/* Copyright (C) 2002-2004 RealVNC Ltd.  All Rights Reserved.
 *    
 * This 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 software 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 software; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 * USA.
 */

// -=- Single-Threaded VNC Server implementation


// Note about how sockets get closed:
//
// Closing sockets to clients is non-trivial because the code which calls
// VNCServerST must explicitly know about all the sockets (so that it can block
// on them appropriately).  However, VNCServerST may want to close clients for
// a number of reasons, and from a variety of entry points.  The simplest is
// when processSocketEvent() is called for a client, and the remote end has
// closed its socket.  A more complex reason is when processSocketEvent() is
// called for a client which has just sent a ClientInit with the shared flag
// set to false - in this case we want to close all other clients.  Yet another
// reason for disconnecting clients is when the desktop size has changed as a
// result of a call to setPixelBuffer().
//
// Because we don't want to mess up any data structures which the calling code
// may maintain regarding sockets with data to process, we can't just delete a
// socket when we decide to close the connection to a client.  Instead, we only
// go as far as calling shutdown() on the socket.  This should ensure that
// eventually the calling code will get round to calling processSocketEvent()
// for that socket.  Then we can delete the VNCSConnectionST object and its
// associated network::Socket object, and return false from that call to let
// the calling code know that the socket has been deleted.  This is the only
// way that these objects get deleted.
//
// It is possible that there are platforms where calling shutdown() cannot
// guarantee that processSocketEvent() will be called - if so then it may be
// necessary to introduce some kind of "socket closure callback", but we'll
// only do that if it proves absolutely necessary.
//
// One minor complication is that we don't allocate a VNCSConnectionST object
// for a blacklisted host (since we want to minimise the resources used for
// dealing with such a connection).  So we maintain a separate list of
// closingSockets for this purpose.


#include <rfb/ServerCore.h>
#include <rfb/VNCServerST.h>
#include <rfb/VNCSConnectionST.h>
#include <rfb/ComparingUpdateTracker.h>
#include <rfb/SSecurityFactoryStandard.h>
#include <rfb/util.h>

#include <rdr/types.h>

using namespace rfb;

static LogWriter slog("VNCServerST");
LogWriter VNCServerST::connectionsLog("Connections");
static SSecurityFactoryStandard defaultSecurityFactory;

//
// -=- VNCServerST Implementation
//

// -=- Constructors/Destructor

VNCServerST::VNCServerST(const char* name_, SDesktop* desktop_,
                         SSecurityFactory* sf)
  : blHosts(&blacklist), desktop(desktop_), desktopStarted(false), pb(0),
    name(strDup(name_)), pointerClient(0), comparer(0),
    renderedCursorInvalid(false),
    securityFactory(sf ? sf : &defaultSecurityFactory),
    queryConnectionHandler(0), useEconomicTranslate(false),
    lastConnectionTime(0)
{
  lastUserInputTime = lastDisconnectTime = time(0);
  slog.debug("creating single-threaded server %s", name.buf);
}

VNCServerST::~VNCServerST()
{
  slog.debug("shutting down server %s", name.buf);

  // Close any active clients, with appropriate logging & cleanup
  closeClients("Server shutdown");

  // Delete all the clients, and their sockets, and any closing sockets
  //   NB: Deleting a client implicitly removes it from the clients list
  while (!clients.empty()) {
    delete clients.front()->getSock();
    delete clients.front();
  }
  while (!closingSockets.empty()) {
    delete closingSockets.front();
    closingSockets.pop_front();
  }

  // Stop the desktop object if active, *only* after deleting all clients!
  if (desktopStarted) {
    desktopStarted = false;
    desktop->stop();
  }

  delete comparer;
}


// SocketServer methods

void VNCServerST::addClient(network::Socket* sock)
{
  addClient(sock, false);
}

void VNCServerST::addClient(network::Socket* sock, bool reverse)
{
  // - Check the connection isn't black-marked
  // *** do this in getSecurity instead?
  CharArray address(sock->getPeerAddress());
  if ((rfb::Server::blacklistLevel == 2) &&
      blHosts->isBlackmarked(address.buf)) {
    connectionsLog.error("blacklisted: %s", address.buf);
    try {
      SConnection::writeConnFailedFromScratch("Too many security failures",
                                              &sock->outStream());
    } catch (rdr::Exception&) {
    }
    sock->shutdown();
    closingSockets.push_back(sock);
    return;
  }

  if (clients.empty()) {
    lastConnectionTime = time(0);
  }

  VNCSConnectionST* client = new VNCSConnectionST(this, sock, reverse);
  client->init();
}

bool VNCServerST::processSocketEvent(network::Socket* sock)
{
  // - Find the appropriate VNCSConnectionST and process the event
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    if ((*ci)->getSock() == sock) {
      if ((*ci)->processMessages())
        return true;
      // processMessages failed, so delete the client
      delete *ci;
      break;
    }
  }

  // - If no client is using the Socket then delete it
  closingSockets.remove(sock);
  delete sock;

  // - Check that the desktop object is still required
  if (authClientCount() == 0 && desktopStarted) {
    slog.debug("no authenticated clients - stopping desktop");
    desktopStarted = false;
    desktop->stop();
  }
  
  // - Inform the caller not to continue handling the Socket
  return false;
}

int VNCServerST::checkTimeouts()
{
  int timeout = 0;
  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci=clients.begin();ci!=clients.end();ci=ci_next) {
    ci_next = ci; ci_next++;
    soonestTimeout(&timeout, (*ci)->checkIdleTimeout());
  }

  int timeLeft;
  time_t now;

  // Optimization: Only call time() if using any maxTime. 
  if (rfb::Server::maxDisconnectionTime || rfb::Server::maxConnectionTime || rfb::Server::maxIdleTime) {
    now = time(0);
  }
  
  // Check MaxDisconnectionTime 
  if (rfb::Server::maxDisconnectionTime && clients.empty()) {
    if (now < lastDisconnectTime) {
      // Someone must have set the time backwards. 
      slog.info("Time has gone backwards - resetting lastDisconnectTime");
      lastDisconnectTime = now;
    }
    timeLeft = lastDisconnectTime + rfb::Server::maxDisconnectionTime - now;
    if (timeLeft < -60) {
      // Someone must have set the time forwards.
      slog.info("Time has gone forwards - resetting lastDisconnectTime");
      lastDisconnectTime = now;
      timeLeft = rfb::Server::maxDisconnectionTime;
    }
    if (timeLeft <= 0) { 
      slog.info("MaxDisconnectionTime reached, exiting");
      exit(0);
    }
    soonestTimeout(&timeout, timeLeft * 1000);
  }

  // Check MaxConnectionTime 
  if (rfb::Server::maxConnectionTime && lastConnectionTime && !clients.empty()) {
    if (now < lastConnectionTime) {
      // Someone must have set the time backwards. 
      slog.info("Time has gone backwards - resetting lastConnectionTime");
      lastConnectionTime = now;
    }
    timeLeft = lastConnectionTime + rfb::Server::maxConnectionTime - now;
    if (timeLeft < -60) {
      // Someone must have set the time forwards.
      slog.info("Time has gone forwards - resetting lastConnectionTime");
      lastConnectionTime = now;
      timeLeft = rfb::Server::maxConnectionTime;
    }
    if (timeLeft <= 0) {
      slog.info("MaxConnectionTime reached, exiting");
      exit(0);
    }
    soonestTimeout(&timeout, timeLeft * 1000);
  }

  
  // Check MaxIdleTime 
  if (rfb::Server::maxIdleTime) {
    if (now < lastUserInputTime) {
      // Someone must have set the time backwards. 
      slog.info("Time has gone backwards - resetting lastUserInputTime");
      lastUserInputTime = now;
    }
    timeLeft = lastUserInputTime + rfb::Server::maxIdleTime - now;
    if (timeLeft < -60) {
      // Someone must have set the time forwards.
      slog.info("Time has gone forwards - resetting lastUserInputTime");
      lastUserInputTime = now;
      timeLeft = rfb::Server::maxIdleTime;
    }
    if (timeLeft <= 0) {
      slog.info("MaxIdleTime reached, exiting");
      exit(0);
    }
    soonestTimeout(&timeout, timeLeft * 1000);
  }
  
  return timeout;
}


// VNCServer methods

void VNCServerST::setPixelBuffer(PixelBuffer* pb_)
{
  pb = pb_;
  delete comparer;
  comparer = 0;

  if (pb) {
    comparer = new ComparingUpdateTracker(pb);
    cursor.setPF(pb->getPF());
    renderedCursor.setPF(pb->getPF());

    std::list<VNCSConnectionST*>::iterator ci, ci_next;
    for (ci=clients.begin();ci!=clients.end();ci=ci_next) {
      ci_next = ci; ci_next++;
      (*ci)->pixelBufferChange();
    }
  } else {
    if (desktopStarted)
      throw Exception("setPixelBuffer: null PixelBuffer when desktopStarted?");
  }
}

void VNCServerST::setColourMapEntries(int firstColour, int nColours)
{
  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->setColourMapEntriesOrClose(firstColour, nColours);
  }
}

void VNCServerST::bell()
{
  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->bell();
  }
}

void VNCServerST::serverCutText(const char* str, int len)
{
  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->serverCutText(str, len);
  }
}

void VNCServerST::add_changed(const Region& region)
{
  comparer->add_changed(region);
}

void VNCServerST::add_copied(const Region& dest, const Point& delta)
{
  comparer->add_copied(dest, delta);
}

bool VNCServerST::clientsReadyForUpdate()
{
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    if ((*ci)->readyForUpdate())
      return true;
  }
  return false;
}

void VNCServerST::tryUpdate()
{
  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->writeFramebufferUpdateOrClose();
  }
}

void VNCServerST::setCursor(int width, int height, int newHotspotX,
                            int newHotspotY, void* data, void* mask)
{
  cursor.hotspot.x = newHotspotX;
  cursor.hotspot.y = newHotspotY;
  cursor.setSize(width, height);
  memcpy(cursor.data, data, cursor.dataLen());
  memcpy(cursor.mask.buf, mask, cursor.maskLen());

  cursor.crop();

  renderedCursorInvalid = true;

  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->renderedCursorChange();
    (*ci)->setCursorOrClose();
  }
}

void VNCServerST::setCursorPos(int x, int y)
{
  if (cursorPos.x != x || cursorPos.y != y) {
    cursorPos.x = x;
    cursorPos.y = y;
    renderedCursorInvalid = true;
    std::list<VNCSConnectionST*>::iterator ci;
    for (ci = clients.begin(); ci != clients.end(); ci++)
      (*ci)->renderedCursorChange();
  }
}

// Other public methods

void VNCServerST::approveConnection(network::Socket* sock, bool accept,
                                    const char* reason)
{
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    if ((*ci)->getSock() == sock) {
      (*ci)->approveConnectionOrClose(accept, reason);
      return;
    }
  }
}

void VNCServerST::closeClients(const char* reason, network::Socket* except)
{
  std::list<VNCSConnectionST*>::iterator i, next_i;
  for (i=clients.begin(); i!=clients.end(); i=next_i) {
    next_i = i; next_i++;
    if ((*i)->getSock() != except)
      (*i)->close(reason);
  }
}

void VNCServerST::getSockets(std::list<network::Socket*>* sockets)
{
  sockets->clear();
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    sockets->push_back((*ci)->getSock());
  }
  std::list<network::Socket*>::iterator si;
  for (si = closingSockets.begin(); si != closingSockets.end(); si++) {
    sockets->push_back(*si);
  }
}

SConnection* VNCServerST::getSConnection(network::Socket* sock) {
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    if ((*ci)->getSock() == sock)
      return *ci;
  }
  return 0;
}


// -=- Internal methods

void VNCServerST::startDesktop()
{
  if (!desktopStarted) {
    slog.debug("starting desktop");
    desktop->start(this);
    desktopStarted = true;
    if (!pb)
      throw Exception("SDesktop::start() did not set a valid PixelBuffer");
  }
}

int VNCServerST::authClientCount() {
  int count = 0;
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++) {
    if ((*ci)->authenticated())
      count++;
  }
  return count;
}

inline bool VNCServerST::needRenderedCursor()
{
  std::list<VNCSConnectionST*>::iterator ci;
  for (ci = clients.begin(); ci != clients.end(); ci++)
    if ((*ci)->needRenderedCursor()) return true;
  return false;
}

// checkUpdate() is called just before sending an update.  It checks to see
// what updates are pending and propagates them to the update tracker for each
// client.  It uses the ComparingUpdateTracker's compare() method to filter out
// areas of the screen which haven't actually changed.  It also checks the
// state of the (server-side) rendered cursor, if necessary rendering it again
// with the correct background.

void VNCServerST::checkUpdate()
{
  bool renderCursor = needRenderedCursor();

  if (comparer->is_empty() && !(renderCursor && renderedCursorInvalid))
    return;

  Region toCheck = comparer->get_changed().union_(comparer->get_copied());

  if (renderCursor) {
    Rect clippedCursorRect
      = cursor.getRect(cursorTL()).intersect(pb->getRect());

    if (!renderedCursorInvalid && (toCheck.intersect(clippedCursorRect)
                                   .is_empty())) {
      renderCursor = false;
    } else {
      renderedCursorTL = clippedCursorRect.tl;
      renderedCursor.setSize(clippedCursorRect.width(),
                             clippedCursorRect.height());
      toCheck.assign_union(clippedCursorRect);
    }
  }

  pb->grabRegion(toCheck);

  if (rfb::Server::compareFB)
    comparer->compare();

  if (renderCursor) {
    pb->getImage(renderedCursor.data,
                 renderedCursor.getRect(renderedCursorTL));
    renderedCursor.maskRect(cursor.getRect(cursorTL()
                                           .subtract(renderedCursorTL)),
                            cursor.data, cursor.mask.buf);
    renderedCursorInvalid = false;
  }

  std::list<VNCSConnectionST*>::iterator ci, ci_next;
  for (ci = clients.begin(); ci != clients.end(); ci = ci_next) {
    ci_next = ci; ci_next++;
    (*ci)->add_copied(comparer->get_copied(), comparer->get_delta());
    (*ci)->add_changed(comparer->get_changed());
  }

  comparer->clear();
}