Using setsockopt

#//using setsockopt

#include <stdio.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

void

usage()

{

    printf("usage: setsock [-s <size>]\n");

    exit(1);

}

main(argc,argv)

int argc;

char **argv;

{

    char           c;

    unsigned int   ksize;

    int            fd;

    int            ret;

    unsigned long  size;

    socklen_t      len;

    while (( c = getopt (argc, argv, "s:")) != EOF) {

        switch (c) {

           case 's':

               ksize = atoi(optarg);

               break;

           default:

               usage();

        }

    }

    fd = socket(AF_INET, SOCK_STREAM, 0);

    if (-1 == fd) {

        printf("socket call failed.\n");

        exit(1);

    }

    size = ksize * 1024;

    ret = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, (void *)&size, sizeof(size));

    if (0 == ret) {

        printf("Successfully set the socket send buf size to %lu\n", size);

        len = sizeof(size);

        ret = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, (void *)&size,

                         (int *)&len);

        printf("getsockopt ret is %d. errno is %d. len is %d, "

               "size is %lu\n", ret,

               errno, len, size);

        exit(0);

    }

    printf("Failed to set the socket send buf size to %lu.  "

           "ret = %d, errno = %d.\n",

           ret, size, errno);

        ret = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, (void *)&size,

                         (int *)&len);

        printf("getsockopt ret is %d. errno is %d. len is %d, "

               "size is %lu\n", ret,

               errno, len, size);

    exit(1);

}