SMTP File Transfer using C

smtp.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <netdb.h>         /* gethostbyname  */
#include <netinet/in.h>    /* htons          */
#include <sys/socket.h>
#include <sys/types.h>


int main()
{
	
	const char* hostname = "google.com";
	int port = 25;
	
	// address to host
	struct sockaddr_in server_address;
	
	// host information
	struct hostent *host; 
	
	// socket file descriptor
	int sock = 0;
	
	// step - 1
	// create socket connection
	sock = socket( AF_INET, SOCK_STREAM, 0 );
	// ( type of service, type of socket, type of protocol )
	
	// step - 2
	// configure the address
	server_address.sin_family = AF_INET;
	server_address.sin_port = htons( (unsigned short) port );
	server_address.sin_addr.s_addr = 0;
	
	// step - 3
	// getting host information
	host = gethostbyname( hostname );
	
	// step - 4 
	// copying host address to server field
	memcpy( (char *) &server_address.sin_addr, host->h_addr, host->h_length );
	
	// ( jahan copy karna hai, jo copy karna hai, copy karne ka size )
	
	
	// step - 5 
	// connect to server
	connect( sock, (struct sockaddr *) &server_address, sizeof( server_address ));
	// ( file desc sock, address, sizeof address )
	
	// step -6 
	// send the mail
	/*
	 * 	HELO [email protected]
	 *  MAIL FROM: [email protected]
	 *  RCPT TO: [email protected]
	 *  DATA
	 *  From: [email protected]
	 *  To: [email protected]
	 *  Subject: Le mera mail
	 * 
	 *  Madarchod mail padh le  
	 *  .
	 *  QUIT
	 * 
	 */
	
	const char* from = "[email protected]";
	const char* to = "[email protected]";
	const char* subject = "Le mera Mail";
	const char* body = "madarchod mail padh mera";
	 
	sendmail( sock, "HELO %s\n", from );
	sendmail( sock, "MAIL FROM: %s\n", from );
	sendmail( sock, "RCPT TO: %s\n", to );
	sendmail( sock, "DATA\n", NULL );
	sendmail( sock, "From: %s\n", from );
	sendmail( sock, "To: %s\n", to );
	sendmail( sock, "Subject: %s\n\n", subject );
	sendmail( sock, "%s\n.\nQUIT\n", body );
	
	
	
	// step - 7
	// closing connection
	close( sock );
	
	
	return 0;
}


void sendmail( int sock, char *str, const char *data )
{
	// send -> ( file desc sock, string, string length , 0 )
	// recv
	
	char buffer[1024];
	
	snprintf( buffer, 1024, str, data );
	// ex : printf( str, data ) -> printf(" MAIL FROM: %s\n", from );
	
	send( sock, buffer, strlen(buffer), 0 );
	
}