mcs/class/Mono.Security/Mono.Security.Protocol.Tls.Handshake.Server/TlsClientHello.cs

   1 // Transport Security Layer (TLS)
   2 // Copyright (c) 2003-2004 Carlos Guzman Alvarez
   3 // Copyright (C) 2006 Novell, Inc (http://www.novell.com)
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining
   6 // a copy of this software and associated documentation files (the
   7 // "Software"), to deal in the Software without restriction, including
   8 // without limitation the rights to use, copy, modify, merge, publish,
   9 // distribute, sublicense, and/or sell copies of the Software, and to
  10 // permit persons to whom the Software is furnished to do so, subject to
  11 // the following conditions:
  12 //
  13 // The above copyright notice and this permission notice shall be
  14 // included in all copies or substantial portions of the Software.
  15 //
  16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  18 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  19 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  20 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  21 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  22 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23 //
  24
  25 using System;
  26 using System.Security.Cryptography;
  27
  28 namespace Mono.Security.Protocol.Tls.Handshake.Server
  29 {
  30         internal class TlsClientHello : HandshakeMessage
  31         {
  32                 #region Private Fields
  33
  34                 private byte[]  random;
  35                 private byte[]  sessionId;
  36                 private short[] cipherSuites;
  37                 private byte[]  compressionMethods;
  38
  39                 #endregion
  40
  41                 #region Constructors
  42
  43                 public TlsClientHello(Context context, byte[] buffer)
  44                         : base(context, HandshakeType.ClientHello, buffer)
  45                 {
  46                 }
  47
  48                 #endregion
  49
  50                 #region Methods
  51
  52                 public override void Update()
  53                 {
  54                         base.Update();
  55
  56                         this.selectCipherSuite();
  57                         this.selectCompressionMethod();
  58
  59                         this.Context.SessionId                  = this.sessionId;
  60                         this.Context.ClientRandom               = this.random;
  61                         this.Context.ProtocolNegotiated = true;
  62                 }
  63
  64                 #endregion
  65
  66                 #region Protected Methods
  67
  68                 protected override void ProcessAsSsl3()
  69                 {
  70                         this.ProcessAsTls1();
  71                 }
  72
  73                 protected override void ProcessAsTls1()
  74                 {
  75                         // Client Version
  76                         this.processProtocol(this.ReadInt16());
  77
  78                         // Random bytes - Unix time + Radom bytes [28]
  79                         this.random = this.ReadBytes(32);
  80
  81                         // Session id
  82                         // Send the session ID empty
  83                         this.sessionId = this.ReadBytes(this.ReadByte());
  84
  85                         // Read Supported Cipher Suites count
  86                         this.cipherSuites = new short[this.ReadInt16()/2];
  87
  88                         // Read Cipher Suites
  89                         for (int i = 0; i < this.cipherSuites.Length; i++)
  90                         {
  91                                 this.cipherSuites[i] = this.ReadInt16();
  92                         }
  93
  94                         // Compression methods length
  95                         this.compressionMethods = new byte[this.ReadByte()];
  96
  97                         for (int i = 0; i < this.compressionMethods.Length; i++)
  98                         {
  99                                 this.compressionMethods[i] = this.ReadByte();
 100                         }
 101                 }
 102
 103                 #endregion
 104
 105                 #region Private Methods
 106
 107                 private void processProtocol(short protocol)
 108                 {
 109                         // a server MUST reply with the hight version supported (`true` for fallback)
 110                         // so a TLS 1.2 client (like Google Chrome) will be returned that the server uses TLS 1.0
 111                         // instead of an alert about the protocol
 112                         SecurityProtocolType clientProtocol = Context.DecodeProtocolCode (protocol, true);
 113
 114                         if ((clientProtocol & this.Context.SecurityProtocolFlags) == clientProtocol ||
 115                                 (this.Context.SecurityProtocolFlags & SecurityProtocolType.Default) == SecurityProtocolType.Default)
 116                         {
 117                                 this.Context.SecurityProtocol = clientProtocol;
 118                                 this.Context.SupportedCiphers.Clear();
 119                                 this.Context.SupportedCiphers = null;
 120                                 this.Context.SupportedCiphers = CipherSuiteFactory.GetSupportedCiphers(clientProtocol);
 121                         }
 122                         else
 123                         {
 124                                 throw new TlsException(AlertDescription.ProtocolVersion, "Incorrect protocol version received from server");
 125                         }
 126                 }
 127
 128                 private void selectCipherSuite()
 129                 {
 130                         int index = 0;
 131
 132                         for (int i = 0; i < this.cipherSuites.Length; i++)
 133                         {
 134                                 if ((index = this.Context.SupportedCiphers.IndexOf(this.cipherSuites[i])) != -1)
 135                                 {
 136                                         this.Context.Negotiating.Cipher = this.Context.SupportedCiphers[index];
 137                                         break;
 138                                 }
 139                         }
 140
 141                         if (this.Context.Negotiating.Cipher == null)
 142                         {
 143                                 throw new TlsException(AlertDescription.InsuficientSecurity, "Insuficient Security");
 144                         }
 145                 }
 146
 147                 private void selectCompressionMethod()
 148                 {
 149                         this.Context.CompressionMethod = SecurityCompressionType.None;
 150                 }
 151
 152                 #endregion
 153         }
 154 }