command_loop.c

   1 /*
   2  * User FTP Server,  Share folders over FTP without being root.
   3  * Copyright (C) 2008  Isaac Jurado
   4  *
   5  * This program is free software; you can redistribute it and/or modify it under
   6  * the terms of the GNU General Public License as published by the Free Software
   7  * Foundation; either version 2 of the License, or (at your option) any later
   8  * version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  13  * details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  18  */
  19 #include "uftps.h"
  20
  21 /*
  22  * Main FTP server loop which attends one client.
  23  *
  24  * It seems unbelievable but it's possible to implement a FTP server without
  25  * the need of select() or poll().  In fact, this kind of complexity is present
  26  * in the client.
  27  *
  28  * Commands not implemented are interpreted as unknown.  There used to be
  29  * dedicated dummy messages for some of them but code simplicity is preferred.
  30  */
  31
  32 #include <ctype.h>
  33 #include <unistd.h>
  34 #include <stdlib.h>
  35 #include <stdio.h>
  36
  37
  38 void command_loop (void)
  39 {
  40         int  l;
  41
  42         while (1) {
  43                 switch (next_command()) {
  44
  45                 /*
  46                  * Straightforward implementations.
  47                  */
  48                 case FTP_NOOP:
  49                         reply_c("200 I'm alive, don't worry\r\n");
  50                         break;
  51
  52                 case FTP_FEAT:
  53                         reply_c("211-Feature list:\r\n"
  54                                 "211- MDTM\r\n"
  55                                 "211- REST STREAM\r\n"
  56                                 "211- SIZE\r\n"
  57                                 "211- TVFS\r\n"
  58                                 "211 End.\r\n");
  59                         break;
  60
  61                 case FTP_PASS:
  62                 case FTP_USER:
  63                         reply_c("230 I don't care.\r\n");
  64                         break;
  65
  66                 case FTP_SYST:
  67                         reply_c("215 UNIX Type: L8\r\n");
  68                         break;
  69
  70                 case FTP_OPTS:
  71                         reply_c("501 Option not understood.\r\n");
  72                         break;
  73
  74                 case FTP_ACCT:
  75                 case FTP_SMNT:
  76                         reply_c("202 Unimplemented, ignored.\r\n");
  77                         break;
  78
  79                 case FTP_REIN:
  80                         reply_c("220 Nothing to REIN.\r\n");
  81                         break;
  82
  83                 /*
  84                  * A bit more complex commands.
  85                  */
  86                 case FTP_MODE:
  87                         if (toupper(SS.arg[0]) == 'S')
  88                                 reply_c("200 MODE set to stream.\r\n");
  89                         else
  90                                 reply_c("504 Mode not supported.\r\n");
  91                         break;
  92
  93                 case FTP_STRU:
  94                         if (toupper(SS.arg[0]) == 'F')
  95                                 reply_c("200 STRUcture set to file.\r\n");
  96                         else
  97                                 reply_c("504 Structure not supported.\r\n");
  98                         break;
  99
 100                 case FTP_TYPE:
 101                         switch (toupper(SS.arg[0])) {
 102                         case 'I':
 103                         case 'A':
 104                         case 'L':
 105                                 reply_c("200 Whatever.\r\n");
 106                                 break;
 107                         default:
 108                                 reply_c("501 Invalid type.\r\n");
 109                         }
 110                         break;
 111
 112                 case FTP_QUIT:
 113                         reply_c("221 Goodbye.\r\n");
 114                         close(SS.control_sk);
 115                         close(SS.passive_bind_sk);
 116                         exit(EXIT_SUCCESS);
 117                         break;
 118
 119                 case FTP_PASV:
 120                         SS.passive_mode = 1;
 121                         reply(SS.passive_str, SS.passive_len);
 122                         break;
 123
 124                 case FTP_PWD:
 125                         l = snprintf(SS.AuxBuf, LINE_SIZE, "257 \"%s\"\r\n", &SS.cwd[1]);
 126                         reply(SS.AuxBuf, l);
 127                         break;
 128
 129                 case FTP_REST:
 130                         /* We don't need str_to_ll() as sscanf() does de job */
 131                         sscanf(SS.arg, "%lld", &SS.offset);
 132                         l = snprintf(SS.AuxBuf, LINE_SIZE, "350 Got it (%lld).\r\n",
 133                                      SS.offset);
 134                         reply(SS.AuxBuf, l);
 135                         break;
 136
 137                 /*
 138                  * Complex commands implemented separately.
 139                  */
 140                 case FTP_PORT:
 141                         client_port();
 142                         break;
 143
 144                 case FTP_NLST:
 145                         list_dir(0);
 146                         break;
 147
 148                 case FTP_LIST:
 149                         list_dir(1);
 150                         break;
 151
 152                 case FTP_MDTM:
 153                         file_stats(0);
 154                         break;
 155
 156                 case FTP_SIZE:
 157                         file_stats(1);
 158                         break;
 159
 160                 case FTP_CWD:
 161                         change_dir();
 162                         break;
 163
 164                 case FTP_RETR:
 165                         send_file();
 166                         break;
 167
 168                 case FTP_NONE:
 169                         reply_c("500 Command unrecognized.\r\n");
 170                         break;
 171
 172                 default:
 173                         reply_c("500 Command not implemented.\r\n");
 174                 }
 175         }
 176 }
 177