/*
 * Initial commit by Yibo @ Jul. 28, 2015
 * Last update by Yanzi @ Sept. 26, 2016
 * This is using sendfile to achieve zero-copy (one copy actually due to lack of driver support).
 *
 * TODO: "Presently (Linux 2.6.9 [and, in fact, as of this writing in June 2010]): in_fd, must
 * correspond to a file which supports mmap()-like operations (i.e., it cannot be a socket);
 * and out_fd must refer to a socket."
 * based on http://blog.superpat.com/2010/06/01/zero-copy-in-linux-with-sendfile-and-splice/.
 * need to double check in newer kernels
 */
 
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <sys/sendfile.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>

// #define BUF_SIZ     8192

char isNumber(char number[])
{
    int i = 0;

    //checking for negative numbers
    if (number[0] == '-')
        i = 1;
    for (; number[i] != 0; i++)
    {
        //if (number[i] > '9' || number[i] < '0')
        if (!isdigit(number[i]))
            return 0;
    }
    return 1;
}

int main(int argc, char *argv[])
{
    // defaults
    uint slotLength = 10000; // in microseconds, for bandwidth control
    uint quota = 1000000000; // default bytes per slot, default 1GB/slot
    uint sentInSlot = 0, slot = 1;
    uint total_bytes_sent = 0;
    // for timing
    double elapsedTime;
    struct timeval t_start, t_end, t_now;
    // for socket
    int fd; // file descriptor of file to send
    int sockfd; // socket
    struct sockaddr_in servaddr;
    // struct sockaddr_ll socket_address;
    // for misc
    int ret;
    int sendsize = 1460; // 1500 MTU - 20 IPv4 - 20 TCP
    int bytes2send = 0;
    struct stat st;

    if (argc < 4)
    {
        printf("Usage: %s <bytes2send/file2send> <ip> <port> <[optional] bandwidth (bps)> <[optional] sendsize (bytes)>\n", argv[0]);
        exit(0);
    }

    // set bandwidth
    if (argc > 4)
        quota = atoi(argv[4]) / 8 / (1000000 / slotLength);

    // set sendsize (if larger than 1460 will do packetization (fragmentation))
    if (argc > 5)
        sendsize = atoi(argv[5]);

    // adjust slotLength to address packet size issue in the end
    if ((quota % sendsize) > 0)
    {
        // printf("quota:%d,sendsize:%d,slotLength:%d\n", quota, sendsize, slotLength);
        slotLength = (uint)((double)(quota / sendsize + 1) * sendsize / quota * slotLength);
        quota = (quota / sendsize + 1) * sendsize;
        // printf("quota:%d,sendsize:%d,slotLength:%d\n", quota, sendsize, slotLength);
    }

    // get file size (bytes2send)
    if (isNumber(argv[1]))
    {
        // set bytes to send
        bytes2send = atoi(argv[1]);
        // open file descriptor
        fd = open("/data/local/tmp/bigfile", O_RDONLY);
        if (fd == -1)
        {
            fprintf(stderr, "! Unable to open /data/local/tmp/bigfile.\n");
            exit(1);
        }
    }
    else
    {
        // open file descriptor
        fd = open(argv[1], O_RDONLY);
        if (fd == -1)
        {
            fprintf(stderr, "! Unable to open file %s.\n", argv[1]);
            exit(1);
        }
        fstat(fd, &st);
        bytes2send = st.st_size;
        printf("bytes2send:%d\n", bytes2send);
    }
    
    // bind socket
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(argv[2]);
    servaddr.sin_port = htons(atoi(argv[3]));

    // connect socket
    if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
    {
        fprintf(stderr, "! Unable to connect the server.\n");
        exit(1);
    }
    
    // start timing
    gettimeofday(&t_start, NULL);

    // start to send
    while (total_bytes_sent < bytes2send)
    {
        if ((bytes2send - total_bytes_sent) < quota)
        {
            quota = bytes2send - total_bytes_sent;
        }
        // send in slots
        while (sentInSlot < quota)
        {
            // printf(
            //     "before: total_bytes_sent %d, sentInSlot %d, quota - sentInSlot %d\n",
            //     total_bytes_sent, sentInSlot, quota - sentInSlot);
            ret = sendfile(sockfd, fd, (off_t *)&total_bytes_sent, quota - sentInSlot);
            if (ret <= 0)
            {
                fprintf(stderr, "! Fail to send: ret:%d, err:%d; wait for 100us..\n", ret, errno);
                usleep(100);
                continue;
            }
            sentInSlot += ret;
            // printf(
            //     "after: total_bytes_sent %d, sentInSlot %d, quota - sentInSlot %d\n",
            //     total_bytes_sent, sentInSlot, quota - sentInSlot);
        }
        // control bandwidth
        gettimeofday(&t_now, NULL);
        elapsedTime = (t_now.tv_sec - t_start.tv_sec) * 1000000.0 + (t_now.tv_usec - t_start.tv_usec);
        if (elapsedTime < slotLength * slot)
        {
            // printf(
            //     "sent %d, quota %d, bytes2send %d, usleep %lfus\n",
            //     total_bytes_sent, quota, bytes2send, slotLength * slot - elapsedTime);
            usleep((int)(slotLength * slot - elapsedTime));
        }
        sentInSlot = 0;
        ++slot;
    }

    // end timing
    gettimeofday(&t_end, NULL);
    elapsedTime = (t_end.tv_sec - t_start.tv_sec) + (t_end.tv_usec - t_start.tv_usec) / 1000000.0;
    printf(
        "sent(bytes):%d\nduration(s):%lf\nthroughput(bps):%lf\n",
        total_bytes_sent, elapsedTime, total_bytes_sent * 8 / elapsedTime);

    
    close(sockfd);
    close(fd);
    
    return 0;
}