NCTU_NP - Intro to Network Programming  - Homework 1 - Bulletin Board System -  Part 1 - Solved

In this project, you are asked to design Bulletin Board System (BBS) server and client. Your program should be able to handle multiple connections and receive user command from standard input. After receiving command, the server send the corresponding message back.  

Requirement
The service accepts the following commands and at least 10 clients:

When client enter command incompletely E.g., missing parameters, the server should show command format for client.

Command format 
Description 
Result 
register <username> <email> <password> 
Register with username, email and password. 

<username> must be unique. <email> and <password> have no limitation. 

If username is already used, show failed message, otherwise it is success. Note: You have to send this command and get associated message by UDP. 
Success 
Register successfully. 
Fail 
Username is already used. 
login <username> <password> 
Login with username and password. 

Fail (1): User already login. Fail (2): Username or password is incorrect. If login successfully, server should send a randomly generated number as the 

identification for the subsequent udp command. Note: You have to send this command and get associated message by TCP. 
Success 
Welcome, <username>. 
Fail (1) 
Please logout first. 
Fail (2) 
Login failed.  
logout 
Logout account. 

If you haven’t logged in yet, show failed message, otherwise logout successfully. Note: You have to send this command and get associated message by TCP. 
Success 
Bye, <username>. 
Fail 
Please login first. 
whoami 
Show your username. Send whoami <received random number> to server. If you haven’t logged in yet, show failed message. 

Otherwise, show username. Note: You have to send this command and get associated message by UDP. 
Success 
<username> 
Fail 
Please login first. 
 

General
Please make sure you develop your program on Linux. For development environment, you can just apply NCTU CSCC account to use Linux workstation. If you don’t want to apply anything, you can use VM for develop.

Use ‘’% “ as the command line prompt. Notice that there is only one space after the prompt.

The server close connection if client use exit command, but server still running and client can connect again.  

For manage user information, storing data in your server is necessary. Therefore, you must have some methods to handle this, like manage a simple database e.g. SQLite and then design tables by yourself or only use data structure to store data.  

To run your server, you must to provide port number for your program. E.g., bash$ ./server 7890

Now, you can use your client program to connect to your server, when client connect to server, the server print message “New connection.”

Assume your server is running on localhost and listening at port 7890. E.g., bash$ client 127.0.0.1 7890 


Scenario
bash$ client 127.0.0.1 7890 

******************************** 

** Welcome to the BBS server. ** ******************************** 

% register 

Usage: register <username> <email> <password> 

% register Bob bob@qwer.asdf 123456 Register successfully. 

% register Bob asdf@asdf.asdf 123456 

Username is already used. 

% login 

Usage: login <username> <password> % login Bob 

Usage: login <username> <password> 

% login Bob 654321 Login failed. 

% login Tom 654321 Login failed. 

% login Bob 123456 Welcome, Bob. 

% login Bob 123456 

Please logout first. 

% whoami Bob 

% logout 

Bye, Bob. 

% logout 

Please login first. 

% whoami 

Please login first. 

% list-user 

Name      Email 

Bob       bob@qwer.asdf 

% exit 

 
       


Reference
1.    C/C++ Socket 

2.    SQLite C/C++ Interface 

3.    Linux socket SELECT 

4.    Database table example 

CREATE TABLE USERS( 

    UID INTEGER PRIMARY KEY AUTOINCREMENT, 

    Username TEXT NOT NULL UNIQUE, 

    Email TEXT NOT NULL, 

    Password TEXT NOT NULL 

);