ServicePoint.cs

//
// System.Net.ServicePoint
//
// Authors:
// 	Lawrence Pit (loz@cable.a2000.nl)
//	Gonzalo Paniagua Javier (gonzalo@ximian.com)
//
// (c) 2002 Lawrence Pit
// (c) 2003 Ximian, Inc. (http://www.ximian.com)
//

// Copyright (c) 2018 Nivloc Enterprises Ltd

//
// 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.Collections;
#if SSHARP
using Crestron.SimplSharp;
using SSMono.Security.Cryptography.X509Certificates;
using Timer = Crestron.SimplSharp.CTimer;
using Socket = Crestron.SimplSharp.CrestronSockets.CrestronClientSocket;
#else
using System.Diagnostics;
using System.Net.Sockets;
using System.Security.Cryptography.X509Certificates;
using System.Threading;
#endif

#if SSHARP
namespace SSMono.Net
#else
namespace System.Net
#endif
	{
	public class ServicePoint
		{
		private Uri uri;
		private int connectionLimit;
		private int maxIdleTime;
		private int currentConnections;
		private DateTime idleSince;
		private Version protocolVersion;
		private X509Certificate certificate;
		private X509Certificate clientCertificate;
		private IPHostEntry host;
		private bool usesProxy;
		private Dictionary<string, WebConnectionGroup> groups;
		private bool sendContinue = true;
		private bool useConnect;
		private object hostE = new object ();
		private bool useNagle;
		private BindIPEndPoint endPointCallback = null;
		private bool tcp_keepalive;
		private int tcp_keepalive_time;
		private int tcp_keepalive_interval;
		private Timer idleTimer;

		// Constructors

		internal ServicePoint (Uri uri, int connectionLimit, int maxIdleTime)
			{
			this.uri = uri;
			this.connectionLimit = connectionLimit;
			this.maxIdleTime = maxIdleTime;
			this.currentConnections = 0;
			this.idleSince = DateTime.UtcNow;
			}

		// Properties

		public Uri Address
			{
			get { return uri; }
			}

		private static Exception GetMustImplement ()
			{
			return new NotImplementedException ();
			}

		public BindIPEndPoint BindIPEndPointDelegate
			{
			get { return endPointCallback; }
			set { endPointCallback = value; }
			}

		public X509Certificate Certificate
			{
			get { return certificate; }
			}

		public X509Certificate ClientCertificate
			{
			get { return clientCertificate; }
			}

		[MonoTODO]
		public int ConnectionLeaseTimeout
			{
			get { throw GetMustImplement (); }
			set { throw GetMustImplement (); }
			}

		public int ConnectionLimit
			{
			get { return connectionLimit; }
			set
				{
				if (value <= 0)
					throw new ArgumentOutOfRangeException ();

				connectionLimit = value;
				}
			}

		public string ConnectionName
			{
			get { return uri.Scheme; }
			}

		public int CurrentConnections
			{
			get { return currentConnections; }
			}

		public DateTime IdleSince
			{
			get { return idleSince.ToLocalTime (); }
			}

		public int MaxIdleTime
			{
			get { return maxIdleTime; }
			set
				{
				if (value < Timeout.Infinite || value > Int32.MaxValue)
					throw new ArgumentOutOfRangeException ();

				lock (this)
					{
					maxIdleTime = value;
					if (idleTimer != null)
						idleTimer.Change (maxIdleTime, maxIdleTime);
					}
				}
			}

		public virtual Version ProtocolVersion
			{
			get { return protocolVersion; }
			}

		[MonoTODO]
		public int ReceiveBufferSize
			{
			get { throw GetMustImplement (); }
			set { throw GetMustImplement (); }
			}

		public bool SupportsPipelining
			{
			get { return HttpVersion.Version11.Equals (protocolVersion); }
			}

		public bool Expect100Continue
			{
			get { return SendContinue; }
			set { SendContinue = value; }
			}

		public bool UseNagleAlgorithm
			{
			get { return useNagle; }
			set { useNagle = value; }
			}

		internal bool SendContinue
			{
			get { return sendContinue && (protocolVersion == null || protocolVersion == HttpVersion.Version11); }
			set { sendContinue = value; }
			}

		// Methods

		public void SetTcpKeepAlive (bool enabled, int keepAliveTime, int keepAliveInterval)
			{
			if (enabled)
				{
				if (keepAliveTime <= 0)
					throw new ArgumentOutOfRangeException ("keepAliveTime", "Must be greater than 0");
				if (keepAliveInterval <= 0)
					throw new ArgumentOutOfRangeException ("keepAliveInterval", "Must be greater than 0");
				}

			tcp_keepalive = enabled;
			tcp_keepalive_time = keepAliveTime;
			tcp_keepalive_interval = keepAliveInterval;
			}

		internal void KeepAliveSetup (Socket socket)
			{
#if SSHARP
#else
			if (!tcp_keepalive)
				return;

			byte[] bytes = new byte[12];
			PutBytes (bytes, (uint)(tcp_keepalive ? 1 : 0), 0);
			PutBytes (bytes, (uint)tcp_keepalive_time, 4);
			PutBytes (bytes, (uint)tcp_keepalive_interval, 8);
			socket.IOControl (IOControlCode.KeepAliveValues, bytes, null);
#endif
			}

		private static void PutBytes (byte[] bytes, uint v, int offset)
			{
			if (BitConverter.IsLittleEndian)
				{
				bytes[offset] = (byte)(v & 0x000000ff);
				bytes[offset + 1] = (byte)((v & 0x0000ff00) >> 8);
				bytes[offset + 2] = (byte)((v & 0x00ff0000) >> 16);
				bytes[offset + 3] = (byte)((v & 0xff000000) >> 24);
				}
			else
				{
				bytes[offset + 3] = (byte)(v & 0x000000ff);
				bytes[offset + 2] = (byte)((v & 0x0000ff00) >> 8);
				bytes[offset + 1] = (byte)((v & 0x00ff0000) >> 16);
				bytes[offset] = (byte)((v & 0xff000000) >> 24);
				}
			}

		// Internal Methods

		internal bool UsesProxy
			{
			get { return usesProxy; }
			set { usesProxy = value; }
			}

		internal bool UseConnect
			{
			get { return useConnect; }
			set { useConnect = value; }
			}

		private WebConnectionGroup GetConnectionGroup (string name)
			{
			if (name == null)
				name = "";

			/*
			 * Optimization:
			 * 
			 * In the vast majority of cases, we only have one single WebConnectionGroup per ServicePoint, so we
			 * don't need to allocate a dictionary.
			 * 
			 */

			WebConnectionGroup group;
			if (groups != null && groups.TryGetValue (name, out group))
				return group;

			group = new WebConnectionGroup (this, name);
			group.ConnectionClosed += (s, e) => currentConnections--;

			if (groups == null)
				groups = new Dictionary<string, WebConnectionGroup> ();
			groups.Add (name, group);

			return group;
			}

		private void RemoveConnectionGroup (WebConnectionGroup group)
			{
			if (groups == null)
				return;

			if (groups.Count == 0)
				throw new InvalidOperationException ();

			groups.Remove (group.Name);
			}

		internal bool CheckAvailableForRecycling (out DateTime outIdleSince)
			{
			outIdleSince = DateTime.MinValue;

			TimeSpan idleTimeSpan;
			List<WebConnectionGroup> groupList = null, removeList = null;
			lock (this)
				{
				if (groups == null || groups.Count == 0)
					{
					idleSince = DateTime.MinValue;
					return true;
					}

				idleTimeSpan = TimeSpan.FromMilliseconds (maxIdleTime);

				/*
				 * WebConnectionGroup.TryRecycle() must run outside the lock, so we need to
				 * copy the group dictionary if it exists.
				 * 
				 * In most cases, we only have a single connection group, so we can simply store
				 * that in a local variable instead of copying a collection.
				 * 
				 */

				groupList = new List<WebConnectionGroup> (groups.Values);
				}

			foreach (var group in groupList)
				{
				if (!group.TryRecycle (idleTimeSpan, ref outIdleSince))
					continue;
				if (removeList == null)
					removeList = new List<WebConnectionGroup> ();
				removeList.Add (group);
				}

			lock (this)
				{
				idleSince = outIdleSince;

				if (removeList != null)
					{
					foreach (var group in removeList)
						RemoveConnectionGroup (group);
					}

				if (groups != null && groups.Count == 0)
					groups = null;

				if (groups == null)
					{
					if (idleTimer != null)
						{
						idleTimer.Dispose ();
						idleTimer = null;
						}
					return true;
					}

				return false;
				}
			}

		private void IdleTimerCallback (object obj)
			{
			DateTime dummy;
			CheckAvailableForRecycling (out dummy);
			}

		internal IPHostEntry HostEntry
			{
			get
				{
				lock (hostE)
					{
					if (host != null)
						return host;

					string uriHost = uri.Host;

					// There is no need to do DNS resolution on literal IP addresses
					if (uri.HostNameType == UriHostNameType.IPv6 || uri.HostNameType == UriHostNameType.IPv4)
						{
						if (uri.HostNameType == UriHostNameType.IPv6)
							{
							// Remove square brackets
							uriHost = uriHost.Substring (1, uriHost.Length - 2);
							}

						// Creates IPHostEntry
						host = new IPHostEntry ();
						host.AddressList = new IPAddress[] {IPAddress.Parse (uriHost)};

						return host;
						}

					// Try DNS resolution on host names
					try
						{
#if SSHARP
						IPAddress[] addrs = DnsEx.GetHostAddresses (uriHost);
						host = new IPHostEntry { AddressList = addrs, HostName = uriHost };
#else
						host = Dns.GetHostByName (uriHost);
#endif
						}
					catch
						{
						return null;
						}
					}

				return host;
				}
			}

		internal void SetVersion (Version version)
			{
			protocolVersion = version;
			}

		internal EventHandler SendRequest (HttpWebRequest request, string groupName)
			{
			WebConnection cnc;

			lock (this)
				{
				bool created;
				WebConnectionGroup cncGroup = GetConnectionGroup (groupName);
				cnc = cncGroup.GetConnection (request, out created);
				if (created)
					{
					++currentConnections;
					if (idleTimer == null)
						idleTimer = new Timer (IdleTimerCallback, null, maxIdleTime, maxIdleTime);
					}
				}

			return cnc.SendRequest (request);
			}

		public bool CloseConnectionGroup (string connectionGroupName)
			{
			lock (this)
				{
				WebConnectionGroup cncGroup = GetConnectionGroup (connectionGroupName);
				if (cncGroup != null)
					{
					cncGroup.Close ();
					return true;
					}
				}

			return false;
			}

		internal void SetCertificates (X509Certificate client, X509Certificate server)
			{
			certificate = server;
			clientCertificate = client;
			}

		internal bool CallEndPointDelegate (Socket sock, IPEndPoint remote)
			{
			if (endPointCallback == null)
				return true;

			int count = 0;
			for (;;)
				{
				IPEndPoint local = null;
				try
					{
					local = endPointCallback (this, remote, count);
					}
				catch
					{
					// This is to differentiate from an
					// OverflowException, which should propagate.
					return false;
					}

				if (local == null)
					return true;

#if SSHARP
				return false;
#else
				try
					{
					//sock.LocalEndPoint = local;
					sock.Bind (local);
					}
				catch (SocketException)
					{
					// This is intentional; the docs say
					// that if the Bind fails, we keep
					// going until there is an
					// OverflowException on the retry
					// count.
					checked
						{
						++count;
						}
					continue;
					}

				return true;
#endif
				}
			}
		}
	}