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

// 定義ICMP信息類型
#define ICMP_ECHOREPLY      0  // 回應答復
#define ICMP_DESTUNREACH    3  // 目標機無法到達
#define ICMP_ECHO           8  // 回應請求
#define ICMP_TIMEOUT       11  // 超時消息
#define MAX_HOPS           30  // 默認的最大跳數
#define ICMP_PACKET_MIN    8   // 最小的ICMP包長度
#define ICMP_PACKET_SIZE   32  
#define MAX_PACKET_SIZE    1024

// 定義IP首部格式
typedef struct _IPHeader 
{
	u_char  VIHL;			// 版本和首部長度
	u_char	ToS;			// 服務類型
	u_short	TotalLen;		// 總長度
	u_short	ID;			// 標識號
	u_short	Frag_Flags;		// 段偏移量
	u_char	TTL;			// 生存時間
	u_char	Protocol;		// 協議
	u_short	Checksum;		// 首部校驗和
	struct	in_addr SrcIP;	// 源IP地址
	struct	in_addr DestIP;	// 目的地址  
} IPHeader;

// 定義ICMP首部格式
typedef struct _ICMPHeader 
{
    unsigned char   Type;    // 類型          
    unsigned char   Code;    // 代碼             
    u_short Checksum;        // 首部校驗和      
    u_short ID;              // 標識  
    u_short Seq;             // 序列號   
    u_long Timestamp;        // 時間戳
} ICMPHeader;


// 計算校驗和
u_short checksum(u_short *buffer, int len)
{
	register int nleft = len;
	register u_short *w = buffer;
	register u_short answer;
	register int sum = 0;
    // 使用32bit的累加器，進行16bit的反饋計算
	while( nleft > 1 )  {
		sum += *w++;
		nleft -= 2;
	}
	// 補全奇數位
	if( nleft == 1 ) {
		u_short	u = 0;

		*(u_char *)(&u) = *(u_char *)w ;
		sum += u;
	}
    // 將反饋的16bit從高位移至地位
	sum = (sum >> 16) + (sum & 0xffff);	
	sum += (sum >> 16);			
	answer = ~sum;				
	return (answer);
}

// 設置套接字TTL值
int SetTTL(SOCKET s, int nTTL)
{
    int     ret;
    
    ret = setsockopt(s, IPPROTO_IP, IP_TTL, (LPSTR)&nTTL,
                sizeof(int));
    if (ret == SOCKET_ERROR)
    {
        printf("setsockopt(IP_TTL) error: %d\n", 
            WSAGetLastError());
        return 0;
    }
    return 1;
}

//解析回應數據包
int ParseResp(char *buf, int bytes, SOCKADDR_IN *src, int ttl)
{
    IPHeader       *iphdr = NULL;
    ICMPHeader     *icmphdr = NULL;
    unsigned short  iphdrlen;
    struct hostent *lpHostent = NULL;
    struct in_addr  inaddr = src->sin_addr;

    // 提取ICMP包
    icmphdr = (ICMPHeader*)(buf + sizeof(IPHeader));

    switch (icmphdr->Type)
    {
        case ICMP_ECHOREPLY:     // 得到回應
            lpHostent = gethostbyaddr((const char *)&src->sin_addr, 
                AF_INET, sizeof(struct in_addr));
            if (lpHostent != NULL)
                printf("%2d  %s [%s]\n", ttl, lpHostent->h_name, 
                    inet_ntoa(inaddr));
            return 1;
            break;
        case ICMP_TIMEOUT:      // 得到路由器超時信息
            printf("%2d  %s\n", ttl, inet_ntoa(inaddr));
            return 0;
            break;
        case ICMP_DESTUNREACH:  // 不能到達目的地址
            printf("%2d  %s  reports: Host is unreachable\n", ttl, 
                inet_ntoa(inaddr));
            return 1;
            break;
        default:
            printf("non-echo type %d recvd\n", icmphdr->Type);
            return 1;
            break;
    }
    return 0;
}


// 填充ICMP包
void FillIMCPData(char * icmp_data, int datasize)
{
    ICMPHeader *icmp_hdr;
    char       *datapart;

    icmp_hdr = (ICMPHeader*)icmp_data;

	// 設置ICMP包
    icmp_hdr->Type = ICMP_ECHO;
    icmp_hdr->Code = 0;
    icmp_hdr->ID   = (u_short)GetCurrentProcessId();
    icmp_hdr->Checksum = 0;
    icmp_hdr->Seq = 0;
  
    datapart = icmp_data + sizeof(ICMPHeader);
	// 在數據區域隨便填寫一些內容
    memset(datapart,'A', datasize - sizeof(ICMPHeader));
}

int main(int argc, char **argv)
{
    WSADATA      wsd;
    SOCKET       sockRaw;
    HOSTENT     *hp = NULL;
    SOCKADDR_IN  destAddr; // 源地址
    SOCKADDR_IN  srcAddr;  // 目標機地址
    int          ret;
    int          datasize;
    int          srclen = sizeof(srcAddr);
    int          timeout; // 超時時間
    int          done=0; // 標識是否探測完畢
    int          maxhops; // 最大跳數
    int          ttl = 1;
    char        *icmp_data; 
    char        *recvbuf;
    BOOL         bOpt;
    u_short      seq_no = 0;

    // 初始化Winsock
    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)
    {
        printf("WSAStartup() error: %d\n", GetLastError());
        return -1;
    }
    if (argc < 2)
		printf("usage: tracert host-name [max-hops]\n");
    if (argc == 3)
        maxhops = atoi(argv[2]);
    else
        maxhops = MAX_HOPS;
    // 創建ICMP類型的原始套接字
    sockRaw = WSASocket (AF_INET, SOCK_RAW, IPPROTO_ICMP,
                         NULL, 0,WSA_FLAG_OVERLAPPED);
    if (sockRaw == INVALID_SOCKET) 
    {
        printf("WSASocket() error: %d\n", WSAGetLastError());
        ExitProcess(-1);
    }
    // 設置超時時間
    timeout = 1000;
    ret = setsockopt(sockRaw, SOL_SOCKET, SO_RCVTIMEO, 
            (char *)&timeout, sizeof(timeout));
    if (ret == SOCKET_ERROR)
    {
        printf("setsockopt(SO_RCVTIMEO) error: %d\n", 
            WSAGetLastError());
        return -1;
    }
    timeout = 1000;
    ret = setsockopt(sockRaw, SOL_SOCKET, SO_SNDTIMEO, 
        (char *)&timeout, sizeof(timeout));
    if (ret == SOCKET_ERROR)
    {
        printf("setsockopt(SO_SNDTIMEO) error: %d\n", 
            WSAGetLastError());
        return -1;
    }

	
	
    // 解析主機IP地址，判斷是否有效
	memset(&destAddr,0,sizeof(destAddr));
    destAddr.sin_family = AF_INET;
    if ((destAddr.sin_addr.s_addr = inet_addr(argv[1])) == INADDR_NONE)
    {
        hp = gethostbyname(argv[1]);
        if (hp)
            memcpy(&(destAddr.sin_addr), hp->h_addr, hp->h_length);
        else
        {
            printf("Unable to resolve %s\n",argv[1]);
            ExitProcess(-1);
        }
    }
    // 設置發送的包大小
    datasize = ICMP_PACKET_SIZE;
        
    datasize += sizeof(ICMPHeader);  
    // 分配緩沖區空間
	icmp_data = new char[MAX_PACKET_SIZE];
	recvbuf = new char[MAX_PACKET_SIZE];

    // 設置套接字不路由，指示位于基層的網絡堆棧，忽略路由表的存在
    bOpt = TRUE;
    if (setsockopt(sockRaw, SOL_SOCKET, SO_DONTROUTE, (char *)&bOpt, 
            sizeof(BOOL)) == SOCKET_ERROR) 
        printf("setsockopt(SO_DONTROUTE) error: %d\n", 
            WSAGetLastError());

    // 填充ICMP首部
    memset(icmp_data, 0, MAX_PACKET_SIZE);
    FillIMCPData(icmp_data, datasize);

    printf("\nTracing route to %s [%s] over a maximum of %d hops:\n\n", 
        argv[1],inet_ntoa(destAddr.sin_addr), maxhops);

	// 開始循環探測路由
    for(ttl = 1; ((ttl < maxhops) && (!done)); ttl++)
    {

        // 設置套接字的TTL值
        SetTTL(sockRaw, ttl);

        // 設置ICMP首部數據段
        ((ICMPHeader*)icmp_data)->Checksum = 0;
        ((ICMPHeader*)icmp_data)->Timestamp = GetTickCount();
        ((ICMPHeader*)icmp_data)->Seq = seq_no++;
        ((ICMPHeader*)icmp_data)->Checksum = checksum((u_short*)icmp_data, 
            datasize);
        // 發送ICMP數據包到目標主機
        ret = sendto(sockRaw, icmp_data, datasize, 0, 
                    (SOCKADDR *)&destAddr, sizeof(destAddr));
        if (ret == SOCKET_ERROR)
        {
            if (WSAGetLastError() == WSAETIMEDOUT) 
            {
                printf("%2d  Send request timed out.\n", ttl);
                continue;
            }
            printf("sendto() error: %d\n", WSAGetLastError());
            return -1;
        }
        // 接收從目標機或路由返回的數據
        ret = recvfrom(sockRaw, recvbuf, MAX_PACKET_SIZE, 0, 
            (struct sockaddr*)&srcAddr, &srclen);
        if (ret == SOCKET_ERROR)
        {
            if (WSAGetLastError() == WSAETIMEDOUT) 
            {
                printf("%2d  Request timed out.\n", ttl);
                continue;
            }
            printf("recvsrc() error: %d\n", WSAGetLastError());
            return -1;
        }
        // 解析返回的響應
        done = ParseResp(recvbuf, ret, &srcAddr, ttl);
        Sleep(1000);
    }
	delete recvbuf;
	delete icmp_data;

    return 0;
}