C语言检查本机公网IP并发送邮件

    这是一个用来获取本机公网IP地址，并检查是否是配置里保存的IP地址，假设不是，就向指定的邮箱发送一个邮件，报告这个IP地址的一段小代码。放到开机启动中，电脑不设password的时候万一丢了，还能有个念想..........功能不强——仅仅简单实现了获取地址，发送邮件的功能，仅供练习之用，并且仅仅能用163的邮箱来发邮件......

    发送邮件的函数是百度上copy的，仅仅是简单的改动了一下

#include <windows.h>
#include <stdio.h>
#include <WinSock.h>
#include <URLMON.H>
#include <FSTREAM>
#include <iostream>
#define N 500
using namespace std;
#pragma  comment(lib, "ws2_32.lib")
#pragma comment(lib,"urlmon.lib")

struct Base64Date6
{
	unsigned int d4:6;
	unsigned int d3:6;
	unsigned int d2:6;
	unsigned int d1:6;
};
// 协议中加密部分使用的是base64方法
char ConvertToBase64  (char   c6);
void EncodeBase64     (char   *dbuf, char *buf128, int len);
void SendMail         (char   *emailTo,char *emailFrom,char *emailPd,char *body);
int  OpenSocket       (struct sockaddr *addr);

int CheckIP(char currentIP[])       //0读取文件失败，1IP非信任 2下载文件失败 3信任的IP地址
{
	HRESULT hr=URLDownloadToFile(0,"http://www.ip138.com/ips1388.asp","currentIP.txt",0,NULL);
	if(hr!=S_OK)
	{
		return 2;
	}
	ifstream readFile("IPlist.txt");
	if(!readFile)
	{
		cout<<"Can‘t find IPlist.txt"<<endl;
		return 0;
	}
	char listIP[N];
	readFile.getline(listIP,N,‘\n‘);
	readFile.close();
	readFile.clear();
	readFile.open("currentIP.txt");
	if(!readFile)
	{
		cout<<"Can‘t find currentIP.txt"<<endl;
		return 0;
	}
	char readTemp[N*4];
	while(!readFile.eof())
	{
			readFile.getline(readTemp,N*4,‘\n‘);  //getline函数參数说明：參数1-->指针头，參数2-->最大读取值，參数3-->读取结束符
			if(readFile.fail()) break;
			else 
			{
				char *temp=strstr(readTemp,"您的IP地址是");
				if(temp!=NULL)
				{
					temp=strchr(temp,‘[‘);
					for(int i=0;;i++)
					{
						if(temp[i+1]==‘]‘) 
						{
							currentIP[i]=‘\0‘;
							break;
						}
						else
							currentIP[i]=temp[i+1];
					}
					break;
				}
			}
	}
	readFile.close();
	readFile.clear();
	char *p=strstr(listIP,currentIP);
	if(p!=NULL) 
	{
		cout<<"Been trusted!"<<endl;
		return 3;
	}
	else 
	{
		cout<<"Unknown Address!Send E-mail immediately!"<<endl;
		return 1;
	}
}

int main()
{
	char currentIP[16];
	int n=0,ir;
	while(1)
	{
		ir=CheckIP(currentIP);
		if(ir==2)
		{
			if(n!=10)
			{
				cout<<"Connection failed...It‘s too bad!I will try again one minute later."<<endl;
				n++;
				Sleep(60*1000);
			}
			else
			{
				cout<<"Connection failed for 10 times.Application will exit immediately!"<<endl;
				return 0;
			}
		}
		else 
			break;
	}
	if(ir==0)
	{
		cout<<"Read file error!Application will exit immediately!"<<endl;
		return 0;
	}
	else if(ir==3)
	{
		cout<<"Been trusted!Have fun!"<<endl;
		return 0;
	}
	else 
	{
		char emailTo[100];
		char emailFrom[100];
		char emailPd[100];
		fstream readFile("email.ini");
		if(!readFile)
		{
			cout<<"Can‘t open email.ini"<<endl;
			return 0;
		}
		while(!readFile.eof())
		{
			readFile.getline(emailTo,100,‘\n‘);  //getline函数參数说明：參数1-->指针头，參数2-->最大读取值，參数3-->读取结束符
			readFile.getline(emailFrom,100,‘\n‘);
			readFile.getline(emailPd,100,‘\n‘);
		}
		readFile.close();
		readFile.clear();
		char EmailContents[N]   = "From: \"YourPC\"<110110110@163.com>\r\n"
			"To: \"MyMaster\"<911911911@163.com>\r\n"
			"Subject: IP address has been changed!\r\n\r\n";
		strcat(EmailContents,"The address is:");
		strcat(EmailContents,currentIP);
		strcat(EmailContents,"!!!Please check!");
		SendMail(emailTo,emailFrom,emailPd,EmailContents);
		return 0;
	}
}

char ConvertToBase64(char uc)
{
	if(uc < 26)
	{
		return ‘A‘ + uc;
	}
	if(uc < 52)
	{
		return ‘a‘ + (uc - 26);
	}
	if(uc < 62)
	{
		return ‘0‘ + (uc - 52);
	}
	if(uc == 62)
	{
		return ‘+‘;
	}
	return ‘/‘;
}

// base64的实现
void EncodeBase64(char *dbuf, char *buf128, int len)
{
	struct Base64Date6 *ddd      = NULL;
	int           i        = 0;
	char          buf[256] = {0};
	char          *tmp     = NULL;
	char          cc       = ‘\0‘;

	memset(buf, 0, 256);
	strcpy_s(buf, 256, buf128);
	for(i = 1; i <= len/3; i++)
	{
		tmp             = buf + (i-1)*3;
		cc              = tmp[2];
		tmp[2]          = tmp[0];
		tmp[0]          = cc;
		ddd             = (struct Base64Date6 *)tmp;
		dbuf[(i-1)*4+0] = ConvertToBase64((unsigned int)ddd->d1);
		dbuf[(i-1)*4+1] = ConvertToBase64((unsigned int)ddd->d2);
		dbuf[(i-1)*4+2] = ConvertToBase64((unsigned int)ddd->d3);
		dbuf[(i-1)*4+3] = ConvertToBase64((unsigned int)ddd->d4);
	}
	if(len % 3 == 1)
	{
		tmp             = buf + (i-1)*3;
		cc              = tmp[2];
		tmp[2]          = tmp[0];
		tmp[0]          = cc;
		ddd             = (struct Base64Date6 *)tmp;
		dbuf[(i-1)*4+0] = ConvertToBase64((unsigned int)ddd->d1);
		dbuf[(i-1)*4+1] = ConvertToBase64((unsigned int)ddd->d2);
		dbuf[(i-1)*4+2] = ‘=‘;
		dbuf[(i-1)*4+3] = ‘=‘;
	}
	if(len%3 == 2)
	{
		tmp             = buf+(i-1)*3;
		cc              = tmp[2];
		tmp[2]          = tmp[0];
		tmp[0]          = cc;
		ddd             = (struct Base64Date6 *)tmp;
		dbuf[(i-1)*4+0] = ConvertToBase64((unsigned int)ddd->d1);
		dbuf[(i-1)*4+1] = ConvertToBase64((unsigned int)ddd->d2);
		dbuf[(i-1)*4+2] = ConvertToBase64((unsigned int)ddd->d3);
		dbuf[(i-1)*4+3] = ‘=‘;
	}
	return;
}
// 发送邮件
void SendMail(char *emailTo,char *emailFrom,char *emailPd,char *body)
{
	int     sockfd     = {0};
	char    buf[1500]  = {0};
	char    rbuf[1500] = {0};
	char    login[128] = {0};
	char    pass[128]  = {0};
	WSADATA WSAData;
	struct sockaddr_in their_addr = {0};
	WSAStartup(MAKEWORD(2, 2), &WSAData);
	memset(&their_addr, 0, sizeof(their_addr));

	their_addr.sin_family = AF_INET;
	their_addr.sin_port   = htons(25);
	hostent* hptr         = gethostbyname("smtp.163.com"); 
	memcpy(&their_addr.sin_addr.S_un.S_addr, hptr->h_addr_list[0], hptr->h_length); 
	printf("IP of smpt.163.com is : %d:%d:%d:%d\n", 
		their_addr.sin_addr.S_un.S_un_b.s_b1, 
		their_addr.sin_addr.S_un.S_un_b.s_b2, 
		their_addr.sin_addr.S_un.S_un_b.s_b3, 
		their_addr.sin_addr.S_un.S_un_b.s_b4); 

	// 连接邮件server，假设连接后没有响应，则2 秒后又一次连接
	sockfd = OpenSocket((struct sockaddr *)&their_addr);
	memset(rbuf, 0, 1500);
	while(recv(sockfd, rbuf, 1500, 0) == 0)
	{
		cout<<"reconnect..."<<endl;
		Sleep(2000);
		sockfd = OpenSocket((struct sockaddr *)&their_addr);
		memset(rbuf, 0, 1500);
	}

	cout<<rbuf<<endl;

	// EHLO
	memset(buf, 0, 1500);
	sprintf_s(buf, 1500, "EHLO HYL-PC\r\n");
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"EHLO REceive: "<<rbuf<<endl;

	// AUTH LOGIN
	memset(buf, 0, 1500);
	sprintf_s(buf, 1500, "AUTH LOGIN\r\n");
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Auth Login Receive: "<<rbuf<<endl;

	// USER
	memset(buf, 0, 1500);
	sprintf_s(buf, 1500, emailFrom);//你的邮箱账号
	memset(login, 0, 128);
	EncodeBase64(login, buf, strlen(buf));
	sprintf_s(buf, 1500, "%s\r\n", login);
	send(sockfd, buf, strlen(buf), 0);
	cout<<"Base64 UserName: "<<buf<<endl;
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"User Login Receive: "<<rbuf<<endl;

	// PASSWORD
	sprintf_s(buf, 1500, emailPd);//你的邮箱password
	memset(pass, 0, 128);
	EncodeBase64(pass, buf, strlen(buf));
	sprintf_s(buf, 1500, "%s\r\n", pass);
	send(sockfd, buf, strlen(buf), 0);
	cout<<"Base64 Password: "<<buf<<endl;

	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Send Password Receive: "<<rbuf<<endl;
	// MAIL FROM
	char mailFrom[100]="MAIL FROM: <";
	strcat(mailFrom,emailFrom);
	strcat(mailFrom,">\r\n");
	memset(buf, 0, 1500);
	sprintf_s(buf, 1500, mailFrom);
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"set Mail From Receive: "<<rbuf<<endl;
	// RCPT TO 第一个收件人
	sprintf_s(buf, 1500, "RCPT TO:<%s>\r\n", emailTo);
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Tell Sendto Receive: "<<rbuf<<endl;

	// DATA 准备開始发送邮件内容
	sprintf_s(buf, 1500, "DATA\r\n");
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Send Mail Prepare Receive: "<<rbuf<<endl;

	// 发送邮件内容，\r\n.\r\n内容结束标记
	sprintf_s(buf, 1500, "%s\r\n.\r\n", body);
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Send Mail Receive: "<<rbuf<<endl;

	// QUIT
	sprintf_s(buf, 1500, "QUIT\r\n");
	send(sockfd, buf, strlen(buf), 0);
	memset(rbuf, 0, 1500);
	recv(sockfd, rbuf, 1500, 0);
	cout<<"Quit Receive: "<<rbuf<<endl;

	//清理工作
	closesocket(sockfd);
	WSACleanup();
	return;
}
// 打开TCP Socket连接
int OpenSocket(struct sockaddr *addr)
{
	int sockfd = 0;
	sockfd=socket(PF_INET, SOCK_STREAM, 0);
	if(sockfd < 0)
	{
		cout<<"Open sockfd(TCP) error!"<<endl;
		exit(-1);
	}
	if(connect(sockfd, addr, sizeof(struct sockaddr)) < 0)
	{
		cout<<"Connect sockfd(TCP) error!"<<endl;
		exit(-1);
	}
	return sockfd;
} 

附上资源下载地址：http://download.csdn.net/detail/yangyangsnr/7367321。