CODEWITHSUNDEEP
pythonpython-3.xformatudp
user1977050
user1977050

Reputation: 526

python integer format conversion

I need an application that will do the following:

  1. read UDP message, get data from it - the data is textual, comma separated.
  2. build a new message based on this values
  3. send a new UDP message to other destination.

For the first and the last I'm fine. for the second I have a challenge: Lets say that the data I've received is Year = 2020. The message on the Wireshark (step 3), I shall see it as 2 bytes valued 07 e4

How can I do it? I've tried couple of ways, none of them provided me with the desired format.

Sample of the code:

data1 = '\xab\xcd\xef\xgh'
...
data, addr = sock.recvfrom (200)
elements = data.decode().split(",")
Date=elements[15].split("/")
Year = int(Date(2))
year = <do something with Year to convert to right format>
newMsg = data1 + year
...
newSock.sendto(newMsg.encode('charmap'), (IP, int(port)))

Python version 3.5

Upvotes: 0

Views: 104

Answers (1)

Sam Mason
Sam Mason

Reputation: 16214

there seem to be a couple of issues here. first, if your data1 is really supposed to be raw bytes then you're better off declaring it as such by prefixing it with a b, something like:

data1 = b'\xab\xcd\xef\xff'

if it comes from somewhere else, then encode it to bytes appropriately.

for answering your main question, the struct module has useful tools for encoding numbers as bytes in the way you want. ctypes can also be useful, but struct tends to be easier to use for these sorts of things:

data, addr = sock.recvfrom (200)
elements = data.decode().split(",")
date = elements[15].split("/")
year = int(date(2))
newMsg = data1 + struct.pack('!h', year)

and then you can send it with:

newSock.sendto(newMsg, (IP, int(port)))

Upvotes: 1

Related Questions