// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/base/network_change_notifier_mac.h"

#include <netinet/in.h>
#include <SystemConfiguration/SCDynamicStoreKey.h>
#include <SystemConfiguration/SCNetworkReachability.h>
#include <SystemConfiguration/SCSchemaDefinitions.h>

#include "base/mac/scoped_cftyperef.h"
#include "base/synchronization/lock.h"

namespace net {

static bool CalculateReachability(SCNetworkConnectionFlags flags) {
  bool reachable = flags & kSCNetworkFlagsReachable;
  bool connection_required = flags & kSCNetworkFlagsConnectionRequired;
  return reachable && !connection_required;
}

NetworkChangeNotifierMac::NetworkChangeNotifierMac()
    : forwarder_(this),
      config_watcher_(&forwarder_),
      network_reachable_(true) {}

NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {
  if (reachability_.get() && run_loop_.get()) {
    SCNetworkReachabilityUnscheduleFromRunLoop(reachability_.get(),
                                               run_loop_.get(),
                                               kCFRunLoopCommonModes);
  }
}

bool NetworkChangeNotifierMac::IsCurrentlyOffline() const {
  base::AutoLock lock(network_reachable_lock_);
  return !network_reachable_;
}

void NetworkChangeNotifierMac::SetDynamicStoreNotificationKeys(
    SCDynamicStoreRef store) {
  // Called on notifier thread.
  run_loop_.reset(CFRunLoopGetCurrent());
  CFRetain(run_loop_.get());

  base::mac::ScopedCFTypeRef<CFMutableArrayRef> notification_keys(
      CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks));
  base::mac::ScopedCFTypeRef<CFStringRef> key(
      SCDynamicStoreKeyCreateNetworkGlobalEntity(
          NULL, kSCDynamicStoreDomainState, kSCEntNetInterface));
  CFArrayAppendValue(notification_keys.get(), key.get());
  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
      NULL, kSCDynamicStoreDomainState, kSCEntNetIPv4));
  CFArrayAppendValue(notification_keys.get(), key.get());
  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
      NULL, kSCDynamicStoreDomainState, kSCEntNetIPv6));
  CFArrayAppendValue(notification_keys.get(), key.get());

  // Set the notification keys.  This starts us receiving notifications.
  bool ret = SCDynamicStoreSetNotificationKeys(
      store, notification_keys.get(), NULL);
  // TODO(willchan): Figure out a proper way to handle this rather than crash.
  CHECK(ret);

  // Try to reach 0.0.0.0. This is the approach taken by Firefox:
  //
  // http://mxr.mozilla.org/mozilla2.0/source/netwerk/system/mac/nsNetworkLinkService.mm
  //
  // From my (adamk) testing on Snow Leopard, 0.0.0.0
  // seems to be reachable if any network connection is available.
  struct sockaddr_in addr = {0};
  addr.sin_len = sizeof(addr);
  addr.sin_family = AF_INET;
  reachability_.reset(SCNetworkReachabilityCreateWithAddress(
      kCFAllocatorDefault, reinterpret_cast<struct sockaddr*>(&addr)));

  // 1. Get the initial network state synchronously.
  SCNetworkConnectionFlags flags;
  if (SCNetworkReachabilityGetFlags(reachability_.get(), &flags)) {
    bool reachable = CalculateReachability(flags);
    base::AutoLock lock(network_reachable_lock_);
    network_reachable_ = reachable;
  } else
    LOG(ERROR) << "Could not get initial network state.";

  // 2. Set up periodic callbacks when the state changes.
  SCNetworkReachabilityContext reachability_context = {
    0,     // version
    this,  // user data
    NULL,  // retain
    NULL,  // release
    NULL   // description
  };
  if (!SCNetworkReachabilitySetCallback(
          reachability_.get(),
          &NetworkChangeNotifierMac::ReachabilityCallback,
          &reachability_context)) {
    LOG(DFATAL) << "Could not set network reachability callback";
    reachability_.reset();
  } else if (!SCNetworkReachabilityScheduleWithRunLoop(reachability_.get(),
                                                       run_loop_,
                                                       kCFRunLoopCommonModes)) {
    LOG(DFATAL) << "Could not schedule network reachability on run loop";
    reachability_.reset();
  }
}

void NetworkChangeNotifierMac::OnNetworkConfigChange(CFArrayRef changed_keys) {
  DCHECK_EQ(run_loop_.get(), CFRunLoopGetCurrent());

  for (CFIndex i = 0; i < CFArrayGetCount(changed_keys); ++i) {
    CFStringRef key = static_cast<CFStringRef>(
        CFArrayGetValueAtIndex(changed_keys, i));
    if (CFStringHasSuffix(key, kSCEntNetIPv4) ||
        CFStringHasSuffix(key, kSCEntNetIPv6)) {
      NotifyObserversOfIPAddressChange();
      return;
    }
    if (CFStringHasSuffix(key, kSCEntNetInterface)) {
      // TODO(willchan): Does not appear to be working.  Look into this.
      // Perhaps this isn't needed anyway.
    } else {
      NOTREACHED();
    }
  }
}

// static
void NetworkChangeNotifierMac::ReachabilityCallback(
    SCNetworkReachabilityRef target,
    SCNetworkConnectionFlags flags,
    void* notifier) {
  NetworkChangeNotifierMac* notifier_mac =
      static_cast<NetworkChangeNotifierMac*>(notifier);

  DCHECK_EQ(notifier_mac->run_loop_.get(), CFRunLoopGetCurrent());

  bool new_reachability = CalculateReachability(flags);
  bool old_reachability;
  {
    base::AutoLock lock(notifier_mac->network_reachable_lock_);
    old_reachability = notifier_mac->network_reachable_;
    notifier_mac->network_reachable_ = new_reachability;
  }
  if (old_reachability != new_reachability)
    NotifyObserversOfOnlineStateChange();
}

}  // namespace net