NCTU_NP - Introduction to Network Programming - Final Exam - Chat-room - Solved

 You have to create a TCP server which is a chat room. All clients are in the chat room.

•         Server will give client a name by connection order.

For example, the first client connects to the server, it will be named user1, the second client will be user2, the third client will be user3.

•         Each client will receive a message of “Welcome, userX.” when enter the chat room server.

•         Clients can send a private message to another user. Any client can not send a message to himself. Ex.

Command format:

•         Server

•         ./server {port}

•         Client

•         ./client {server-ip} {server-port}

Notes:

●            mute command – (5%)

●            unmute command – (5%)

●            yell command – (15%)

●            tell command – (15%)

●            system message – (5%)

●            exit command – (5%)

 

Command​

Output​
mute
The client will not receive any message, including public and private message.
Success
Mute mode.
Fail
You are already in mute mode.
unmute
The client can receive messages again.
Success
Unmute mode.
Fail
You are already in unmute mode.
yell <message>
Send a message to others in the chat room.
Success
<username>: <message> Ex. user1: Hello world.
tell <receiver> <message>
<sender> sends a private message to <receiver> in the chat room. <sender> and <receiver> are usernames.
Success
<sender> told you: <message> ex.

When user1 sends a private message to user2, user2 will receive: user1 told you: It is nice to see you.
Fail
<receiver> does not exist.
Exit
Close chat room and disconnect from the server.
 
Scenario：

User0
User1
User2
bash$ ./client ​     127.0.0.1 7890

**************************

*​    Welcome      to     the     BBS

server.​    *

************************** Welcome, user0.
bash$ ./client ​     127.0.0.1 7890

**************************

*​    Welcome      to     the     BBS

server.​    *

************************** Welcome, user1. yell Hello world
bash$ ./client ​     127.0.0.1 7890

**************************

*​    Welcome      to     the     BBS

server.​    *

************************** Welcome, user2.
user1: Hello world mute

Mute mode.
yell Hello world2
user1: Hello world user1: Hello world2
unmute Unmute mode.

user1: Hello world3
yell Hello world3
user1: Hello world3
 
tell user2 It is nice to see you.
user1 told you: It is nice to see you.
exit
exit
exit
p.s Bold means command.

2.       (50%)Share memory (mutex)：

•       You have to implement a TCP Server with two accounts, ACCOUNT1, ACCOUNT2 respectively. Initial accounts are zeros. Give client a name by connection order.

For example, the first client connects to the server, it will be named A, the second client will be B, the third client will be C, the fourth client will be D.

•       When a client connects/disconnects to the server, server should output message: New connection from ip:port (user#) / (user#) ip:port disconnected​  (system message)

Note：

Don't deposit a negative number into accounts or withdraw excess money from accounts.

The client does the following functions:

•       The service accepts the following commands and only 4 clients:

When a client enters command incompletely, e.g., missing parameters, the server should show command format for client.

Command​
Description​
Output​
show-accounts
Show the money in ACCOUNT1, ACCOUNT2.
Success
ACCOUNT1: <money>

ACCOUNT2: <money>
deposit <account> <money>
Deposit the amount of money into <account> by client.

<money> is only positive integer.

Ex.

1.Client C deposits $100 into

ACCOUNT1.

-> deposit ACCOUNT1 100
Success
Successfully deposits <money> into <account>.
Fail
Deposit a non-positive number into accounts.
withdraw <account> <money>
Withdraw the amount of money from <account> by client.

<money> is only positive integer.

Ex. Client D withdraws $300 from ACCOUNT1.

-> withdraw ACCOUNT1 300
Success
Successfully withdraws

<money> from <account>.
Fail(1)
Withdraw excess money from accounts.
Fail(2)
Withdraw a non-positive number into accounts.
exit
Disconnect from the server.
 
•       Scenario：

A
B
bash$ ./client ​    127.0.0.1 7890

**************************

* Welcome to the TCP server. * ************************** deposit ACCOUNT1 1000

Successfully deposits 1000 into ACCOUNT1.
bash$ ./client ​    127.0.0.1 7890

**************************

* Welcome to the TCP server. *

************************** withdraw ACCOUNT1 500

Successfully withdraws 500 from ACCOUNT1.
deposit ACCOUNT2 1000

Successfully deposits 1000 into ACCOUNT2. deposit ACCOUNT1 -3

Deposit a non-positive number into accounts. deposit ACCOUNT1 0

Deposit a non-positive number into accounts.
withdraw ACCOUNT1 1500

Withdraw excess money from accounts.

withdraw ACCOUNT1 0

Withdraw a non-positive number into accounts.
withdraw ACCOUNT1 -100

Withdraw a non-positive number into accounts.
show-accounts

ACCOUNT1: 500

ACCOUNT2: 1000
exit
exit
Notes:

●            system message – (5%)

●            show-accounts command – (10%)

●            deposit command – (15%)

●            withdraw command – (15%)

●            exit command – (5%)