/* tinyproxy - A fast light-weight HTTP proxy
 * Copyright (C) 1998 Steven Young <sdyoung@miranda.org>
 * Copyright (C) 1998-2002 Robert James Kaes <rjkaes@users.sourceforge.net>
 * Copyright (C) 2000 Chris Lightfoot <chris@ex-parrot.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* The initialize routine. Basically sets up all the initial stuff (logfile,
 * listening socket, config options, etc.) and then sits there and loops
 * over the new connections until the daemon is closed. Also has additional
 * functions to handle the "user friendly" aspects of a program (usage,
 * stats, etc.) Like any good program, most of the work is actually done
 * elsewhere.
 */

#include "tinyproxy.h"

#include "anonymous.h"
#include "buffer.h"
#include "conffile.h"
#include "daemon.h"
#include "heap.h"
#include "filter.h"
#include "child.h"
#include "log.h"
#include "reqs.h"
#include "sock.h"
#include "stats.h"
#include "utils.h"

RETSIGTYPE takesig (int sig);

/*
 * Global Structures
 */
struct config_s config;
float load = 0.00;
unsigned int received_sighup = FALSE;   /* boolean */
unsigned int processed_config_file = FALSE;     /* boolean */

/*
 * Handle a signal
 */
RETSIGTYPE
takesig (int sig)
{
  pid_t pid;
  int status;

  switch (sig)
    {
    case SIGHUP:
      received_sighup = TRUE;
      break;

    case SIGTERM:
      config.quit = TRUE;
      break;

    case SIGCHLD:
      while ((pid = waitpid (-1, &status, WNOHANG)) > 0);
      break;
    }

  return;
}

/*
 * Display the version information for the user.
 */
static void
display_version (void)
{
  printf ("%s %s (%s)\n", PACKAGE, VERSION, TARGET_SYSTEM);
}

/*
 * Display the copyright and license for this program.
 */
static void
display_license (void)
{
  display_version ();

  printf ("\
  Copyright 1998       Steven Young (sdyoung@well.com)\n\
  Copyright 1998-2002  Robert James Kaes (rjkaes@users.sourceforge.net)\n\
  Copyright 1999       George Talusan (gstalusan@uwaterloo.ca)\n\
  Copyright 2000       Chris Lightfoot (chris@ex-parrot.com)\n\
\n\
  This program is free software; you can redistribute it and/or modify\n\
  it under the terms of the GNU General Public License as published by\n\
  the Free Software Foundation; either version 2, or (at your option)\n\
  any later version.\n\
\n\
  This program is distributed in the hope that it will be useful,\n\
  but WITHOUT ANY WARRANTY; without even the implied warranty of\n\
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n\
  GNU General Public License for more details.\n\
\n\
  You should have received a copy of the GNU General Public License\n\
  along with this program; if not, write to the Free Software\n\
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.\n");
}

/*
 * Display usage to the user.
 */
static void
display_usage (void)
{
  printf ("Usage: %s [options]\n", PACKAGE);
  printf ("\
Options:\n\
  -d		Operate in DEBUG mode.\n\
  -c FILE	Use an alternate configuration file.\n\
  -h		Display this usage information.\n\
  -l            Display the license.\n\
  -v            Display the version number.\n");

  /* Display the modes compiled into tinyproxy */
  printf ("\nFeatures compiled in:\n");
#ifdef XTINYPROXY_ENABLE
  printf ("    XTinyproxy header\n");
#endif /* XTINYPROXY */
#ifdef FILTER_ENABLE
  printf ("    Filtering\n");
#endif /* FILTER_ENABLE */
#ifndef NDEBUG
  printf ("    Debugging code\n");
#endif /* NDEBUG */
#ifdef TRANSPARENT_PROXY
  printf ("    Transparent proxy support\n");
#endif /* TRANSPARENT_PROXY */
#ifdef REVERSE_SUPPORT
  printf ("    Reverse proxy support\n");
#endif /* REVERSE_SUPPORT */
}

static int
get_id (char *str)
{
  char *tstr;

  if (str == NULL)
    return -1;

  tstr = str;
  while (*tstr != 0)
    {
      if (!isdigit (*tstr))
        return -1;
      tstr++;
    }

  return atoi (str);
}

int
main (int argc, char **argv)
{
  int optch;
  unsigned int godaemon = TRUE; /* boolean */
  struct passwd *thisuser = NULL;
  struct group *thisgroup = NULL;
  FILE *config_file;

  /* Only allow u+rw bits. This may be required for some versions
   * of glibc so that mkstemp() doesn't make us vulnerable.
   */
  umask (0177);

  /* Default configuration file location */
  config.config_file = DEFAULT_CONF_FILE;

  /*
   * Process the various options
   */
  while ((optch = getopt (argc, argv, "c:vldh")) != EOF)
    {
      switch (optch)
        {
        case 'v':
          display_version ();
          exit (EX_OK);
        case 'l':
          display_license ();
          exit (EX_OK);
        case 'd':
          godaemon = FALSE;
          break;
        case 'c':
          config.config_file = safestrdup (optarg);
          if (!config.config_file)
            {
              fprintf (stderr, "%s: Could not allocate memory.\n", argv[0]);
              exit (EX_SOFTWARE);
            }
          break;
        case 'h':
        default:
          display_usage ();
          exit (EX_OK);
        }
    }

  log_message (LOG_INFO, "Initializing " PACKAGE " ...");

  /*
   * Make sure the HTML error pages array is NULL to begin with.
   * (FIXME: Should have a better API for all this)
   */
  config.errorpages = NULL;

  /*
   * Read in the settings from the config file.
   */
  config_file = fopen (config.config_file, "r");
  if (!config_file)
    {
      fprintf (stderr,
               "%s: Could not open configuration file \"%s\".\n",
               argv[0], config.config_file);
      exit (EX_SOFTWARE);
    }
  if (config_compile () || config_parse (&config, config_file))
    {
      fprintf (stderr,
               "Unable to parse configuration file.  Not starting.\n");
      exit (EX_SOFTWARE);
    }
  fclose (config_file);

  /*
   * Write to a user supplied log file if it's defined.  This
   * will override using the syslog even if syslog is defined.
   */
  if (config.logf_name)
    {
      if (open_log_file (config.logf_name) < 0)
        {
          fprintf (stderr, "%s: Could not create log file.\n", argv[0]);
          exit (EX_SOFTWARE);
        }
      config.syslog = FALSE;    /* disable syslog */
    }
  else if (config.syslog)
    {
      if (godaemon == TRUE)
        openlog ("tinyproxy", LOG_PID, LOG_DAEMON);
      else
        openlog ("tinyproxy", LOG_PID, LOG_USER);
    }
  else
    {
      fprintf (stderr,
               "%s: Either define a logfile or enable syslog logging.\n",
               argv[0]);
      exit (EX_SOFTWARE);
    }

  processed_config_file = TRUE;
  send_stored_logs ();

  /*
   * Set the default values if they were not set in the config file.
   */
  if (config.port == 0)
    {
      fprintf (stderr,
               "%s: You MUST set a Port in the configuration file.\n",
               argv[0]);
      exit (EX_SOFTWARE);
    }
  if (!config.stathost)
    {
      log_message (LOG_INFO, "Setting stathost to \"%s\".", DEFAULT_STATHOST);
      config.stathost = DEFAULT_STATHOST;
    }
  if (!config.user)
    {
      log_message (LOG_WARNING,
                   "You SHOULD set a UserName in the configuration file. "
                   "Using current user instead.");
    }
  if (config.idletimeout == 0)
    {
      log_message (LOG_WARNING,
                   "Invalid idle time setting. Only values greater than zero "
                   "allowed; therefore setting idle timeout to %u seconds.",
                   MAX_IDLE_TIME);
      config.idletimeout = MAX_IDLE_TIME;
    }

  init_stats ();

  /*
   * If ANONYMOUS is turned on, make sure that Content-Length is
   * in the list of allowed headers, since it is required in a
   * HTTP/1.0 request. Also add the Content-Type header since it goes
   * hand in hand with Content-Length.
   *     - rjkaes
   */
  if (is_anonymous_enabled ())
    {
      anonymous_insert ("Content-Length");
      anonymous_insert ("Content-Type");
    }

  if (godaemon == TRUE)
    makedaemon ();

  if (config.pidpath)
    {
      if (pidfile_create (config.pidpath) < 0)
        {
          fprintf (stderr, "%s: Could not create PID file.\n", argv[0]);
          exit (EX_OSERR);
        }
    }

  if (set_signal_handler (SIGPIPE, SIG_IGN) == SIG_ERR)
    {
      fprintf (stderr, "%s: Could not set the \"SIGPIPE\" signal.\n",
               argv[0]);
      exit (EX_OSERR);
    }
#ifdef FILTER_ENABLE
  if (config.filter)
    filter_init ();
#endif /* FILTER_ENABLE */

  /*
   * Start listening on the selected port.
   */
  if (child_listening_sock (config.port) < 0)
    {
      fprintf (stderr, "%s: Could not create listening socket.\n", argv[0]);
      exit (EX_OSERR);
    }

  /*
   * Switch to a different user.
   */
  if (geteuid () == 0)
    {
      if (config.group && strlen (config.group) > 0)
        {
          int gid = get_id (config.group);
          if (gid < 0)
            {
              thisgroup = getgrnam (config.group);
              if (!thisgroup)
                {
                  fprintf (stderr,
                           "%s: Unable to find "
                           "group \"%s\".\n", argv[0], config.group);
                  exit (EX_NOUSER);
                }
              gid = thisgroup->gr_gid;
            }
          if (setgid (gid) < 0)
            {
              fprintf (stderr,
                       "%s: Unable to change to "
                       "group \"%s\".\n", argv[0], config.group);
              exit (EX_CANTCREAT);
            }
          log_message (LOG_INFO, "Now running as group \"%s\".",
                       config.group);
        }
      if (config.user && strlen (config.user) > 0)
        {
          int uid = get_id (config.user);
          if (uid < 0)
            {
              thisuser = getpwnam (config.user);
              if (!thisuser)
                {
                  fprintf (stderr,
                           "%s: Unable to find "
                           "user \"%s\".\n", argv[0], config.user);
                  exit (EX_NOUSER);
                }
              uid = thisuser->pw_uid;
            }
          if (setuid (uid) < 0)
            {
              fprintf (stderr,
                       "%s: Unable to change to user \"%s\".\n",
                       argv[0], config.user);
              exit (EX_CANTCREAT);
            }
          log_message (LOG_INFO, "Now running as user \"%s\".", config.user);
        }
    }
  else
    {
      log_message (LOG_WARNING,
                   "Not running as root, so not changing UID/GID.");
    }

  if (child_pool_create () < 0)
    {
      fprintf (stderr, "%s: Could not create the pool of children.\n", argv[0]);
      exit (EX_SOFTWARE);
    }

  /*
   * These signals are only for the parent process.
   */
  log_message (LOG_INFO, "Setting the various signals.");
  if (set_signal_handler (SIGCHLD, takesig) == SIG_ERR)
    {
      fprintf (stderr, "%s: Could not set the \"SIGCHLD\" signal.\n",
               argv[0]);
      exit (EX_OSERR);
    }
  if (set_signal_handler (SIGTERM, takesig) == SIG_ERR)
    {
      fprintf (stderr, "%s: Could not set the \"SIGTERM\" signal.\n",
               argv[0]);
      exit (EX_OSERR);
    }
  if (set_signal_handler (SIGHUP, takesig) == SIG_ERR)
    {
      fprintf (stderr, "%s: Could not set the \"SIGHUP\" signal.\n", argv[0]);
      exit (EX_OSERR);
    }

  /*
   * Start the main loop.
   */
  log_message (LOG_INFO, "Starting main loop. Accepting connections.");

  child_main_loop ();

  log_message (LOG_INFO, "Shutting down.");

  child_kill_children ();
  child_close_sock ();

  /*
   * Remove the PID file.
   */
  if (unlink (config.pidpath) < 0)
    {
      log_message (LOG_WARNING,
                   "Could not remove PID file \"%s\": %s.",
                   config.pidpath, strerror (errno));
    }
#ifdef FILTER_ENABLE
  if (config.filter)
    filter_destroy ();
#endif /* FILTER_ENABLE */

  if (config.syslog)
    closelog ();
  else
    close_log_file ();

  exit (EX_OK);
}