opened")))
> data = binascii.b2a_base64(f.read((Pkt_Num+1 *
> DataRate))) #<<<<<<!!!!!!!<<<<<<<< reading from file
I don't understand what you're trying to do when you're reading from
the file. For a start:
Pkt_Num+1 * DataRate
is the same as:
Pkt_Num + (1 * DataRate)
or:
Pkt_Num + DataRate
and that's how many bytes you're reading.
> f.close()
> self.usr_dict[client][PKT] = Pkt_Num
> return EncodeAES(CIPHER,
> str((Pkt_Num, data)))
>
> elif Pkt_Num == Old_Pkt_Num:
> if Pkt_Num * DataRate >=
> os.path.getsize("files/"+self.usr_dict[client][FILENAME]):
> return EncodeAES(CIPHER,
> str((-2, "File Transfer Complete")))
> try:
> f = open("files/"+self.usr_dict[client][FILENAME],
> "rb")
> except IOError:
> return EncodeAES(CIPHER,
> str((-3, "File Could Not be opened")))
> data = f.read((Pkt_Num+1 * DataRate))
Here you're reading:
Pkt_Num + DataRate
bytes again,
> data = None
discarding what you've just read,
> data = binascii.b2a_base64(f.read(DataRate))
> #<<<<<<<<!!!!!!!<<<<<<< reading from file
and then reading:
DataRate
more bytes.
I think what you meant to do is .seek to the position in the file and
then read some bytes:
f.seek(Pkt_Num * DataRate)
data = f.read(DataRate)
ie, send the contents of the file in chunks which are DataRate bytes
long (the last chunk will be shorter if the file size isn't a multiple
of DataRate bytes).
> f.close()
> self.usr_dict[client][PKT] = Pkt_Num +1
>
> return EncodeAES(CIPHER,
> str((Pkt_Num+1, data)))
>
> else:
>
> return EncodeAES(CIPHER,
> str((-3, "Incorrect Packet Requested")))
>
>
>
> Thank you all for the help, I know there are better ways and transfer
> protocol modules to but I'd like to do this without them.
>
I'm not surprised that the transfer is failing! :-)