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 #ifdef __MINGW32__
  22 #  include "hase.h"
  23 #else
  24 #  include <sys/socket.h>
  25 #  include <unistd.h>
  26 #endif
  27 #include <errno.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <ctype.h>
  31
  32 #include "command_parser.h"
  33
  34
  35 /*
  36  * Read data from the control channel until a complete request (delimited by
  37  * CRLF) is found.
  38  *
  39  * Control channel processing is implemented in a pipelined fashion.  Trailing
  40  * bytes belonging to the following request are left in the buffer; to be read
  41  * in the next call to this function.
  42  */
  43 static void read_request (void)
  44 {
  45         int  l, i, b;
  46
  47         i = 0;
  48         l = SS.input_len;
  49         /* Shift trailing data from previous call */
  50         if (SS.input_offset > 0)
  51                 memmove(SS.input, SS.input + SS.input_offset, l);
  52
  53         do {
  54                 while (i < l && SS.input[i] != '\n')
  55                         i++;
  56                 if (SS.input[i] == '\n')
  57                 {
  58                         if (i > 0 && SS.input[i - 1] == '\r')
  59                                 break;
  60                         else
  61                                 continue;
  62                 }
  63
  64                 /* Buffer data exhausted, get more from the network */
  65                 b = recv(SS.control_sk, SS.input + l, LINE_SIZE - l, 0);
  66                 if (b <= 0)
  67                 {
  68                         if (b == -1)
  69                                 fatal("Control channel input");
  70                         else if (l == LINE_SIZE)
  71                         {
  72                                 errno = 0;
  73                                 fatal("Input buffer overflow");
  74                         }
  75                         else
  76                         {
  77                                 notice("Peer closed control connection");
  78                                 closesocket(SS.control_sk);
  79                                 exit(EXIT_SUCCESS);
  80                         }
  81                 }
  82
  83                 l += b;
  84         } while (1);
  85
  86         /* Mark residual (trailing) bytes for the next call */
  87         SS.input[i - 1] = '\0';
  88         SS.input[i]     = '\0';
  89         i++;
  90         SS.input_len    =  l - i;
  91         SS.input_offset = (l - i > 0 ? i : 0);
  92
  93         debug("Request : %s", SS.input);
  94 }
  95
  96
  97 /*
  98  * Parse the current request from the control channel and return the
  99  * corresponding command number.  The command argument (SS.arg) is filled
 100  * accordingly.
 101  */
 102 enum command next_command (void)
 103 {
 104         const struct Cmd  *cmd;
 105         int                i;
 106
 107         read_request();
 108
 109         i = 0;
 110         while (SS.input[i] != ' ' && SS.input[i] != '\0')
 111         {
 112                 SS.input[i] = toupper(SS.input[i] & 0x07F);
 113                 i++;
 114         }
 115
 116         SS.arg      = (SS.input[i] == ' ' ? &SS.input[i + 1] : NULL);
 117         SS.input[i] = '\0';
 118
 119         cmd = parse_command(SS.input, i);
 120         if (cmd == NULL)
 121                 return FTP_NONE;
 122         return cmd->value;
 123 }
 124