代写一个网络嗅探器，可以获取网络数据包。
Purpose
This project will assess your understanding of introductory C99 programming
language features, including its controlstructures, 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 week6.
Nearly all devices that connect to the Internet use networking hardware that
conforms to IEEE802 standards, commonly termed the Ethernet standards. It is
common for desktop and laptop computers to have two Ethernet interfaces, one
wired (the IEEE802.3 standard) and one wireless (the IEEE802.11 standard),
while mobile devices and smartphones will typically have a single wireless
Ethernet interface and a Bluetooth interface (the IEEE802.15.1 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 6bytes 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
74E2F520F98B is the same address.
When devices communicate using WiFi (the IEEE802.11 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 6byte MAC address comprises two 3byte parts. The first 3bytes 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 textfile providing information about each WiFi
packet, one packet per line. Here is a samplepacket 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 textfile 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: sampleOUIfilesmall
(40 entries) and sampleOUIfilelarge (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 UNKNOWNVENDOR.
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 systemcalls fork() and execv()
(and possibly others) to invoke /usr/bin/sort. Your program must not just call
the C function system(). Note that the commandline options supported by
/usr/bin/sort on OSX, 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
datastructures and datatypes, and appropriate choice of controlflow
constructs.
Assessment
Projects will be marked using an automatic marking program (for correctness)
and by visual inspection (for good programming practices). It is thus
important that your program produces its output in the correct format. This
project is worth 15% of your final mark for CITS2002. It will be marked out of
40. The project may be completed individually or in teams of two (working as a
team is STRONGLY encouraged).
During the marking, attention will obviously be given to the correctness of
your solution. However, a correct and efficient solution should not be
considered as the perfect, nor necessarily desirable, form of solution.
Preference will be given to well presented, well documented solutions that use
the appropriate features of the language to complete tasks in an easy to
understand and easy to follow manner. Your program must employ sound
programming practices, including the use of meaningful comments, well chosen
identifier names, appropriate choice of basic datastructures and datatypes,
and appropriate choice of controlflow constructs. Do not expect to receive
full marks for your program simply because it works correctly. Remember, a
computer program should not only convey a message to the computer, but also to
other human programmers.
Your project will be marked on the computers in CSSE Lab 2.03, using the macOS
environment. No allowance will be made for a program that “works at home” but
not on CSSE Lab 2.03 under macOS, so be sure that your code compiles and
executes correctly on these machines before you submit it.
Submission requirements
- The deadline for the project is 12noon Friday 22nd September (end of week 8).
- Your submission will be compiled, run, and examined using the macOS platform on computers in CSSE Lab 2.03. Your submission must work as expected on this platform. While you may develop your project on other computers, excuses such as “it worked at home, just not in the lab!” will not be accepted.
- Your submission’s C99 source file should each begin with the following lines. If working in a team of two students, only one needs to submit the project.
- You must submit your program electronically using cssubmit. No other method of submission is accepted. You should submit a single C sourcecode file named wifistats.c to be assessed. You do not need to submit any input test files that you used while developing your project. The cssubmit facility will give you a receipt of your submission. You should print and retain this receipt in case of any dispute. Note also that the cssubmit facility does not archive submissions and will simply overwrite any previous submission with your latest submission.
- You are expected to have read and understood the University Policy on Academic Conduct. In accordance with this policy, you may discuss with other students the general principles required to understand this project, but the work you submit must be the result of your own efforts.
