Understanding and creating a protocol for Python

Question

I have documentation on how to use a TCP/IP binary stream API. The attached images show the protocol. I have a working example of this in C#. I want to do this using python instead, as I don't know c# or windows.

I am assuming I would use python sockets, then I have to send the API messages, with payloads looking at this docs.

Could you point me in the right direction to get this going with python?

How would I set it to know this is the authentication message, 0x21 and compress the data etc?

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
s.sendall(u"{'username':'username', 'password':'password'}".encode('utf8'))

Not sure what is stopping you? You know Python, you know how to implement TCP communication in Python? You have the Protocol docs ... — Fildor
– Fildor, Commented Feb 10, 2017 at 8:58
I don't know it that well, I'm unsure how you set encoding, compression etc. Im used to http posts — Harry
– Harry, Commented Feb 10, 2017 at 9:00
About these two your Docu sais: "Note that the server will use the same as was used to send the client auth message" ( not an exact citation ). So I'd start without compression and whatever suits you best (JSON/BSON). If that works, move on. oh and it also sais "UTF-8" :) — Fildor
– Fildor, Commented Feb 10, 2017 at 9:25
Your header has to be setup from bytes according to the docs: 1 byte version, 4 bytes sequence ( big-endian ) ... maybe this will help: stackoverflow.com/a/18311133/982149 — Fildor
– Fildor, Commented Feb 10, 2017 at 10:44

ralf htp · Accepted Answer · 2017-02-10 09:45:01Z

in OSI model you are above layer 4 (transport, TCP/IP,...) on at least layer 5 (session). there are some examples of implementations of session layer protocols like http, ftp,... i.e. in http://github.com/python-git/python/blob/master/Lib/ftplib.py or http://github.com/python-git/python/blob/master/Lib/httplib.py

as your protocol includes headers maybe http is the better example

to use the TCP/IP API in http protocol see http://www.stackoverflow.com/questions/8315209/sending-http-headers-with-python

import socket

sock = socket.socket()
sock.bind(('', 8080))
sock.listen(5)
client, adress = sock.accept()

print "Incoming:", adress
print client.recv(1024)
print

client.send('HTTP/1.0 200 OK\r\n')
client.send("Content-Type: text/html\r\n\r\n")
client.send('<html><body><h1>Hello World</body></html>')
client.close()

print "Answering ..."
print "Finished."

sock.close()

as far as i can see you skipped the headers (version, sequence, type, encoding, ...) in your code completely you have to add them whenever you send a frame

so try

self.socket.send(...headers...)
self.socket.send(u"{'username':'username', 'password':'password'}".encode('utf8')) // has to be send as JSON ???

see also http://www.stackoverflow.com/questions/22083359/send-tetx-http-over-python-socket

ftp example (no headers...)

    # Internal: send one line to the server, appending CRLF
    def putline(self, line):
    line = line + CRLF
    if self.debugging > 1: print '*put*', self.sanitize(line)
    self.sock.sendall(line)

also see scapy

Tural Muzaffarli · Accepted Answer · 2017-02-10 09:15:55Z

0

I try to use tcp protocol once. You can send authorization values(username ,password ) in all requests.And other data with it exp({'username':'username', 'password':'password','data':'value'}).With this there is no any current standart for data. Many of tcp clients send that data like this #A#:username;password;#D:value\n (A -authorization ,D -data), example

answered Feb 10, 2017 at 9:15

Tural Muzaffarli

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