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using System;
using System.Collections.Generic;
using System.IO;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.IO;
namespace Org.BouncyCastle.Tls
{
public sealed class ClientHello
{
private readonly ProtocolVersion m_version;
private readonly byte[] m_random;
private readonly byte[] m_sessionID;
private readonly byte[] m_cookie;
private readonly int[] m_cipherSuites;
private readonly IDictionary<int, byte[]> m_extensions;
private readonly int m_bindersSize;
public ClientHello(ProtocolVersion version, byte[] random, byte[] sessionID, byte[] cookie,
int[] cipherSuites, IDictionary<int, byte[]> extensions, int bindersSize)
{
this.m_version = version;
this.m_random = random;
this.m_sessionID = sessionID;
this.m_cookie = cookie;
this.m_cipherSuites = cipherSuites;
this.m_extensions = extensions;
this.m_bindersSize = bindersSize;
}
public int BindersSize
{
get { return m_bindersSize; }
}
public int[] CipherSuites
{
get { return m_cipherSuites; }
}
public byte[] Cookie
{
get { return m_cookie; }
}
public IDictionary<int, byte[]> Extensions
{
get { return m_extensions; }
}
public byte[] Random
{
get { return m_random; }
}
public byte[] SessionID
{
get { return m_sessionID; }
}
public ProtocolVersion Version
{
get { return m_version; }
}
/// <summary>Encode this <see cref="ClientHello"/> to a <see cref="Stream"/>.</summary>
/// <param name="context">the <see cref="TlsContext"/> of the current connection.</param>
/// <param name="output">the <see cref="Stream"/> to encode to.</param>
/// <exception cref="IOException"/>
public void Encode(TlsContext context, Stream output)
{
if (m_bindersSize < 0)
throw new TlsFatalAlert(AlertDescription.internal_error);
TlsUtilities.WriteVersion(m_version, output);
output.Write(m_random, 0, m_random.Length);
TlsUtilities.WriteOpaque8(m_sessionID, output);
if (null != m_cookie)
{
TlsUtilities.WriteOpaque8(m_cookie, output);
}
TlsUtilities.WriteUint16ArrayWithUint16Length(m_cipherSuites, output);
TlsUtilities.WriteUint8ArrayWithUint8Length(new short[]{ CompressionMethod.cls_null }, output);
TlsProtocol.WriteExtensions(output, m_extensions, m_bindersSize);
}
/// <summary>Parse a <see cref="ClientHello"/> from a <see cref="MemoryStream"/>.</summary>
/// <param name="messageInput">the <see cref="MemoryStream"/> to parse from.</param>
/// <param name="dtlsOutput">for DTLS this should be non-null; the input is copied to this
/// <see cref="Stream"/>, minus the cookie field.</param>
/// <returns>a <see cref="ClientHello"/> object.</returns>
/// <exception cref="TlsFatalAlert"/>
public static ClientHello Parse(MemoryStream messageInput, Stream dtlsOutput)
{
try
{
return ImplParse(messageInput, dtlsOutput);
}
catch (TlsFatalAlert)
{
throw;
}
catch (IOException e)
{
throw new TlsFatalAlert(AlertDescription.decode_error, e);
}
}
/// <exception cref="IOException"/>
private static ClientHello ImplParse(MemoryStream messageInput, Stream dtlsOutput)
{
Stream input = messageInput;
if (null != dtlsOutput)
{
input = new TeeInputStream(input, dtlsOutput);
}
ProtocolVersion clientVersion = TlsUtilities.ReadVersion(input);
byte[] random = TlsUtilities.ReadFully(32, input);
byte[] sessionID = TlsUtilities.ReadOpaque8(input, 0, 32);
byte[] cookie = null;
if (null != dtlsOutput)
{
/*
* RFC 6347 This specification increases the cookie size limit to 255 bytes for greater
* future flexibility. The limit remains 32 for previous versions of DTLS.
*/
int maxCookieLength = ProtocolVersion.DTLSv12.IsEqualOrEarlierVersionOf(clientVersion) ? 255 : 32;
cookie = TlsUtilities.ReadOpaque8(messageInput, 0, maxCookieLength);
}
int cipher_suites_length = TlsUtilities.ReadUint16(input);
if (cipher_suites_length < 2 || (cipher_suites_length & 1) != 0
|| Convert.ToInt32(messageInput.Length - messageInput.Position) < cipher_suites_length)
{
throw new TlsFatalAlert(AlertDescription.decode_error);
}
/*
* NOTE: "If the session_id field is not empty (implying a session resumption request) this
* vector must include at least the cipher_suite from that session."
*/
int[] cipherSuites = TlsUtilities.ReadUint16Array(cipher_suites_length / 2, input);
short[] compressionMethods = TlsUtilities.ReadUint8ArrayWithUint8Length(input, 1);
if (!Arrays.Contains(compressionMethods, CompressionMethod.cls_null))
throw new TlsFatalAlert(AlertDescription.handshake_failure);
/*
* NOTE: Can't use TlsProtocol.ReadExtensions directly because TeeInputStream a) won't have
* 'Length' or 'Position' properties in the FIPS provider, b) isn't a MemoryStream.
*/
IDictionary<int, byte[]> extensions = null;
if (messageInput.Position < messageInput.Length)
{
byte[] extBytes = TlsUtilities.ReadOpaque16(input);
TlsProtocol.AssertEmpty(messageInput);
extensions = TlsProtocol.ReadExtensionsDataClientHello(extBytes);
}
return new ClientHello(clientVersion, random, sessionID, cookie, cipherSuites, extensions, -1);
}
}
}
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