/***************************************************************************
 * nmap_tty.cc -- Handles runtime interaction with Nmap, so you can        *
 * increase verbosity/debugging or obtain a status line upon request.      *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *                                                                         *
 * The Nmap Security Scanner is (C) 1996-2018 Insecure.Com LLC ("The Nmap  *
 * Project"). Nmap is also a registered trademark of the Nmap Project.     *
 * This program is free software; you may redistribute and/or modify it    *
 * under the terms of the GNU General Public License as published by the   *
 * Free Software Foundation; Version 2 ("GPL"), BUT ONLY WITH ALL OF THE   *
 * CLARIFICATIONS AND EXCEPTIONS DESCRIBED HEREIN.  This guarantees your   *
 * right to use, modify, and redistribute this software under certain      *
 * conditions.  If you wish to embed Nmap technology into proprietary      *
 * software, we sell alternative licenses (contact sales@nmap.com).        *
 * Dozens of software vendors already license Nmap technology such as      *
 * host discovery, port scanning, OS detection, version detection, and     *
 * the Nmap Scripting Engine.                                              *
 *                                                                         *
 * Note that the GPL places important restrictions on "derivative works",  *
 * yet it does not provide a detailed definition of that term.  To avoid   *
 * misunderstandings, we interpret that term as broadly as copyright law   *
 * allows.  For example, we consider an application to constitute a        *
 * derivative work for the purpose of this license if it does any of the   *
 * following with any software or content covered by this license          *
 * ("Covered Software"):                                                   *
 *                                                                         *
 * o Integrates source code from Covered Software.                         *
 *                                                                         *
 * o Reads or includes copyrighted data files, such as Nmap's nmap-os-db   *
 * or nmap-service-probes.                                                 *
 *                                                                         *
 * o Is designed specifically to execute Covered Software and parse the    *
 * results (as opposed to typical shell or execution-menu apps, which will *
 * execute anything you tell them to).                                     *
 *                                                                         *
 * o Includes Covered Software in a proprietary executable installer.  The *
 * installers produced by InstallShield are an example of this.  Including *
 * Nmap with other software in compressed or archival form does not        *
 * trigger this provision, provided appropriate open source decompression  *
 * or de-archiving software is widely available for no charge.  For the    *
 * purposes of this license, an installer is considered to include Covered *
 * Software even if it actually retrieves a copy of Covered Software from  *
 * another source during runtime (such as by downloading it from the       *
 * Internet).                                                              *
 *                                                                         *
 * o Links (statically or dynamically) to a library which does any of the  *
 * above.                                                                  *
 *                                                                         *
 * o Executes a helper program, module, or script to do any of the above.  *
 *                                                                         *
 * This list is not exclusive, but is meant to clarify our interpretation  *
 * of derived works with some common examples.  Other people may interpret *
 * the plain GPL differently, so we consider this a special exception to   *
 * the GPL that we apply to Covered Software.  Works which meet any of     *
 * these conditions must conform to all of the terms of this license,      *
 * particularly including the GPL Section 3 requirements of providing      *
 * source code and allowing free redistribution of the work as a whole.    *
 *                                                                         *
 * As another special exception to the GPL terms, the Nmap Project grants  *
 * permission to link the code of this program with any version of the     *
 * OpenSSL library which is distributed under a license identical to that  *
 * listed in the included docs/licenses/OpenSSL.txt file, and distribute   *
 * linked combinations including the two.                                  *
 *                                                                         *
 * The Nmap Project has permission to redistribute Npcap, a packet         *
 * capturing driver and library for the Microsoft Windows platform.        *
 * Npcap is a separate work with it's own license rather than this Nmap    *
 * license.  Since the Npcap license does not permit redistribution        *
 * without special permission, our Nmap Windows binary packages which      *
 * contain Npcap may not be redistributed without special permission.      *
 *                                                                         *
 * Any redistribution of Covered Software, including any derived works,    *
 * must obey and carry forward all of the terms of this license, including *
 * obeying all GPL rules and restrictions.  For example, source code of    *
 * the whole work must be provided and free redistribution must be         *
 * allowed.  All GPL references to "this License", are to be treated as    *
 * including the terms and conditions of this license text as well.        *
 *                                                                         *
 * Because this license imposes special exceptions to the GPL, Covered     *
 * Work may not be combined (even as part of a larger work) with plain GPL *
 * software.  The terms, conditions, and exceptions of this license must   *
 * be included as well.  This license is incompatible with some other open *
 * source licenses as well.  In some cases we can relicense portions of    *
 * Nmap or grant special permissions to use it in other open source        *
 * software.  Please contact fyodor@nmap.org with any such requests.       *
 * Similarly, we don't incorporate incompatible open source software into  *
 * Covered Software without special permission from the copyright holders. *
 *                                                                         *
 * If you have any questions about the licensing restrictions on using     *
 * Nmap in other works, we are happy to help.  As mentioned above, we also *
 * offer an alternative license to integrate Nmap into proprietary         *
 * applications and appliances.  These contracts have been sold to dozens  *
 * of software vendors, and generally include a perpetual license as well  *
 * as providing support and updates.  They also fund the continued         *
 * development of Nmap.  Please email sales@nmap.com for further           *
 * information.                                                            *
 *                                                                         *
 * If you have received a written license agreement or contract for        *
 * Covered Software stating terms other than these, you may choose to use  *
 * and redistribute Covered Software under those terms instead of these.   *
 *                                                                         *
 * Source is provided to this software because we believe users have a     *
 * right to know exactly what a program is going to do before they run it. *
 * This also allows you to audit the software for security holes.          *
 *                                                                         *
 * Source code also allows you to port Nmap to new platforms, fix bugs,    *
 * and add new features.  You are highly encouraged to send your changes   *
 * to the dev@nmap.org mailing list for possible incorporation into the    *
 * main distribution.  By sending these changes to Fyodor or one of the    *
 * Insecure.Org development mailing lists, or checking them into the Nmap  *
 * source code repository, it is understood (unless you specify            *
 * otherwise) that you are offering the Nmap Project the unlimited,        *
 * non-exclusive right to reuse, modify, and relicense the code.  Nmap     *
 * will always be available Open Source, but this is important because     *
 * the inability to relicense code has caused devastating problems for     *
 * other Free Software projects (such as KDE and NASM).  We also           *
 * occasionally relicense the code to third parties as discussed above.    *
 * If you wish to specify special license conditions of your               *
 * contributions, just say so when you send them.                          *
 *                                                                         *
 * 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 Nmap      *
 * license file for more details (it's in a COPYING file included with     *
 * Nmap, and also available from https://svn.nmap.org/nmap/COPYING)        *
 *                                                                         *
 ***************************************************************************/

#ifndef WIN32
#include "nmap_config.h"
#endif

#include "nmap.h"

#include <sys/types.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#if HAVE_TERMIOS_H
#include <termios.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>

#include "nmap_tty.h"
#include "NmapOps.h"

extern NmapOps o;

#ifdef WIN32
#include <conio.h>

// Microsoft's runtime makes this fairly simple. :)
void tty_init() { return; }
static int tty_getchar() { return _kbhit() ? _getch() : -1; }
static void tty_done() { return; }

static void tty_flush(void)
{
        static HANDLE stdinput = GetStdHandle(STD_INPUT_HANDLE);

        FlushConsoleInputBuffer(stdinput);
}

#else  //!win32
#include <signal.h>
#if !defined(O_NONBLOCK) && defined(O_NDELAY)
#define O_NONBLOCK			O_NDELAY
#endif

#ifdef __CYGWIN32__
#include <string.h>
#include <sys/socket.h>
#ifndef __CYGWIN__
extern int tcgetattr(int fd, struct termios *termios_p);
extern int tcsetattr(int fd, int actions, struct termios *termios_p);
#endif
#endif

static int tty_fd = 0;
static struct termios saved_ti;

static int tty_getchar()
{
        int c, numChars;
#ifdef __CYGWIN32__
        fd_set set;
        struct timeval tv;
#endif

        if (tty_fd && tcgetpgrp(tty_fd) == getpgrp()) {

        // This is so that when the terminal has been disconnected, it will be
        // reconnected when possible. If it slows things down, just remove it
        // tty_init();

#ifdef __CYGWIN32__
                FD_ZERO(&set); FD_SET(tty_fd, &set);
                tv.tv_sec = 0; tv.tv_usec = 0;
                if (select(tty_fd + 1, &set, NULL, NULL, &tv) <= 0)
                        return -1;
#endif
                c = 0;
                numChars = read(tty_fd, &c, 1);
                if (numChars > 0) return c;
        }

        return -1;
}

static void tty_done()
{
        if (!tty_fd) return;

        tcsetattr(tty_fd, TCSANOW, &saved_ti);

        close(tty_fd);
        tty_fd = 0;
}

static void tty_flush(void)
{
        /* we don't need to test for tty_fd==0 here because
         * this isn't called unless we succeeded
         */

        tcflush(tty_fd, TCIFLUSH);
}

static void install_handler(int signo, void (*handler) (int signo))
{
        struct sigaction sa;
        sa.sa_handler = handler;
        sigfillset(&sa.sa_mask); /* block all signals during handler execution */
        sa.sa_flags = 0;
        sigaction(signo, &sa, NULL);
}

static void shutdown_clean(int signo)
{
        sigset_t set;

/* We reinstall the default handler and call tty_done */
        install_handler(signo, SIG_DFL);
        tty_done();

/* Unblock signo and raise it (thus allowing the default handler to occur) */
        sigemptyset(&set);
        sigaddset(&set, signo);
        sigprocmask(SIG_UNBLOCK, &set, NULL);
        raise(signo); /* This _should_ kill us */
        _exit(EXIT_FAILURE); /* If it does not */
}

static void install_all_handlers() {
        install_handler(SIGINT, shutdown_clean);
        install_handler(SIGTERM, shutdown_clean);
        install_handler(SIGQUIT, shutdown_clean);
}

/*
 * Initializes the terminal for unbuffered non-blocking input. Also
 * registers tty_done() via atexit().  You need to call this before
 * you ever call keyWasPressed().
 */
void tty_init()
{
        struct termios ti;

        if(o.noninteractive)
                return;

        install_all_handlers();

        if (tty_fd)
                return;

        if ((tty_fd = open("/dev/tty", O_RDONLY | O_NONBLOCK)) < 0) return;

#ifndef __CYGWIN32__
        if (tcgetpgrp(tty_fd) != getpgrp()) {
                close(tty_fd); return;
        }
#endif

        tcgetattr(tty_fd, &ti);
        saved_ti = ti;
        ti.c_lflag &= ~(ICANON | ECHO);
        ti.c_cc[VMIN] = 1;
        ti.c_cc[VTIME] = 0;
        tcsetattr(tty_fd, TCSANOW, &ti);

        atexit(tty_done);
}

#endif  //!win32

/* Catches all of the predefined
   keypresses and interpret them, and it will also tell you if you
   should print anything. A value of true being returned means a
   nonstandard key has been pressed and the calling method should
   print a status message */
bool keyWasPressed()
{
  /* Where we keep the automatic stats printing schedule. */
  static struct timeval stats_time = { 0 };
  int c;

  if (o.noninteractive)
    return false;

  if ((c = tty_getchar()) >= 0) {
    tty_flush(); /* flush input queue */

    // printf("You pressed key '%c'!\n", c);
    if (c == 'v') {
       if (o.verbose < 10) o.verbose++;
       log_write(LOG_STDOUT, "Verbosity Increased to %d.\n", o.verbose);
    } else if (c == 'V') {
       if (o.verbose > 0) o.verbose--;
       log_write(LOG_STDOUT, "Verbosity Decreased to %d.\n", o.verbose);
    } else if (c == 'd') {
       if (o.debugging < 10) o.debugging++;
       log_write(LOG_STDOUT, "Debugging Increased to %d.\n", o.debugging);
    } else if (c == 'D') {
       if (o.debugging > 0) o.debugging--;
       log_write(LOG_STDOUT, "Debugging Decreased to %d.\n", o.debugging);
    } else if (c == 'p') {
       o.setPacketTrace(true);
       log_write(LOG_STDOUT, "Packet Tracing enabled.\n");
    } else if (c == 'P') {
       o.setPacketTrace(false);
       log_write(LOG_STDOUT, "Packet Tracing disabled.\n");
    } else if (c == '?') {
      log_write(LOG_STDOUT,
                "Interactive keyboard commands:\n"
                "?               Display this information\n"
                "v/V             Increase/decrease verbosity\n"
                "d/D             Increase/decrease debugging\n"
                "p/P             Enable/disable packet tracing\n"
                "anything else   Print status\n"
                "More help: https://nmap.org/book/man-runtime-interaction.html\n");
    } else {
       printStatusMessage();
       return true;
    }
  }

  /* Check if we need to print a status update according to the --stats-every
     option. */
  if (o.stats_interval != 0.0) {
    struct timeval now;

    gettimeofday(&now, NULL);
    if (stats_time.tv_sec == 0) {
      /* Initialize the scheduled stats time. */
      stats_time = *o.getStartTime();
      TIMEVAL_ADD(stats_time, stats_time, (time_t) (o.stats_interval * 1000000));
    }

    if (TIMEVAL_AFTER(now, stats_time)) {
      /* Advance to the next print time. */
      TIMEVAL_ADD(stats_time, stats_time, (time_t) (o.stats_interval * 1000000));
      /* If it's still in the past, catch it up to the present,
       * plus half a second to avoid double-printing without any progress. */
      if (TIMEVAL_AFTER(now, stats_time))
        TIMEVAL_MSEC_ADD(stats_time, now, 500);
      printStatusMessage();
      /* Instruct the caller to print status too. */
      return true;
    }
  }

  return false;
}