Embedded Files
AIM: Implement the chat application
THEORY:
A chat application using socket programming facilitates real-time communication between a client and a server. It follows a client-server model where the server creates a TCP socket, binds it to a specific port, and listens for incoming client connections. Once a client connects, the server accepts the connection and enables bidirectional communication. The client, on the other hand, establishes a connection with the server, sends messages, and receives responses. Both the client and server continuously exchange messages until the user types "exit," which terminates the connection. This implementation ensures reliable data transmission using TCP and supports full-duplex communication, meaning both parties can send and receive messages simultaneously. Such applications form the foundation of real-time messaging systems, VoIP services, and other interactive communication platforms
CODE:
SERVER:
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define SERVER_TCP_PORT 5750 /* Well-known port */
#define BUFLEN 256 /* Buffer length */
#define MAX 90
int flag = 0;
void func(int sockfd) {
char buff[MAX];
int n;
for (;;) {
if (flag == 1) break;
bzero(buff, MAX);
n = read(sockfd, buff, sizeof(buff));
printf("Message from client: %s", buff);
if (strncmp("exit", buff, 4) == 0) {
printf("Server Exit...\n");
flag = 1;
break;
}
printf("Enter message to be sent to client: ");
fgets(buff, sizeof(buff), stdin);
write(sockfd, buff, strlen(buff));
bzero(buff, MAX);
}
}
int main(int argc, char **argv) {
int sd, new_sd, client_len, port;
struct sockaddr_in server, client;
char buff[BUFLEN];
int yes = 1;
if (argc < 2) {
fprintf(stderr, "Usage: %s <port>\n", argv[0]);
exit(1);
}
port = atoi(argv[1]);
/* Create a stream socket */
if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf(stderr, "Can't create a socket\n");
exit(1);
}
/* Allow reuse of address */
if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) == -1) {
perror("setsockopt");
exit(1);
}
/* Bind an address to the socket */
server.sin_family = AF_INET;
server.sin_port = htons(port);
server.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(sd, (struct sockaddr *)&server, sizeof(server)) == -1) {
fprintf(stderr, "Can't bind name to socket\n");
exit(1);
}
/* Queue up to 5 connection requests */
listen(sd, 5);
while (1) {
client_len = sizeof(client);
if ((new_sd = accept(sd, (struct sockaddr *)&client, &client_len)) == -1) {
fprintf(stderr, "Can't accept client\n");
exit(1);
}
func(new_sd);
close(new_sd);
}
close(sd);
return 0;
}
CLIENT:
#include <stdio.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define BUFLEN 256 /* Buffer length */
#define MAX 80
void func(int sockfd) {
char buff[MAX];
int n;
for (;;) {
bzero(buff, sizeof(buff));
printf("Enter the message to be sent: ");
fgets(buff, sizeof(buff), stdin);
if ((strncmp(buff, "exit", 4)) == 0) {
printf("Client Exit...\n");
break;
}
write(sockfd, buff, strlen(buff));
bzero(buff, sizeof(buff));
read(sockfd, buff, sizeof(buff));
printf("Message from Server: %s", buff);
}
}
int main(int argc, char **argv) {
int sd, port;
struct sockaddr_in server;
if (argc < 2) {
fprintf(stderr, "Usage: %s <port>\n", argv[0]);
exit(1);
}
port = atoi(argv[1]);
/* Create a stream socket */
if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf(stderr, "Can't create a socket\n");
exit(1);
}
/* Set up the server address */
server.sin_family = AF_INET;
server.sin_port = htons(port);
server.sin_addr.s_addr = inet_addr("127.0.0.1");
/* Connect to the server */
if (connect(sd, (struct sockaddr *)&server, sizeof(server)) == -1) {
fprintf(stderr, "Can't connect\n");
exit(1);
}
func(sd);
close(sd);
return 0;
}
OUTPUT:
CONCLUSION:
This chat application demonstrates the fundamental concept of socket programming using TCP communication in C. The server listens for incoming client connections, receives messages, and responds, while the client connects to the server, sends messages, and receives responses. The program enables a basic two-way communication system, allowing messages to be exchanged until either party sends "exit," terminating the connection. This implementation provides a strong foundation for developing more advanced network-based applications.
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