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，如果不是，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，电脑不设密码的时候万一丢了，还能有个念想..........功能不强——只简单实现了获取地址，发送邮件的功能，仅供练习之用，而且只能用163的邮箱来发邮件......

附上资源下载地址

具体下载目录在 /2014年资料/5月/19日/C语言检查本机公网IP并发送邮件

发送邮件的函数是百度上copy的，只是简单的修改了一下

#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函数参数说明：参数1-->指针头，参数2-->最大读取值，参数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函数参数说明：参数1-->指针头，参数2-->最大读取值，参数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\"<[email protected]>\r\n"
   "To: \"MyMaster\"<[email protected]>\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);

 // 连接邮件服务器，如果连接后没有响应，则2 秒后重新连接
 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);//你的邮箱密码
 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 准备开始发送邮件内容
 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;
}

将C语言梳理一下，分布在以下10个章节中：

1. Linux-C成长之路（一）：Linux下C编程概要 http://www.linuxidc.com/Linux/2014-05/101242.htm
2. Linux-C成长之路（二）：基本数据类型 http://www.linuxidc.com/Linux/2014-05/101242p2.htm
3. Linux-C成长之路（三）：基本IO函数操作 http://www.linuxidc.com/Linux/2014-05/101242p3.htm
4. Linux-C成长之路（四）：运算符 http://www.linuxidc.com/Linux/2014-05/101242p4.htm
5. Linux-C成长之路（五）：控制流 http://www.linuxidc.com/Linux/2014-05/101242p5.htm
6. Linux-C成长之路（六）：函数要义 http://www.linuxidc.com/Linux/2014-05/101242p6.htm
7. Linux-C成长之路（七）：数组与指针 http://www.linuxidc.com/Linux/2014-05/101242p7.htm
8. Linux-C成长之路（八）：存储类，动态内存 http://www.linuxidc.com/Linux/2014-05/101242p8.htm
9. Linux-C成长之路（九）：复合数据类型 http://www.linuxidc.com/Linux/2014-05/101242p9.htm
10. Linux-C成长之路（十）：其他高级议题