uftps.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 <sys/wait.h>
  22 #include <signal.h>
  23 #include <unistd.h>
  24 #include <stdlib.h>
  25 #include <stdio.h>
  26
  27 struct _SessionScope  SS;  /* SS --> Session State*/
  28
  29
  30 /*
  31  * clid_finish
  32  *
  33  * Reaper function.  For "zombies".
  34  */
  35 static void child_finish (int sig)
  36 {
  37         while (waitpid(-1, NULL, WNOHANG) > 0)
  38                 debug("Collecting children");
  39 }
  40
  41
  42 /*
  43  * end
  44  *
  45  * End. What where you expecting?
  46  */
  47 static void end (int sig)
  48 {
  49         notice("Signal caught, exiting");
  50         exit(EXIT_SUCCESS);
  51 }
  52
  53
  54 /*
  55  * Main program.  Opens the command port until a client requests a connection.
  56  * Then the server is forked and the child will manage all that client's
  57  * requests.
  58  */
  59 int main (int argc, char **argv)
  60 {
  61         int                 bind_sk, cmd_sk, e, yes;
  62         int                 port = DEFAULT_PORT;
  63         struct sigaction    my_sa;
  64         struct sockaddr_in  sai;
  65         socklen_t           sai_len = sizeof(struct sockaddr_in);
  66
  67         setlinebuf(stdout);
  68
  69         if (argc > 1)
  70         {
  71                 port = atoi(argv[1]) & 0x00FFFF;
  72                 if (port <= 1024)
  73                         fatal("This port number is restricted");
  74         }
  75
  76         /* Signal handling */
  77         sigfillset(&my_sa.sa_mask);
  78         my_sa.sa_flags   = SA_RESTART;
  79         my_sa.sa_handler = child_finish;
  80         sigaction(SIGCHLD, &my_sa, NULL);
  81
  82         my_sa.sa_flags   = SA_NOMASK;
  83         my_sa.sa_handler = end;
  84         sigaction(SIGINT, &my_sa, NULL);
  85
  86         /* Connection handling */
  87         sai.sin_family      = AF_INET;
  88         sai.sin_port        = htons(port);
  89         sai.sin_addr.s_addr = INADDR_ANY;
  90
  91         bind_sk = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
  92         if (bind_sk == -1)
  93                 fatal("Creating main server socket");
  94
  95         yes = 1;
  96         setsockopt(bind_sk, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
  97         e = bind(bind_sk, (struct sockaddr *) &sai, sai_len);
  98         if (e == -1)
  99                 fatal("Binding main server socket");
 100
 101         e = listen(bind_sk, 5);
 102         if (e == -1)
 103                 fatal("Listening at main server socket");
 104
 105         notice("UFTPS listening on port %d (TCP)", port);
 106         notice("Use CTRL + C to finish");
 107         notice("If you want to use a different port, specify it as the only argument in the command line");
 108
 109         /* Main server loop (accepting connections) */
 110         do {
 111                 sai_len = sizeof(struct sockaddr_in);
 112                 cmd_sk  = accept(bind_sk, (struct sockaddr *) &sai, &sai_len);
 113                 if (cmd_sk == -1)
 114                 {
 115                         error("Accepting incoming connection");
 116                         continue;
 117                 }
 118
 119                 e = fork();
 120                 if (e == 0)
 121                 {
 122                         /***  CHILD  ***/
 123                         close(bind_sk);
 124                         init_session(cmd_sk);
 125                         command_loop();
 126                 }
 127                 else
 128                 {
 129                         /***  PARENT  ***/
 130                         if (e == -1)
 131                                 error("Could not create a child process");
 132                         close(cmd_sk);
 133                 }
 134         } while (1);
 135
 136         return EXIT_SUCCESS;
 137 }
 138