rawsocket发送icmp包

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#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

#define PING_DATA_LEN 56

//ICMP消息头部
struct ICMPHeader
{
    unsigned char type;//消息类型
    unsigned char code;//消息代码
    unsigned short checksum;//校验和
    union{
        struct{
            unsigned short id;
            unsigned short sequence;
        }echo;
        unsigned int gateway;
        struct{
            unsigned short unsed;
            unsigned short nextmtu;
        }frag; //pmtu实现
    }un;
    unsigned char data[0];//ICMP数据占位符
};

struct IPHeader
{
    unsigned char headerLen:4;
    unsigned char version:4;
    unsigned char tos; //服务类型
    unsigned short totalLen; //总长度
    unsigned short id; //标识
    unsigned short flagOffset; //3位标志+13位片偏移
    unsigned char ttl; //TTL
    unsigned char protocol; //协议
    unsigned short checksum; //首部检验和
    unsigned int srcIP; //源IP地址
    unsigned int dstIP; //目的IP地址
};


//This function calculates the 16-bit one's complement sum
//of the supplied buffer (ICMP) header
unsigned short checksum(unsigned short* buffer, int size)
{
    unsigned long cksum = 0;

    while (size > 1)
    {
        cksum += *buffer++;
        size -= sizeof(unsigned short);
    }

    if (size)
    {
        cksum += *(unsigned char*)buffer;
    }

    cksum = (cksum>>16) + (cksum & 0xffff);
    cksum += (cksum>>16);

    return (unsigned short)(~cksum);
}

//校验和算法
unsigned short cal_chksum(unsigned short *addr,int len)
{
    int nleft=len;
    int sum=0;
    unsigned short *w=addr;
    unsigned short answer=0;

    //把ICMP报头二进制数据以2字节为单位累加起来
    while(nleft>1)
    {
        sum+=*w++;
        nleft-=2;
    }

    //若ICMP报头为奇数个字节，会剩下最后一字节。把最后一个字节视为一个2字节数据的高字节，这个2字节数据的低字节为0，继续累加
    if( nleft==1)
    {
        *(unsigned char *)(&answer)=*(unsigned char *)w;
        sum+=answer;
    }
    sum=(sum>>16)+(sum&0xffff);
    sum+=(sum>>16);
    answer=~sum;
    return answer;
}

//ip数字转字符串
void ip_ll_to_str(long long ip_num,char* ip_str)
{
    unsigned int iptok1 = (ip_num & 0xFF000000) >> 24;
    unsigned int iptok2 = (ip_num & 0x00FF0000) >> 16;
    unsigned int iptok3 = (ip_num & 0x0000FF00) >> 8;
    unsigned int iptok4 = ip_num & 0x000000FF;
    char ip[32];
    bzero(ip,sizeof(ip));
    snprintf(ip,sizeof(ip),"%d.%d.%d.%d",iptok1,iptok2,iptok3,iptok4);
    strcpy(ip_str,ip);
}

//发送ICMP报文
void send_icmp_packet(int sockfd,sockaddr_in* dst_addr,int pid,bool build_ip_protocl)
{
    char sendBuf[1024] = "";

    int totalLen = sizeof(IPHeader) + sizeof(ICMPHeader)+PING_DATA_LEN;
    int pos = 0;
    if(build_ip_protocl)
    {
        IPHeader* ipHeader = (IPHeader *)sendBuf;
        ipHeader->headerLen = sizeof(IPHeader)>>2;
        ipHeader->version = IPVERSION;
        //服务类型
        ipHeader->tos = 0;
        ipHeader->totalLen = htons(totalLen);
        ipHeader->id=0;
        //设置flag标记为0
        ipHeader->flagOffset=0;
        //运用的协议为ICMP协议
        ipHeader->protocol=IPPROTO_ICMP;
        //一个封包在网络上可以存活的时间
        ipHeader->ttl=255;
        //目的地址
        ipHeader->dstIP = dst_addr->sin_addr.s_addr;
        pos = sizeof(IPHeader);
    }

    ICMPHeader *icmpHeader = (ICMPHeader*)(sendBuf+pos);
    icmpHeader->type = ICMP_ECHO;
    icmpHeader->code = 0;
    icmpHeader->un.echo.id = pid;

    //计算校验和
    icmpHeader->checksum = cal_chksum( (unsigned short *)icmpHeader,totalLen);

    IPHeader* ipHeader = (IPHeader *)sendBuf;
    char ipHeaderStr[256] = "";
    char srcIPStr[64] = "",dstIPStr[64]="";
    ip_ll_to_str(ipHeader->srcIP,srcIPStr);
    ip_ll_to_str(ipHeader->dstIP,dstIPStr);
    snprintf(ipHeaderStr,sizeof(ipHeaderStr),"request ip header info: version:%d,tos:%d,protocol:%d,ttl:%d,srcIP:%s,dstIP:%s",ipHeader->version,ipHeader->tos,ipHeader->protocol,ipHeader->ttl,srcIPStr,dstIPStr);
    cout << ipHeaderStr << endl;

    if(sendto(sockfd,sendBuf,totalLen,0,(struct sockaddr *)dst_addr,sizeof(*dst_addr))<0){
        perror("sendto error");
    }
}


//接收解析ICMP报文
void parse_icmp_packet(int sockfd,int pid)
{
    sockaddr_in cliaddr;
    bzero(&cliaddr,sizeof(cliaddr));
    socklen_t cliLen = sizeof(cliaddr);
    char recvBuf[256] = "";
    int recvLen = recvfrom(sockfd,recvBuf,sizeof(recvBuf),0,(sockaddr*)&cliaddr,&cliLen);
    if( recvLen <0)
    {
        if(errno==EINTR){
            return;
        }
        printf("recvfrom error:%s",strerror(errno));
        return;
    }

    IPHeader *ipHeader = (IPHeader*)recvBuf;
    char ipHeaderStr[256] = "";
    char srcIPStr[64] = "",dstIPStr[64]="";
    ip_ll_to_str(ntohl(ipHeader->srcIP),srcIPStr);
    ip_ll_to_str(ntohl(ipHeader->dstIP),dstIPStr);
    snprintf(ipHeaderStr,sizeof(ipHeaderStr),"response ip header info: version:%d,tos:%d,protocol:%d,ttl:%d,srcIP:%s,dstIP:%s",ipHeader->version,ipHeader->tos,ipHeader->protocol,ipHeader->ttl,srcIPStr,dstIPStr);
    cout << ipHeaderStr << endl;

    int ipHeaderLen = sizeof(IPHeader);
    ICMPHeader *icmpHeader = (ICMPHeader *)(recvBuf+sizeof(IPHeader));  //越过ip报头,指向ICMP报头
    int icmpLen = recvLen - ipHeaderLen;
    //小于ICMP报头长度则不合理
    if( icmpLen < 8)
    {
        printf("ICMP packets/'s length is less than 8/n");
        exit(1);
    }
    //确保所接收的是我所发的的ICMP的回应
    if(icmpHeader->type!=ICMP_ECHOREPLY || icmpHeader->un.echo.id!=pid){
        exit(1);
    }
    char icmpStr[256] = "";
    snprintf(icmpStr,sizeof(icmpStr),"%d byte from %s: icmp_seq=%d,ttl=%dms",icmpLen,inet_ntoa(cliaddr.sin_addr),icmpHeader->un.echo.sequence,ipHeader->ttl);
    cout << icmpStr << endl;
}

int main()
{
    int sockfd = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
    if( sockfd < 0)
    {
        cout << strerror(errno) << endl;
        return -1;
    }

    //扩大套接字接收缓冲区到50K这样做主要为了减小接收缓冲区溢出的的可能性,若无意中ping一个广播地址或多播地址,将会引来大量应答
    int bufSize=50*1024;
    setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&bufSize,sizeof(bufSize) );

    //是否自己构造ip协议头
    bool build_ip_protocol = true;

    if(build_ip_protocol)
    {
        int on = 1;
        setsockopt(sockfd,IPPROTO_IP,IP_HDRINCL,&on,sizeof(on));
    }

    //用主机名或ip地址都可以
    //www.baidu.com
    char dst_str[32] = "220.181.112.244";
    sockaddr_in dst_addr;
    bzero(&dst_addr,sizeof(dst_addr));
    dst_addr.sin_family=AF_INET;
    dst_addr.sin_addr.s_addr = inet_addr(dst_str);

    if( dst_addr.sin_addr.s_addr == INADDR_NONE)
    {
        hostent *host=gethostbyname(dst_str);
        if(host==NULL) //是主机名
        {
            cout << "gethostbyname error:" << strerror(errno) <h_addr,host->h_length);
    }

    //获取main的进程id,用于设置ICMP的标志符
    int pid=getpid();

    //发送ICMP报文
    send_icmp_packet(sockfd,&dst_addr,pid,build_ip_protocol);

    cout << "PING " << dst_str << "(" << inet_ntoa(dst_addr.sin_addr) << ") " << PING_DATA_LEN << " bytes data in ICMP packets" << endl;

    //解析所有ICMP报文
    parse_icmp_packet(sockfd,pid);
    close(sockfd);
    return 0;

}


//这里的srcIP是0.0.0.0,但实际发出去的报文是我本地的ip,也就是说如果你没设置IP,则系统会自动给你加上IP
request ip header info: version:4,tos:0,protocol:1,ttl:255,srcIP:0.0.0.0,dstIP:244.112.181.220
PING 220.181.112.244(220.181.112.244) 56 bytes data in ICMP packets
response ip header info: version:4,tos:0,protocol:1,ttl:45,srcIP:220.181.112.244,dstIP:172.16.96.52
64 byte from 220.181.112.244: icmp_seq=0,ttl=45ms