mirror of
https://github.com/sshnet/SSH.NET.git
synced 2026-09-10 17:25:51 +00:00
drieseng
76a92cfb0a
- Remove ZeroReaderIndex from SshData; offset should instead be specified when instance is created/loaded. - LoadBytes is now private, and is always invoked when a message is loaded. - Eliminate ResetReader(). SshDataStream.cs: - Added overload taking buffer, offset and count. KeyExchange*Message.cs: - Remove ResetReader() calls. Message.cs: - Remove ZeroReaderIndex override. SftpMessage.cs: - Pass offset and count to Load overload to allow skipping byte representing the message type. - Remove ZeroReaderIndex override. SftpSession.cs: - Avoid buffering when packet contains full SFTP response message. Session.cs: - Pass offset and count to Load overload to allow skipping offset bytes. General: - Temporarily add (too) verbose tracing.
98 lines
4.4 KiB
C#
98 lines
4.4 KiB
C#
using System;
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using System.Net.Sockets;
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using Renci.SshNet.Abstractions;
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namespace Renci.SshNet
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{
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public partial class Session
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{
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#if FEATURE_SOCKET_POLL
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/// <summary>
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/// Holds the lock object to ensure read access to the socket is synchronized.
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/// </summary>
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private readonly object _socketReadLock = new object();
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#endif // FEATURE_SOCKET_POLL
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#if FEATURE_SOCKET_POLL
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/// <summary>
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/// Gets a value indicating whether the socket is connected.
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/// </summary>
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/// <param name="isConnected"><c>true</c> if the socket is connected; otherwise, <c>false</c></param>
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/// <remarks>
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/// <para>
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/// As a first check we verify whether <see cref="Socket.Connected"/> is
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/// <c>true</c>. However, this only returns the state of the socket as of
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/// the last I/O operation.
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/// </para>
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/// <para>
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/// Therefore we use the combination of <see cref="Socket.Poll(int, SelectMode)"/> with mode <see cref="SelectMode.SelectRead"/>
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/// and <see cref="Socket.Available"/> to verify if the socket is still connected.
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/// </para>
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/// <para>
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/// The MSDN doc mention the following on the return value of <see cref="Socket.Poll(int, SelectMode)"/>
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/// with mode <see cref="SelectMode.SelectRead"/>:
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/// <list type="bullet">
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/// <item>
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/// <description><c>true</c> if data is available for reading;</description>
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/// </item>
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/// <item>
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/// <description><c>true</c> if the connection has been closed, reset, or terminated; otherwise, returns <c>false</c>.</description>
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/// </item>
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/// </list>
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/// </para>
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/// <para>
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/// <c>Conclusion:</c> when the return value is <c>true</c> - but no data is available for reading - then
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/// the socket is no longer connected.
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/// </para>
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/// <para>
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/// When a <see cref="Socket"/> is used from multiple threads, there's a race condition
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/// between the invocation of <see cref="Socket.Poll(int, SelectMode)"/> and the moment
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/// when the value of <see cref="Socket.Available"/> is obtained. As a workaround, we signal
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/// when bytes are read from the <see cref="Socket"/>.
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/// </para>
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/// </remarks>
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#else
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/// <summary>
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/// Gets a value indicating whether the socket is connected.
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/// </summary>
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/// <param name="isConnected"><c>true</c> if the socket is connected; otherwise, <c>false</c></param>
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/// <remarks>
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/// We verify whether <see cref="Socket.Connected"/> is <c>true</c>. However, this only returns the state
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/// of the socket as of the last I/O operation.
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/// </remarks>
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#endif
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partial void IsSocketConnected(ref bool isConnected)
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{
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isConnected = (_socket != null && _socket.Connected);
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#if FEATURE_SOCKET_POLL
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if (isConnected)
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{
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// synchronize this to ensure thread B does not reset the wait handle before
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// thread A was able to check whether "bytes read from socket" signal was
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// actually received
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lock (_socketReadLock)
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{
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DiagnosticAbstraction.Log(string.Format("[{0}] {1} Checking socket", ToHex(SessionId), DateTime.Now.Ticks));
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// reset waithandle, as we're only interested in reads that take
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// place between Poll and the Available check
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_bytesReadFromSocket.Reset();
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var connectionClosedOrDataAvailable = _socket.Poll(100, SelectMode.SelectRead);
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isConnected = !(connectionClosedOrDataAvailable && _socket.Available == 0);
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if (!isConnected)
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{
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// the race condition is between the Socket.Poll call and
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// Socket.Available, but the event handler - where we signal that
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// bytes have been received from the socket - is sometimes invoked
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// shortly after
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isConnected = _bytesReadFromSocket.WaitOne(500);
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}
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DiagnosticAbstraction.Log(string.Format("[{0}] {1} Checked socket", ToHex(SessionId), DateTime.Now.Ticks));
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}
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}
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#endif // FEATURE_SOCKET_POLL
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}
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}
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}
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