/* mswindows.c -- Windows-specific support
   Copyright (C) 1996-2011, 2014-2015, 2018-2021 Free Software
   Foundation, Inc.

This file is part of GNU Wget.

GNU Wget 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 3 of the License, or
(at your option) any later version.

GNU Wget 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 Wget.  If not, see <http://www.gnu.org/licenses/>.

Additional permission under GNU GPL version 3 section 7

If you modify this program, or any covered work, by linking or
combining it with the OpenSSL project's OpenSSL library (or a
modified version of that library), containing parts covered by the
terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
grants you additional permission to convey the resulting work.
Corresponding Source for a non-source form of such a combination
shall include the source code for the parts of OpenSSL used as well
as that of the covered work.  */

#define INHIBIT_WRAP /* avoid wrapping of socket, bind, ... */

#include "wget.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <math.h>


#include "utils.h"
#include "url.h"
#include "exits.h"

#ifndef ES_SYSTEM_REQUIRED
#define ES_SYSTEM_REQUIRED  0x00000001
#endif

#ifndef ES_CONTINUOUS
#define ES_CONTINUOUS       0x80000000
#endif


/* Windows version of xsleep in utils.c.  */

void
xsleep (double seconds)
{
#if defined(HAVE_USLEEP) && defined(HAVE_SLEEP)
  if (seconds >= 1)
    {
      /* Explained in utils.c. */
      sleep (seconds);
      seconds -= (long) seconds;
    }
  usleep (seconds * 1000000);
#else  /* not HAVE_USLEEP */
  SleepEx ((DWORD) (seconds * 1000 + .5), FALSE);
#endif /* not HAVE_USLEEP */
}

void
windows_main (char **exec_name)
{
  char *p;

  /* Remove .EXE from filename if it has one.  */
  *exec_name = xstrdup (*exec_name);
  p = strrchr (*exec_name, '.');
  if (p)
    *p = '\0';
}

static void
ws_cleanup (void)
{
  xfree (exec_name);
  WSACleanup ();
}

#if defined(CTRLBREAK_BACKGND) || defined(CTRLC_BACKGND)
static void
ws_hangup (const char *reason)
{
  fprintf (stderr, _("Continuing in background.\n"));
  redirect_output (true, reason);

  /* Detach process from the current console.  Under Windows 9x, if we
     were launched from a 16-bit process (which is usually the case;
     command.com is 16-bit) the parent process should resume right away.
     Under NT or if launched from a 32-process under 9x, this is a futile
     gesture as the parent will wait for us to terminate before resuming.  */
  FreeConsole ();
}
#endif

/* Construct the name for a named section (a.k.a. `file mapping') object.
   The returned string is dynamically allocated and needs to be xfree()'d.  */
static char *
make_section_name (DWORD pid)
{
  return aprintf ("gnu_wget_fake_fork_%lu", pid);
}

/* This structure is used to hold all the data that is exchanged between
   parent and child.  */
struct fake_fork_info
{
  HANDLE event;
  bool logfile_changed;
  char lfilename[MAX_PATH + 1];
};

/* Determines if we are the child and if so performs the child logic.
   Return values:
     < 0  error
       0  parent
     > 0  child
*/
static int
fake_fork_child (void)
{
  HANDLE section, event;
  struct fake_fork_info *info;
  char *name;

  name = make_section_name (GetCurrentProcessId ());
  section = OpenFileMapping (FILE_MAP_WRITE, FALSE, name);
  xfree (name);
  /* It seems that Windows 9x and NT set last-error inconsistently when
     OpenFileMapping() fails; so we assume it failed because the section
     object does not exist.  */
  if (!section)
    return 0;                   /* We are the parent.  */

  info = MapViewOfFile (section, FILE_MAP_WRITE, 0, 0, 0);
  if (!info)
    {
      CloseHandle (section);
      return -1;
    }

  event = info->event;

  info->logfile_changed = false;
  if (!opt.lfilename && (!opt.quiet || opt.server_response))
    {
      /* See utils:fork_to_background for explanation. */
      FILE *new_log_fp = unique_create (DEFAULT_LOGFILE, false, &opt.lfilename);
      if (new_log_fp)
        {
          info->logfile_changed = true;
          snprintf (info->lfilename, sizeof (info->lfilename), "%s",
                    opt.lfilename);
          fclose (new_log_fp);
        }
    }

  UnmapViewOfFile (info);
  CloseHandle (section);

  /* Inform the parent that we've done our part.  */
  if (!SetEvent (event))
    return -1;

  CloseHandle (event);
  return 1;                     /* We are the child.  */
}

/* Windows doesn't support the fork() call; so we fake it by invoking
   another copy of Wget with the same arguments with which we were
   invoked.  The child copy of Wget should perform the same initialization
   sequence as the parent; so we should have two processes that are
   essentially identical.  We create a specially named section object that
   allows the child to distinguish itself from the parent and is used to
   exchange information between the two processes.  We use an event object
   for synchronization.  */
static void
fake_fork (void)
{
  char exe[MAX_PATH + 1];
  DWORD exe_len, le;
  SECURITY_ATTRIBUTES sa;
  HANDLE section, event, h[2];
  STARTUPINFO si;
  PROCESS_INFORMATION pi;
  struct fake_fork_info *info;
  char *name;
  BOOL rv;

  section = pi.hProcess = pi.hThread = NULL;

  /* Get the fully qualified name of our executable.  This is more reliable
     than using argv[0].  */
  exe_len = GetModuleFileName (GetModuleHandle (NULL), exe, sizeof (exe));
  if (!exe_len || (exe_len >= sizeof (exe)))
    return;

  sa.nLength = sizeof (sa);
  sa.lpSecurityDescriptor = NULL;
  sa.bInheritHandle = TRUE;

  /* Create an anonymous inheritable event object that starts out
     non-signaled.  */
  event = CreateEvent (&sa, FALSE, FALSE, NULL);
  if (!event)
    return;

  /* Create the child process detached form the current console and in a
     suspended state.  */
  xzero (si);
  si.cb = sizeof (si);
  rv = CreateProcess (exe, GetCommandLine (), NULL, NULL, TRUE,
                      CREATE_SUSPENDED | DETACHED_PROCESS,
                      NULL, NULL, &si, &pi);
  if (!rv)
    goto cleanup;

  /* Create a named section object with a name based on the process id of
     the child.  */
  name = make_section_name (pi.dwProcessId);
  section =
      CreateFileMapping (INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
                         sizeof (struct fake_fork_info), name);
  le = GetLastError();
  xfree (name);
  /* Fail if the section object already exists (should not happen).  */
  if (!section || (le == ERROR_ALREADY_EXISTS))
    {
      rv = FALSE;
      goto cleanup;
    }

  /* Copy the event handle into the section object.  */
  info = MapViewOfFile (section, FILE_MAP_WRITE, 0, 0, 0);
  if (!info)
    {
      rv = FALSE;
      goto cleanup;
    }

  info->event = event;

  UnmapViewOfFile (info);

  /* Start the child process.  */
  rv = ResumeThread (pi.hThread);
  if (!rv)
    {
      TerminateProcess (pi.hProcess, (DWORD) -1);
      goto cleanup;
    }

  /* Wait for the child to signal to us that it has done its part.  If it
     terminates before signaling us it's an error.  */

  h[0] = event;
  h[1] = pi.hProcess;
  rv = WAIT_OBJECT_0 == WaitForMultipleObjects (2, h, FALSE, 5 * 60 * 1000);
  if (!rv)
    goto cleanup;

  info = MapViewOfFile (section, FILE_MAP_READ, 0, 0, 0);
  if (!info)
    {
      rv = FALSE;
      goto cleanup;
    }

  /* Ensure string is properly terminated.  */
  if (info->logfile_changed &&
      !memchr (info->lfilename, '\0', sizeof (info->lfilename)))
    {
      rv = FALSE;
      goto cleanup;
    }

  printf (_("Continuing in background, pid %lu.\n"), pi.dwProcessId);
  if (info->logfile_changed)
    printf (_("Output will be written to %s.\n"), quote (info->lfilename));

  UnmapViewOfFile (info);

cleanup:

  if (event)
    CloseHandle (event);
  if (section)
    CloseHandle (section);
  if (pi.hThread)
    CloseHandle (pi.hThread);
  if (pi.hProcess)
    CloseHandle (pi.hProcess);

  /* We're the parent.  If all is well, terminate.  */
  if (rv)
    exit (WGET_EXIT_SUCCESS);

  /* We failed, return.  */
}

/* This is the corresponding Windows implementation of the
   fork_to_background() function in utils.c.  */
bool
fork_to_background (void)
{
  int rv;

  rv = fake_fork_child ();
  if (rv < 0)
    {
      fprintf (stderr, _("fake_fork_child() failed\n"));
      abort ();
    }
  else if (rv == 0)
    {
      /* We're the parent.  */
      fake_fork ();
      /* If fake_fork() returns, it failed.  */
      fprintf (stderr, _("fake_fork() failed\n"));
      abort ();
    }
  /* If we get here, we're the child.  */
  return false;
}

static BOOL WINAPI
ws_handler (DWORD dwEvent)
{
  switch (dwEvent)
    {
#ifdef CTRLC_BACKGND
    case CTRL_C_EVENT:
      ws_hangup ("CTRL+C");
      return TRUE;
#endif
#ifdef CTRLBREAK_BACKGND
    case CTRL_BREAK_EVENT:
      ws_hangup ("CTRL+Break");
      return TRUE;
#endif
    default:
      return FALSE;
    }
}

static char *title_buf = NULL;
static char *curr_url  = NULL;
static int old_percentage = -1;

/* Updates the console title with the URL of the current file being
   transferred.  */
void
ws_changetitle (const char *url)
{
  xfree (title_buf);
  xfree (curr_url);
  title_buf = xmalloc (strlen (url) + 20);
  curr_url = xstrdup (url);
  old_percentage = -1;
  sprintf (title_buf, "Wget %s", curr_url);
  SetConsoleTitle (title_buf);
}

/* Updates the console title with the percentage of the current file
   transferred.  */
void
ws_percenttitle (double percentage_float)
{
  int percentage;

  if (!title_buf || !curr_url)
    return;

  percentage = (int) percentage_float;

  /* Clamp percentage value.  */
  if (percentage < 0)
    percentage = 0;
  if (percentage > 100)
    percentage = 100;

  /* Only update the title when the percentage has changed.  */
  if (percentage == old_percentage)
    return;

  old_percentage = percentage;

  sprintf (title_buf, "Wget [%d%%] %s", percentage, curr_url);
  SetConsoleTitle (title_buf);
}

/* Returns a pointer to the fully qualified name of the directory that
   contains the Wget binary (wget.exe).  The returned path does not have a
   trailing path separator.  Returns NULL on failure.  */
char *
ws_mypath (void)
{
  static char *wspathsave = NULL;

  if (!wspathsave)
    {
      char buf[MAX_PATH + 1];
      char *p;
      DWORD len;

      len = GetModuleFileName (GetModuleHandle (NULL), buf, sizeof (buf));
      if (!len || (len >= sizeof (buf)))
        return NULL;

      p = strrchr (buf, PATH_SEPARATOR);
      if (!p)
        return NULL;

      *p = '\0';
      wspathsave = xstrdup (buf);
    }

  return wspathsave;
}

/* Prevent Windows entering sleep/hibernation-mode while Wget is doing
   a lengthy transfer.  Windows does not, by default, consider network
   activity in console-programs as activity!  Works on Win-98/ME/2K
   and up.  */
static void
set_sleep_mode (void)
{
  typedef DWORD (WINAPI *func_t) (DWORD);
  func_t set_exec_state;

  set_exec_state =
      (func_t) GetProcAddress (GetModuleHandle ("KERNEL32.DLL"),
                               "SetThreadExecutionState");

  if (set_exec_state)
    set_exec_state (ES_SYSTEM_REQUIRED | ES_CONTINUOUS);
}

/* Perform Windows specific initialization.  */
void
ws_startup (void)
{
  WSADATA data;
  WORD requested = MAKEWORD (1, 1);
  int err = WSAStartup (requested, &data);
  if (err != 0)
    {
      fprintf (stderr, _("%s: Couldn't find usable socket driver.\n"),
               exec_name);
      exit (WGET_EXIT_GENERIC_ERROR);
    }

  if (data.wVersion < requested)
    {
      fprintf (stderr, _("%s: Couldn't find usable socket driver.\n"),
               exec_name);
      WSACleanup ();
      exit (WGET_EXIT_GENERIC_ERROR);
    }

  atexit (ws_cleanup);
  set_sleep_mode ();
  SetConsoleCtrlHandler (ws_handler, TRUE);
}

/* run_with_timeout Windows implementation.  */

/* Stack size 0 uses default thread stack-size (reserve+commit).
   Determined by what's in the PE header.  */
#define THREAD_STACK_SIZE  0

struct thread_data
{
  void (*fun) (void *);
  void *arg;
  DWORD ws_error;
};

/* The callback that runs FUN(ARG) in a separate thread.  This
   function exists for two reasons: a) to not require FUN to be
   declared WINAPI/__stdcall[1], and b) to retrieve Winsock errors,
   which are per-thread.  The latter is useful when FUN calls Winsock
   functions, which is how run_with_timeout is used in Wget.

   [1] MSVC can use __fastcall globally (cl /Gr) and on Watcom this is
   the default (wcc386 -3r).  */

static DWORD WINAPI
thread_helper (void *arg)
{
  struct thread_data *td = (struct thread_data *) arg;

  /* Initialize Winsock error to what it was in the parent.  That way
     the subsequent call to WSAGetLastError will return the same value
     if td->fun doesn't change Winsock error state.  */
  WSASetLastError (td->ws_error);

  td->fun (td->arg);

  /* Return Winsock error to the caller, in case FUN ran Winsock
     code.  */
  td->ws_error = WSAGetLastError ();
  return 0;
}

/* Call FUN(ARG), but don't allow it to run for more than TIMEOUT
   seconds.  Returns true if the function was interrupted with a
   timeout, false otherwise.

   This works by running FUN in a separate thread and terminating the
   thread if it doesn't finish in the specified time.  */

bool
run_with_timeout (double seconds, void (*fun) (void *), void *arg)
{
  HANDLE thread_hnd;
  struct thread_data thread_arg;
  DWORD thread_id;
  bool rc;

  DEBUGP (("seconds %.2f, ", seconds));

  if (seconds == 0)
    {
    blocking_fallback:
      fun (arg);
      return false;
    }

  thread_arg.fun = fun;
  thread_arg.arg = arg;
  thread_arg.ws_error = WSAGetLastError ();
  thread_hnd = CreateThread (NULL, THREAD_STACK_SIZE, thread_helper,
                             &thread_arg, 0, &thread_id);
  if (!thread_hnd)
    {
      DEBUGP (("CreateThread() failed; [%#lx]\n",
               (unsigned long) GetLastError ()));
      goto blocking_fallback;
    }

  if (WaitForSingleObject (thread_hnd, (DWORD)(1000 * seconds))
      == WAIT_OBJECT_0)
    {
      /* Propagate error state (which is per-thread) to this thread,
         so the caller can inspect it.  */
      WSASetLastError (thread_arg.ws_error);
      DEBUGP (("Winsock error: %d\n", WSAGetLastError ()));
      rc = false;
    }
  else
    {
      TerminateThread (thread_hnd, 1);
      rc = true;
    }

  CloseHandle (thread_hnd);     /* Clear-up after TerminateThread().  */
  thread_hnd = NULL;
  return rc;
}


#ifdef ENABLE_IPV6
/* An inet_ntop implementation that uses WSAAddressToString.
   Prototype complies with POSIX 1003.1-2004.  This is only used under
   IPv6 because Wget prints IPv4 addresses using inet_ntoa.  */

const char *
inet_ntop (int af, const void *src, char *dst, socklen_t cnt)
{
  /* struct sockaddr can't accommodate struct sockaddr_in6. */
  union {
    struct sockaddr_in6 sin6;
    struct sockaddr_in sin;
  } sa;
  DWORD dstlen = cnt;
  size_t srcsize;

  xzero (sa);
  switch (af)
    {
    case AF_INET:
      sa.sin.sin_family = AF_INET;
      sa.sin.sin_addr = *(struct in_addr *) src;
      srcsize = sizeof (sa.sin);
      break;
    case AF_INET6:
      sa.sin6.sin6_family = AF_INET6;
      sa.sin6.sin6_addr = *(struct in6_addr *) src;
      srcsize = sizeof (sa.sin6);
      break;
    default:
      abort ();
    }

  if (WSAAddressToString ((struct sockaddr *) &sa, srcsize, NULL, dst, &dstlen) != 0)
    {
      errno = WSAGetLastError();
      return NULL;
    }
  return (const char *) dst;
}
#endif


void
set_windows_fd_as_blocking_socket (int fd)
{
    /* 04/2011
     gnulib select() converts blocking sockets to nonblocking in windows
     discussed here:
     http://old.nabble.com/blocking-socket-is-nonblocking-after-calling-gnulib-
     select%28%29-in-windows-td31432857.html

     wget uses blocking sockets so we must convert them back to blocking.
    */
    int ret = 0;
    int wsagle = 0;
    const int zero = 0;

    do
    {
        if(wsagle == WSAEINPROGRESS)
          Sleep(1);  /* use windows sleep */

        WSASetLastError (0);
        ret = ioctl (fd, FIONBIO, &zero);
        wsagle = WSAGetLastError ();
    }
  while (ret && (wsagle == WSAEINPROGRESS));

  if(ret)
    {
      fprintf (stderr,
               _("ioctl() failed.  The socket could not be set as blocking.\n") );
      DEBUGP (("Winsock error: %d\n", WSAGetLastError ()));
      abort ();
    }
  return;
}