qgsfcgiserverresponse.cpp

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/***************************************************************************
                          qgsfcgiserverresponse.cpp
 
  Define response wrapper for fcgi response
  -------------------
  begin                : 2017-01-03
  copyright            : (C) 2017 by David Marteau
  email                : david dot marteau at 3liz dot 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.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsfcgiserverresponse.h"
 
#include "qgis.h"
#include "qgslogger.h"
#include "qgsmessagelog.h"
 
#include <QDebug>
#include <QString>
#include <QThread>
 
#include <fcgi_stdio.h>
 
using namespace Qt::StringLiterals;
 
#if defined( Q_OS_UNIX ) && !defined( Q_OS_ANDROID )
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <chrono>
 
//
// QgsFCGXStreamData copied from libfcgi FCGX_Stream_Data
//
typedef struct QgsFCGXStreamData
{
    unsigned char *buff;      /* buffer after alignment */
    int bufflen;              /* number of bytes buff can store */
    unsigned char *mBuff;     /* buffer as returned by Malloc */
    unsigned char *buffStop;  /* reader: last valid byte + 1 of entire buffer.
                               * stop generally differs from buffStop for
                               * readers because of record structure.
                               * writer: buff + bufflen */
    int type;                 /* reader: FCGI_PARAMS or FCGI_STDIN
                               * writer: FCGI_STDOUT or FCGI_STDERR */
    int eorStop;              /* reader: stop stream at end-of-record */
    int skip;                 /* reader: don't deliver content bytes */
    int contentLen;           /* reader: bytes of unread content */
    int paddingLen;           /* reader: bytes of unread padding */
    int isAnythingWritten;    /* writer: data has been written to ipcFd */
    int rawWrite;             /* writer: write data without stream headers */
    FCGX_Request *reqDataPtr; /* request data not specific to one stream */
} QgsFCGXStreamData;
#endif
 
// to be able to use 333ms expression as a duration
using namespace std::chrono_literals;
 
 
// QgsSocketMonitoringThread constructor
QgsSocketMonitoringThread::QgsSocketMonitoringThread( std::shared_ptr<QgsFeedback> feedback )
  : mFeedback( std::move( feedback ) )
{
  Q_ASSERT( mFeedback );
 
  mShouldStop.store( false );
 
#if defined( Q_OS_UNIX ) && !defined( Q_OS_ANDROID )
  if ( FCGI_stdout && FCGI_stdout->fcgx_stream && FCGI_stdout->fcgx_stream->data )
  {
    QgsFCGXStreamData *stream = static_cast<QgsFCGXStreamData *>( FCGI_stdout->fcgx_stream->data );
    if ( stream && stream->reqDataPtr )
    {
      mIpcFd = stream->reqDataPtr->ipcFd;
    }
    else
    {
      QgsMessageLog::logMessage(
        u"FCGI_stdout stream data is null! Socket monitoring disabled."_s, //
        u"FCGIServer"_s,                                                   //
        Qgis::MessageLevel::Warning
      );
    }
  }
  else
  {
    QgsMessageLog::logMessage(
      u"FCGI_stdout is null! Socket monitoring disabled."_s, //
      u"FCGIServer"_s,                                       //
      Qgis::MessageLevel::Warning
    );
  }
#endif
}
 
// Informs the thread to quit
void QgsSocketMonitoringThread::stop()
{
  mShouldStop.store( true );
  // Release the mutex so the try_lock in the thread will not wait anymore and
  // the thread will end its loop as we have set 'mShouldStop' to true
  mMutex.unlock();
}
 
void QgsSocketMonitoringThread::run()
{
  // Lock the thread mutex: every try_lock will take 333ms
  mMutex.lock();
 
  if ( mIpcFd < 0 )
  {
    QgsMessageLog::logMessage( u"Socket monitoring disabled: no socket fd!"_s, u"FCGIServer"_s, Qgis::MessageLevel::Warning );
    return;
  }
 
#if defined( Q_OS_UNIX ) && !defined( Q_OS_ANDROID )
  quint64 threadId = reinterpret_cast<quint64>( QThread::currentThreadId() );
 
  char c;
 
  fd_set setOptions;
  FD_ZERO( &setOptions );        // clear the set
  FD_SET( mIpcFd, &setOptions ); // add our file descriptor to the set
 
  struct timeval timeout;
  timeout.tv_sec = 0;
  timeout.tv_usec = 10000; // max 10ms of timeout for select
 
  while ( !mShouldStop.load() )
  {
    // 'select' function will check if the socket is still valid after a 10ms timeout
    // see https://stackoverflow.com/a/30395738
    int rv = select( mIpcFd + 1, &setOptions, nullptr, nullptr, &timeout );
    if ( rv == -1 )
    {
      // socket closed, nothing can be read
      QgsMessageLog::logMessage(
        u"FCGIServer %1: remote socket has been closed (select)! errno: %2"_s //
          .arg( threadId )
          .arg( errno ),
        u"FCGIServer"_s,
        Qgis::MessageLevel::Warning
      );
      mFeedback->cancel();
      break;
    }
    else
    {
      // check if there is something in the socket without reading it and without blocking
      // see https://stackoverflow.com/a/12402596
      const ssize_t x = recv( mIpcFd, &c, 1, MSG_PEEK | MSG_DONTWAIT );
      if ( x != 0 )
      {
        // Ie. we are still connected but we have an 'error' as there is nothing to read
        QgsDebugMsgLevel(
          u"FCGIServer %1: remote socket still connected. errno: %2, x: %3"_s //
            .arg( threadId )
            .arg( errno )
            .arg( x ),
          5
        );
      }
      else
      {
        // socket closed, nothing can be read
        QgsMessageLog::logMessage(
          u"FCGIServer %1: remote socket has been closed (recv)! errno: %2, x: %3"_s //
            .arg( threadId )
            .arg( errno )
            .arg( x ),
          u"FCGIServer"_s,
          Qgis::MessageLevel::Warning
        );
        mFeedback->cancel();
        break;
      }
    }
 
    // If lock is acquired this means the response has finished and we will exit the while loop
    // else we will wait max for 333ms.
    if ( mMutex.try_lock_for( 333ms ) )
      mMutex.unlock();
  }
 
  if ( mShouldStop.load() )
  {
    QgsMessageLog::logMessage( u"FCGIServer::run %1: socket monitoring quits normally."_s.arg( threadId ), u"FCGIServer"_s, Qgis::MessageLevel::Info );
  }
  else
  {
    QgsMessageLog::logMessage(
      u"FCGIServer::run %1: socket monitoring quits: no more socket."_s //
        .arg( threadId ),                                               //
      u"FCGIServer"_s,
      Qgis::MessageLevel::Warning
    );
  }
#endif
}
 
 
//
// QgsFcgiServerResponse
//
QgsFcgiServerResponse::QgsFcgiServerResponse( QgsServerRequest::Method method )
  : mMethod( method )
  , mFeedback( new QgsFeedback )
{
  mBuffer.open( QIODevice::ReadWrite );
  setDefaultHeaders();
 
  mSocketMonitoringThread = std::make_unique<QgsSocketMonitoringThread>( mFeedback );
 
  // Start the monitoring thread
  mThread = std::thread( &QgsSocketMonitoringThread::run, mSocketMonitoringThread.get() );
}
 
QgsFcgiServerResponse::~QgsFcgiServerResponse()
{
  mFinished = true;
 
  // Inform the thread to quit asap
  mSocketMonitoringThread->stop();
 
  // Just to be sure
  mThread.join();
}
 
void QgsFcgiServerResponse::removeHeader( const QString &key )
{
  mHeaders.remove( key );
}
 
void QgsFcgiServerResponse::addHeader( const QString &key, const QString &value )
{
  if ( !mHeadersSent )
  {
    if ( !mHeaders.contains( key ) )
    {
      mHeaders[key] = QList<QString>();
    }
    mHeaders[key].append( value );
  }
}
 
 
void QgsFcgiServerResponse::setHeader( const QString &key, const QString &value )
{
  mHeaders[key] = QList<QString>() << value;
}
 
QString QgsFcgiServerResponse::header( const QString &key ) const
{
  const QList<QString> values = mHeaders.value( key );
  return values.isEmpty() ? QString() : values.last();
}
 
QMap<QString, QString> QgsFcgiServerResponse::headers() const
{
  QMap<QString, QString> singleHeaders;
  for ( auto it = mHeaders.keyBegin(); it != mHeaders.keyEnd(); ++it )
  {
    singleHeaders.insert( *it, header( *it ) );
  }
  return singleHeaders;
}
 
QList<QString> QgsFcgiServerResponse::fullHeader( const QString &key ) const
{
  return mHeaders.value( key );
}
 
bool QgsFcgiServerResponse::headersSent() const
{
  return mHeadersSent;
}
 
void QgsFcgiServerResponse::setStatusCode( int code )
{
  // fcgi applications must return HTTP status in header
  removeHeader( u"Status"_s );
  setHeader( u"Status"_s, u" %1"_s.arg( code ) );
  // Store the code to make it available for plugins
  mStatusCode = code;
}
 
void QgsFcgiServerResponse::sendError( int code, const QString &message )
{
  if ( mHeadersSent )
  {
    QgsMessageLog::logMessage( "Cannot send error after headers written", u"FCGIServer"_s, Qgis::MessageLevel::Warning );
    return;
  }
 
  clear();
  setStatusCode( code );
  setHeader( u"Content-Type"_s, u"text/html;charset=utf-8"_s );
  write( u"<html><body>%1</body></html>"_s.arg( message ) );
  finish();
}
 
QIODevice *QgsFcgiServerResponse::io()
{
  return &mBuffer;
}
 
void QgsFcgiServerResponse::finish()
{
  if ( mFinished )
  {
    QgsMessageLog::logMessage( "finish() called twice", u"FCGIServer"_s, Qgis::MessageLevel::Warning );
    return;
  }
 
  if ( mFeedback->isCanceled() )
  {
    clear();                                          // we clear all buffers as the socket is dead
    FCGI_stdout->fcgx_stream->wasFCloseCalled = true; // avoid sending FCGI end protocol as the socket is dead
    mFinished = true;
    return;
  }
 
  if ( !mHeadersSent )
  {
    if ( !mHeaders.contains( "Content-Length" ) )
    {
      setHeader( u"Content-Length"_s, QString::number( mBuffer.pos() ) );
    }
  }
  flush();
  mFinished = true;
}
 
void QgsFcgiServerResponse::flush()
{
  if ( !mHeadersSent )
  {
    // Send all headers
    QMap<QString, QList<QString>>::const_iterator it;
    for ( it = mHeaders.constBegin(); it != mHeaders.constEnd(); ++it )
    {
      for ( const QString &headerValue : std::as_const( it.value() ) )
      {
        fputs( it.key().toUtf8(), FCGI_stdout );
        fputs( ": ", FCGI_stdout );
        fputs( headerValue.toUtf8(), FCGI_stdout );
        fputs( "\n", FCGI_stdout );
      }
    }
    fputs( "\n", FCGI_stdout );
    mHeadersSent = true;
  }
 
  mBuffer.seek( 0 );
  if ( mMethod == QgsServerRequest::HeadMethod )
  {
    // Ignore data for head method as we only
    // write headers for HEAD requests
    mBuffer.buffer().clear();
  }
  else if ( mBuffer.bytesAvailable() > 0 )
  {
    QByteArray &ba = mBuffer.buffer();
    const size_t count = fwrite( ( void * ) ba.data(), ba.size(), 1, FCGI_stdout );
#ifdef QGISDEBUG
    qDebug() << u"Sent %1 blocks of %2 bytes"_s.arg( count ).arg( ba.size() );
#else
    Q_UNUSED( count )
#endif
    // Reset the internal buffer
    ba.clear();
  }
}
 
 
void QgsFcgiServerResponse::clear()
{
  mHeaders.clear();
  mBuffer.seek( 0 );
  mBuffer.buffer().clear();
}
 
 
QByteArray QgsFcgiServerResponse::data() const
{
  return mBuffer.data();
}
 
 
void QgsFcgiServerResponse::truncate()
{
  mBuffer.seek( 0 );
  mBuffer.buffer().clear();
}
 
 
void QgsFcgiServerResponse::setDefaultHeaders()
{
  QgsFcgiServerResponse::setHeader( u"Server"_s, u" QGIS FCGI server - QGIS version %1"_s.arg( Qgis::version() ) );
}