/* darkstat 3
 * copyright (c) 2001-2007 Emil Mikulic.
 *
 * darkstat.c: signals, cmdline parsing, program body.
 *
 * You may use, modify and redistribute this file under the terms of the
 * GNU General Public License version 2. (see COPYING.GPL)
 */

#include "darkstat.h"
#include "acct.h"
#include "cap.h"
#include "conv.h"
#include "daylog.h"
#include "db.h"
#include "dns.h"
#include "http.h"
#include "hosts_db.h"
#include "localip.h"
#include "ncache.h"
#include "pidfile.h"

#include "err.h"
#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pcap.h>

#include "now.h"
time_t now;

#ifndef INADDR_NONE
# define INADDR_NONE (-1) /* Solaris */
#endif

/* --- Signal handling --- */
static volatile int running = 1;
static void sig_shutdown(int signum _unused_) { running = 0; }

static volatile int reset_pending = 0;
static void sig_reset(int signum _unused_) { reset_pending = 1; }

/* --- Commandline parsing --- */
const char *interface = NULL;
static void cb_interface(const char *arg) { interface = arg; }

int want_daemonize = 1;
static void cb_debug(const char *arg _unused_) { want_daemonize = 0; }

int want_promisc = 1;
static void cb_no_promisc(const char *arg _unused_) { want_promisc = 0; }

int want_dns = 1;
static void cb_no_dns(const char *arg _unused_) { want_dns = 0; }

unsigned short bindport = 667;
static void cb_port(const char *arg)
{
   unsigned long p;
   char *ep;

   errno = 0;
   p = strtoul(arg, &ep, 10);
   if (*ep != '\0')
      errx(1, "\"%s\" is not a valid number", arg);
   if ((errno == ERANGE) || (p > 65535))
      errx(1, "\"%s\" is out of range", arg);
   bindport = (unsigned short)p;
}

in_addr_t bindaddr = INADDR_ANY;
static void cb_bindaddr(const char *arg)
{
   bindaddr = inet_addr(arg);
   if (bindaddr == (in_addr_t)INADDR_NONE)
      errx(1, "malformed address \"%s\"", arg);
}

const char *filter = NULL;
static void cb_filter(const char *arg) { filter = arg; }

static void cb_local(const char *arg) { acct_init_localnet(arg); }

const char *chroot_dir = NULL;
static void cb_chroot(const char *arg) { chroot_dir = arg; }

const char *privdrop_user = NULL;
static void cb_user(const char *arg) { privdrop_user = arg; }

const char *daylog_fn = NULL;
static void cb_daylog(const char *arg)
{
   if (chroot_dir == NULL)
      errx(1, "the daylog file is relative to the chroot.\n"
      "You must specify a --chroot dir before you can use --daylog.");
   else
      daylog_fn = arg;
}

const char *import_fn = NULL;
static void cb_import(const char *arg)
{
   if (chroot_dir == NULL)
      errx(1, "the import file is relative to the chroot.\n"
      "You must specify a --chroot dir before you can use --import.");
   else
      import_fn = arg;
}

const char *export_fn = NULL;
static void cb_export(const char *arg)
{
   if (chroot_dir == NULL)
      errx(1, "the export file is relative to the chroot.\n"
      "You must specify a --chroot dir before you can use --export.");
   else
      export_fn = arg;
}

static const char *pid_fn = NULL;
static void cb_pidfile(const char *arg)
{
   if (chroot_dir == NULL)
      errx(1, "the pidfile is relative to the chroot.\n"
      "You must specify a --chroot dir before you can use --pidfile.");
   else
      pid_fn = arg;
}

/* --- */

struct cmdline_arg {
   const char *name, *arg_name; /* NULL arg_name means no arg */
   const enum { MANDATORY, OPTIONAL } need;
   void (*callback)(const char *arg);
   int num_seen;
};

static struct cmdline_arg cmdline_args[] = {
   {"-i",           "interface",       MANDATORY, cb_interface,  0},
   {"--debug",      NULL,              OPTIONAL,  cb_debug,      0},
   {"--no-promisc", NULL,              OPTIONAL,  cb_no_promisc, 0},
   {"--no-dns",     NULL,              OPTIONAL,  cb_no_dns,     0},
   {"-p",           "port",            OPTIONAL,  cb_port,       0},
   {"-b",           "bindaddr",        OPTIONAL,  cb_bindaddr,   0},
   {"-f",           "filter",          OPTIONAL,  cb_filter,     0},
   {"-l",           "network/netmask", OPTIONAL,  cb_local,      0},
   {"--chroot",     "dir",             OPTIONAL,  cb_chroot,     0},
   {"--user",       "username",        OPTIONAL,  cb_user,       0},
   {"--daylog",     "filename",        OPTIONAL,  cb_daylog,     0},
   {"--import",     "filename",        OPTIONAL,  cb_import,     0},
   {"--export",     "filename",        OPTIONAL,  cb_export,     0},
   {"--pidfile",    "filename",        OPTIONAL,  cb_pidfile,    0},
   {NULL,           NULL,              OPTIONAL,  NULL,          0}
};

static void
pad(const int width)
{
   int i;
   for (i=0; i<width; i++) printf(" ");
}

/*
 * We autogenerate the usage statement from the cmdline_args data structure.
 */
static void
usage(void)
{
   int width, first;
   struct cmdline_arg *arg;

   printf("\n");
   width = printf("usage: darkstat ");
   first = 1;

   for (arg = cmdline_args; arg->name != NULL; arg++) {
      if (first) first = 0; else pad(width);
      if (arg->need == OPTIONAL) printf("[ ");
      printf("%s", arg->name);
      if (arg->arg_name != NULL) printf(" %s", arg->arg_name);
      if (arg->need == OPTIONAL) printf(" ]");
      printf("\n");
   }
   printf("\n"
"Please refer to the darkstat(1) manual page for further\n"
"documentation and usage examples.\n");
}

static void
parse_sub_cmdline(const int argc, char * const *argv)
{
   struct cmdline_arg *arg;

   if (argc == 0) return;
   for (arg = cmdline_args; arg->name != NULL; arg++)
      if (strcmp(argv[0], arg->name) == 0) {
         if ((arg->arg_name != NULL) && (argc == 1)) {
            printf("\nerror: argument \"%s\" requires parameter \"%s\"\n",
               arg->name, arg->arg_name);
            usage();
            exit(EXIT_FAILURE);
         }
         if (arg->num_seen > 0) {
            printf("\nerror: already specified argument \"%s\"\n",
               arg->name);
            usage();
            exit(EXIT_FAILURE);
         }

         arg->num_seen++;
         if (arg->arg_name == NULL) {
            arg->callback(NULL);
            parse_sub_cmdline(argc-1, argv+1);
         } else {
            arg->callback(argv[1]);
            parse_sub_cmdline(argc-2, argv+2);
         }
         return;
      }

   printf("\nerror: illegal argument: \"%s\"\n", argv[0]);
   usage();
   exit(EXIT_FAILURE);
}

static void
parse_cmdline(const int argc, char * const *argv)
{
   struct cmdline_arg *arg;

   if (argc < 1) {
      /* Not enough args. */
      usage();
      exit(EXIT_FAILURE);
   }

   parse_sub_cmdline(argc, argv);

   for (arg = cmdline_args; arg->name != NULL; arg++)
      if ((arg->need == MANDATORY) && (arg->num_seen == 0)) {
         printf("\nerror: failed to specify mandatory argument \"%s\"\n",
            arg->name);
         usage();
         exit(EXIT_FAILURE);
      }

   /* some default values */
   if (chroot_dir == NULL) chroot_dir = CHROOT_DIR;
   if (privdrop_user == NULL) privdrop_user = PRIVDROP_USER;
}

/* --- Program body --- */
int
main(int argc, char **argv)
{
   test_64order();
   printf(PACKAGE_STRING " (built with libpcap %d.%d)\n",
      PCAP_VERSION_MAJOR, PCAP_VERSION_MINOR);

   parse_cmdline(argc-1, argv+1);

   /* must verbosef() before first fork to init lock */
   verbosef("starting up");
   if (pid_fn) pidfile_create(chroot_dir, pid_fn, privdrop_user);

   if (want_daemonize) {
      verbosef("daemonizing to run in the background!");
      daemonize_start();
      verbosef("I am the main process");
   }
   if (pid_fn) pidfile_write_close();

   /* do this first as it forks - minimize memory use */
   if (want_dns) dns_init(privdrop_user);

   /* Need root privs for these: */
   cap_init(interface, filter, want_promisc);
   http_init(bindaddr, bindport, /*maxconn=*/ -1);
   ncache_init(); /* don't need priv, but must do before chroot */

   privdrop(chroot_dir, privdrop_user);

   /* Don't need root privs for these: */
   if (daylog_fn != NULL) daylog_init(daylog_fn);
   graph_init();
   hosts_db_init();
   if (import_fn != NULL) db_import(import_fn);
   localip_init(interface);

   if (signal(SIGTERM, sig_shutdown) == SIG_ERR)
      errx(1, "signal(SIGTERM) failed");
   if (signal(SIGINT, sig_shutdown) == SIG_ERR)
      errx(1, "signal(SIGINT) failed");
   if (signal(SIGUSR1, sig_reset) == SIG_ERR)
      errx(1, "signal(SIGUSR1) failed");

   verbosef("entering main loop");
   daemonize_finish();

   while (running) {
      int select_ret, max_fd = -1, use_timeout = 0;
      struct timeval timeout;
      fd_set rs, ws;

      if (reset_pending) {
         if (export_fn != NULL) db_export(export_fn); /* FIXME: USR2? */
         hosts_db_reset();
         graph_reset();
         reset_pending = 0;
      }

      now = time(NULL);

      FD_ZERO(&rs);
      FD_ZERO(&ws);

      cap_fd_set(&rs, &max_fd, &timeout, &use_timeout);
      http_fd_set(&rs, &ws, &max_fd, &timeout, &use_timeout);

      select_ret = select(max_fd+1, &rs, &ws, NULL,
         (use_timeout) ? &timeout : NULL);

      if ((select_ret == 0) && (!use_timeout))
            errx(1, "select() erroneously timed out");

      if (select_ret == -1) {
         if (errno == EINTR)
            continue;
         else
            err(1, "select()");
      }
      else {
         hosts_db_reduce();
         graph_rotate();
         cap_poll(&rs);
         dns_poll();
         http_poll(&rs, &ws);
      }
   }

   verbosef("shutting down");
   cap_stop();
   dns_stop();
   if (export_fn != NULL) db_export(export_fn);
   hosts_db_free();
   graph_free();
   if (daylog_fn != NULL) daylog_free();
   ncache_free();
   if (pid_fn) pidfile_unlink();
   verbosef("shut down");
   return (EXIT_SUCCESS);
}

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