In The Provided Client And Server Program ✓ Solved

In the provided client.c and server.c program (please download

In the provided client.c and server.c program, after the client receives “This server has been contacted 1 time” from the server, the client process exits. Modify the client.c and server.c so that after the client receives “This server has been contacted 1 times”, instead of exiting, the client sends back “This client has been contacted 1 times” to the server. The server then sends back “This server has been contacted 2 times”, and the client sends back “This client has been contacted 2 times” to the server, and so on. Both the client and the server should not exit; they must alternatively send messages to each other.

Paper For Above Instructions

The process of communication between a client and server is fundamental in computer networking, particularly in applications that rely on socket programming. The task requires modifying the client and server code so that they can communicate in an ongoing manner instead of terminating after a single message exchange.

In the original implementation of the programs, the client's behavior is to terminate after receiving a message from the server indicating how many times it has been contacted. This behavior limits the potential for dynamic interaction between the client and server. However, to facilitate continuous communication, we must alter this behavior in both the client and server programs.

Understanding the Socket Communication

Before diving into the code modifications, it is important to understand the socket communication concept. A socket is an endpoint for sending and receiving data across a network. In our case, the client initiates the connection to the server, which listens for requests. Once connected, data can be exchanged in a bi-directional manner.

Modifying client.c

The client code must be modified to remove the exit condition after the first message is received and implement a loop to continue sending messages back to the server. Here is how the modifications can be implemented:

include <stdio.h>


include <string.h>


include <unistd.h>


include <sys/socket.h>


include <arpa/inet.h>


define PORT 8080


int main() {


int sock = 0;


struct sockaddr_in serv_addr;


char buffer[1024] = {0};


int contactCount = 1;


if ((sock = socket(AF_INET, SOCK_STREAM, 0)) 

printf("Socket creation error\n");


return -1;


}


serv_addr.sin_family = AF_INET;


serv_addr.sin_port = htons(PORT);


inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr);


if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) 

printf("Connection failed\n");


return -1;


}


// Start the communication loop


while (1) {


// Receiving message from server


read(sock, buffer, 1024);


printf("%s\n", buffer);


// Sending message back to server


snprintf(buffer, sizeof(buffer), "This client has been contacted %d times", contactCount);


send(sock, buffer, strlen(buffer), 0);


contactCount++;


}


close(sock);


return 0;


}

In this updated client code, we introduced a while loop that keeps the client alive, allowing it to read messages from the server continuously. After each message is received, it sends a response back to the server, including how many times it has been contacted.

Modifying server.c

The server code also needs modifications to handle the continuous communication. It should accept messages from the client and reply accordingly:

include <stdio.h>


include <string.h>


include <unistd.h>


include <sys/socket.h>


include <arpa/inet.h>


define PORT 8080


int main() {


int server_fd, new_socket;


struct sockaddr_in address;


int opt = 1;


int addrlen = sizeof(address);


char buffer[1024] = {0};


int contactCount = 1;


if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {


printf("Socket creation error\n");


return -1;


}


// Setting socket options


if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {


printf("setsockopt error\n");


return -1;


}


address.sin_family = AF_INET;


address.sin_addr.s_addr = INADDR_ANY;


address.sin_port = htons(PORT);


if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) 

printf("Bind failed\n");


return -1;


}


if (listen(server_fd, 3) 

printf("Listen failed\n");


return -1;


}


if ((new_socket = accept(server_fd, (struct sockaddr )&address, (socklen_t)&addrlen)) 

printf("Accept failed\n");


return -1;


}


// Start the communication loop


while (1) {


// Sending initial message


snprintf(buffer, sizeof(buffer), "This server has been contacted %d times", contactCount);


send(new_socket, buffer, strlen(buffer), 0);


contactCount++;


// Receiving message from client


read(new_socket, buffer, 1024);


printf("%s\n", buffer);


}


close(new_socket);


close(server_fd);


return 0;


}

Similar to the client, the server is modified to maintain a loop that allows it to send messages and wait for responses from the client. After sending an initial message indicating how many times it has been contacted, it reads the reply from the client and prints it out.

Conclusion

The modifications to both client.c and server.c are essential for ensuring that the client and server can continuously communicate without exiting. This behavior simulates a conversation where both endpoints can send and receive messages interchangeably, demonstrating the potential of socket programming.

References

  • Stevens, W. Richard. "UNIX Network Programming." Volume 1: "Networking APIs: Sockets and Protocols." Prentice Hall, 2003.
  • Beej's Guide to Network Programming. Retrieved from https://beej.us/guide/bgpd/
  • Comer, Douglas. "Internetworking with TCP/IP Volume I." 6th Edition, Pearson, 2013.
  • Linux Man Pages. "socket(2)." Retrieved from https://man7.org/linux/man-pages/man2/socket.2.html
  • Ramalho, Luciano. "Fluent Python." O'Reilly Media, 2015.
  • Java Network Programming. "Socket Programming." Retrieved from https://docs.oracle.com/javase/tutorial/networking/sockets/index.html
  • Postel, J., & Reynolds, J. "RFC 793: Transmission Control Protocol." Retrieved from https://tools.ietf.org/html/rfc793
  • Tanenbaum, Andrew S. "Computer Networks." 5th Edition, Prentice Hall, 2011.
  • Floyd, Sally. "TCP and UDP: Two Transport Protocols." Retrieved from https://www.rfc-editor.org/rfc/rfc793
  • Kurose, James F., and Ross, Keith W. "Computer Networking: A Top-Down Approach." 7th Edition, Pearson, 2016.

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