[System.Net.Http] Move Mac/iOS specific HttpMessageHandler's to Xamarin.*.dll (#13746)

* Revert "[System.Net.Http] Move NSUrlSessionHandler from xamarin-macios to mono (#13229)"

This reverts commit 5bf74a995465dd54ceb4a2311c2d6041258e8fe0.

* [System.Net.Http] Move Mac/iOS specific HttpMessageHandler's to Xamarin.*.dll

We decided to move these types into Xamarin products since they can't be
used without the underlying infrastructure anyway.

* Bump API snapshot submodule

* [csproj] Update project files

16 files changed, 66 insertions, 1829 deletions

diff --git a/mcs/class/System.Net.Http/Assembly/AssemblyInfo.cs b/mcs/class/System.Net.Http/Assembly/AssemblyInfo.cs
index 7cd48a91baa..0e3386fdc81 100644
--- a/mcs/class/System.Net.Http/Assembly/AssemblyInfo.cs
+++ b/mcs/class/System.Net.Http/Assembly/AssemblyInfo.cs
@@ -66,3 +66,9 @@ using System.Runtime.InteropServices;
 
 [assembly: InternalsVisibleTo ("System.Net.Http.WebRequest, PublicKey=002400000480000094000000060200000024000052534131000400000100010007d1fa57c4aed9f0a32e84aa0faefd0de9e8fd6aec8f87fb03766c834c99921eb23be79ad9d5dcc1dd9ad236132102900b723cf980957fc4e177108fc607774f29e8320e92ea05ece4e821c0a5efe8f1645c4c0c93c1ab99285d622caa652c1dfad63d745d6f2de5f17e5eaf0fc4963d261c8a12436518206dc093344d5ad293")]
 
+#if MONOTOUCH || XAMMAC || XAMMAC_4_5
+[assembly: TypeForwardedToAttribute (typeof(System.Net.Http.NSUrlSessionHandler))]
+#if !MONOTOUCH_WATCH
+[assembly: TypeForwardedToAttribute (typeof(System.Net.Http.CFNetworkHandler))]
+#endif
+#endif
diff --git a/mcs/class/System.Net.Http/CFContentStream.cs b/mcs/class/System.Net.Http/CFContentStream.cs
deleted file mode 100644
index d8bba8f0f9a..00000000000
--- a/mcs/class/System.Net.Http/CFContentStream.cs
+++ /dev/null
@@ -1,156 +0,0 @@
-//
-// CFContentStream.cs
-//
-// Authors:
-//	Marek Safar  <marek.safar@gmail.com>
-//
-// Copyright (C) 2013 Xamarin Inc (http://www.xamarin.com)
-//
-// Permission is hereby granted, free of charge, to any person obtaining
-// a copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to
-// permit persons to whom the Software is furnished to do so, subject to
-// the following conditions:
-//
-// The above copyright notice and this permission notice shall be
-// included in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
-// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-//
-
-using System.Threading;
-using System.Threading.Tasks;
-using System.IO;
-using System.Net;
-using System.Runtime.ExceptionServices;
-
-#if XAMCORE_4_0
-using CFNetwork;
-using CoreFoundation;
-#elif XAMCORE_2_0
-using CoreServices;
-using CoreFoundation;
-#else
-using MonoTouch.CoreServices;
-using MonoTouch.CoreFoundation;
-#endif
-
-namespace System.Net.Http
-{
-	class BufferData 
-	{
-		public byte[] Buffer;
-		public int Length;
-	}
-
-	class CFContentStream : HttpContent
-	{
-		readonly CFHTTPStream http_stream;
-		BufferData data;
-		Mutex data_mutex;
-		AutoResetEvent data_event;
-		AutoResetEvent data_read_event;
-		ExceptionDispatchInfo http_exception;
-
-		// The requirements are:
-		// * We must read at least one byte from the stream every time
-		//   we get a HasBytesAvailable event.
-		// * SerializeToStreamAsync is executed on a separate thread,
-		//   so reads must somehow be synchronized with that thread.
-		//
-		// Current implementation:
-		// * We read data in ReadStreamData (on the same thread
-		//   we got the HasBytesAvailable event, i.e. inside the 
-		//   HasBytesAvailable event handler).
-		// * Data is stored in a class-level buffer.
-		// * SerializeToStreamAsync blocks while waiting for
-		//   data from ReadStreamData.
-		// * ReadStreamData will only read more data once SerializeToStreamAsync
-		//   has consumed any existing data. This means we'll be
-		//   blocking in the HasBytesAvailable event handler until
-		//   any previously read data has been processed (this prevents
-		//   any unbound memory growth).
-
-		public CFContentStream (CFHTTPStream stream)
-		{
-			this.http_stream = stream;
-			this.http_stream.ErrorEvent += HandleErrorEvent;
-			data = new BufferData () {
-				Buffer = new byte [4096],
-			};
-			data_event = new AutoResetEvent (false);
-			data_read_event = new AutoResetEvent (true);
-			data_mutex = new Mutex ();
-		}
-
-		void HandleErrorEvent (object sender, CFStream.StreamEventArgs e)
-		{
-			var gotMutex = data_mutex.WaitOne ();
-			if (gotMutex) {
-				var stream = (CFHTTPStream)sender;
-				if (e.EventType == CFStreamEventType.ErrorOccurred)
-					Volatile.Write (ref http_exception, ExceptionDispatchInfo.Capture (stream.GetError ()));
-				data_mutex.ReleaseMutex ();
-			}
-		}
-
-		public void ReadStreamData ()
-		{
-			data_read_event.WaitOne (); // make sure there's no pending data.
-
-			data_mutex.WaitOne ();
-			data.Length = (int) http_stream.Read (data.Buffer, 0, data.Buffer.Length);
-			data_mutex.ReleaseMutex ();
-
-			data_event.Set ();
-		}
-
-		public void Close ()
-		{
-			data_read_event.WaitOne (); // make sure there's no pending data
-
-			data_mutex.WaitOne ();
-			data = null;
-			this.http_stream.ErrorEvent -= HandleErrorEvent;
-			data_mutex.ReleaseMutex ();
-
-			data_event.Set ();
-		}
-
-		protected internal override async Task SerializeToStreamAsync (Stream stream, TransportContext context)
-		{
-			while (data_event.WaitOne ()) {
-				data_mutex.WaitOne ();
-				if (http_exception != null) {
-					http_exception.Throw ();
-					data_mutex.ReleaseMutex ();
-					break;
-				}
-				if (data == null || data.Length <= 0) {
-					data_mutex.ReleaseMutex ();
-					data_read_event.Set ();
-					break;
-				}
-
-				await stream.WriteAsync (data.Buffer, 0, data.Length).ConfigureAwait (false);
-				data_mutex.ReleaseMutex ();
-
-				data_read_event.Set ();
-			}
-		}
-
-		protected internal override bool TryComputeLength (out long length)
-		{
-			length = 0;
-			return false;
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/CFNetworkHandler.cs b/mcs/class/System.Net.Http/CFNetworkHandler.cs
deleted file mode 100644
index 617d572592c..00000000000
--- a/mcs/class/System.Net.Http/CFNetworkHandler.cs
+++ /dev/null
@@ -1,389 +0,0 @@
-//
-// CFNetworkHandler.cs
-//
-// Authors:
-//	Marek Safar  <marek.safar@gmail.com>
-//
-// Copyright (C) 2013 Xamarin Inc (http://www.xamarin.com)
-//
-// Permission is hereby granted, free of charge, to any person obtaining
-// a copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to
-// permit persons to whom the Software is furnished to do so, subject to
-// the following conditions:
-//
-// The above copyright notice and this permission notice shall be
-// included in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
-// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-//
-
-using System.Threading;
-using System.Net.Http.Headers;
-using System.Threading.Tasks;
-using System.IO;
-using System.Collections.Generic;
-using System.Net;
-
-#if XAMCORE_4_0
-using CFNetwork;
-using CoreFoundation;
-using CF=CoreFoundation;
-#elif XAMCORE_2_0
-using CoreServices;
-using CoreFoundation;
-using CF=CoreFoundation;
-#else
-using MonoTouch.CoreServices;
-using MonoTouch.CoreFoundation;
-using CF=MonoTouch.CoreFoundation;
-#endif
-
-namespace System.Net.Http
-{
-	public class CFNetworkHandler : HttpMessageHandler
-	{
-		class StreamBucket
-		{
-			public TaskCompletionSource<HttpResponseMessage> Response;
-			public HttpRequestMessage Request;
-			public CancellationTokenRegistration CancellationTokenRegistration;
-			public CFContentStream ContentStream;
-			public bool StreamCanBeDisposed;
-
-			public void Close ()
-			{
-				CancellationTokenRegistration.Dispose ();
-				if (ContentStream != null) {
-					// The Close method of the CFContentStream blocks as you can see:
-					// public void Close ()
-					// {
-					//	data_read_event.WaitOne (); // make sure there's no pending data
-					//
-					//	data_mutex.WaitOne ();
-					//	data = null;
-					//	this.http_stream.ErrorEvent -= HandleErrorEvent;
-					//	data_mutex.ReleaseMutex ();
-					//
-					//	data_event.Set ();
-					// }
-					// This means. that when we want to ignore the data of the content, which happens
-					// in the first request of a redirect, if we want to close, ignoring the content
-					// we will have a deadlock.
-					// Dispose will clean all the data, without waiting for the read, which by design in the
-					// CFContentStream, blocks the thread. This happens ONLY after the first request that gets
-					// a redirect status code. All other cases should call close.
-					if (StreamCanBeDisposed)
-						ContentStream.Dispose ();
-					else
-						ContentStream.Close ();
-				}
-			}
-		}
-
-		bool allowAutoRedirect;
-		bool sentRequest;
-		bool useSystemProxy;
-		CookieContainer cookies;
-
-		Dictionary<IntPtr, StreamBucket> streamBuckets;
-
-		public CFNetworkHandler ()
-		{
-			allowAutoRedirect = true;
-			streamBuckets = new Dictionary<IntPtr, StreamBucket> ();
-		}
-
-		void EnsureModifiability ()
-		{
-			if (sentRequest)
-				throw new InvalidOperationException (
-					"This instance has already started one or more requests. " +
-					"Properties can only be modified before sending the first request.");
-		}
-
-		public bool AllowAutoRedirect {
-			get {
-				return allowAutoRedirect;
-			}
-			set {
-				EnsureModifiability ();
-				allowAutoRedirect = value;
-			}
-		}
-
-		public CookieContainer CookieContainer {
-			get {
-				return cookies ?? (cookies = new CookieContainer ());
-			}
-			set {
-				EnsureModifiability ();
-				cookies = value;
-			}
-		}
-
-		public bool UseSystemProxy {
-			get {
-				return useSystemProxy;
-			}
-			set {
-				EnsureModifiability ();
-				useSystemProxy = value;
-			}
-		}
-
-		// TODO: Add more properties
-
-		protected override void Dispose (bool disposing)
-		{
-			// TODO: CloseStream remaining stream buckets if there are any
-
-			base.Dispose (disposing);
-		}
-
-		CFHTTPMessage CreateWebRequestAsync (HttpRequestMessage request)
-		{
-			var req = CFHTTPMessage.CreateRequest (request.RequestUri, request.Method.Method, request.Version);
-
-			// TODO:
-/*
-			if (wr.ProtocolVersion == HttpVersion.Version10) {
-				wr.KeepAlive = request.Headers.ConnectionKeepAlive;
-			} else {
-				wr.KeepAlive = request.Headers.ConnectionClose != true;
-			}
-
-			if (useDefaultCredentials) {
-				wr.UseDefaultCredentials = true;
-			} else {
-				wr.Credentials = credentials;
-			}
-
-			if (useProxy) {
-				wr.Proxy = proxy;
-			}
-*/
-			if (cookies != null) {
-				string cookieHeader = cookies.GetCookieHeader (request.RequestUri);
-				if (cookieHeader != "")
-					req.SetHeaderFieldValue ("Cookie", cookieHeader);
-			}
-
-			foreach (var header in request.Headers) {
-				foreach (var value in header.Value) {
-					req.SetHeaderFieldValue (header.Key, value);
-				}
-			}
-
-			if (request.Content != null) {
-				foreach (var header in request.Content.Headers) {
-					foreach (var value in header.Value) {
-						req.SetHeaderFieldValue (header.Key, value);
-					}
-				}
-			}
-
-			return req;
-		}
-
-		protected internal override async Task<HttpResponseMessage> SendAsync (HttpRequestMessage request, CancellationToken cancellationToken)
-		{
-			return await SendAsync (request, cancellationToken, true).ConfigureAwait (false);
-		}
-		
-		internal async Task<HttpResponseMessage> SendAsync (HttpRequestMessage request, CancellationToken cancellationToken, bool isFirstRequest)
-		{
-			sentRequest = true;
-
-			CFHTTPStream stream;
-			using (var message = CreateWebRequestAsync (request))
-			{
-				if (request.Content != null) {
-					var data = await request.Content.ReadAsByteArrayAsync ().ConfigureAwait (false);
-					message.SetBody (data);
-				}
-
-				stream = CFHTTPStream.CreateForHTTPRequest (message);
-			}
-
-			if (useSystemProxy) {
-				var proxies = CF.CFNetwork.GetSystemProxySettings ();
-				if (proxies.HTTPEnable) {
-					stream.SetProxy (proxies);
-				}
-			}
-
-			if (!isFirstRequest && allowAutoRedirect)
-				stream.ShouldAutoredirect = allowAutoRedirect;
-			stream.HasBytesAvailableEvent += HandleHasBytesAvailableEvent;
-			stream.ErrorEvent += HandleErrorEvent;
-			stream.ClosedEvent += HandleClosedEvent;
-
-			var response = new TaskCompletionSource<HttpResponseMessage> ();
-
-			if (cancellationToken.IsCancellationRequested) {
-				response.SetCanceled ();
-				return await response.Task;
-			}
-
-			var bucket = new StreamBucket () {
-				Request = request,
-				Response = response,
-			};
-
-			streamBuckets.Add (stream.Handle, bucket);
-
-			//
-			// Always schedule stream events handling on main-loop. Due to ConfigureAwait (false) we may end up
-			// on any thread-pool thread which may not have run-loop running
-			//
-#if XAMCORE_2_0
-			stream.EnableEvents (CF.CFRunLoop.Main, CF.CFRunLoop.ModeCommon);
-#else
-			stream.EnableEvents (CF.CFRunLoop.Main, CF.CFRunLoop.CFRunLoopCommonModes);
-#endif
-
-			stream.Open ();
-
-			bucket.CancellationTokenRegistration = cancellationToken.Register (() => {
-				StreamBucket bucket2;
-				if (!streamBuckets.TryGetValue (stream.Handle, out bucket2))
-					return;
-
-				bucket2.Response.TrySetCanceled ();
-				CloseStream (stream);
-			});
-
-			if (isFirstRequest) {
-				var initialRequest = await response.Task;
- 				var status = initialRequest.StatusCode;
- 				if (IsRedirect (status) && allowAutoRedirect) {
- 					bucket.StreamCanBeDisposed = true;
-					// remove headers in a redirect for Authentication.
-					request.Headers.Authorization = null;
- 					return await SendAsync (request, cancellationToken, false).ConfigureAwait (false);
- 				}
- 				return initialRequest;
- 			} 
-			return await response.Task;
-		}
-
-		// Decide if we redirect or not, similar to what is done in the managed handler
-		// https://github.com/mono/mono/blob/eca15996c7163f331c9f2cd0a17b63e8f92b1d55/mcs/class/referencesource/System/net/System/Net/HttpWebRequest.cs#L5681
-		static bool IsRedirect (HttpStatusCode status)
-		{
-			return status == HttpStatusCode.Ambiguous || // 300
-				status == HttpStatusCode.Moved || // 301
-				status == HttpStatusCode.Redirect || // 302
-				status == HttpStatusCode.RedirectMethod || // 303
-				status == HttpStatusCode.RedirectKeepVerb; // 307
-		}
-		
-		void HandleErrorEvent (object sender, CFStream.StreamEventArgs e)
-		{
-			var stream = (CFHTTPStream)sender;
-
-			StreamBucket bucket;
-			if (!streamBuckets.TryGetValue (stream.Handle, out bucket))
-				return;
-
-			bucket.Response.TrySetException (stream.GetError ());
-			CloseStream (stream);
-		}
-
-		void HandleClosedEvent (object sender, CFStream.StreamEventArgs e)
-		{
-			var stream = (CFHTTPStream)sender;
-			// might not have been called (e.g. no data) but initialize critical data
-			HandleHasBytesAvailableEvent (sender, e);
-			CloseStream (stream);
-		}
-
-		void CloseStream (CFHTTPStream stream)
-		{
-			lock (streamBuckets) {
-				if (streamBuckets.TryGetValue (stream.Handle, out var bucket)) {
-					bucket.Close ();
-					streamBuckets.Remove (stream.Handle);
-				}
-			}
-			stream.Close ();
-		}
-
-		void HandleHasBytesAvailableEvent (object sender, CFStream.StreamEventArgs e)
-		{
-			var stream = (CFHTTPStream) sender;
-
-			StreamBucket bucket;
-			if (!streamBuckets.TryGetValue (stream.Handle, out bucket))
-				return;
-
-			if (bucket.Response.Task.IsCompleted) {
-				bucket.ContentStream.ReadStreamData ();
-				return;
-			}
-
-			var header = stream.GetResponseHeader ();
-
-			// Is this possible?
-			if (!header.IsHeaderComplete)
-				throw new NotImplementedException ();
-
-			bucket.ContentStream = new CFContentStream (stream);
-				
-			var response_msg = new HttpResponseMessage (header.ResponseStatusCode);
-			response_msg.RequestMessage = bucket.Request;
-			response_msg.ReasonPhrase = header.ResponseStatusLine;
-			response_msg.Content = bucket.ContentStream;
-
-			var fields = header.GetAllHeaderFields ();
-			if (fields != null) {
-				foreach (var entry in fields) {
-					if (entry.Key == null)
-						continue;
-
-					var key = entry.Key.ToString ();
-					var value = entry.Value == null ? string.Empty : entry.Value.ToString ();
-					HttpHeaders item_headers;
-					if (HttpHeaders.GetKnownHeaderKind (key) == Headers.HttpHeaderKind.Content) {
-						item_headers = response_msg.Content.Headers;
-					} else {
-						item_headers = response_msg.Headers;
-
-						if (cookies != null && (key == "Set-Cookie" || key == "Set-Cookie2"))
-							AddCookie (value, bucket.Request.RequestUri, key);
-					}
-
-					item_headers.TryAddWithoutValidation (key, value);
-				}
-			}
-
-			// cancellation (CancellationTokenRegistration) can happen in parallel
-			if (!bucket.Response.Task.IsCanceled) {
-				bucket.Response.TrySetResult (response_msg);
-
-				bucket.ContentStream.ReadStreamData ();
-			}
-		}
-
-		void AddCookie (string value, Uri uri, string header)
-		{
-			CookieCollection cookies1 = null;
-			try {
-				cookies1 = cookies.CookieCutter (uri, header, value, false);
-			} catch {
-			}
-
-			if (cookies1 != null && cookies1.Count != 0) 
-				cookies.Add (cookies1);
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/HttpClientEx.cs b/mcs/class/System.Net.Http/HttpClientEx.cs
deleted file mode 100644
index fd5621c22e3..00000000000
--- a/mcs/class/System.Net.Http/HttpClientEx.cs
+++ /dev/null
@@ -1,229 +0,0 @@
-using System;
-using System.IO;
-using System.Net;
-#if XAMCORE_2_0
-using CoreFoundation;
-using Foundation;
-using ObjCRuntime;
-#elif MONOMAC
-using MonoMac.CoreFoundation;
-using MonoMac.Foundation;
-using MonoMac.ObjCRuntime;
-#else
-using MonoTouch.CoreFoundation;
-using MonoTouch.Foundation;
-using MonoTouch.ObjCRuntime;
-#endif
-
-#if SYSTEM_NET_HTTP && !MONOMAC
-namespace System.Net.Http {
-
-	public partial class HttpClient {
-
-		public HttpClient ()
-			: this (GetDefaultHandler (), true)
-		{
-		}
-
-		// note: the linker will re-write this to only reference the selected handler
-		// but we want this to work "as expected" even if the application is not being linked
-		static HttpMessageHandler GetDefaultHandler ()
-		{
-#if MONOTOUCH_WATCH
-			// There's only one valid handler type for watchOS
-			return new NSUrlSessionHandler ();
-#else
-			return RuntimeOptions.GetHttpMessageHandler ();
-#endif
-		}
-	}
-#else
-// due to historical reasons (around CFNetwork) Xamarin.Mac includes this inside it's profile assembly
-// and not a custom System.Net.Http assembly
-namespace Foundation {
-#endif
-
-	partial class NSUrlSessionHandler {
-
-		bool allowAutoRedirect;
-		ICredentials credentials;
-		bool sentRequest;
-
-		public bool AllowAutoRedirect {
-			get {
-				return allowAutoRedirect;
-			}
-			set {
-				EnsureModifiability ();
-				allowAutoRedirect = value;
-			}
-		}
-
-		public ICredentials Credentials {
-			get {
-				return credentials;
-			}
-			set {
-				EnsureModifiability ();
-				credentials = value;
-			}
-		}
-
-		internal void EnsureModifiability ()
-		{
-			if (sentRequest)
-				throw new InvalidOperationException (
-					"This instance has already started one or more requests. " +
-					"Properties can only be modified before sending the first request.");
-		}
-
-		// almost identical to ModernHttpClient version but it uses the constants from monotouch.dll | Xamarin.[iOS|WatchOS|TVOS].dll
-		static Exception createExceptionForNSError(NSError error)
-		{
-			// var webExceptionStatus = WebExceptionStatus.UnknownError;
-
-			var innerException = new NSErrorException(error);
-
-			// errors that exists in both share the same error code, so we can use a single switch/case
-			// this also ease watchOS integration as if does not expose CFNetwork but (I would not be 
-			// surprised if it)could return some of it's error codes
-#if MONOTOUCH_WATCH
-			if (error.Domain == NSError.NSUrlErrorDomain) {
-#else
-			if ((error.Domain == NSError.NSUrlErrorDomain) || (error.Domain == NSError.CFNetworkErrorDomain)) {
-#endif
-				// Parse the enum into a web exception status or exception. Some
-				// of these values don't necessarily translate completely to
-				// what WebExceptionStatus supports, so made some best guesses
-				// here.  For your reading pleasure, compare these:
-				//
-				// Apple docs: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_Constants/index.html#//apple_ref/doc/constant_group/URL_Loading_System_Error_Codes
-				// .NET docs: http://msdn.microsoft.com/en-us/library/system.net.webexceptionstatus(v=vs.110).aspx
-				switch ((NSUrlError) (long) error.Code) {
-				case NSUrlError.Cancelled:
-				case NSUrlError.UserCancelledAuthentication:
-#if !MONOTOUCH_WATCH
-				case (NSUrlError) NSNetServicesStatus.CancelledError:
-#endif
-					// No more processing is required so just return.
-					return new OperationCanceledException(error.LocalizedDescription, innerException);
-// 				case NSUrlError.BadURL:
-// 				case NSUrlError.UnsupportedURL:
-// 				case NSUrlError.CannotConnectToHost:
-// 				case NSUrlError.ResourceUnavailable:
-// 				case NSUrlError.NotConnectedToInternet:
-// 				case NSUrlError.UserAuthenticationRequired:
-// 				case NSUrlError.InternationalRoamingOff:
-// 				case NSUrlError.CallIsActive:
-// 				case NSUrlError.DataNotAllowed:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.Socks5BadCredentials:
-// 				case (NSUrlError) CFNetworkErrors.Socks5UnsupportedNegotiationMethod:
-// 				case (NSUrlError) CFNetworkErrors.Socks5NoAcceptableMethod:
-// 				case (NSUrlError) CFNetworkErrors.HttpAuthenticationTypeUnsupported:
-// 				case (NSUrlError) CFNetworkErrors.HttpBadCredentials:
-// 				case (NSUrlError) CFNetworkErrors.HttpBadURL:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.ConnectFailure;
-// 					break;
-// 				case NSUrlError.TimedOut:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.NetServiceTimeout:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.Timeout;
-// 					break;
-// 				case NSUrlError.CannotFindHost:
-// 				case NSUrlError.DNSLookupFailed:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.HostNotFound:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceDnsServiceFailure:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.NameResolutionFailure;
-// 					break;
-// 				case NSUrlError.DataLengthExceedsMaximum:
-// 					webExceptionStatus = WebExceptionStatus.MessageLengthLimitExceeded;
-// 					break;
-// 				case NSUrlError.NetworkConnectionLost:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.HttpConnectionLost:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.ConnectionClosed;
-// 					break;
-// 				case NSUrlError.HTTPTooManyRedirects:
-// 				case NSUrlError.RedirectToNonExistentLocation:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.HttpRedirectionLoopDetected:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.ProtocolError;
-// 					break;
-// 				case NSUrlError.RequestBodyStreamExhausted:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.SocksUnknownClientVersion:
-// 				case (NSUrlError) CFNetworkErrors.SocksUnsupportedServerVersion:
-// 				case (NSUrlError) CFNetworkErrors.HttpParseFailure:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.SendFailure;
-// 					break;
-// 				case NSUrlError.BadServerResponse:
-// 				case NSUrlError.ZeroByteResource:
-// 				case NSUrlError.CannotDecodeRawData:
-// 				case NSUrlError.CannotDecodeContentData:
-// 				case NSUrlError.CannotParseResponse:
-// 				case NSUrlError.FileDoesNotExist:
-// 				case NSUrlError.FileIsDirectory:
-// 				case NSUrlError.NoPermissionsToReadFile:
-// 				case NSUrlError.CannotLoadFromNetwork:
-// 				case NSUrlError.CannotCreateFile:
-// 				case NSUrlError.CannotOpenFile:
-// 				case NSUrlError.CannotCloseFile:
-// 				case NSUrlError.CannotWriteToFile:
-// 				case NSUrlError.CannotRemoveFile:
-// 				case NSUrlError.CannotMoveFile:
-// 				case NSUrlError.DownloadDecodingFailedMidStream:
-// 				case NSUrlError.DownloadDecodingFailedToComplete:
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.Socks4RequestFailed:
-// 				case (NSUrlError) CFNetworkErrors.Socks4IdentdFailed:
-// 				case (NSUrlError) CFNetworkErrors.Socks4IdConflict:
-// 				case (NSUrlError) CFNetworkErrors.Socks4UnknownStatusCode:
-// 				case (NSUrlError) CFNetworkErrors.Socks5BadState:
-// 				case (NSUrlError) CFNetworkErrors.Socks5BadResponseAddr:
-// 				case (NSUrlError) CFNetworkErrors.CannotParseCookieFile:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceUnknown:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceCollision:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceNotFound:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceInProgress:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceBadArgument:
-// 				case (NSUrlError) CFNetworkErrors.NetServiceInvalid:
-// #endif
-// 					webExceptionStatus = WebExceptionStatus.ReceiveFailure;
-// 					break;
-// 				case NSUrlError.SecureConnectionFailed:
-// 					webExceptionStatus = WebExceptionStatus.SecureChannelFailure;
-// 					break;
-// 				case NSUrlError.ServerCertificateHasBadDate:
-// 				case NSUrlError.ServerCertificateHasUnknownRoot:
-// 				case NSUrlError.ServerCertificateNotYetValid:
-// 				case NSUrlError.ServerCertificateUntrusted:
-// 				case NSUrlError.ClientCertificateRejected:
-// 				case NSUrlError.ClientCertificateRequired:
-// 					webExceptionStatus = WebExceptionStatus.TrustFailure;
-// 					break;
-// #if !MONOTOUCH_WATCH
-// 				case (NSUrlError) CFNetworkErrors.HttpProxyConnectionFailure:
-// 				case (NSUrlError) CFNetworkErrors.HttpBadProxyCredentials:
-// 				case (NSUrlError) CFNetworkErrors.PacFileError:
-// 				case (NSUrlError) CFNetworkErrors.PacFileAuth:
-// 				case (NSUrlError) CFNetworkErrors.HttpsProxyConnectionFailure:
-// 				case (NSUrlError) CFNetworkErrors.HttpsProxyFailureUnexpectedResponseToConnectMethod:
-// 					webExceptionStatus = WebExceptionStatus.RequestProhibitedByProxy;
-// 					break;
-// #endif
-				}
-			} 
-
-			// Always create a WebException so that it can be handled by the client.
-			return new WebException(error.LocalizedDescription, innerException); //, webExceptionStatus, response: null);
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/Makefile b/mcs/class/System.Net.Http/Makefile
index 88f80d2e8a2..3eef96a6b2f 100644
--- a/mcs/class/System.Net.Http/Makefile
+++ b/mcs/class/System.Net.Http/Makefile
@@ -11,20 +11,30 @@ ifeq (monodroid,$(PROFILE))
 LIB_MCS_FLAGS += -d:XAMARIN_MODERN
 endif
 
-ifneq (,$(filter monotouch monotouch_tv monotouch_watch,$(PROFILE)))
-LIB_MCS_FLAGS += -D:XAMCORE_2_0 -D:XAMARIN_MODERN -D:SYSTEM_NET_HTTP -D:UNIFIED -D:__UNIFIED__
-endif
-
 ifeq (monotouch,$(PROFILE))
 API_BIN_REFS := Xamarin.iOS
+LIB_MCS_FLAGS += -d:XAMARIN_MODERN
 endif
 
 ifeq (monotouch_tv,$(PROFILE))
 API_BIN_REFS := Xamarin.TVOS
+LIB_MCS_FLAGS += -d:XAMARIN_MODERN
 endif
 
 ifeq (monotouch_watch,$(PROFILE))
 API_BIN_REFS := Xamarin.WatchOS
+LIB_MCS_FLAGS += -d:XAMARIN_MODERN
+endif
+
+ifeq (xammac,$(PROFILE))
+API_BIN_REFS := Xamarin.Mac
+LIB_MCS_FLAGS += -d:XAMARIN_MODERN
+endif
+
+ifeq (xammac_net_4_5,$(PROFILE))
+# we can't use API_BIN_REFS for xammac_net_4_5 as it inherits from net_4_x.make
+LIB_MCS_FLAGS += -r:$(topdir)/../external/binary-reference-assemblies/build/monotouch/Xamarin.Mac.dll
+LIB_MCS_FLAGS += -d:XAMARIN_MODERN
 endif
 
 TEST_LIB_REFS = System System.Core
diff --git a/mcs/class/System.Net.Http/NSUrlSessionHandler.cs b/mcs/class/System.Net.Http/NSUrlSessionHandler.cs
deleted file mode 100644
index 17835da99f6..00000000000
--- a/mcs/class/System.Net.Http/NSUrlSessionHandler.cs
+++ /dev/null
@@ -1,896 +0,0 @@
-//
-// NSUrlSessionHandler.cs:
-//
-// Authors:
-//     Paul Betts <paul@paulbetts.org>
-//     Nick Berardi <nick@nickberardi.com>
-//
-// Permission is hereby granted, free of charge, to any person obtaining
-// a copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to
-// permit persons to whom the Software is furnished to do so, subject to
-// the following conditions:
-//
-// The above copyright notice and this permission notice shall be
-// included in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
-// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-//
-
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Linq;
-using System.Net;
-using System.Net.Http;
-using System.Net.Http.Headers;
-using System.Runtime.InteropServices;
-using System.Threading;
-using System.Threading.Tasks;
-using System.Text;
-
-#if UNIFIED
-using CoreFoundation;
-using Foundation;
-using Security;
-#else
-using MonoTouch.CoreFoundation;
-using MonoTouch.Foundation;
-using MonoTouch.Security;
-using System.Globalization;
-using nint = System.Int32;
-using nuint = System.UInt32;
-#endif
-
-#if !MONOMAC
-using UIKit;
-#endif
-
-#if SYSTEM_NET_HTTP
-namespace System.Net.Http {
-#else
-namespace Foundation {
-#endif
-
-	// useful extensions for the class in order to set it in a header
-	static class NSHttpCookieExtensions
-	{
-		static void AppendSegment(StringBuilder builder, string name, string value)
-		{
-			if (builder.Length > 0)
-				builder.Append ("; ");
-
-			builder.Append (name);
-			if (value != null)
-				builder.Append ("=").Append (value);
-		}
-
-		// returns the header for a cookie
-		public static string GetHeaderValue (this NSHttpCookie cookie)
-		{
-			var header = new StringBuilder();
-			AppendSegment (header, cookie.Name, cookie.Value);
-			AppendSegment (header, NSHttpCookie.KeyPath.ToString (), cookie.Path.ToString ());
-			AppendSegment (header, NSHttpCookie.KeyDomain.ToString (), cookie.Domain.ToString ());
-			AppendSegment (header, NSHttpCookie.KeyVersion.ToString (), cookie.Version.ToString ());
-
-			if (cookie.Comment != null)
-				AppendSegment (header, NSHttpCookie.KeyComment.ToString (), cookie.Comment.ToString());
-
-			if (cookie.CommentUrl != null)
-				AppendSegment (header, NSHttpCookie.KeyCommentUrl.ToString (), cookie.CommentUrl.ToString());
-
-			if (cookie.Properties.ContainsKey (NSHttpCookie.KeyDiscard))
-				AppendSegment (header, NSHttpCookie.KeyDiscard.ToString (), null);
-
-			if (cookie.ExpiresDate != null) {
-				// Format according to RFC1123; 'r' uses invariant info (DateTimeFormatInfo.InvariantInfo)
-				var dateStr = ((DateTime) cookie.ExpiresDate).ToUniversalTime ().ToString("r", CultureInfo.InvariantCulture);
-				AppendSegment (header, NSHttpCookie.KeyExpires.ToString (), dateStr);
-			}
-
-			if (cookie.Properties.ContainsKey (NSHttpCookie.KeyMaximumAge)) {
-				var timeStampString = (NSString) cookie.Properties[NSHttpCookie.KeyMaximumAge];
-				AppendSegment (header, NSHttpCookie.KeyMaximumAge.ToString (), timeStampString);
-			}
-
-			if (cookie.IsSecure)
-				AppendSegment (header, NSHttpCookie.KeySecure.ToString(), null);
-
-			if (cookie.IsHttpOnly)
-				AppendSegment (header, "httponly", null); // Apple does not show the key for the httponly
-
-			return header.ToString ();
-		}
-	}
-
-	public partial class NSUrlSessionHandler : HttpMessageHandler
-	{
-		private const string SetCookie = "Set-Cookie";
-		readonly Dictionary<string, string> headerSeparators = new Dictionary<string, string> {
-			["User-Agent"] = " ",
-			["Server"] = " "
-		};
-
-		readonly NSUrlSession session;
-		readonly Dictionary<NSUrlSessionTask, InflightData> inflightRequests;
-		readonly object inflightRequestsLock = new object ();
-#if !MONOMAC && !MONOTOUCH_WATCH
-		readonly bool isBackgroundSession = false;
-		NSObject notificationToken;  // needed to make sure we do not hang if not using a background session
-#endif
-
-		static NSUrlSessionConfiguration CreateConfig ()
-		{
-			// modifying the configuration does not affect future calls
-			var config = NSUrlSessionConfiguration.DefaultSessionConfiguration;
-			// but we want, by default, the timeout from HttpClient to have precedence over the one from NSUrlSession
-			// Double.MaxValue does not work, so default to 24 hours
-			config.TimeoutIntervalForRequest = 24 * 60 * 60;
-			config.TimeoutIntervalForResource = 24 * 60 * 60;
-			return config;
-		}
-
-		public NSUrlSessionHandler () : this (CreateConfig ())
-		{
-		}
-
-		[CLSCompliant (false)]
-		public NSUrlSessionHandler (NSUrlSessionConfiguration configuration)
-		{
-			if (configuration == null)
-				throw new ArgumentNullException (nameof (configuration));
-
-#if !MONOMAC  && !MONOTOUCH_WATCH 
-			// if the configuration has an identifier, we are dealing with a background session, 
-			// therefore, we do not have to listen to the notifications.
-			isBackgroundSession = !string.IsNullOrEmpty (configuration.Identifier);
-#endif
-
-			AllowAutoRedirect = true;
-
-			// we cannot do a bitmask but we can set the minimum based on ServicePointManager.SecurityProtocol minimum
-			var sp = ServicePointManager.SecurityProtocol;
-			if ((sp & SecurityProtocolType.Ssl3) != 0)
-				configuration.TLSMinimumSupportedProtocol = SslProtocol.Ssl_3_0;
-			else if ((sp & SecurityProtocolType.Tls) != 0)
-				configuration.TLSMinimumSupportedProtocol = SslProtocol.Tls_1_0;
-			else if ((sp & SecurityProtocolType.Tls11) != 0)
-				configuration.TLSMinimumSupportedProtocol = SslProtocol.Tls_1_1;
-			else if ((sp & SecurityProtocolType.Tls12) != 0)
-				configuration.TLSMinimumSupportedProtocol = SslProtocol.Tls_1_2;
-
-			session = NSUrlSession.FromConfiguration (configuration, (INSUrlSessionDelegate) new NSUrlSessionHandlerDelegate (this), null);
-			inflightRequests = new Dictionary<NSUrlSessionTask, InflightData> ();
-		}
-
-#if !MONOMAC  && !MONOTOUCH_WATCH
-
-		void AddNotification ()
-		{
-			if (!isBackgroundSession && notificationToken == null)
-				notificationToken = NSNotificationCenter.DefaultCenter.AddObserver (UIApplication.WillResignActiveNotification, BackgroundNotificationCb);
-		}
-
-		void RemoveNotification ()
-		{
-			if (notificationToken != null) {
-				NSNotificationCenter.DefaultCenter.RemoveObserver (notificationToken);
-				notificationToken = null;
-			}
-		}
-
-		void BackgroundNotificationCb (NSNotification obj)
-		{
-			// we do not need to call the lock, we call cancel on the source, that will trigger all the needed code to 
-			// clean the resources and such
-			foreach (var r in inflightRequests.Values) {
-				r.CompletionSource.TrySetCanceled ();
-			}
-		}
-#endif
-
-		public long MaxInputInMemory { get; set; } = long.MaxValue;
-
-		void RemoveInflightData (NSUrlSessionTask task, bool cancel = true)
-		{
-			lock (inflightRequestsLock) {
-				if (inflightRequests.TryGetValue (task, out var data)) {
-					if (cancel)
-						data.CancellationTokenSource.Cancel ();
-					data.Dispose ();
-					inflightRequests.Remove (task);
-				}
-#if !MONOMAC  && !MONOTOUCH_WATCH
-				// do we need to be notified? If we have not inflightData, we do not
-				if (inflightRequests.Count == 0)
-					RemoveNotification ();
-#endif
-			}
-
-			if (cancel)
-				task?.Cancel ();
-
-			task?.Dispose ();
-		}
-
-		protected override void Dispose (bool disposing)
-		{
-#if !MONOMAC  && !MONOTOUCH_WATCH
-			// remove the notification if present, method checks against null
-			RemoveNotification ();
-#endif
-			lock (inflightRequestsLock) {
-				foreach (var pair in inflightRequests) {
-					pair.Key?.Cancel ();
-					pair.Key?.Dispose ();
-					pair.Value?.Dispose ();
-				}
-
-				inflightRequests.Clear ();
-			}
-			base.Dispose (disposing);
-		}
-
-		bool disableCaching;
-
-		public bool DisableCaching {
-			get {
-				return disableCaching;
-			}
-			set {
-				EnsureModifiability ();
-				disableCaching = value;
-			}
-		}
-
-		string GetHeaderSeparator (string name)
-		{
-			string value;
-			if (!headerSeparators.TryGetValue (name, out value))
-				value = ",";
-			return value;
-		}
-
-		async Task<NSUrlRequest> CreateRequest (HttpRequestMessage request)
-		{
-			var stream = Stream.Null;
-			var headers = request.Headers as IEnumerable<KeyValuePair<string, IEnumerable<string>>>;
-
-			if (request.Content != null) {
-				stream = await request.Content.ReadAsStreamAsync ().ConfigureAwait (false);
-				headers = System.Linq.Enumerable.ToArray(headers.Union (request.Content.Headers));
-			}
-
-			var nsrequest = new NSMutableUrlRequest {
-				AllowsCellularAccess = true,
-				CachePolicy = DisableCaching ? NSUrlRequestCachePolicy.ReloadIgnoringCacheData : NSUrlRequestCachePolicy.UseProtocolCachePolicy,
-				HttpMethod = request.Method.ToString ().ToUpperInvariant (),
-				Url = NSUrl.FromString (request.RequestUri.AbsoluteUri),
-				Headers = headers.Aggregate (new NSMutableDictionary (), (acc, x) => {
-					acc.Add (new NSString (x.Key), new NSString (string.Join (GetHeaderSeparator (x.Key), x.Value)));
-					return acc;
-				})
-			};
-			if (stream != Stream.Null) {
-				// HttpContent.TryComputeLength is `protected internal` :-( but it's indirectly called by headers
-				var length = request.Content.Headers.ContentLength;
-				if (length.HasValue && (length <= MaxInputInMemory))
-					nsrequest.Body = NSData.FromStream (stream);
-				else
-					nsrequest.BodyStream = new WrappedNSInputStream (stream);
-			}
-			return nsrequest;
-		}
-
-#if SYSTEM_NET_HTTP || MONOMAC
-		internal
-#endif
-		protected override async Task<HttpResponseMessage> SendAsync (HttpRequestMessage request, CancellationToken cancellationToken)
-		{
-			Volatile.Write (ref sentRequest, true);
-
-			var nsrequest = await CreateRequest (request).ConfigureAwait(false);
-			var dataTask = session.CreateDataTask (nsrequest);
-
-			var tcs = new TaskCompletionSource<HttpResponseMessage> ();
-
-			lock (inflightRequestsLock) {
-#if !MONOMAC  && !MONOTOUCH_WATCH
-				// Add the notification whenever needed
-				AddNotification ();
-#endif
-				inflightRequests.Add (dataTask, new InflightData {
-					RequestUrl = request.RequestUri.AbsoluteUri,
-					CompletionSource = tcs,
-					CancellationToken = cancellationToken,
-					CancellationTokenSource = new CancellationTokenSource (),
-					Stream = new NSUrlSessionDataTaskStream (),
-					Request = request
-				});
-			}
-
-			if (dataTask.State == NSUrlSessionTaskState.Suspended)
-				dataTask.Resume ();
-
-			// as per documentation: 
-			// If this token is already in the canceled state, the 
-			// delegate will be run immediately and synchronously.
-			// Any exception the delegate generates will be 
-			// propagated out of this method call.
-			//
-			// The execution of the register ensures that if we 
-			// receive a already cancelled token or it is cancelled
-			// just before this call, we will cancel the task. 
-			// Other approaches are harder, since querying the state
-			// of the token does not guarantee that in the next
-			// execution a threads cancels it.
-			cancellationToken.Register (() => {
-				RemoveInflightData (dataTask);
-				tcs.TrySetCanceled ();
-			});
-
-			return await tcs.Task.ConfigureAwait (false);
-		}
-
-#if MONOMAC
-		// Needed since we strip during linking since we're inside a product assembly.
-		[Preserve (AllMembers = true)]
-#endif
-		partial class NSUrlSessionHandlerDelegate : NSUrlSessionDataDelegate
-		{
-			readonly NSUrlSessionHandler sessionHandler;
-
-			public NSUrlSessionHandlerDelegate (NSUrlSessionHandler handler)
-			{
-				sessionHandler = handler;
-			}
-
-			InflightData GetInflightData (NSUrlSessionTask task)
-			{
-				var inflight = default (InflightData);
-
-				lock (sessionHandler.inflightRequestsLock)
-					if (sessionHandler.inflightRequests.TryGetValue (task, out inflight)) {
-						// ensure that we did not cancel the request, if we did, do cancel the task
-						if (inflight.CancellationToken.IsCancellationRequested)
-							task?.Cancel ();
-						return inflight;
-					}
-
-				// if we did not manage to get the inflight data, we either got an error or have been canceled, lets cancel the task, that will execute DidCompleteWithError
-				task?.Cancel ();
-				return null;
-			}
-
-			public override void DidReceiveResponse (NSUrlSession session, NSUrlSessionDataTask dataTask, NSUrlResponse response, Action<NSUrlSessionResponseDisposition> completionHandler)
-			{
-				var inflight = GetInflightData (dataTask);
-
-				if (inflight == null)
-					return;
-
-				try {
-					var urlResponse = (NSHttpUrlResponse)response;
-					var status = (int)urlResponse.StatusCode;
-
-					var content = new NSUrlSessionDataTaskStreamContent (inflight.Stream, () => {
-						if (!inflight.Completed) {
-							dataTask.Cancel ();
-						}
-
-						inflight.Disposed = true;
-						inflight.Stream.TrySetException (new ObjectDisposedException ("The content stream was disposed."));
-
-						sessionHandler.RemoveInflightData (dataTask);
-					}, inflight.CancellationTokenSource.Token);
-
-					// NB: The double cast is because of a Xamarin compiler bug
-					var httpResponse = new HttpResponseMessage ((HttpStatusCode)status) {
-						Content = content,
-						RequestMessage = inflight.Request
-					};
-					httpResponse.RequestMessage.RequestUri = new Uri (urlResponse.Url.AbsoluteString);
-
-					foreach (var v in urlResponse.AllHeaderFields) {
-						// NB: Cocoa trolling us so hard by giving us back dummy dictionary entries
-						if (v.Key == null || v.Value == null) continue;
-						// NSUrlSession tries to be smart with cookies, we will not use the raw value but the ones provided by the cookie storage
-						if (v.Key.ToString () == SetCookie) continue;
-
-						httpResponse.Headers.TryAddWithoutValidation (v.Key.ToString (), v.Value.ToString ());
-						httpResponse.Content.Headers.TryAddWithoutValidation (v.Key.ToString (), v.Value.ToString ());
-					}
-
-					var cookies = session.Configuration.HttpCookieStorage.CookiesForUrl (response.Url);
-					for (var index = 0; index < cookies.Length; index++) {
-						httpResponse.Headers.TryAddWithoutValidation (SetCookie, cookies [index].GetHeaderValue ());
-					}
-
-					inflight.Response = httpResponse;
-
-					// We don't want to send the response back to the task just yet.  Because we want to mimic .NET behavior
-					// as much as possible.  When the response is sent back in .NET, the content stream is ready to read or the
-					// request has completed, because of this we want to send back the response in DidReceiveData or DidCompleteWithError
-					if (dataTask.State == NSUrlSessionTaskState.Suspended)
-						dataTask.Resume ();
-
-				} catch (Exception ex) {
-					inflight.CompletionSource.TrySetException (ex);
-					inflight.Stream.TrySetException (ex);
-
-					sessionHandler.RemoveInflightData (dataTask);
-				}
-
-				completionHandler (NSUrlSessionResponseDisposition.Allow);
-			}
-
-			public override void DidReceiveData (NSUrlSession session, NSUrlSessionDataTask dataTask, NSData data)
-			{
-				var inflight = GetInflightData (dataTask);
-
-				if (inflight == null)
-					return;
-
-				inflight.Stream.Add (data);
-				SetResponse (inflight);
-			}
-
-			public override void DidCompleteWithError (NSUrlSession session, NSUrlSessionTask task, NSError error)
-			{
-				var inflight = GetInflightData (task);
-
-				// this can happen if the HTTP request times out and it is removed as part of the cancellation process
-				if (inflight != null) {
-					// set the stream as finished
-					inflight.Stream.TrySetReceivedAllData ();
-
-					// send the error or send the response back
-					if (error != null) {
-						// got an error, cancel the stream operatios before we do anything
-						inflight.CancellationTokenSource.Cancel (); 
-						inflight.Errored = true;
-
-						var exc = createExceptionForNSError (error);
-						inflight.CompletionSource.TrySetException (exc);
-						inflight.Stream.TrySetException (exc);
-					} else {
-						inflight.Completed = true;
-						SetResponse (inflight);
-					}
-
-					sessionHandler.RemoveInflightData (task, cancel: false);
-				}
-			}
-
-			void SetResponse (InflightData inflight)
-			{
-				lock (inflight.Lock) {
-					if (inflight.ResponseSent)
-						return;
-
-					if (inflight.CancellationTokenSource.Token.IsCancellationRequested)
-						return;
-
-					if (inflight.CompletionSource.Task.IsCompleted)
-						return;
-
-					var httpResponse = inflight.Response;
-
-					inflight.ResponseSent = true;
-
-					// EVIL HACK: having TrySetResult inline was blocking the request from completing
-					Task.Run (() => inflight.CompletionSource.TrySetResult (httpResponse));
-				}
-			}
-
-			public override void WillCacheResponse (NSUrlSession session, NSUrlSessionDataTask dataTask, NSCachedUrlResponse proposedResponse, Action<NSCachedUrlResponse> completionHandler)
-			{
-				completionHandler (sessionHandler.DisableCaching ? null : proposedResponse);
-			}
-
-			public override void WillPerformHttpRedirection (NSUrlSession session, NSUrlSessionTask task, NSHttpUrlResponse response, NSUrlRequest newRequest, Action<NSUrlRequest> completionHandler)
-			{
-				completionHandler (sessionHandler.AllowAutoRedirect ? newRequest : null);
-			}
-
-			public override void DidReceiveChallenge (NSUrlSession session, NSUrlSessionTask task, NSUrlAuthenticationChallenge challenge, Action<NSUrlSessionAuthChallengeDisposition, NSUrlCredential> completionHandler)
-			{
-				var inflight = GetInflightData (task);
-
-				if (inflight == null)
-					return;
-
-				// case for the basic auth failing up front. As per apple documentation:
-				// The URL Loading System is designed to handle various aspects of the HTTP protocol for you. As a result, you should not modify the following headers using
-				// the addValue(_:forHTTPHeaderField:) or setValue(_:forHTTPHeaderField:) methods:
-				// 	Authorization
-				// 	Connection
-				// 	Host
-				// 	Proxy-Authenticate
-				// 	Proxy-Authorization
-				// 	WWW-Authenticate
-				// but we are hiding such a situation from our users, we can nevertheless know if the header was added and deal with it. The idea is as follows,
-				// check if we are in the first attempt, if we are (PreviousFailureCount == 0), we check the headers of the request and if we do have the Auth 
-				// header, it means that we do not have the correct credentials, in any other case just do what it is expected.
-				
-				if (challenge.PreviousFailureCount == 0) {
-					var authHeader = inflight.Request?.Headers?.Authorization;
-					if (!(string.IsNullOrEmpty (authHeader?.Scheme) && string.IsNullOrEmpty (authHeader?.Parameter))) {
-						completionHandler (NSUrlSessionAuthChallengeDisposition.RejectProtectionSpace, null);
-						return;
-					}
-				}
-
-				if (sessionHandler.Credentials != null && TryGetAuthenticationType (challenge.ProtectionSpace, out string authType)) {
-					NetworkCredential credentialsToUse = null;
-					if (authType != RejectProtectionSpaceAuthType) {
-						var uri = inflight.Request.RequestUri;
-						credentialsToUse = sessionHandler.Credentials.GetCredential (uri, authType);
-					}
-
-					if (credentialsToUse != null) {
-						var credential = new NSUrlCredential (credentialsToUse.UserName, credentialsToUse.Password, NSUrlCredentialPersistence.ForSession);
-						completionHandler (NSUrlSessionAuthChallengeDisposition.UseCredential, credential);
-					} else {
-						// Rejecting the challenge allows the next authentication method in the request to be delivered to
-						// the DidReceiveChallenge method. Another authentication method may have credentials available.
-						completionHandler (NSUrlSessionAuthChallengeDisposition.RejectProtectionSpace, null);
-					}
-				} else {
-					completionHandler (NSUrlSessionAuthChallengeDisposition.PerformDefaultHandling, challenge.ProposedCredential);
-				}
-			}
-
-			static readonly string RejectProtectionSpaceAuthType = "reject";
-
-			static bool TryGetAuthenticationType (NSUrlProtectionSpace protectionSpace, out string authenticationType)
-			{
-				if (protectionSpace.AuthenticationMethod == NSUrlProtectionSpace.AuthenticationMethodNTLM) {
-					authenticationType = "NTLM";
-				} else if (protectionSpace.AuthenticationMethod == NSUrlProtectionSpace.AuthenticationMethodHTTPBasic) {
-					authenticationType = "basic";
-				} else if (protectionSpace.AuthenticationMethod == NSUrlProtectionSpace.AuthenticationMethodNegotiate ||
-					protectionSpace.AuthenticationMethod == NSUrlProtectionSpace.AuthenticationMethodHTMLForm ||
-					protectionSpace.AuthenticationMethod == NSUrlProtectionSpace.AuthenticationMethodHTTPDigest) {
-					// Want to reject this authentication type to allow the next authentication method in the request to
-					// be used.
-					authenticationType = RejectProtectionSpaceAuthType;
-				} else {
-					// ServerTrust, ClientCertificate or Default.
-					authenticationType = null;
-					return false;
-				}
-				return true;
-			}
-		}
-
-#if MONOMAC
-		// Needed since we strip during linking since we're inside a product assembly.
-		[Preserve (AllMembers = true)]
-#endif
-		class InflightData : IDisposable
-		{
-			public readonly object Lock = new object ();
-			public string RequestUrl { get; set; }
-
-			public TaskCompletionSource<HttpResponseMessage> CompletionSource { get; set; }
-			public CancellationToken CancellationToken { get; set; }
-			public CancellationTokenSource CancellationTokenSource { get; set; }
-			public NSUrlSessionDataTaskStream Stream { get; set; }
-			public HttpRequestMessage Request { get; set; }
-			public HttpResponseMessage Response { get; set; }
-
-			public bool ResponseSent { get; set; }
-			public bool Errored { get; set; }
-			public bool Disposed { get; set; }
-			public bool Completed { get; set; }
-			public bool Done { get { return Errored || Disposed || Completed || CancellationToken.IsCancellationRequested; } }
-
-			public void Dispose()
-			{
-				Dispose (true);
-				GC.SuppressFinalize(this);
-			}
-
-			// The bulk of the clean-up code is implemented in Dispose(bool)
-			protected virtual void Dispose (bool disposing)
-			{
-				if (disposing) {
-					if (CancellationTokenSource != null) {
-						CancellationTokenSource.Dispose ();
-						CancellationTokenSource = null;
-					}
-				}
-			}
-
-		}
-
-#if MONOMAC
-		// Needed since we strip during linking since we're inside a product assembly.
-		[Preserve (AllMembers = true)]
-#endif
-		class NSUrlSessionDataTaskStreamContent : StreamContent
-		{
-			Action disposed;
-
-			public NSUrlSessionDataTaskStreamContent (NSUrlSessionDataTaskStream source, Action onDisposed, CancellationToken token) : base (source, token)
-			{
-				disposed = onDisposed;
-			}
-
-			protected override void Dispose (bool disposing)
-			{
-				var action = Interlocked.Exchange (ref disposed, null);
-				action?.Invoke ();
-
-				base.Dispose (disposing);
-			}
-		}
-
-#if MONOMAC
-		// Needed since we strip during linking since we're inside a product assembly.
-		[Preserve (AllMembers = true)]
-#endif
-		class NSUrlSessionDataTaskStream : Stream
-		{
-			readonly Queue<NSData> data;
-			readonly object dataLock = new object ();
-
-			long position;
-			long length;
-
-			bool receivedAllData;
-			Exception exc;
-
-			NSData current;
-			Stream currentStream;
-
-			public NSUrlSessionDataTaskStream ()
-			{
-				data = new Queue<NSData> ();
-			}
-
-			public void Add (NSData d)
-			{
-				lock (dataLock) {
-					data.Enqueue (d);
-					length += (int)d.Length;
-				}
-			}
-
-			public void TrySetReceivedAllData ()
-			{
-				receivedAllData = true;
-			}
-
-			public void TrySetException (Exception e)
-			{
-				exc = e;
-				TrySetReceivedAllData ();
-			}
-
-			void ThrowIfNeeded (CancellationToken cancellationToken)
-			{
-				if (exc != null)
-					throw exc;
-
-				cancellationToken.ThrowIfCancellationRequested ();
-			}
-
-			public override int Read (byte [] buffer, int offset, int count)
-			{
-				return ReadAsync (buffer, offset, count).Result;
-			}
-
-			public override async Task<int> ReadAsync (byte [] buffer, int offset, int count, CancellationToken cancellationToken)
-			{
-				// try to throw on enter
-				ThrowIfNeeded (cancellationToken);
-
-				while (current == null) {
-					lock (dataLock) {
-						if (data.Count == 0 && receivedAllData && position == length)
-							return 0;
-
-						if (data.Count > 0 && current == null) {
-							current = data.Peek ();
-							currentStream = current.AsStream ();
-							break;
-						}
-					}
-
-					try {
-						await Task.Delay (50, cancellationToken).ConfigureAwait (false);
-					} catch (TaskCanceledException ex) {
-						// add a nicer exception for the user to catch, add the cancelation exception
-						// to have a decent stack
-						throw new TimeoutException ("The request timed out.", ex);
-					}
-				}
-
-				// try to throw again before read
-				ThrowIfNeeded (cancellationToken);
-
-				var d = currentStream;
-				var bufferCount = Math.Min (count, (int)(d.Length - d.Position));
-				var bytesRead = await d.ReadAsync (buffer, offset, bufferCount, cancellationToken).ConfigureAwait (false);
-
-				// add the bytes read from the pointer to the position
-				position += bytesRead;
-
-				// remove the current primary reference if the current position has reached the end of the bytes
-				if (d.Position == d.Length) {
-					lock (dataLock) {
-						// this is the same object, it was done to make the cleanup
-						data.Dequeue ();
-						currentStream?.Dispose ();
-						// We cannot use current?.Dispose. The reason is the following one:
-						// In the DidReceiveResponse, if iOS realizes that a buffer can be reused,
-						// because the data is the same, it will do so. Such a situation does happen
-						// between requests, that is, request A and request B will get the same NSData
-						// (buffer) in the delegate. In this case, we cannot dispose the NSData because
-						// it might be that a different request received it and it is present in
-						// its NSUrlSessionDataTaskStream stream. We can only trust the gc to do the job
-						// which is better than copying the data over. 
-						current = null;
-						currentStream = null;
-					}
-				}
-
-				return bytesRead;
-			}
-
-			public override bool CanRead => true;
-
-			public override bool CanSeek => false;
-
-			public override bool CanWrite => false;
-
-			public override bool CanTimeout => false;
-
-			public override long Length => length;
-
-			public override void SetLength (long value)
-			{
-				throw new InvalidOperationException ();
-			}
-
-			public override long Position {
-				get { return position; }
-				set { throw new InvalidOperationException (); }
-			}
-
-			public override long Seek (long offset, SeekOrigin origin)
-			{
-				throw new InvalidOperationException ();
-			}
-
-			public override void Flush ()
-			{
-				throw new InvalidOperationException ();
-			}
-
-			public override void Write (byte [] buffer, int offset, int count)
-			{
-				throw new InvalidOperationException ();
-			}
-		}
-
-#if MONOMAC
-		// Needed since we strip during linking since we're inside a product assembly.
-		[Preserve (AllMembers = true)]
-#endif
-		class WrappedNSInputStream : NSInputStream
-		{
-			NSStreamStatus status;
-			CFRunLoopSource source;
-			readonly Stream stream;
-			bool notifying;
-
-			public WrappedNSInputStream (Stream inputStream)
-			{
-				status = NSStreamStatus.NotOpen;
-				stream = inputStream;
-				source = new CFRunLoopSource (Handle);
-			}
-
-			public override NSStreamStatus Status => status;
-
-			public override void Open ()
-			{
-				status = NSStreamStatus.Open;
-				Notify (CFStreamEventType.OpenCompleted);
-			}
-
-			public override void Close ()
-			{
-				status = NSStreamStatus.Closed;
-			}
-
-			public override nint Read (IntPtr buffer, nuint len)
-			{
-				var sourceBytes = new byte [len];
-				var read = stream.Read (sourceBytes, 0, (int)len);
-				Marshal.Copy (sourceBytes, 0, buffer, (int)len);
-
-				if (notifying)
-					return read;
-
-				notifying = true;
-				if (stream.CanSeek && stream.Position == stream.Length) {
-					Notify (CFStreamEventType.EndEncountered);
-					status = NSStreamStatus.AtEnd;
-				}
-				notifying = false;
-
-				return read;
-			}
-
-			public override bool HasBytesAvailable ()
-			{
-				return true;
-			}
-
-			protected override bool GetBuffer (out IntPtr buffer, out nuint len)
-			{
-				// Just call the base implemention (which will return false)
-				return base.GetBuffer (out buffer, out len);
-			}
-
-			// NSInvalidArgumentException Reason: *** -propertyForKey: only defined for abstract class.  Define -[System_Net_Http_NSUrlSessionHandler_WrappedNSInputStream propertyForKey:]!
-			protected override NSObject GetProperty (NSString key)
-			{
-				return null;
-			}
-
-			protected override bool SetProperty (NSObject property, NSString key)
-			{
-				return false;
-			}
-
-			protected override bool SetCFClientFlags (CFStreamEventType inFlags, IntPtr inCallback, IntPtr inContextPtr)
-			{
-				// Just call the base implementation, which knows how to handle everything.
-				return base.SetCFClientFlags (inFlags, inCallback, inContextPtr);
-			}
-
-			public override void Schedule (NSRunLoop aRunLoop, string mode)
-			{
-				var cfRunLoop = aRunLoop.GetCFRunLoop ();
-				var nsMode = new NSString (mode);
-
-				cfRunLoop.AddSource (source, nsMode);
-
-				if (notifying)
-					return;
-
-				notifying = true;
-				Notify (CFStreamEventType.HasBytesAvailable);
-				notifying = false;
-			}
-
-			public override void Unschedule (NSRunLoop aRunLoop, string mode)
-			{
-				var cfRunLoop = aRunLoop.GetCFRunLoop ();
-				var nsMode = new NSString (mode);
-
-				cfRunLoop.RemoveSource (source, nsMode);
-			}
-
-			protected override void Dispose (bool disposing)
-			{
-				stream?.Dispose ();
-			}
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/RuntimeOptions.cs b/mcs/class/System.Net.Http/RuntimeOptions.cs
deleted file mode 100644
index 6e4c152ca0e..00000000000
--- a/mcs/class/System.Net.Http/RuntimeOptions.cs
+++ /dev/null
@@ -1,98 +0,0 @@
-using System;
-using System.IO;
-using System.Text;
-using System.Net.Http;
-
-#if XAMCORE_2_0
-using Foundation;
-using ObjCRuntime;
-#elif MONOMAC
-using MonoMac.Foundation;
-using MonoMac.ObjCRuntime;
-#else
-#error Unknown platform
-#endif
-
-namespace System.Net.Http {
-	class RuntimeOptions
-	{
-		const string HttpClientHandlerValue = "HttpClientHandler";
-		const string CFNetworkHandlerValue = "CFNetworkHandler";
-		const string NSUrlSessionHandlerValue = "NSUrlSessionHandler";
-
-		const string DefaultTlsProviderValue = "default";
-		const string LegacyTlsProviderValue = "legacy";
-		const string AppleTlsProviderValue = "appletls";
-
-		string http_message_handler;
-
-
-		internal static RuntimeOptions Read ()
-		{
-			// for iOS NSBundle.ResourcePath returns the path to the root of the app bundle
-			// for macOS apps NSBundle.ResourcePath returns foo.app/Contents/Resources
-			// for macOS frameworks NSBundle.ResourcePath returns foo.app/Versions/Current/Resources
-			Class bundle_finder = new Class (typeof (NSObject.NSObject_Disposer));
-			var resource_dir = NSBundle.FromClass (bundle_finder).ResourcePath;
-			var plist_path = GetFileName (resource_dir);
-
-			if (!File.Exists (plist_path))
-				return null;
-
-			using (var plist = NSDictionary.FromFile (plist_path)) {
-				var options = new RuntimeOptions ();
-				options.http_message_handler = (NSString) plist ["HttpMessageHandler"];
-				return options;
-			}
-		}
-
-#if MONOMAC
-		[Preserve]
-#endif
-		internal static HttpMessageHandler GetHttpMessageHandler ()
-		{
-			RuntimeOptions options = null;
-			
-			try {
-				options = RuntimeOptions.Read ();
-			} catch (FileNotFoundException){
-				// this happens on the Mono SDKs since we don't have a real Xamarin.iOS.dll so we can't resolve NSObject
-			}
-
-			if (options == null) {
-#if MONOTOUCH_WATCH
-				return new NSUrlSessionHandler ();
-#else
-				return new HttpClientHandler ();
-#endif
-			}
-
-			// all types will be present as this is executed only when the linker is not enabled
-			var handler_name = options.http_message_handler;
-			var t = Type.GetType (handler_name, false);
-
-			HttpMessageHandler handler = null;
-			if (t != null)
-				handler = Activator.CreateInstance (t) as HttpMessageHandler;
-			if (handler != null)
-				return handler;
-#if MONOTOUCH_WATCH
-			Console.WriteLine ("{0} is not a valid HttpMessageHandler, defaulting to NSUrlSessionHandler", handler_name);
-			return new NSUrlSessionHandler ();
-#else
-			Console.WriteLine ("{0} is not a valid HttpMessageHandler, defaulting to System.Net.Http.HttpClientHandler", handler_name);
-			return new HttpClientHandler ();
-#endif
-		}
-
-		// Use either Create() or Read().
-		RuntimeOptions ()
-		{
-		}
-
-		static string GetFileName (string resource_dir)
-		{
-			return Path.Combine (resource_dir, "runtime-options.plist");
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/System.Net.Http.csproj b/mcs/class/System.Net.Http/System.Net.Http.csproj
index 911e9419817..3fa5bd74f60 100644
--- a/mcs/class/System.Net.Http/System.Net.Http.csproj
+++ b/mcs/class/System.Net.Http/System.Net.Http.csproj
@@ -39,17 +39,17 @@
   <PropertyGroup Condition=" '$(Platform)' == 'monotouch' ">
     <OutputPath>./../../class/lib/monotouch</OutputPath>
     <IntermediateOutputPath>./../../class/obj/$(AssemblyName)-monotouch</IntermediateOutputPath>
-    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;XAMCORE_2_0;XAMARIN_MODERN;SYSTEM_NET_HTTP;UNIFIED;__UNIFIED__</DefineConstants>
+    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;XAMARIN_MODERN</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'monotouch_watch' ">
     <OutputPath>./../../class/lib/monotouch_watch</OutputPath>
     <IntermediateOutputPath>./../../class/obj/$(AssemblyName)-monotouch_watch</IntermediateOutputPath>
-    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;FEATURE_NO_BSD_SOCKETS;MONOTOUCH_WATCH;XAMCORE_2_0;XAMARIN_MODERN;SYSTEM_NET_HTTP;UNIFIED;__UNIFIED__</DefineConstants>
+    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;FEATURE_NO_BSD_SOCKETS;MONOTOUCH_WATCH;XAMARIN_MODERN</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'monotouch_tv' ">
     <OutputPath>./../../class/lib/monotouch_tv</OutputPath>
     <IntermediateOutputPath>./../../class/obj/$(AssemblyName)-monotouch_tv</IntermediateOutputPath>
-    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;MONOTOUCH_TV;XAMCORE_2_0;XAMARIN_MODERN;SYSTEM_NET_HTTP;UNIFIED;__UNIFIED__</DefineConstants>
+    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MOBILE;MOBILE_LEGACY;MONO;MONOTOUCH;DISABLE_REMOTING;DISABLE_COM;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;FULL_AOT_RUNTIME;MONOTOUCH_TV;XAMARIN_MODERN</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'testing_aot_full_interp' ">
     <OutputPath>./../../class/lib/testing_aot_full_interp</OutputPath>
@@ -74,12 +74,12 @@
   <PropertyGroup Condition=" '$(Platform)' == 'xammac' ">
     <OutputPath>./../../class/lib/xammac</OutputPath>
     <IntermediateOutputPath>./../../class/obj/$(AssemblyName)-xammac</IntermediateOutputPath>
-    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MONO;MOBILE;MOBILE_DYNAMIC;XAMMAC;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;XAMARIN_MODERN</DefineConstants>
+    <DefineConstants>NET_1_1;NET_2_0;NET_2_1;NET_3_5;NET_4_0;NET_4_5;MONO;MOBILE;MOBILE_DYNAMIC;XAMMAC;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;XAMARIN_MODERN;XAMARIN_MODERN</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'xammac_net_4_5' ">
     <OutputPath>./../../class/lib/xammac_net_4_5</OutputPath>
     <IntermediateOutputPath>./../../class/obj/$(AssemblyName)-xammac_net_4_5</IntermediateOutputPath>
-    <DefineConstants>NET_4_0;NET_4_5;NET_4_6;MONO;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;NO_SYSTEM_DRAWING_DEPENDENCY;NO_WINFORMS_DEPENDENCY;NO_SYSTEM_WEB_DEPENDENCY;XAMMAC_4_5;XAMARIN_MODERN</DefineConstants>
+    <DefineConstants>NET_4_0;NET_4_5;NET_4_6;MONO;FEATURE_INTERCEPTABLE_THREADPOOL_CALLBACK;NO_SYSTEM_DRAWING_DEPENDENCY;NO_WINFORMS_DEPENDENCY;NO_SYSTEM_WEB_DEPENDENCY;XAMMAC_4_5;XAMARIN_MODERN;XAMARIN_MODERN</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'orbis' ">
     <OutputPath>./../../class/lib/orbis</OutputPath>
@@ -164,7 +164,7 @@
         <Compile Include="System.Net.Http\DelegatingHandler.cs" />
         <Compile Include="System.Net.Http\FormUrlEncodedContent.cs" />
         <Compile Include="System.Net.Http\HttpClient.cs" />
-        <Compile Include="System.Net.Http\HttpClient.mac.cs" />
+        <Compile Include="System.Net.Http\HttpClient.macios.cs" />
         <Compile Include="System.Net.Http\HttpCompletionOption.cs" />
         <Compile Include="System.Net.Http\HttpContent.cs" />
         <Compile Include="System.Net.Http\HttpMessageHandler.cs" />
@@ -873,10 +873,7 @@
     </When>
     <When Condition="'$(Platform)' == 'monotouch_watch'">
       <ItemGroup>
-        <Compile Include="HttpClientEx.cs" />
-        <Compile Include="NSUrlSessionHandler.cs" />
         <Compile Include="PlatformHelper.Legacy.cs" />
-        <Compile Include="RuntimeOptions.cs" />
         <Compile Include="System.Net.Http.Headers\AuthenticationHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CacheControlHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CollectionExtensions.cs" />
@@ -915,6 +912,7 @@
         <Compile Include="System.Net.Http\DelegatingHandler.cs" />
         <Compile Include="System.Net.Http\FormUrlEncodedContent.cs" />
         <Compile Include="System.Net.Http\HttpClient.cs" />
+        <Compile Include="System.Net.Http\HttpClient.macios.cs" />
         <Compile Include="System.Net.Http\HttpClientHandler.platformnotsupported.cs" />
         <Compile Include="System.Net.Http\HttpCompletionOption.cs" />
         <Compile Include="System.Net.Http\HttpContent.cs" />
@@ -936,16 +934,11 @@
       <ItemGroup>
         <Compile Include="..\..\..\external\corefx\src\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\CancellationHelper.cs" />
         <Compile Include="..\..\..\external\corefx\src\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\ConnectHelper.cs" />
-        <Compile Include="CFContentStream.cs" />
-        <Compile Include="CFNetworkHandler.cs" />
-        <Compile Include="HttpClientEx.cs" />
         <Compile Include="HttpClientHandler.Legacy.cs" />
         <Compile Include="HttpClientHandler.cs" />
         <Compile Include="IMonoHttpClientHandler.cs" />
         <Compile Include="MonoWebRequestHandler.cs" />
-        <Compile Include="NSUrlSessionHandler.cs" />
         <Compile Include="PlatformHelper.Legacy.cs" />
-        <Compile Include="RuntimeOptions.cs" />
         <Compile Include="System.Net.Http.Headers\AuthenticationHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CacheControlHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CollectionExtensions.cs" />
@@ -984,6 +977,7 @@
         <Compile Include="System.Net.Http\DelegatingHandler.cs" />
         <Compile Include="System.Net.Http\FormUrlEncodedContent.cs" />
         <Compile Include="System.Net.Http\HttpClient.cs" />
+        <Compile Include="System.Net.Http\HttpClient.macios.cs" />
         <Compile Include="System.Net.Http\HttpCompletionOption.cs" />
         <Compile Include="System.Net.Http\HttpContent.cs" />
         <Compile Include="System.Net.Http\HttpMessageHandler.cs" />
@@ -1004,16 +998,11 @@
       <ItemGroup>
         <Compile Include="..\..\..\external\corefx\src\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\CancellationHelper.cs" />
         <Compile Include="..\..\..\external\corefx\src\System.Net.Http\src\System\Net\Http\SocketsHttpHandler\ConnectHelper.cs" />
-        <Compile Include="CFContentStream.cs" />
-        <Compile Include="CFNetworkHandler.cs" />
-        <Compile Include="HttpClientEx.cs" />
         <Compile Include="HttpClientHandler.Legacy.cs" />
         <Compile Include="HttpClientHandler.cs" />
         <Compile Include="IMonoHttpClientHandler.cs" />
         <Compile Include="MonoWebRequestHandler.cs" />
-        <Compile Include="NSUrlSessionHandler.cs" />
         <Compile Include="PlatformHelper.Legacy.cs" />
-        <Compile Include="RuntimeOptions.cs" />
         <Compile Include="System.Net.Http.Headers\AuthenticationHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CacheControlHeaderValue.cs" />
         <Compile Include="System.Net.Http.Headers\CollectionExtensions.cs" />
@@ -1052,6 +1041,7 @@
         <Compile Include="System.Net.Http\DelegatingHandler.cs" />
         <Compile Include="System.Net.Http\FormUrlEncodedContent.cs" />
         <Compile Include="System.Net.Http\HttpClient.cs" />
+        <Compile Include="System.Net.Http\HttpClient.macios.cs" />
         <Compile Include="System.Net.Http\HttpCompletionOption.cs" />
         <Compile Include="System.Net.Http\HttpContent.cs" />
         <Compile Include="System.Net.Http\HttpMessageHandler.cs" />
@@ -1231,6 +1221,20 @@
       <Private>False</Private>
     </Reference>
   </ItemGroup>
+  <ItemGroup Condition=" '$(Platform)' == 'xammac' ">
+    <Reference Include="./../../../external/binary-reference-assemblies/build/monotouch/Xamarin.Mac.dll">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>./../../../external/binary-reference-assemblies/build/monotouch/Xamarin.Mac.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+  </ItemGroup>
+  <ItemGroup Condition=" '$(Platform)' == 'xammac_net_4_5' ">
+    <Reference Include="./../../../external/binary-reference-assemblies/build/monotouch/Xamarin.Mac.dll">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>./../../../external/binary-reference-assemblies/build/monotouch/Xamarin.Mac.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+  </ItemGroup>
   <!-- @ALL_REFERENCES@ -->
   <!-- @ALL_RESOURCES@ -->
   <PropertyGroup>
diff --git a/mcs/class/System.Net.Http/System.Net.Http/HttpClient.mac.cs b/mcs/class/System.Net.Http/System.Net.Http/HttpClient.mac.cs
deleted file mode 100644
index 42f664c0ed3..00000000000
--- a/mcs/class/System.Net.Http/System.Net.Http/HttpClient.mac.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-using System;
-using System.Reflection;
-
-[assembly:System.Runtime.CompilerServices.InternalsVisibleTo ("Xamarin.Mac, PublicKey=0024000004800000940000000602000000240000525341310004000011000000438ac2a5acfbf16cbd2b2b47a62762f273df9cb2795ceccdf77d10bf508e69e7a362ea7a45455bbf3ac955e1f2e2814f144e5d817efc4c6502cc012df310783348304e3ae38573c6d658c234025821fda87a0be8a0d504df564e2c93b2b878925f42503e9d54dfef9f9586d9e6f38a305769587b1de01f6c0410328b2c9733db")]
-
-namespace System.Net.Http {
-	public partial class HttpClient {
-
-		public HttpClient ()
-			: this (GetDefaultHandler (), true)
-		{
-		}
-
-		// note: the linker will re-write ObjCRuntime.RuntimeOptions.GetHttpMessageHandler to return the correct type
-		// unlike, XI where this method itself gets rewritten during linking
-		static HttpMessageHandler GetDefaultHandler ()
-		{
-			Type type = Type.GetType("ObjCRuntime.RuntimeOptions, Xamarin.Mac");
-			var method = type.GetMethod ("GetHttpMessageHandler", BindingFlags.Static | BindingFlags.NonPublic);
-			return (HttpMessageHandler)method.Invoke (null, null);
-		}
-	}
-}
diff --git a/mcs/class/System.Net.Http/System.Net.Http/HttpClient.macios.cs b/mcs/class/System.Net.Http/System.Net.Http/HttpClient.macios.cs
new file mode 100644
index 00000000000..a60a7941b23
--- /dev/null
+++ b/mcs/class/System.Net.Http/System.Net.Http/HttpClient.macios.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Reflection;
+
+namespace System.Net.Http {
+	public partial class HttpClient {
+
+		public HttpClient ()
+			: this (CreateDefaultHandler ())
+		{
+		}
+
+		static HttpMessageHandler CreateDefaultHandler ()
+		{
+			return ObjCRuntime.RuntimeOptions.GetHttpMessageHandler ();
+		}
+	}
+}
diff --git a/mcs/class/System.Net.Http/monotouch_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/monotouch_System.Net.Http.dll.sources
index 64cdbb68748..f4de7b4ea31 100644
--- a/mcs/class/System.Net.Http/monotouch_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/monotouch_System.Net.Http.dll.sources
@@ -1,6 +1,2 @@
 #include legacy.sources
-CFContentStream.cs
-CFNetworkHandler.cs
-HttpClientEx.cs
-NSUrlSessionHandler.cs
-RuntimeOptions.cs
+System.Net.Http/HttpClient.macios.cs
diff --git a/mcs/class/System.Net.Http/monotouch_runtime_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/monotouch_runtime_System.Net.Http.dll.sources
index 704cd9f69ab..f4de7b4ea31 100644
--- a/mcs/class/System.Net.Http/monotouch_runtime_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/monotouch_runtime_System.Net.Http.dll.sources
@@ -1 +1,2 @@
 #include legacy.sources
+System.Net.Http/HttpClient.macios.cs
diff --git a/mcs/class/System.Net.Http/monotouch_tv_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/monotouch_tv_System.Net.Http.dll.sources
index 64cdbb68748..f4de7b4ea31 100644
--- a/mcs/class/System.Net.Http/monotouch_tv_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/monotouch_tv_System.Net.Http.dll.sources
@@ -1,6 +1,2 @@
 #include legacy.sources
-CFContentStream.cs
-CFNetworkHandler.cs
-HttpClientEx.cs
-NSUrlSessionHandler.cs
-RuntimeOptions.cs
+System.Net.Http/HttpClient.macios.cs
diff --git a/mcs/class/System.Net.Http/monotouch_watch_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/monotouch_watch_System.Net.Http.dll.sources
index c8cb6acafb1..8f6e9ebbc19 100644
--- a/mcs/class/System.Net.Http/monotouch_watch_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/monotouch_watch_System.Net.Http.dll.sources
@@ -1,5 +1,3 @@
 #include legacy.sources
 System.Net.Http/HttpClientHandler.platformnotsupported.cs
-HttpClientEx.cs
-NSUrlSessionHandler.cs
-RuntimeOptions.cs
+System.Net.Http/HttpClient.macios.cs
diff --git a/mcs/class/System.Net.Http/xammac_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/xammac_System.Net.Http.dll.sources
index c2f4a641674..f4de7b4ea31 100644
--- a/mcs/class/System.Net.Http/xammac_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/xammac_System.Net.Http.dll.sources
@@ -1,2 +1,2 @@
 #include legacy.sources
-System.Net.Http/HttpClient.mac.cs
+System.Net.Http/HttpClient.macios.cs
diff --git a/mcs/class/System.Net.Http/xammac_net_4_5_System.Net.Http.dll.sources b/mcs/class/System.Net.Http/xammac_net_4_5_System.Net.Http.dll.sources
index c2f4a641674..f4de7b4ea31 100644
--- a/mcs/class/System.Net.Http/xammac_net_4_5_System.Net.Http.dll.sources
+++ b/mcs/class/System.Net.Http/xammac_net_4_5_System.Net.Http.dll.sources
@@ -1,2 +1,2 @@
 #include legacy.sources
-System.Net.Http/HttpClient.mac.cs
+System.Net.Http/HttpClient.macios.cs