|
|
Project 1 2017 - report WiFi statistics
|
This project will assess your understanding of
introductory C99 programming language features,
including its control-structures,
simple data-structures,
and its standard library support for handling strings and text files.
The project can be successfully completed using the information presented
in CITS2002's lectures, laboratories, and workshops,
to the end of week-6.
|
Nearly all devices that connect to the Internet use networking hardware
that conforms to
IEEE-802 standards,
commonly termed the Ethernet standards.
It is common for desktop and laptop computers to have two Ethernet interfaces,
one wired (the IEEE-802.3 standard) and
one wireless (the IEEE-802.11 standard),
while mobile devices and smartphones will typically
have a single wireless Ethernet interface
and a Bluetooth interface (the IEEE-802.15.1 standard).
To simplify communication between devices,
each Ethernet interface has a unique networking address,
termed its Media Access Control (MAC) address.
Each MAC address is 6-bytes long but,
to make them easier for humans to read and compare,
they're usually written as a sequence of hexadecimal characters separated
by colons or hyphens,
as in the example 74:e2:f5:20:f9:8b.
When written this way, MAC addresses are case-insensitive -
that is to say that 74-E2-F5-20-F9-8B is the same address.
When devices communicate using WiFi (the IEEE-802.11 standard)
they break their communication into many small packets of data.
Each packet contains MAC addresses to identify
the device which transmitted the packet (the transmitter's address), and
the device for which the packet is intended (the receiver's address).
The special MAC address,
ff:ff:ff:ff:ff:ff,
is termed the broadcast MAC address,
and is used when all devices within range should receive the packet.
Each 6-byte MAC address comprises two 3-byte parts.
The first 3-bytes are termed the Organizationally Unique Identifier (OUI),
and they identify the vendor of the Ethernet interface.
From the address 74:e2:f5:20:f9:8b,
the 74:e2:f5 indicates that the interface was made by Apple
(see www.macvendorlookup.com).
The goal of this project
is to write a C99 program,
named wifistats,
that reports the number of bytes either transmitted or received
by devices using WiFi.
The program may be requested to generate reports sorted by
either the device MACs or by the vendors' names,
from the largest transmitter (most bytes transmitted) to the smallest.
Program requirements
- Your program's single C99 source file must be named wifistats.c
- Your program will be invoked in one of two ways:
-
prompt> ./wifistats what packets
where what is either the single character 't' or 'r' to request
statistics about WiFi transmitters, or receivers, respectively.
For example,
if the program is invoked as
./wifistats t packets
then the program should produce statistics about the data transmissions
of each transmitting device present in the packets file.
packets is the name of a text-file providing
information about each WiFi packet, one packet per line.
Here is a
sample-packet file.
Each line consists of 4 fields, providing
the time that each packet was captured (in seconds and microseconds),
the transmitter's and receiver's MAC addresses,
and the length (in bytes) of the packet.
Each of the fields will be separated by a single TAB ('\t') character.
If we ran:
prompt> ./wifistats t sample-packets
this would be the required output.
If we ran:
prompt> ./wifistats r sample-packets
this would be the required output.
-
prompt> ./wifistats what packets OUIfile
where OUIfile is the name of a text-file providing
the OUIs and names of Ethernet hardware vendors.
If an OUIfile is provided,
the program should report its statistics not on individual
device MAC addresses
but on the vendor that produced each device.
Here are two sample OUIfiles:
sample-OUIfile-small (40 entries) and
sample-OUIfile-large (23,000 entries).
The 2 fields will be separated by a single TAB ('\t') character,
and the vendors' names may contain spaces.
For example, if we ran:
prompt> ./wifistats t sample-packets sample-OUIfile-small
this would be the required output.
If we ran:
prompt> ./wifistats r sample-packets sample-OUIfile-small
this would be the required output.
- You may assume that all input data is in the correct format.
If your program encounters a broadcast MAC address,
your program should ignore that input line.
If your program encounters an OUI not found in a provided OUI file,
it should use/report the vendor's name as UNKNOWN-VENDOR.
- Your program must support these limits
(you may assume that the input data never exceeds these limits):
- maximum number of distinct MAC addresses - 500.
- maximum number of distinct OUIs - 25000.
- maximum length of any vendor name - 90 characters.
- Your program must invoke the standard utility program
/usr/bin/sort
to sort the final results.
Your program must
use the system-calls fork() and execv()
(and possibly others) to invoke
/usr/bin/sort.
Your program must not just call the C function system().
Note that the command-line options supported by
/usr/bin/sort
on OS-X, Linux, and cygwin(Windows) are often different.
If the data totals of two or more MAC addresses,
or two or more vendors (via their OUIs),
are identical,
then the MAC addresses or vendors with identical totals
should be printed in ascending alphabetical order.
- Your program must employ sound programming practices, including
the use of meaningful comments,
well chosen identifier names,
appropriate choice of basic data-structures and data-types,
and
appropriate choice of control-flow constructs.
Good luck!
Chris McDonald.
|
