【SMTP】Linux下C++实现smtp邮件发送

#include <sys/socket.h>

#include <netdb.h>

#include <stdio.h>

#include <string.h>

#include <string>



using std::string;



int Connect(const string& host)

{

  int sock = 0;



  struct hostent * remoteHost;

  if ((remoteHost = gethostbyname(host.c_str())) == 0)

  {

     printf("get host failed:%s\n", host.c_str());

     return 0;

  }



  struct sockaddr_in pin;

  memset(&pin, 0, sizeof(pin));

  pin.sin_family = AF_INET;

  pin.sin_port = htons(25);

  pin.sin_addr.s_addr = ((struct in_addr *)(remoteHost->h_addr))->s_addr;



  printf("remote host ip:%s, %u\n", remoteHost->h_addr, pin.sin_addr.s_addr);



  if((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) 

  {

     printf("create socket failed\n");

     return 0;

  }



  if (connect(sock, (const sockaddr*)&pin, sizeof(pin)) == -1)

  {

    printf("connect failed\n");  // 这里提示连接失败！

    return 0;

  }



  return sock;

}



int main(int argc, const char** argv)

{

  int sock = Connect("mail.google.com");

  if (sock == 0)

  {

    return 1;

  }

  printf("Connect succeed:%d\n", sock);



  string fromAddr = "xxx@gmail.com";

  string msg;

  msg = "mail from:<";

  msg.append(fromAddr);

  msg.append(">\n");



  string toAddr = "xxx@gmail.com";

  msg.append("rcpt to:<");

  msg.append(toAddr);

  msg.append(">\n");



  string subject = "ttttt";

  string content = "aaaaa";

  msg.append("data\n");

  msg.append("subject:");

  msg.append(subject);

  msg.append("\n\n");

  msg.append(content);

  msg.append("\n.\n");



  if (send(sock, msg.c_str(), msg.length(), 0) == -1)

  {

    printf("send fetching request failed\n");

    return 1;

  }



  char recvBuf[1024];

  int l = recv(sock, recvBuf, 1023, 0);

  printf("recv len:%d\n", l);

  printf("%s\n", recvBuf);



  return 0;

}