next_command.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
  20 #include "uftps.h"
  21 #include <errno.h>
  22 #include <unistd.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <ctype.h>
  26
  27 #include "command_parser.h"
  28
  29
  30 /*
  31  * Read data from the control channel until a complete request (delimited by
  32  * CRLF) is found.
  33  *
  34  * Control channel processing is implemented in a pipelined fashion.  Trailing
  35  * bytes belonging to the following request are left in the buffer; to be read
  36  * in the next call to this function.
  37  */
  38 static void read_request (void)
  39 {
  40         int  l, i, b;
  41
  42         i = 0;
  43         l = SS.input_len;
  44         /* Shift trailing data from previous call */
  45         if (SS.input_offset > 0)
  46                 memmove(SS.input, SS.input + SS.input_offset, l);
  47
  48         do {
  49                 while (i < l && SS.input[i] != '\n')
  50                         i++;
  51                 if (SS.input[i] == '\n')
  52                 {
  53                         if (i > 0 && SS.input[i - 1] == '\r')
  54                                 break;
  55                         else
  56                                 continue;
  57                 }
  58
  59                 /* Buffer data exhausted, get more from the network */
  60                 b = recv(SS.control_sk, SS.input + l, LINE_SIZE - l, 0);
  61                 if (b <= 0)
  62                 {
  63                         if (b == -1)
  64                                 fatal("Control channel input");
  65                         else if (l == LINE_SIZE)
  66                         {
  67                                 errno = 0;
  68                                 fatal("Input buffer overflow");
  69                         }
  70                         else
  71                         {
  72                                 notice("Peer closed control connection");
  73                                 close(SS.control_sk);
  74                                 exit(EXIT_SUCCESS);
  75                         }
  76                 }
  77
  78                 l += b;
  79         } while (1);
  80
  81         /* Mark residual (trailing) bytes for the next call */
  82         SS.input[i - 1] = '\0';
  83         SS.input[i]     = '\0';
  84         i++;
  85         SS.input_len    =  l - i;
  86         SS.input_offset = (l - i > 0 ? i : 0);
  87
  88         debug("Request : %s", SS.input);
  89 }
  90
  91
  92 /*
  93  * Parse the current request from the control channel and return the
  94  * corresponding command number.  The command argument (SS.arg) is filled
  95  * accordingly.
  96  */
  97 enum command next_command (void)
  98 {
  99         const struct Cmd  *cmd;
 100         int                i;
 101
 102         read_request();
 103
 104         i = 0;
 105         while (SS.input[i] != ' ' && SS.input[i] != '\0')
 106         {
 107                 SS.input[i] = toupper(SS.input[i] & 0x07F);
 108                 i++;
 109         }
 110
 111         SS.arg      = (SS.input[i] == ' ' ? &SS.input[i + 1] : NULL);
 112         SS.input[i] = '\0';
 113
 114         cmd = parse_command(SS.input, i);
 115         if (cmd == NULL)
 116                 return FTP_NONE;
 117         return cmd->value;
 118 }
 119