Programming Lab: Networked TCP Time Server & Client

Objective

The goal of this lab is to help students understand the basic concepts of networking in C by converting a simple time server into a networked TCP server. Students will then implement a basic TCP client that connects to the server to retrieve the current date and time.

Setup

• You are provided with a simple C program that returns the current time as a string. Your task is to network this program by implementing a TCP server that will listen on port 8013. When a client connects, the server will send the current time, and then close the connection.

• Use the following simple datetime program as a base for the server:

#include <stdio.h>
#include <time.h>

int main() {
    time_t rawtime;
    struct tm *timeinfo;
    char time_string[100];

    // Get the current time
    time(&rawtime);
    
    // Convert the time to local time
    timeinfo = localtime(&rawtime);
    
    // Format the time as string
    strftime(time_string, sizeof(time_string), "%Y-%m-%d %H:%M:%S", timeinfo);

    printf("Current time: %s\n", time_string);

    return 0;
}

• Use the TCP server developed during class as a reference or starting point for your implementation.

Server Task

1. TCP Time Server Implementation

• Create a simple TCP server that listens on port 8013 for incoming client connections.
• When a client connects, the server should:
  • Send the current time to the client.
  • Print the time sent to the client and the client’s connection information (IP address, port, etc.).
  • Close the connection after sending the time.
• Use the code provided as a starting point and integrate it into a TCP server by using socket(), bind(), listen(), accept(), send(), and close().

2. Display Client Information

• Display details such as the client’s IP address and port number each time a new client connects.
• The server should handle one connection at a time (for simplicity).

3. Expected Output (Server)

The server will output information about the connected client and the time sent to the client.

Client Task

1. TCP Client Implementation

• Create a simple TCP client that connects to the server (on localhost or the server’s IP address) at port 8013.
• Once the client connects, the client should receive the current time from the server and print it to the console.

2. Expected Output (Client)

The client will print the time it receives from the server.

Extra Credit

1. Time Zone Support

• Modify the server to accept an optional time zone argument from the client. If the client sends a specific time zone (e.g., "GMT", "UTC", "PST", etc.), the server should convert the current time to that time zone and send it to the client.
• For example, the server could send the time in multiple time zones (like UTC or PST) if the client requests a specific one.

Submission Instructions

Post your answers in Marmoset by the scheduled due date in the syllabus.

1. Code Submission

• Submit the source code for both the server and client (server.c, client.c).

2. Wireshark Packet Capture

• Capture and submit the packets exchanged between the server and client using Wireshark.
• Ensure the packet capture includes the initial connection handshake and the transmission of the time data from the server to the client.
• Save the packet capture in .pcapng format.

3. Answer Questions/Observations

• Include any questions, observations, or issues you encountered during the implementation.
• Describe any challenges faced and how you overcame them.
• Discuss any assumptions made during the project (e.g., using localhost for testing).

Note: Double-check that any screenshots clearly show packet details and are legible.