/*
 * Copyright (C) Tildeslash Ltd. All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 *
 * You must obey the GNU Affero General Public License in all respects
 * for all of the code used other than OpenSSL.  
 */

#include "config.h"

#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#ifdef HAVE_STRING_H
#include <string.h>
#endif

#include "protocol.h"


/* Private prototypes */
static int say(Socket_T s, char *msg);
static int expect(Socket_T s, int expect, int log);


/**
 * Check the server for greeting code 220 and send EHLO. If that failed
 * try HELO and test for return code 250 and finally send QUIT and check
 * for return code 221. If alive return TRUE else return FALSE.
 *
 *  @file
 */
int check_smtp(Socket_T socket) {
        ASSERT(socket);
        
        /* Try HELO also before giving up as of rfc2821 4.1.1.1 */
        if (expect(socket, 220, TRUE) 
            && ((say(socket, "EHLO localhost\r\n") && expect(socket, 250, FALSE)) || (say(socket, "HELO localhost\r\n") && expect(socket, 250, TRUE))) 
            && (say(socket, "QUIT\r\n") && expect(socket, 221, TRUE)))
                return TRUE;
        
        return FALSE;
}


/* --------------------------------------------------------------- Private */


static int say(Socket_T socket, char *msg) {
        if (socket_write(socket, msg, strlen(msg)) < 0) {
                socket_setError(socket, "SMTP: error sending data -- %s\n", STRERROR);
                return FALSE;
        }
        return TRUE;
}


static int expect(Socket_T socket, int expect, int log) {
        int status;
        char buf[STRLEN];
        
        do {
                if (! socket_readln(socket, buf, STRLEN)) {
                        socket_setError(socket, "SMTP: error receiving data -- %s\n", STRERROR);
                        return FALSE;
                }
                Str_chomp(buf);
        } while (buf[3] == '-'); // Discard multi-line response
        if (sscanf(buf, "%d", &status) != 1) {
                if(log) 
                        socket_setError(socket, "SMTP error: %s\n", buf);
                return FALSE;
        }
        return TRUE;
}