C言語で簡単なSMTPメール送信を実現

//C       SMTP    
#include 
#include 
#include 
#include 
using namespace std;


/*
#pragma        ，           。
                         。
      C         ，             。
   #pragma  ，                     。
     : #pragma Para。  Para    。
*/
#pragma  comment(lib, "ws2_32.lib")
//  :http://blog.csdn.net/CL18652469346/article/details/53199167


struct Base64Date6
{
  unsigned int d4:6;
  unsigned int d3:6;
  unsigned int d2:6;
  unsigned int d1:6;
};

//            base64  
char ConvertToBase64  (char   c6);
void EncodeBase64     (char   *dbuf, char *buf128, int len);
void SendMail         (char   *email,char *body);
int  OpenSocket       (struct sockaddr *addr);

int main()
{
  char EmailTo[]         = "[email protected]";
  char EmailContents[]   = "From: \"lucy\"\r
"
                           "To: \"dasiy\"\r
"
                           "Subject: Hello\r
\r
"
                           "Hello World, Hello Email!";
  SendMail(EmailTo, 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   
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;
}
//     
void SendMail(char *email, 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
", 
          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); 

  //        ，         ， 2       
  sockfd = OpenSocket((struct sockaddr *)&their_addr);
  memset(rbuf, 0, 1500);
  while(recv(sockfd, rbuf, 1500, 0) == 0)
  {
    cout<<"reconnect..."<2);
    sockfd = OpenSocket((struct sockaddr *)&their_addr);
    memset(rbuf, 0, 1500);
  }

  cout<// EHLO
  memset(buf, 0, 1500);
  sprintf_s(buf, 1500, "EHLO HYL-PC\r
");
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"EHLO REceive: "<// AUTH LOGIN
  memset(buf, 0, 1500);
  sprintf_s(buf, 1500, "AUTH LOGIN\r
");
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Auth Login Receive: "<// USER
  memset(buf, 0, 1500);
  sprintf_s(buf, 1500, "[email protected]");//      
  memset(login, 0, 128);
  EncodeBase64(login, buf, strlen(buf));
  sprintf_s(buf, 1500, "%s\r
", login);
  send(sockfd, buf, strlen(buf), 0);
  cout<<"Base64 UserName: "<memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"User Login Receive: "<// PASSWORD
  sprintf_s(buf, 1500, "xxxxxxxxxxxxxx");//      
  memset(pass, 0, 128);
  EncodeBase64(pass, buf, strlen(buf));
  sprintf_s(buf, 1500, "%s\r
", pass);
  send(sockfd, buf, strlen(buf), 0);
  cout<<"Base64 Password: "<memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Send Password Receive: "<// MAIL FROM
  memset(buf, 0, 1500);
  sprintf_s(buf, 1500, "MAIL FROM: \r
");
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"set Mail From Receive: "<// RCPT TO       
  sprintf_s(buf, 1500, "RCPT TO:\r
", email);
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Tell Sendto Receive: "<// DATA           
  sprintf_s(buf, 1500, "DATA\r
");
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Send Mail Prepare Receive: "<//       ，\r
.\r
      
  sprintf_s(buf, 1500, "%s\r
.\r
", body);
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Send Mail Receive: "<// QUIT
  sprintf_s(buf, 1500, "QUIT\r
");
  send(sockfd, buf, strlen(buf), 0);
  memset(rbuf, 0, 1500);
  recv(sockfd, rbuf, 1500, 0);
  cout<<"Quit Receive: "<//    
  closesocket(sockfd);
  WSACleanup();
  return;
}
//   TCP Socket  
int OpenSocket(struct sockaddr *addr)
{
  int sockfd = 0;
  sockfd=socket(PF_INET, SOCK_STREAM, 0);
  if(sockfd < 0)
  {
    cout<<"Open sockfd(TCP) error!"<exit(-1);
  }
  if(connect(sockfd, addr, sizeof(struct sockaddr)) < 0)
  {
    cout<<"Connect sockfd(TCP) error!"<exit(-1);
  }
  return sockfd;
}