A preliminary study of SMTP protocol (ii)----Linux under C Programming implementation of email __ block chain

Modeled on, SMTP protocol (i)--My previous blog, combined with the material on the web, using sockets, wrote a Linux under the C programming implementation of the email program.

You can take their own mailbox to do experiments, Base64 is a way of encoding, online can find a Web page, you can query the password of the Base64 code is how much. Of course, I can also manually calculate (I have not tried).

The specific source code is as follows:

#include <iostream> #include <sys/types.h> #include <sys/socket.h> #include <netinet/i n.h> #include <netdb.h> #include <stdio.h> #include <string.h>//using namespace St      
D #define EHLO "EHLO ***\r\n"//*** for the mailbox username #define DATA "data\r\n" #define QUIT "quit\r\n"//#define H_ADDR H_ad     
Dr_list[0]//file *fin;     
int sock;     
struct SOCKADDR_IN server;     
struct Hostent *hp, *gethostbyname ();     
Char buf[bufsiz+1];     
int Len;     
Char *host_id= "smtp.126.com";     
Char *from_id= "***@126.com";     
Char *to_id= "60462**** @qq. com";     
Char *sub= "testmail\r\n";      

Char wkstr[100]= "Hello how r u\r\n";         
	/*=====send a string to the socket=====*/void Send_socket (char *s) {write (Sock,s,strlen (s));         
	Write (1,s,strlen (s));     
printf ("client:%s\n", s); }//=====read a string from the socket=====*/void Read_socket () {len = Read (Sock,buf,bufsiz);
	Write (1,buf,len);     
printf ("server:%s\n", buf); /*=====main=====*/int MAIN (int argc, char* argv[]) {/*=====create socket=====*/sock = Socke     
	T (af_inet, SOCK_STREAM, 0);
		if (sock==-1) {perror ("opening stream socket");  
		Exit (1);   
	return 1;
		else//cout << "Socket created\n";

	printf ("Socket created\n");
	/*=====verify host=====*/server.sin_family = af_inet;
	HP = gethostbyname (host_id);
		if (hp== (struct hostent *) 0) {fprintf (stderr, "%s:unknown host\n", host_id);
		Exit (2);
	return 2; }/*=====connect to port on remote host=====*/memcpy ((char *) &server.sin_addr, (char *) HP-&GT;H_ADDR, hp->     	 				
	H_length); Server.sin_port=htons (25); /* SMTP PORT/if (Connect (sock, (struct sockaddr *) &server, sizeof server) ==-1) {perror ("Connecting Stream SOC
		Ket ");
		Exit (1);
	return 1;
		else//cout << "connected\n"; printf ("Connected\n "); /*=====write Some data then read some =====*/read_socket (); * * SMTP Server logon string/Send_socket (EHLO); /* Introduce ourselves * * Read_socket ();
	/*read Reply * * * **added by Fupeng * * Send_socket ("AUTH LOGIN");
	Send_socket ("\ r \ n");
	Read_socket ();
	Send_socket ("*******");//user name Base64 encoding send_socket ("\ r \ n");
	Read_socket ();
	Send_socket ("Hu Jintao");//Password base64 encoding Send_socket ("\ r \ n");

	Read_socket ();
	Send_socket ("Mail from <");
	Send_socket (from_id);
	Send_socket (">");
	Send_socket ("\ r \ n"); Read_socket ();
	/* Sender OK * *//send_socket ("VRFY");
	Send_socket (from_id);     
	Send_socket ("\ r \ n"); Read_socket (); Sender OK * * Send_socket ("RCPT to <");
	/*mail to*/Send_socket (to_id);
	Send_socket (">");
	Send_socket ("\ r \ n"); Read_socket (); 
	Recipient ok*/Send_socket (DATA);//Body to follow*/read_socket ();
	Send_socket ("from:***@126.com");
	Send_socket ("Subject:");
	Send_socket (sub); Read_socket (); Recipient ok*/Send_socket ("\r\n\r\n");
	Send_socket (WKSTR);
	Send_socket (". \ r \ n");
	Read_socket (); Send_socket (QUIT); /* Quit * * Read_socket ();
	Log off *///=====close socket and finish=====*/close (sock);
	Exit (0);
return 0;  }

The results are shown in the following picture: