/*
 * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy)
 * Copyright (c) 2005 - 2006 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino, CACE Technologies 
 * nor the names of its contributors may be used to endorse or promote 
 * products derived from this software without specific prior written 
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <stdlib.h>
#include <stdio.h>

#include <pcap.h>

void usage();

void dispatcher_handler(u_char *, const struct pcap_pkthdr *, const u_char *);


void main(int argc, char **argv)
{
pcap_t *fp;
char errbuf[PCAP_ERRBUF_SIZE];
struct timeval st_ts;
u_int netmask;
struct bpf_program fcode;
  
    /* 检查命令行参数的合法性 */
    if (argc != 2)
    {
        usage();
        return;
    }
        
    /* 打开输出适配器 */
    if ( (fp= pcap_open(argv[1], 100, PCAP_OPENFLAG_PROMISCUOUS, 1000, NULL, errbuf) ) == NULL)
    {
        fprintf(stderr,"\nUnable to open adapter %s.\n", errbuf);
        return;
    }

    /* 不用关心掩码，在这个过滤器中，它不会被使用 */
    netmask=0xffffff; 

    //编译过滤器
    if (pcap_compile(fp, &fcode, "tcp", 1, netmask) <0 )
    {
        fprintf(stderr,"\nUnable to compile the packet filter. Check the syntax.\n");
        /* 释放设备列表 */
        return;
    }
    
    //设置过滤器
    if (pcap_setfilter(fp, &fcode)<0)
    {
        fprintf(stderr,"\nError setting the filter.\n");
        pcap_close(fp);
        /* 释放设备列表 */
        return;
    }

    /* 将接口设置为统计模式 */
    if (pcap_setmode(fp, MODE_STAT)<0)
    {
        fprintf(stderr,"\nError setting the mode.\n");
        pcap_close(fp);
        /* 释放设备列表 */
        return;
    }


    printf("TCP traffic summary:\n");

    /* 开始主循环 */
    pcap_loop(fp, 0, dispatcher_handler, (PUCHAR)&st_ts);

    pcap_close(fp);
    return;
}

void dispatcher_handler(u_char *state, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
    struct timeval *old_ts = (struct timeval *)state;
    u_int delay;
    LARGE_INTEGER Bps,Pps;
    struct tm ltime;
    char timestr[16];
    time_t local_tv_sec;

    /* 以毫秒计算上一次采样的延迟时间 */
    /* 这个值通过采样到的时间戳获得 */
    delay=(header->ts.tv_sec - old_ts->tv_sec) * 1000000 - old_ts->tv_usec + header->ts.tv_usec;
    /* 获取每秒的比特数b/s */
    Bps.QuadPart=(((*(LONGLONG*)(pkt_data + 8)) * 8 * 1000000) / (delay));
    /*                                            ^      ^
                                                  |      |
                                                  |      | 
                                                  |      |
                         将字节转换成比特 --       |
                                                         |
                    延时是以毫秒表示的 --
    */

    /* 得到每秒的数据包数量 */
    Pps.QuadPart=(((*(LONGLONG*)(pkt_data)) * 1000000) / (delay));

    /* 将时间戳转化为可识别的格式 */
    local_tv_sec = header->ts.tv_sec;
    localtime_s(&ltime, &local_tv_sec);
    strftime( timestr, sizeof timestr, "%H:%M:%S", &ltime);

    /* 打印时间戳 */
    printf("%s ", timestr);

    /* 打印采样结果 */
    printf("BPS=%I64u ", Bps.QuadPart);
    printf("PPS=%I64u\n", Pps.QuadPart);

    //存储当前的时间戳
    old_ts->tv_sec=header->ts.tv_sec;
    old_ts->tv_usec=header->ts.tv_usec;
}


void usage()
{
    
    printf("\nShows the TCP traffic load, in bits per second and packets per second.\nCopyright (C) 2002 Loris Degioanni.\n");
    printf("\nUsage:\n");
    printf("\t tcptop adapter\n");
    printf("\t You can use \"WinDump -D\" if you don't know the name of your adapters.\n");

    exit(0);
}