#include <winsock2.h>
#include <iostream>
#include <windows.h>
#include <tchar.h>

using namespace std;

#define DATA_SIZE 32
#define RECV_MAX_SIZE 1024
#pragma comment(lib, "ws2_32.lib")//该库对应ws2_32.dll，提供了一些网络相关API的支持

typedef struct tag_icmphdr		//icmp头，长8字节
{
	unsigned char	icmp_type;		//ICMP类型，只用8号和0号数据报，回送请求和回送回答报文
	unsigned char	icmp_code;		//ICMP代码
	unsigned short	icmp_checksum;	//ICMP校验和
	unsigned short	icmp_id;		//ICMP标识符
	unsigned short	icmp_sequence;	//ICMP序列号
	unsigned long	icmp_timestamp; //ICMP时间戳
} ICMPHDR, *PICMPHDR;

typedef struct tag_iphdr		//ip头，长20字节
{
	UCHAR	iphVerLen;
	UCHAR	ipTOS;
	USHORT	ipLength;
	USHORT	ipID;
	USHORT	ipFlags;
	UCHAR	ipTTL;
	UCHAR	ipProtacol;
	USHORT	ipChecksum;
	ULONG	ipSource;
	ULONG	ipDestination;
} IPHDR;

USHORT CheckSum(USHORT *buf, int size)//计算校验和
{
	USHORT cksum = 0;
	while (size>1)
	{
		cksum += *buf++;
		size -= sizeof(USHORT);
	}
	if (size)
		cksum += *buf++;
	cksum = (cksum >> 16) + (cksum & 0xffff);
	cksum += (cksum >> 16);
	return (USHORT)(~cksum);
}

void FillIcmp(PICMPHDR p) //ICMP报文填充
{
	p->icmp_type = 8;	//ICMP报文类型8，不同类型结构不同
	p->icmp_code = 0;
	p->icmp_checksum = 0;
	p->icmp_id = (unsigned short)::GetCurrentProcessId();//按进程号处理
	p->icmp_sequence = 0;
	p->icmp_timestamp = 0;
}

int _tmain(int argc, _TCHAR* argv[])
{
	//初始化套接字环境
	WORD version = MAKEWORD(2, 2);
	WSADATA data;
	WSAStartup(version, &data);
	if (LOBYTE(data.wVersion) != 2 || HIBYTE(data.wVersion) != 2)
	{
		cout << "WSAStartup failed" << endl;
		WSACleanup();//关闭环境
		return 0;
	}

	char ip[20]; //IP地址
	cout << "ping: ";
	cin >> ip;

	SOCKADDR_IN addr;															//目标主机地址，仅使用IP地址，不含域名解析
	addr.sin_family = AF_INET;
	addr.sin_addr.S_un.S_addr = inet_addr(ip);
	addr.sin_port = htons(0);

	SOCKET sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);						//创建原始套接字（缺少错误处理）

	int outTime = 3000;	//超时时间，设为3秒
	int rst;

	rst = setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char*)&outTime, sizeof(int));	//设置发送时限
	if (SOCKET_ERROR == rst)
	{
		cout << "setsockopt error" << endl;
		closesocket(sock);
		WSACleanup();
		return -1;
	}

	rst = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char*)&outTime, sizeof(int));	//设置接收时限
	if (SOCKET_ERROR == rst)
	{
		cout << "setsockopt error" << endl;
		closesocket(sock);
		WSACleanup();
		return -1;
	}


	char *icmp = (char*)malloc(sizeof(ICMPHDR) + DATA_SIZE);	//为icmp包申请内存
	memset(icmp, 0, sizeof(ICMPHDR) + DATA_SIZE);				//内存空间置零
	PICMPHDR picmp = (PICMPHDR)icmp;

	FillIcmp(picmp);		//填充icmp包

	unsigned short sequence = 0;	//序列号
	int count = 4;					//发送请求次数,一般4次
	char recvbuf[RECV_MAX_SIZE];	//创建接收缓冲区，最大1024字节
	SOCKADDR_IN addrfrom;			//接收地址
	int len = sizeof(SOCKADDR);		//地址大小
	int ipTTL = 0;					//TTL

	while (count--)
	{//每次请求中：
		picmp->icmp_checksum = 0;
		picmp->icmp_timestamp = ::GetTickCount();	//获取当前时间作为时间戳
		picmp->icmp_sequence = sequence++;
		picmp->icmp_checksum = CheckSum((USHORT*)icmp, sizeof(ICMPHDR) + DATA_SIZE);

		int result;
		result = sendto(sock, icmp, sizeof(ICMPHDR) + DATA_SIZE, 0, (SOCKADDR*)&addr, sizeof(SOCKADDR));//向目标主机发送icmp请求包
		if (SOCKET_ERROR == result)
		{
			if (WSAETIMEDOUT == WSAGetLastError())
			{
				cout << "time out" << endl;
				continue;
			}
			else
			{
				cout << "sendto error" << endl;
				closesocket(sock);
				WSACleanup();
				return -1;
			}
		}

		result = recvfrom(sock, recvbuf, RECV_MAX_SIZE, 0, (SOCKADDR*)&addrfrom, &len);//接收目标主机的icmp应答包
		if (SOCKET_ERROR == result)
		{
			if (WSAETIMEDOUT == GetLastError())
			{
				cout << "time out" << endl;
				continue;
			}
			else
			{
				cout << "recvform error" << endl;
				closesocket(sock);
				WSACleanup();
				return -1;
			}
		}

		int nTick = ::GetTickCount();//当前时间
		if (result < sizeof(IPHDR) + sizeof(ICMPHDR) + DATA_SIZE)
		{//检验收到包的大小
			cout << "too few bytes" << endl;
		}

		IPHDR *pIP = (IPHDR*)recvbuf;//缓冲区内容强制类型转换成hdr，可直接使用（一个解码过程）
		ipTTL = (int)pIP->ipTTL;	//获取目标主机TTL

		PICMPHDR p = (PICMPHDR)(recvbuf + sizeof(IPHDR));//指针p从IP头移动到ICMP头
		if (p->icmp_type != 0)
		{//收到错误类型的包
			cout << "error type " << p->icmp_type << " receved" << endl;
			return -1;
		}

		if (p->icmp_id != (USHORT)::GetCurrentProcessId())
		{//得到的包id错误
			cout << "someone else's packet" << endl;
			return -1;
		}

		cout << "reply from: " << inet_ntoa(addrfrom.sin_addr);
		cout << " data: " << DATA_SIZE << "bytes ";					//IP长8字节，ICMP长20字节，数据长32字节，共应60字节
		cout << " time: " << nTick - p->icmp_timestamp << "ms";		//传输时间=当前时间-ICMP产生时的时间
		cout << " TTL=" << ipTTL << endl;
	}
	system("pause");
	return 0;
}