Protostar - Net #2

About:

This code tests the ability to add up 4 unsigned 32-bit integers. Hint: Keep in mind that it wraps. (link)


Source Code:

Solution:

This ones a bit more complicated than net0 and net1, but overall very similar.

Your job is to read 4 32-bit little-endian integers, add them up, and send them back.

I wrote a quick python script that does it:

#!/usr/bin/env python
#

import socket
import struct

HOST = "127.0.0.1"
PORT = 2997

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect((HOST, PORT))

total = 0
for i in range(4):
    val = int(struct.unpack("I", s.recv(4))[0])
    total += val
    print val

total &= 0xffffffff

to_send = struct.pack("I", total) + "\n"
print to_send

s.sendall(to_send)
print "sending:", to_send

print "response:", s.recv(1024)


Running it gives the following output:

user@protostar:/opt/protostar/bin$ python /tmp/net2.py
1642506226
1314001069
1294629977
29888033
C+?

sending: C+?

response: you added them correctly