server.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>

void error(const char *msg){
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[]){
    if(argc < 2){
        fprintf(stderr, "Please provide port number. Exiting..");
        exit(1);
    }
int sockfd, newsockfd, portno;
char buffer[255];

struct sockaddr_in serv_addr, cli_addr;
socklen_t clilen;

sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
    error("Error opening socket");

bzero((char *)&serv_addr, sizeof(serv_addr));

portno = atoi(argv[1]);

serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);

if(bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    error("Binding failed.");

listen(sockfd, 5);
clilen = sizeof(cli_addr);

newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);

if(newsockfd == -1)
    error("Error Accepting!");
int n;
while(1){
    bzero(buffer, 255);
    n = read(newsockfd, buffer, 255);
    if(n < 0)
        error("Error reading!");
    printf("Client : %s\n", buffer);
    bzero(buffer, 255);
    fgets(buffer, 255, stdin);

    n = write(newsockfd, buffer, strlen(buffer));

    if(n < 0){
        error("Error on Writing!");
    }
    int i = strncmp("sayonara", buffer, 8);

    int j = strncmp("Sayonara", buffer, 8);

    if(i == 0 || j == 0){
        break;
    }
}
    close(newsockfd);
    close(sockfd);
    return 0;

}