sd = WSASocket(AF_INET, SOCK_RAW, IPPROTO_ICMP, 0, 0, 0);

//初试化RAW Socket, 设置ttl, 初试化dest// 返回值 <0 表失败int setup_for_ping(char* host, int ttl, SOCKET& sd, sockaddr_in& dest){    // Create the socket    sd = WSASocket(AF_INET, SOCK_RAW, IPPROTO_ICMP, 0, 0, 0);    if (sd == INVALID_SOCKET) {        cerr << "Failed to create raw socket: " << WSAGetLastError() <<                endl;        return -1;    }    if (setsockopt(sd, IPPROTO_IP, IP_TTL, (const char*)&ttl,             sizeof(ttl)) == SOCKET_ERROR) {        cerr << "TTL setsockopt failed: " << WSAGetLastError() << endl;        return -1;    }    // Initialize the destination host info block    memset(&dest, 0, sizeof(dest));    // Turn first passed parameter into an IP address to ping    unsigned int addr = inet_addr(host);    if (addr != INADDR_NONE) {        // It was a dotted quad number, so save result        dest.sin_addr.s_addr = addr;        dest.sin_family = AF_INET;    }    else {        // Not in dotted quad form, so try and look it up        hostent* hp = gethostbyname(host);        if (hp != 0) {            // Found an address for that host, so save it            memcpy(&(dest.sin_addr), hp->h_addr, hp->h_length);            dest.sin_family = hp->h_addrtype;        }        else {            // Not a recognized hostname either!            cerr << "Failed to resolve " << host << endl;            return -1;        }    }    return 0;}