Dalhousie University Faculty of Computer Science
CSCI 3171 Network Computing Winter 2020 Assignment 3 [20 marks]
Submission Deadline: FRIDAY, MARCH 20, at 11:59PM
ASSIGNMENT TASK
Design a client-server application using TCP sockets, where you use the client to play a game of “Prisoner’s Dilemma” with the server.
You may complete this assignment in groups of 2 students. Only one submission per group is required. Use C or C++ for writing the code and gcc (or g++) for compiling your code.
ASSIGNMENT DETAILS:
The Prisoner’s Dilemma:
The prisoner’s dilemma is a standard example of a game analyzed in game theory that shows why two completely “rational” individuals might not cooperate, even if it appears that it is in their best interests to do so.1
It is presented as follows:
“Two members of a criminal gang are arrested and imprisoned. Each prisoner is in solitary confinement with no means of communicating with the other. The prosecutors lack sufficient evidence to convict the pair on the principal charge. They hope to get both sentenced to a year in prison on a lesser charge. Simultaneously, the prosecutors offer each prisoner a bargain. Each prisoner is given the opportunity either to: betray the other by testifying that the other committed the crime, or to cooperate with the other by remaining silent. The offer is:
• If A and B each betray the other, each of them serves 2 years in prison
• If A betrays B but B remains silent, A will be set free and B will serve 3 years
in prison (and vice versa)
• If A and B both remain silent, both will only serve 1 year in prison (on the
lesser charge)”1
This is summarized in the figure on the right. The following YouTube video also explains Prisoner’s Dilemma (you only need to watch up to 1:50 minutes of this video): https://www.youtube.com/watch?v=t9Lo2fgxWHw
Your Task:
you will write simple client-server application(s) in which the client acts as prisoner A and the server acts as prisoner B. The protocol between the client and server should be as follows:
• The server program is started on a user-defined port.
• The client program is started and connects to the server
using the server IP and port number provided on the command line. 1 https://en.wikipedia.org/wiki/Prisoner%27s_dilemma].
• The client asks the user for input. The input may either be S (for Silent) or B (for Betray). Any other input should result in an error message, asking the user to try again.
• The user’s input is sent to the server via the connected socket.
• The server (acting as prisoner B) may decide to remain Silent (S) or Betray (B). How the
server decides is completely up to you. For a fair game, you may use a random approach.
• The server reads the user’s input from the client socket, evaluates the outcome (years in
prison for both Prisoner A i.e. client, and Prisoner B i.e. server), and sends the result
(Prisoner B’s decision and the Prison Sentence) back to the client.
• The client should display the server’s reply to the user.
• The client should give the user an option to try again or quit.
Socket Programming Help and Reading:
• In the lab, you were shown how to write a server program.
• Following are some helpful tutorials on socket programming using TCP including code
samples. Feel free to study and understand any or all of these before starting on your assignment.
o http://www.linuxhowtos.org/C_C++/socket.htm
o https://www.codeproject.com/Articles/586000/Networking-and-Socket-
programming-tutorial-in-C
o http://www.csd.uoc.gr/~hy556/material/tutorials/cs556-3rd-tutorial.pdf
Note that any code you write should be your own. Any code copied directly from other resources or from the server program shared in the lab should be clearly identified and cited. A direct copy with citation may result in deduction of marks. Direct copy or modified segments of copied code without citation will be referred to the Academic Integrity Office.
SUBMISSION DETAILS:
Upload a single zip file containing:
1. your code (consisting of your c or c++ file(s)),
2. an image file (.jpg or .png) showing a screen capture of your program in action, and
3. a readme.txt file containing names of the group members, the specific contribution of each
member, and instructions to compile your program.
to the Assignment 3 dropbox on Brightspace. Do not submit the executable.
SUBMISSION DEADLINE:
Friday, 20-March-2020, 11:59PM
GRADING CRITERIA:
• Code for both the client and the server compiles using gcc/g++. Assignment instructions are
properly followed. (Note that you may decide to build a single app with a command line option to run it as either a client or a server.)
o You will get a zero in this assignment if your code does not compile with gcc/g++ according to instructions provided in your readme.txt file.
o Alsonotethatmarksmaybedeductedforanywarningsgeneratedduringcompilation.
• Client can connect to the server running on either a local or a remote host through a user specified port number. Be sure to test your client’s connectivity by connecting to the server running on a different machine. [6]
• Client’s message is received by the server, server correctly finds the outcome (i.e. the prison sentence) and displays this information. [4]
• Server’s message is received by the client and the client can display this information (i.e. the choices and result) to the user. [4]
• Code is well written, properly formatted and commented. User input error handling is done. Return values for all system functions are properly handled. [4]
• Readme.txt file is provided with the correct compilation string and specific contribution made by group members (if applicable). [2]
[Note: You do not need to write a multi-threaded server. Connecting a single client at a time is enough]