socket——tcp-nonblocking-server-client

server.c

// gcc server.c -o server
// indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *

/***************************************************************************/
/* */
/* 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 <arpa/inet.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 */

int 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");
                }
            }
        }
    }
    return 0;
}

client.c

// gcc client.c -o client
// indent -npro -kr -i8 -ts8 -sob -l280 -ss -ncs -cp1 *

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

#define PORT 3456        /* the port client will be connecting to */

#define MAXDATASIZE 100        /* max number of bytes we can get at once */

int main(int argc, char *argv[])
{
    int sockfd, numbytes;
    char buf[MAXDATASIZE];
    struct hostent *he;
    struct sockaddr_in their_addr;    /* connector's address information */

    if (argc != 2) {
        fprintf(stderr, "usage: client hostname\n");
        exit(1);
    }

    if ((he = gethostbyname(argv[1])) == NULL) {    /* get the host info */
        herror("gethostbyname");
        exit(1);
    }

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

    their_addr.sin_family = AF_INET;    /* host byte order */
    their_addr.sin_port = htons(PORT);    /* short, network byte order */
    their_addr.sin_addr = *((struct in_addr *)he->h_addr);
    bzero(&(their_addr.sin_zero), 8);    /* zero the rest of the struct */

    if (connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct sockaddr)) == -1) {
        perror("connect");
        exit(1);
    }
    /* sleep(5); */
    while (1) {
        if (send(sockfd, "Hello, world!\n", 14, 0) == -1)
            perror("send");
        printf("In loop \n");
        sleep(2);
    }
    close(sockfd);

    return 0;
}