tcp-nonblocking-server.c

/***************************************************************************/
/*                                                                         */
/* Server program which wait for the client to connect and reads the data  */
/*     using non-blocking socket.                                          */
/* The reading of non-blocking sockets is done in a loop until data        */
/*     arrives to the sockfd.                                              */
/*                                                                         */
/* based on Beej's program - look in the simple TCP server for further doc.*/
/*                                                                         */
/*                                                                         */
/***************************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <fcntl.h> /* Added for the nonblocking socket */

#define MYPORT 3456    /* the port users will be connecting to */
#define BACKLOG 10     /* how many pending connections queue will hold */

main()
{
    int 			sockfd, new_fd;  /* listen on sock_fd, new connection on new_fd */
    struct 	sockaddr_in 	my_addr;    /* my address information */
    struct 	sockaddr_in 	their_addr; /* connector's address information */
    int 			sin_size;
    char			string_read[255];
    int 			n,i;
    int			last_fd;	/* Thelast sockfd that is connected	*/

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }

    last_fd = sockfd;

    my_addr.sin_family = AF_INET;         /* host byte order */
    my_addr.sin_port = htons(MYPORT);     /* short, network byte order */
    my_addr.sin_addr.s_addr = INADDR_ANY; /* auto-fill with my IP */
    bzero(&(my_addr.sin_zero), 8);        /* zero the rest of the struct */

    if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) \
                                                                      == -1) {
        perror("bind");
        exit(1);
    }

    if (listen(sockfd, BACKLOG) == -1) {
        perror("listen");
        exit(1);
    }

    if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, \
       			&sin_size)) == -1) {
        perror("accept");
    }
    fcntl(last_fd, F_SETFL, O_NONBLOCK); /* Change the socket into non-blocking state	*/
    fcntl(new_fd, F_SETFL, O_NONBLOCK); /* Change the socket into non-blocking state	*/

    while(1){
        for (i=sockfd;i<=last_fd;i++){
            printf("Round number %d\n",i);
            if (i = sockfd){
                sin_size = sizeof(struct sockaddr_in);
                if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, \
        					&sin_size)) == -1) {
                    perror("accept");
                }
                printf("server: got connection from %s\n", \
					 inet_ntoa(their_addr.sin_addr));
                fcntl(new_fd, F_SETFL, O_NONBLOCK);
                last_fd = new_fd;
            }
            else{
                n=recv(new_fd,string_read,sizeof(string_read),0);
                if (n < 1){
                    perror("recv - non blocking \n");
                    printf("Round %d, and the data read size is: n=%d \n",i,n);
                }
                else{
                    string_read[n] = '\0';
                    printf("The string is: %s \n",string_read);
                    if (send(new_fd, "Hello, world!\n", 14, 0) == -1)
                        perror("send");
                }
            }
        }
    }


}