s

/*udp demo */
/* usage:
 * ./client serv_ip serv_port 
*/
#include "net.h"
void usage (char *s)
{
    printf ("\nThis is multicast demo!\n");
    printf ("\nUsage:\n\t %s serv_ip serv_port", s);
    printf ("\n\t serv_ip: udp server ip address(between 224~239 segment)");
    printf ("\n\t serv_port: udp server port(serv_port > 5000)\n\n");
}
int main (int argc, char *argv[])
{
    int fd = -1;
    int port = SERV_PORT;
    port = atoi (argv[2]);
    if (port < 0 || (port > 0 && port <= 5000)) {
        usage (argv[0]);
        exit (1);
    }
    struct sockaddr_in sin;
    if (argc != 3) {
        usage (argv[0]);
        exit (1);
    }
    /* 1. 创建socket fd */
    if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) {    //UDP编程
        perror ("socket");
        exit (1);
    }
    /*2.1 填充struct sockaddr_in结构体变量 */
    bzero (&sin, sizeof (sin));
    sin.sin_family = AF_INET;
    sin.sin_port = htons (SERV_PORT);    //网络字节序的端口号
#if 0
    sin.sin_addr.s_addr = inet_addr (argv[1]);
#else
    if (inet_pton (AF_INET, argv[1], (void *) &sin.sin_addr) != 1) {
        perror ("inet_pton");
        exit (1);
    }
#endif
    printf ("multicast started!\n");
    char buf[BUFSIZ];
    while (1) {
        fprintf (stderr, "pls input string:");
        bzero (buf, BUFSIZ);
        if (fgets (buf, BUFSIZ - 1, stdin) == NULL) {
            perror ("fgets");
            continue;
        }
        sendto (fd, buf, strlen (buf), 0, (struct sockaddr *) &sin, sizeof (sin));
        if (!strncasecmp (buf, QUIT_STR, strlen (QUIT_STR))) {    //用户输入了quit字符
            printf ("Client is exited!\n");
            break;
        }
    }
    close (fd);
    return 0;
}