Reachability.cs

using System;
using System.Net;
using MonoTouch.CoreFoundation;
using MonoTouch.SystemConfiguration;

public enum NetworkStatus
{
	NotReachable,
	ReachableViaCarrierDataNetwork,
	ReachableViaWiFiNetwork
}

public static class Reachability
{
	public static string HostName = "www.google.com";
	
	public static bool IsReachableWithoutRequiringConnection (NetworkReachabilityFlags flags)
	{
		// Is it reachable with the current network configuration?
		bool isReachable = (flags & NetworkReachabilityFlags.Reachable) != 0;

		// Do we need a connection to reach it?
		bool noConnectionRequired = (flags & NetworkReachabilityFlags.ConnectionRequired) == 0;

		// Since the network stack will automatically try to get the WAN up,
		// probe that
		if ((flags & NetworkReachabilityFlags.IsWWAN) != 0)
			noConnectionRequired = true;

		return isReachable && noConnectionRequired;
	}

	// Is the host reachable with the current network configuration
	public static bool IsHostReachable (string host)
	{
		if (host == null || host.Length == 0)
			return false;

		using (var r = new NetworkReachability (host)) {
			NetworkReachabilityFlags flags;
			
			if (r.TryGetFlags (out flags)) {
				return IsReachableWithoutRequiringConnection (flags);
			}
		}
		return false;
	}

	// 
	// Raised every time there is an interesting reachable event, 
	// we do not even pass the info as to what changed, and 
	// we lump all three status we probe into one
	//
	public static event EventHandler ReachabilityChanged;
	
	static void OnChange (NetworkReachabilityFlags flags)
	{
		var h = ReachabilityChanged;
		if (h != null)
			h (null, EventArgs.Empty);
	}
	
	//
	// Returns true if it is possible to reach the AdHoc WiFi network
	// and optionally provides extra network reachability flags as the
	// out parameter
	//
	static NetworkReachability adHocWiFiNetworkReachability;

	public static bool IsAdHocWiFiNetworkAvailable (out NetworkReachabilityFlags flags)
	{
		if (adHocWiFiNetworkReachability == null) {
			adHocWiFiNetworkReachability = new NetworkReachability (new IPAddress (new byte [] {169,254,0,0}));
			adHocWiFiNetworkReachability.SetNotification (OnChange);
			adHocWiFiNetworkReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
		}
		
		if (!adHocWiFiNetworkReachability.TryGetFlags (out flags))
			return false;
		
		return IsReachableWithoutRequiringConnection (flags);
	}
	
	static NetworkReachability defaultRouteReachability;

	static bool IsNetworkAvaialable (out NetworkReachabilityFlags flags)
	{
		if (defaultRouteReachability == null) {
			defaultRouteReachability = new NetworkReachability (new IPAddress (0));
			defaultRouteReachability.SetNotification (OnChange);
			defaultRouteReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
		}
		if (defaultRouteReachability.TryGetFlags (out flags))
			return false;
		return IsReachableWithoutRequiringConnection (flags);
	}
	
	static NetworkReachability remoteHostReachability;

	public static NetworkStatus RemoteHostStatus ()
	{
		NetworkReachabilityFlags flags;
		bool reachable;
		
		if (remoteHostReachability == null) {
			remoteHostReachability = new NetworkReachability (HostName);

			// Need to probe before we queue, or we wont get any meaningful values
			// this only happens when you create NetworkReachability from a hostname
			reachable = remoteHostReachability.TryGetFlags (out flags);
			
			remoteHostReachability.SetNotification (OnChange);
			remoteHostReachability.Schedule (CFRunLoop.Current, CFRunLoop.ModeDefault);
		} else
			reachable = remoteHostReachability.TryGetFlags (out flags);			
		
		if (!reachable)
			return NetworkStatus.NotReachable;

		if (!IsReachableWithoutRequiringConnection (flags))
			return NetworkStatus.NotReachable;
		
		if ((flags & NetworkReachabilityFlags.IsWWAN) != 0)
			return NetworkStatus.ReachableViaCarrierDataNetwork;
				
		return NetworkStatus.ReachableViaWiFiNetwork;
	}
	
	public static NetworkStatus InternetConnectionStatus ()
	{
		NetworkReachabilityFlags flags;
		bool defaultNetworkAvailable = IsNetworkAvaialable (out flags);
		if (defaultNetworkAvailable) {
			if ((flags & NetworkReachabilityFlags.IsDirect) != 0)
				return NetworkStatus.NotReachable;
		} else if ((flags & NetworkReachabilityFlags.IsWWAN) != 0)
			return NetworkStatus.ReachableViaCarrierDataNetwork;
		return NetworkStatus.ReachableViaWiFiNetwork;
	}
	
	public static NetworkStatus LocalWifiConnectionStatus ()
	{
		NetworkReachabilityFlags flags;
		if (IsAdHocWiFiNetworkAvailable (out flags)) {
			if ((flags & NetworkReachabilityFlags.IsDirect) != 0)
				return NetworkStatus.ReachableViaWiFiNetwork;
		}
		return NetworkStatus.NotReachable;
	}
}