原始套接字

 

利用原始套接字可以訪問位於基層的傳輸協議。原始套接字向程序員提供了讀寫IP/ICMP/IGMP以及構造特殊的IP報文的功能：

SOCKET s;
s=socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
//或者
WSASocket(AF_INET,SOCK_RAW,IPPROTO_TCMP,NULL,0,WSA_FLAG_OVERLAPPED);

一般情況下，原始套接字不調用bind和connect函數。

 

Ping程序：

#include<stdio.h>
#include<winsock2.h>
#include<ws2tcpip.h>
#include<process.h>
#pragma comment(lib,"ws2_32.lib")

typedef struct iphdr
{
    unsigned char ver_hlen;//4位IPv4版本的4位頭長度（用32位字表示）
    unsigned char tos;//服務的IP類型
    unsigned short total_len;//總長
    unsigned short ident;//唯一標識符
    unsigned short frag_and_flags;//片段偏移字段
    unsigned char ttl;//生存時間
    unsigned char proto;//協議
    unsigned short checksum;//IP校驗和
    unsigned int sourceIP;//源地址
    unsigned int destIP;//目的地址

}IPHeader;

typedef struct icmphdr
{
    unsigned char type;
    unsigned char code;
    unsigned short cksum;
    unsigned short id;
    unsigned short seq;
}ICMPHeader;

#define ICMP_ECHO_REPLY    0
#define ICMP_ECHO_REQUEST  8

#define PACKAGE_SIZE sizeof(IPHeader)+sizeof(ICMPHeader)

#define xmalloc(s)  HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,(s))
#define xfree(p)    HeapFree(GetProcessHeap(),0,(p))

void usage();
void HandleError(char *);
void FillPackage(char *, unsigned long, u_short);
USHORT CheckSum(USHORT*, int);

int main(int argc,char *argv[])
{
    unsigned long dstIP;
    BOOL bBroadcast = FALSE;
    if(argc==2)
    {
        dstIP=inet_addr(argv[1]);
        if(dstIP==INADDR_NONE)
        {
            usage();
            return -1;
        }
    }
    else if(argc==3)
    {
        if(strcmp(argv[1],"-b")!=0)
        {
            usage();
            return -1;
        }
    }
    else
    {
        usage();
        return -1;
    }

    int pid = _getpid();

    WSAData wsaData;
    WSAStartup(/*MAKEWORD(2,2)*/WINSOCK_VERSION, &wsaData);
    SOCKET sock = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
    if(INVALID_SOCKET==sock)
    {
        HandleError("socket");
        WSACleanup();
        return -1;
    }

    BOOL on = TRUE;
    if(SOCKET_ERROR==setsockopt(sock,IPPROTO_IP,IP_HDRINCL,(char*)&on,sizeof(on)))
    {
        HandleError("setsockopt");
        WSACleanup();
        return -1;
    }

    SOCKADDR_IN to,from;
    memset(&to,0,sizeof(to));
    to.sin_family=AF_INET;
    to.sin_addr.s_addr=dstIP;
    int len = sizeof(to);

    char *buf = (char*)xmalloc(PACKAGE_SIZE);
    struct timeval tv;
    fd_set readSet;

    BOOL bError = FALSE;
    for(int i=0;i<30&&!bError;i++)
    {
        printf("ping %s...%d\n",inet_ntoa(to.sin_addr),i+1);
        FillPackage(buf,dstIP,(u_short)pid);
        if(SOCKET_ERROR==sendto(sock,buf,PACKAGE_SIZE,0,(SOCKADDR*)&to,len))
        {
            HandleError("sendto");
            break;
        }
        while(TRUE)
        {
            tv.tv_sec=3;
            tv.tv_usec=0;
            FD_ZERO(&readSet);
            FD_SET(sock,&readSet);

            int res=select(sock+1,&readSet,NULL,NULL,&tv);
            if(SOCKET_ERROR==res)
            {
                HandleError("select");
                bError = TRUE;
                break;
            }
            if(0==res)
            {
                //printf("Error:%d\n",WSAGetLastError());
                if(!bBroadcast)
                    printf("time out!\n");
                break;
            }
            if(FD_ISSET(sock,&readSet))
            {
                memset(buf,0,PACKAGE_SIZE);
                memset(&from,0,sizeof(from));
                len=sizeof(from);
                if(SOCKET_ERROR==recvfrom(sock,buf,PACKAGE_SIZE,0,(SOCKADDR*)&from,&len))
                {
                    HandleError("recvfrom");
                    bError=TRUE;
                    break;
                }
                IPHeader *pIPHdr = (IPHeader*)buf;
                ICMPHeader *pICMPHdr = (ICMPHeader*)(buf+sizeof(IPHeader));
                if(pICMPHdr->id==htons((u_short)pid)
                    &&pICMPHdr->seq==htons((u_short)pid)
                    &&pICMPHdr->type==ICMP_ECHO_REPLY)
                {
                    printf("Echo Reply From %s.\n",inet_ntoa(from.sin_addr));
                    if(!bBroadcast)
                        break;
                }
            }
        }
    }
    xfree(buf);
    closesocket(sock);
    WSACleanup();

    system("pause");
    return 0;
}

void FillPackage(char * pData, unsigned long dstIP, u_short id)
{
    memset(pData,0,PACKAGE_SIZE);
    IPHeader *pIPHeader = (IPHeader*)pData;
    int nVersion = 4;
    int nHeadSize = sizeof(IPHeader)/4;
    unsigned long srcIP = inet_addr("192.168.1.222");//183.211.29.69
    unsigned long destIp = dstIP;

    pIPHeader->ver_hlen=(nVersion<<4)|nHeadSize;
    pIPHeader->tos=0;
    pIPHeader->total_len=htons(PACKAGE_SIZE);
    pIPHeader->ident=htons(1234);
    pIPHeader->frag_and_flags=0;
    pIPHeader->ttl=255;
    pIPHeader->proto=IPPROTO_ICMP;
    pIPHeader->checksum=0;
    pIPHeader->sourceIP=srcIP;
    pIPHeader->destIP=destIp;

    pIPHeader->checksum = CheckSum((USHORT*)pData,sizeof(IPHeader));

    ICMPHeader* pICMPHeader = (ICMPHeader*)(pData+sizeof(IPHeader));
    pICMPHeader->type=ICMP_ECHO_REQUEST;
    pICMPHeader->code=0;
    pICMPHeader->cksum=0;
    pICMPHeader->id=htons(id);
    pICMPHeader->seq=htons(id);
    pICMPHeader->cksum=CheckSum((USHORT*)((char*)pData+sizeof(IPHeader)),sizeof(ICMPHeader));
}

USHORT CheckSum(USHORT* pUShort, int size)
{
    unsigned long cksum = 0;

    while(size>1)
    {
        cksum += *pUShort++;
        size -= sizeof(USHORT);
    }
    if(size)
    {
        cksum += *(UCHAR*)pUShort;
    }
    cksum = (cksum>>16) + (cksum& 0xffff);
    cksum += (cksum>>16);

    return (USHORT)(~cksum);
}

void usage()
{
    printf("usage:ping [-b] hostIP\n");
    printf("notes:如果ping廣播地址必須加上-b，否則無法得到完整輸出.\n");
}

void HandleError(char *cfun)
{
    int errCode = WSAGetLastError();
    char info[65] = {0};
    _snprintf(info,64,"%s:  %d\n",cfun, errCode);
    printf(info);
}