//
// THIS CODE IS BASED ON THE CODE FROM 
// THE BOOK WINSOCK 2.0 BY LEWIS NAPPER...
// 
//

#include "RestfulFunc.h"

#if defined(_MSC_VER)

#include <winsock.h>

//路由选项类型，占用3字节
#define IP_RECORD_ROUTE 0x7
//IP时间戳选项
#define IP_TIMESTAMP 0x44
#define DEFAULT_PACKET_SIZE 32
#define MAX_PACKET 1024 + 12 + 20 + 1
#define MAX_IP_HDR_SIZE 60

//回送请求或回答
#define ICMP_ECHO 8
#define ICMP_ECHO_REPLY 0

#define MAX_UNSIGNED_SHORT 65535

#define DEFAULT_TIMEOUT 3000
#define DEFAULT_INTERVAL 1000

typedef struct _iphdr
{
	//注意顺序，网络字节序，大端
	unsigned int h_len : 4;
	unsigned int version : 4;

	unsigned char tos;				// type of service
	unsigned short total_len;		// Total length of the packet
	unsigned short ident;			// Unique identifier
	unsigned short frag_and_flags;	// 标志和片偏移
	unsigned char ttl;				// time to live
	unsigned char proto;
	unsigned short checksum;

	unsigned int sourceIP;
	unsigned int destIP;

}IpHeader;

#define DEFAULT_IP_HEAD_SIZE 20

typedef struct _icmphdr
{
	BYTE btType;		//type of icmp
	BYTE btCode;		// code of icmp 进一步定义查询或消息的类型 默认0
	USHORT usCksum;		//16bits 对ICMP头内容的一个补余求和

	USHORT usId;		//identification
	USHORT usSeq;

	//选项值
	ULONG ulTimestamp;

}IcmpHeader;

#define	DEFAULT_ICMP_HEAD_SIZE sizeof(IcmpHeader)

const double MAX_GSM_SIGNAL_STRENGTH = 31.0;


///*TODO: to implement!!!! (80374374@11/15/2023)*/
int PingTest(const std::string& dst_ip)
{
	return -1;
}


#else

#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<netinet/ip_icmp.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<sys/time.h>

typedef uint32_t DWORD;
typedef   int  SOCKET;
typedef struct sockaddr_in* LPSOCKADDR_IN;
typedef struct hostent* LPHOSTENT;

#define SOCKET_ERROR (-1)
#define FAILURE   (-1)
#define SIZE_LINE_NORMAL (1024)
#define SUCCESS (0)

#pragma pack(1)
#define ICMP_ECHOREPLY	0
#define ICMP_ECHOREQ	8

// IP Header -- RFC 791
typedef struct tagIPHDR
{
	u_char  VIHL;			// Version and IHL
	u_char	TOS;			    // Type Of Service
	short	TotLen;			// Total Length
	short	ID;				// Identification
	short	FlagOff;		// Flags and Fragment Offset
	u_char	TTL;			     // Time To Live
	u_char	Protocol;		// Protocol
	u_short	Checksum;		// Checksum
	struct	in_addr iaSrc;	// Internet Address - Source
	struct	in_addr iaDst;	// Internet Address - Destination
} IPHDR, * PIPHDR;


// ICMP Header - RFC 792
typedef struct tagICMPHDR
{
	u_char	Type;		     	// Type
	u_char	Code;			    // Code
	u_short	Checksum;		// Checksum
	u_short	ID;				   // Identification
	u_short	Seq;			       // Sequence
	char	Data;			       // Data
} ICMPHDR, * PICMPHDR;


#define REQ_DATASIZE 32		// Echo Request Data size

// ICMP Echo Request
typedef struct tagECHOREQUEST
{
	ICMPHDR icmpHdr;
	DWORD	dwTime;
	char	cData[REQ_DATASIZE];
} ECHOREQUEST, * PECHOREQUEST;


// ICMP Echo Reply
typedef struct tagECHOREPLY
{
	IPHDR	ipHdr;
	ECHOREQUEST	echoRequest;
	char    cFiller[256];
} ECHOREPLY, * PECHOREPLY;

#pragma pack()

static u_short api_checksum16(u_short* buffer, int size);
static int gen_icmp_packet(struct icmp* icmp_packet, int type, int seq);

int gen_icmp_packet(struct icmp* icmp_packet, int type, int seq)
{
	if (!icmp_packet) {
		return FAILURE;
	}

	icmp_packet->icmp_type = type;
	icmp_packet->icmp_code = 0;
	icmp_packet->icmp_cksum = 0;
	icmp_packet->icmp_id = htons(getpid());
	icmp_packet->icmp_seq = htons(seq);

	gettimeofday((struct timeval*)icmp_packet->icmp_data, NULL);
	icmp_packet->icmp_cksum = api_checksum16((unsigned short*)icmp_packet, sizeof(struct icmp));

	return SUCCESS;
}

u_short api_checksum16(u_short* buffer, int size)
{
	u_int cksum = 0;

	if (!buffer) {
		printf("NULL\n");
		return 0;
	}

	while (size > 1) {
		printf("1. Cksum: 0x%08x + 0x%04x\n", cksum, *buffer);
		cksum += *buffer++;
		size -= sizeof(u_short);
	}

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

	printf("2. Cksum: 0x%08x\n", cksum);

	/* 32 bit change to 16 bit */
	while (cksum >> 16) {
		cksum = (cksum >> 16) + (cksum & 0xFFFF);
		printf("3. Cksum: 0x%08x\n", cksum);
	}

	return (u_short)(~cksum);
}

int PingTest(const std::string& dst_ip)
{
	int ret = FAILURE;
	int sd = 0;

	char buf[SIZE_LINE_NORMAL] = { 0 };

	struct ip* ip = NULL;
	struct sockaddr_in dst_addr = { 0 };
	struct icmp icmp_packet = { 0 };

	struct timeval tm = { .tv_sec = 1, .tv_usec = 0 };

	fd_set rdfds;

	if (dst_ip.empty()) {
		goto _E1;
	}

	sd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
	if (sd < 0) {
		printf("socket fail: %d\n", errno);
		goto _E1;
	}

	dst_addr.sin_family = AF_INET;
	dst_addr.sin_addr.s_addr = inet_addr(dst_ip.c_str());

	ret = gen_icmp_packet(&icmp_packet, 8, 1);
	if (SUCCESS != ret) {
		goto _E2;
	}

	ret = sendto(sd, &icmp_packet, sizeof(struct icmp), 0,
		(struct sockaddr*)&dst_addr, sizeof(struct sockaddr_in));
	if (ret < 0) {
		goto _E2;
	}

	/* Timeout 1s to recv icmp */
	FD_ZERO(&rdfds);
	FD_SET(sd, &rdfds);

	ret = select(sd + 1, &rdfds, NULL, NULL, &tm);
	if (-1 == ret && EINTR != errno) {
		/* if serial error */
		printf("select fail\n");
		goto _E2;
	} else if (0 == ret) {
		/* timeout */
		printf("recv timeout\n");
		ret = FAILURE;
		goto _E2;
	}
	if (FD_ISSET(sd, &rdfds)) {
		ret = recv(sd, buf, sizeof(buf), 0);
		if (ret <= 0) {
			perror("recv\n");
			goto _E2;
		}

		ip = (struct ip*)buf;
		printf("from: %s\n", inet_ntoa(ip->ip_src));
		printf("  to: %s\n", inet_ntoa(ip->ip_dst));
	}

	ret = SUCCESS;

_E2:
	close(sd);
_E1:
	return ret;
}


#endif //_MSC_VER