webrtc/modules/rtp_rtcp/source/ssrc_database.cc

/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "webrtc/modules/rtp_rtcp/source/ssrc_database.h"

#include <assert.h>
#include <stdlib.h>

#include "webrtc/system_wrappers/include/critical_section_wrapper.h"

#ifdef _WIN32
#include <windows.h>
#include <MMSystem.h>  // timeGetTime

// TODO(hellner): investigate if it is necessary to disable these warnings.
#pragma warning(disable : 4311)
#pragma warning(disable : 4312)
#else
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>
#endif

namespace webrtc {
SSRCDatabase* SSRCDatabase::StaticInstance(CountOperation count_operation) {
  SSRCDatabase* impl = GetStaticInstance<SSRCDatabase>(count_operation);
  return impl;
}

SSRCDatabase* SSRCDatabase::GetSSRCDatabase() {
  return StaticInstance(kAddRef);
}

void SSRCDatabase::ReturnSSRCDatabase() {
  StaticInstance(kRelease);
}

uint32_t SSRCDatabase::CreateSSRC() {
  CriticalSectionScoped lock(_critSect);

  uint32_t ssrc = GenerateRandom();

  while (_ssrcMap.find(ssrc) != _ssrcMap.end()) {
    ssrc = GenerateRandom();
  }
  _ssrcMap[ssrc] = 0;

  return ssrc;
}

int32_t SSRCDatabase::RegisterSSRC(const uint32_t ssrc) {
  CriticalSectionScoped lock(_critSect);
  _ssrcMap[ssrc] = 0;
  return 0;
}

int32_t SSRCDatabase::ReturnSSRC(const uint32_t ssrc) {
  CriticalSectionScoped lock(_critSect);
  _ssrcMap.erase(ssrc);
  return 0;
}

SSRCDatabase::SSRCDatabase() {
// we need to seed the random generator, otherwise we get 26500 each time,
// hardly a random value :)
#ifdef _WIN32
  srand(timeGetTime());
#else
  struct timeval tv;
  struct timezone tz;
  gettimeofday(&tv, &tz);
  srand(tv.tv_usec);
#endif

  _critSect = CriticalSectionWrapper::CreateCriticalSection();
}

SSRCDatabase::~SSRCDatabase() {
  _ssrcMap.clear();
  delete _critSect;
}

uint32_t SSRCDatabase::GenerateRandom() {
  uint32_t ssrc = 0;
  do {
    ssrc = rand();
    ssrc = ssrc << 16;
    ssrc += rand();
  } while (ssrc == 0 || ssrc == 0xffffffff);

  return ssrc;
}
}  // namespace webrtc