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<td width="68%" background="DDl_back2.jpg" height="44"><big><big><font face="黑体"><p align="center">               ● UNIX网络编程                       (BM: clown)                </font></big></big></td></tr>
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<tr><td width="100%" colspan="2" height="100" align="center" valign="top"><br><p align="center">[<a href="index.htm">回到开始</a>][<a href="321.htm">上一层</a>][<a href="460.htm">下一篇</a>]
<hr><p align="left"><small> cyclone 于 2001-5-13 17:40:50 加贴在 绿盟科技论坛(bbs.nsfocus.com)--UNIX系统 <br>

安全： <br>

我想还是把代码贴出来吧：请各位帮我看看 <br>

我用sniffer抓到的数据包也只有一个，并没有想象的那样给出三个分离的 <br>

ICMP（echo）数据包！ <br>

========================= pthread ping ========================== <br>

#include ..... <br>

#define IP_HEAD_LEN 20 <br>

#define ICMP_LEN 8 <br>

#define TIMEOUT 2    //second <br>

void send_icmp(int j); <br>

int recv_icmp(int j); <br>

unsigned short ip_checksum( unsigned short *pcheck, int check_len); <br>

typedef struct destnation{ <br>

    char destip[16]; <br>

    int i; <br>

}destnation_ping; <br>

destnation_ping ping_dst[3]; <br>

char send_buf[3][1024]; <br>

char recv_buf[3][1024]; <br>

int p_id[3]; <br>

int sequence[3]; <br>

int icmp_fd[3]; <br>



int packet_len=IP_HEAD_LEN+ICMP_LEN; <br>

int pingf=0;    // timeout flags <br>

int icmp_back=0;// Works for return int * <br>

struct sockaddr_in send_addr[3]; <br>

fd_set fdR[3]; <br>

/* <br>

* timeout_p:用于处理超时原因引起的备份服务器操作 <br>

*/ <br>

void timeout_p() <br>

{ <br>

    pingf=0; <br>

    printf("\nThe last result: --%d--\n\n", pingf); <br>

} <br>

/* <br>

* send_icmp:用于发送含ICMP报文的IP数据包 <br>

*/ <br>

void send_icmp(int j) <br>

{ <br>

    int len; <br>

    struct icmphdr *icmp_p; <br>

    icmp_p=(struct icmphdr *)send_buf[j]; <br>

    /* 填写ICMP报文的类型 */ <br>



    icmp_p->type=ICMP_ECHO; <br>

    /* 填写ICMP报文的代码 */ <br>

    icmp_p->code=0; <br>

    /* 填写ICMP报文的标示符 */ <br>

    (icmp_p->un).echo.id=p_id[j]; <br>

    /* 填写ICMP报文的序号 */ <br>

    (icmp_p->un).echo.sequence=sequence[j]; <br>

    gettimeofday( (struct timeval *)(icmp_p+1), NULL); <br>

    /*报文的长度等于IP包头的长度加上ICMP报文头的长度和数据的长度 */ <br>

    len=sizeof(struct timeval)+packet_len; <br>

    /* 使用IP计算IP包头校验和的计算方法来计算ICMP的校验和 */ <br>

    icmp_p->checksum=0; <br>

    icmp_p->checksum=ip_checksum( (u_short *)icmp_p, len); <br>

    /* 发送IP书记包 */ <br>

    printf("sendto %s. sequence[%d]=%d\n", inet_ntoa(send_addr[j].sin_addr), <br>

  <br>

                        j, sequence[j]); <br>

    len=sendto(icmp_fd[j], send_buf[j], len, 0, <br>

        (struct sockaddr *)&send_addr[j], sizeof(send_addr[j])); <br>

    if(len<0) <br>

        fprintf(stderr, "sendto error.\n"); <br>

    sequence[j]++; <br>



} <br>

/* <br>

* recv_icmp() 用于接受包含ICMP包文的IP数据包 <br>

*/ <br>

int recv_icmp(int j) <br>

{ <br>

    int len; <br>

    int n=0; <br>

    struct ip *ip_p; <br>

    struct timeval *time_now, *time_send; <br>

    struct timeval now, timeout; <br>

    int iphead_len; <br>

    int icmp_len; <br>

    struct icmphdr* icmp_p; <br>

    float delay; <br>

    timeout.tv_sec=TIMEOUT; <br>

    timeout.tv_usec=0; <br>

    FD_SET(icmp_fd[j], &fdR[j]); <br>

    switch( select(icmp_fd[j]+1, &fdR[j], NULL, NULL, &timeout)){ <br>

        case -1: <br>

        perror("select"); <br>

        close(icmp_fd[j]); <br>



        return(1); <br>

        case 0: <br>

        printf("timeout\n"); <br>

        close(icmp_fd[j]); <br>

        pingf++;    // Tell main file the ping is timeout; <br>

        return(1); <br>

        default: <br>

        if( FD_ISSET(icmp_fd[j], &fdR[j])){ <br>

            n=recvfrom(icmp_fd[j],recv_buf[j], sizeof(recv_buf[j]),0,NULL,NU <br>

LL); <br>

            if(n<0){ <br>

            if(errno==EINTR){ <br>

                perror("receive"); <br>

            }else{ <br>

                printf("recvfrom error"); <br>

                perror("receive"); <br>

            } <br>

            } <br>

            ip_p=(struct ip*)recv_buf[j]; <br>

            /* 获取IP包头的长度*/ <br>

            iphead_len=ip_p->ip_hl<<2; <br>

            /* 获取IP数据包中包含的ICMP报文 */ <br>



            icmp_p=(struct icmphdr *)(recv_buf[j]+iphead_len); <br>

            /* 计算ICMP报文的长度，它等于接收到的长度减去IP包头的长度 */ <br>

            icmp_len=n-iphead_len; <br>

            if(icmp_len<8) <br>

            fprintf(stderr, "error icmp len=%d.\n", icmp_len); <br>

            /* 如果ICMP的类型相同则输出显示 */ <br>

            if(icmp_p->type==ICMP_ECHOREPLY){ <br>

            if(( icmp_p->un).echo.id!=p_id[j]) <br>

                return 0; <br>

            if( icmp_len<16) <br>

                printf("icmplen=%d.\n", icmp_len); <br>

            gettimeofday(&now, NULL); <br>

            time_now=&now; <br>

            time_send=(struct timeval*)(icmp_p+1); <br>

            if(time_now->tv_usec-=time_send->tv_usec<0){ <br>

                time_now->tv_sec--; <br>

                time_now->tv_usec+=1000000; <br>

            } <br>

            time_now->tv_sec-=time_send->tv_sec; <br>

            /* 计算时延长度 */ <br>

            delay=time_now->tv_sec*1000.0+time_now->tv_usec/1000.0; <br>

            printf("%d bytes recv from %s: sequence=%d, ttl=%d, rtt=%fms.\n" <br>



  <br>

,icmp_len, inet_ntoa(send_addr[j].sin_addr), (icmp_p->un).echo.sequence, ip_ <br>

p->ip_ttl, <br>

delay); <br>

            close(icmp_fd[j]); <br>

            return(1); <br>

            } <br>

        } <br>

    } //End of switch <br>

    close(icmp_fd[j]); <br>

} <br>

/* <br>

*    ip_checksum:IP数据包头校验和的计算方法 <br>

*/ <br>

unsigned short ip_checksum(unsigned short *pcheck, int check_len) <br>

{ <br>

    int nleft=check_len; <br>

    int sum=0; <br>

    unsigned short *p=pcheck; <br>

    unsigned short result=0; <br>

    while(nleft>1){ <br>

        sum=sum+(*p++); <br>



        nleft-=2; <br>

    } <br>

    if(nleft==1){ <br>

        *(unsigned char *)(&result)=*(unsigned char *)p; <br>

        sum+=result; <br>

    } <br>

    sum=(sum>>16)+(sum&0xFFFF); <br>

    sum+=(sum>>16); <br>

    result=~sum; <br>

    return result; <br>

} <br>

int *ping(struct destnation *ipaddr) <br>

{ <br>

    p_id[ipaddr->i]==getpid(); <br>

//    setuid(getuid()); <br>

    inet_aton(ipaddr->destip, &send_addr[ipaddr->i].sin_addr); <br>

    icmp_fd[ipaddr->i]=socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); <br>

    if(icmp_fd[ipaddr->i]<0){ <br>

        fprintf(stderr, "raw socket error.\n"); <br>

        icmp_back=1; <br>

        return(&icmp_back); <br>

    } <br>

    } <br>

    send_icmp(ipaddr->i); <br>

    icmp_back=recv_icmp(ipaddr->i); <br>

} <br>

int main() <br>

{ <br>

    char line[128]; <br>

    pthread_t p_tid[3]; <br>

    int p_return[3; <br>

    sequence[0]=random(); <br>

    sequence[1]=random(); <br>

    sequence[2]=random(); <br>

    printf("\n After random <br>

sequence={%d,%d,%d}\n\n",sequence[0],sequence[1],sequence[2]); <br>

    strncpy( ping_dst[0].destip, "192.168.1.10", 16); <br>

    strncpy( ping_dst[1].destip, "192.168.1.11", 16); <br>

    strncpy( ping_dst[2].destip, "192.168.1.12", 16); <br>

    ping_dst[0].i=0; <br>

    ping_dst[1].i=1; <br>

    ping_dst[2].i=2; <br>

    while(1){ <br>

        bzero(recv_buf, 3*sizeof(recv_buf[0])); <br>

        pthread_create(&p_tid[0],NULL,(void *)ping,(void *)&ping_dst[0]); <br>



        pthread_create(&p_tid[1],NULL,(void *)ping,(void *)&ping_dst[1]); <br>

        pthread_create(&p_tid[2],NULL,(void *)ping,(void *)&ping_dst[2]); <br>

        pthread_join(p_tid[0], (void *)&p_return[0]); <br>

        pthread_join(p_tid[1], (void *)&p_return[1]); <br>

        pthread_join(p_tid[2], (void *)&p_return[2]); <br>

        printf("\n=============== SLEEPING 10 sec =============\n\n"); <br>

        sleep(10); <br>

    } <br>

    printf("Main id =%d\n", getpid()); <br>

} <br>

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