ICMP类型统计代码

/*
记录icmp_tpye类型数据包接收的数量。
kill -SIGHUP $(pidof filename) 生成文件
kill -SIGQUIT $(pidof filename) 退出程序
程序在接收到SIGHUP信号后在当前目录下生成result文件，
接收SIGQUIT信号后退出程序，并删除result文件。
*/

#include <pcap.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/icmp.h>

#define SNAP_LEN 1518        /*数据包最大长度*/
#define MIN_LEN    (sizeof(struct ethhdr) + sizeof(struct iphdr) \
                 + sizeof(struct icmphdr))        /* 所分析的数据包最小长度 避免访问到空指针 */
#define ICMP_TPYE 19        /* icmp_tpye的类型为0~18 */
#define MAXBUFSIZE 1024        /* 路径数组的长度 */

static pcap_t *handle;
static struct bpf_program fp;
static unsigned int count[ICMP_TPYE];
//static int fd;
static FILE *fd;
static char path[MAXBUFSIZE];

static void Exit_Free()
{
    /* cleanup */
    pcap_freecode(&fp);
    pcap_close(handle);
    unlink(path);
    exit(EXIT_SUCCESS);
}

static void Print_Count()
{
    int i, len;
    char buffer[256] = {0};

#if 0
    if ((fd = open(path, O_CREAT|O_WRONLY|O_TRUNC, 0644)) == -1)    exit(EXIT_FAILURE);
    for(i=0; i<ICMP_TPYE; i++){
        if ((len = snprintf(buffer, sizeof(buffer)-1,
            "The Tpye: %2d, Count: %d\n", i, count[i])) == -1)    exit(EXIT_FAILURE);
        if (write(fd, buffer, len) != len)    exit(EXIT_FAILURE);
    }
    close(fd);
#endif

    if ((fd = fopen(path, "w")) == NULL)    exit(EXIT_FAILURE);
    for(i=0; i<ICMP_TPYE; i++){
        fprintf(fd, "The Tpye: %2d, Count: %d\n", i, count[i]);
    }
    fclose(fd);
}

static void packet_callback(u_char *args, const struct pcap_pkthdr *header,
                            const u_char *packet)
{
    struct icmphdr *ih;
    size_t qlen, hlen;

    /* 长度校验 */
    if (header->caplen < MIN_LEN)    return;
    /* 取得ICMP报文首部地址 */
    hlen = MIN_LEN - sizeof(struct icmphdr);
    /* 获得icmphdr头部指针地址 */
    packet += hlen;
    ih = (struct icmphdr *)packet;
    /* 计数统计 */
    count[ih->type]++;
    return;
}

int main(int argc, char **argv)
{
    char *dev = NULL;            /* capture device name */
    char filter_exp[] = "icmp";        /* filter expression [3] */
    char errbuf[PCAP_ERRBUF_SIZE];        /* error buffer */
    bpf_u_int32 mask;            /* subnet mask */
    bpf_u_int32 net;            /* ip */
    int num_packets = -1;        /* 包捕获的数量，-1为无限捕获 */

//    unsigned int *count = (unsigned int *)malloc(ICMP_TPYE * sizeof(unsigned int));
//    memset(count, 0, sizeof(unsigned int));

    /* check for capture device name on command-line */
    if (argc == 2) {
        dev = argv[1];
    } else if (argc > 2) {
        fprintf(stderr, "error: unrecognized command-line options\n\n");
        exit(EXIT_FAILURE);
    } else {
        /* find a capture device if not specified on command-line */
        dev = pcap_lookupdev(errbuf);
        if (dev == NULL) {
            fprintf(stderr, "Couldn't find default device: %s\n",
                    errbuf);
            exit(EXIT_FAILURE);
        }
    }

#if 0
    printf("Device: %s\n", dev);
    printf("Number of packets: %d\n", num_packets);
    printf("Filter expression: %s\n", filter_exp);
#endif



    /* get network number and mask associated with capture device */
    if (pcap_lookupnet(dev, &net, &mask, errbuf) == -1) {
        fprintf(stderr, "Couldn't get netmask for device %s: %s\n",
                dev, errbuf);
        net = 0;
        mask = 0;
    }

    /* open capture device */
    handle = pcap_open_live(dev, SNAP_LEN, 1, 1000, errbuf);
    if (handle == NULL) {
        fprintf(stderr, "Couldn't open device %s: %s\n",
                dev, errbuf);
        exit(EXIT_FAILURE);
    }

    /* make sure we're capturing on an Ethernet device [2] */
    if (pcap_datalink(handle) != DLT_EN10MB) {
        fprintf(stderr, "%s is not an Ethernet\n", dev);
        exit(EXIT_FAILURE);
    }

    /* compile the filter expression */
    if (pcap_compile(handle, &fp, filter_exp, 0, net) == -1) {
        fprintf(stderr, "Couldn't parse filter %s: %s\n",
                filter_exp, pcap_geterr(handle));
        exit(EXIT_FAILURE);
    }

    /* apply the compiled filter */
    if (pcap_setfilter(handle, &fp) == -1) {
        fprintf(stderr, "Couldn't install filter %s: %s\n",
                filter_exp, pcap_geterr(handle));
        exit(EXIT_FAILURE);
    }

    /* 接收到信号触发函数 */
    signal(SIGHUP, Print_Count);
    signal(SIGQUIT, Exit_Free);

    /* 获得当前路径 */
    getcwd(path, MAXBUFSIZE);
    strcat(path,"/result");
    daemon(0, 0);

    /* now we can set our callback function */
    pcap_loop(handle, num_packets, packet_callback, NULL);

    return 0;
}