Reachability.m

/*
 
 File: Reachability.m
 Abstract: Basic demonstration of how to use the SystemConfiguration Reachablity APIs.
 
 Version: 2.2
 
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*/
 
#import <sys/socket.h>
#import <netinet/in.h>
#import <netinet6/in6.h>
#import <arpa/inet.h>
#import <ifaddrs.h>
#import <netdb.h>
 
#import <CoreFoundation/CoreFoundation.h>
 
#import "Reachability.h"
 
#define kShouldPrintReachabilityFlags 1
 
static void PrintReachabilityFlags(SCNetworkReachabilityFlags flags, const char *comment)
{
#if kShouldPrintReachabilityFlags
 
  NSLog(@"Reachability Flag Status: %c%c %c%c%c%c%c%c%c %s\n",
        (flags & kSCNetworkReachabilityFlagsIsWWAN) ? 'W' : '-',
        (flags & kSCNetworkReachabilityFlagsReachable) ? 'R' : '-',
 
        (flags & kSCNetworkReachabilityFlagsTransientConnection) ? 't' : '-',
        (flags & kSCNetworkReachabilityFlagsConnectionRequired) ? 'c' : '-',
        (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) ? 'C' : '-',
        (flags & kSCNetworkReachabilityFlagsInterventionRequired) ? 'i' : '-',
        (flags & kSCNetworkReachabilityFlagsConnectionOnDemand) ? 'D' : '-',
        (flags & kSCNetworkReachabilityFlagsIsLocalAddress) ? 'l' : '-',
        (flags & kSCNetworkReachabilityFlagsIsDirect) ? 'd' : '-', comment);
#endif
}
 
@implementation Reachability
static void ReachabilityCallback(SCNetworkReachabilityRef target, SCNetworkReachabilityFlags flags,
                                 void *info)
{
#pragma unused(target, flags)
  NSCAssert(info != NULL, @"info was NULL in ReachabilityCallback");
  NSCAssert([(NSObject *)info isKindOfClass:[Reachability class]],
            @"info was wrong class in ReachabilityCallback");
 
  // We're on the main RunLoop, so an NSAutoreleasePool is not necessary, but is added defensively
  // in case someone uses the Reachablity object in a different thread.
  NSAutoreleasePool *myPool = [[NSAutoreleasePool alloc] init];
 
  Reachability *noteObject = (Reachability *)info;
  // Post a notification to notify the client that the network reachability changed.
  [[NSNotificationCenter defaultCenter] postNotificationName:kReachabilityChangedNotification
                                                      object:noteObject];
 
  [myPool release];
}
 
- (BOOL)startNotifier
{
  BOOL retVal = NO;
  SCNetworkReachabilityContext context = { 0, self, NULL, NULL, NULL };
  if (SCNetworkReachabilitySetCallback(reachabilityRef, ReachabilityCallback, &context))
  {
    if (SCNetworkReachabilityScheduleWithRunLoop(reachabilityRef, CFRunLoopGetCurrent(),
                                                 kCFRunLoopDefaultMode))
    {
      retVal = YES;
    }
  }
  return retVal;
}
 
- (void)stopNotifier
{
  if (reachabilityRef != NULL)
  {
    SCNetworkReachabilityUnscheduleFromRunLoop(reachabilityRef, CFRunLoopGetCurrent(),
                                               kCFRunLoopDefaultMode);
  }
}
 
- (void)dealloc
{
  [self stopNotifier];
  if (reachabilityRef != NULL)
  {
    CFRelease(reachabilityRef);
  }
  [super dealloc];
}
 
+ (Reachability *)reachabilityWithHostName:(NSString *)hostName;
{
  Reachability *retVal = NULL;
  SCNetworkReachabilityRef reachability =
      SCNetworkReachabilityCreateWithName(NULL, [hostName UTF8String]);
  if (reachability != NULL)
  {
    retVal = [[[self alloc] init] autorelease];
    if (retVal != NULL)
    {
      retVal->reachabilityRef = reachability;
      retVal->localWiFiRef = NO;
    }
  }
  return retVal;
}
 
+ (Reachability *)reachabilityWithAddress:(const struct sockaddr_in *)hostAddress;
{
  SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(
      kCFAllocatorDefault, (const struct sockaddr *)hostAddress);
  Reachability *retVal = NULL;
  if (reachability != NULL)
  {
    retVal = [[[self alloc] init] autorelease];
    if (retVal != NULL)
    {
      retVal->reachabilityRef = reachability;
      retVal->localWiFiRef = NO;
    }
  }
  return retVal;
}
 
+ (Reachability *)reachabilityForInternetConnection;
{
  struct sockaddr_in zeroAddress;
  bzero(&zeroAddress, sizeof(zeroAddress));
  zeroAddress.sin_len = sizeof(zeroAddress);
  zeroAddress.sin_family = AF_INET;
  return [self reachabilityWithAddress:&zeroAddress];
}
 
+ (Reachability *)reachabilityForLocalWiFi;
{
  struct sockaddr_in localWifiAddress;
  bzero(&localWifiAddress, sizeof(localWifiAddress));
  localWifiAddress.sin_len = sizeof(localWifiAddress);
  localWifiAddress.sin_family = AF_INET;
  // IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0
  localWifiAddress.sin_addr.s_addr = htonl(IN_LINKLOCALNETNUM);
  Reachability *retVal = [self reachabilityWithAddress:&localWifiAddress];
  if (retVal != NULL)
  {
    retVal->localWiFiRef = YES;
  }
  return retVal;
}
 
#pragma mark Network Flag Handling
 
- (NetworkStatus)localWiFiStatusForFlags:(SCNetworkReachabilityFlags)flags
{
  PrintReachabilityFlags(flags, "localWiFiStatusForFlags");
 
  BOOL retVal = NotReachable;
  if ((flags & kSCNetworkReachabilityFlagsReachable) &&
      (flags & kSCNetworkReachabilityFlagsIsDirect))
  {
    retVal = ReachableViaWiFi;
  }
  return retVal;
}
 
- (NetworkStatus)networkStatusForFlags:(SCNetworkReachabilityFlags)flags
{
  PrintReachabilityFlags(flags, "networkStatusForFlags");
  if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
  {
    // if target host is not reachable
    return NotReachable;
  }
 
  BOOL retVal = NotReachable;
 
  if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
  {
    // if target host is reachable and no connection is required
    //  then we'll assume (for now) that your on Wi-Fi
    retVal = ReachableViaWiFi;
  }
 
  if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand) != 0) ||
       (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
  {
    // ... and the connection is on-demand (or on-traffic) if the
    //     calling application is using the CFSocketStream or higher APIs
 
    if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
    {
      // ... and no [user] intervention is needed
      retVal = ReachableViaWiFi;
    }
  }
 
  if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
  {
    // ... but WWAN connections are OK if the calling application
    //     is using the CFNetwork (CFSocketStream?) APIs.
    retVal = ReachableViaWWAN;
  }
  return retVal;
}
 
- (BOOL)connectionRequired;
{
  NSAssert(reachabilityRef != NULL, @"connectionRequired called with NULL reachabilityRef");
  SCNetworkReachabilityFlags flags;
  if (SCNetworkReachabilityGetFlags(reachabilityRef, &flags))
  {
    return (flags & kSCNetworkReachabilityFlagsConnectionRequired);
  }
  return NO;
}
 
- (NetworkStatus)currentReachabilityStatus
{
  NSAssert(reachabilityRef != NULL, @"currentNetworkStatus called with NULL reachabilityRef");
  NetworkStatus retVal = NotReachable;
  SCNetworkReachabilityFlags flags;
  if (SCNetworkReachabilityGetFlags(reachabilityRef, &flags))
  {
    if (localWiFiRef)
    {
      retVal = [self localWiFiStatusForFlags:flags];
    }
    else
    {
      retVal = [self networkStatusForFlags:flags];
    }
  }
  return retVal;
}
@end