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Merged
merged 2 commits into from
May 4, 2025
Merged

Read the underlying buffer in SshDataStream #1638

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d586e06
Read the underlying buffer in SshDataStream
Rob-Hague May 3, 2025
4dc69af
Merge branch 'develop' into sshdatastream
Rob-Hague May 4, 2025
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24 changes: 24 additions & 0 deletions src/Renci.SshNet/Common/Extensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,9 @@ namespace Renci.SshNet.Common
/// </summary>
internal static class Extensions
{
#pragma warning disable S4136 // Method overloads should be grouped together
internal static byte[] ToArray(this ServiceName serviceName)
#pragma warning restore S4136 // Method overloads should be grouped together
{
switch (serviceName)
{
Expand Down Expand Up @@ -382,6 +384,28 @@ internal static bool Remove<TKey, TValue>(this Dictionary<TKey, TValue> dictiona
value = default;
return false;
}

internal static ArraySegment<T> Slice<T>(this ArraySegment<T> arraySegment, int index)
{
return new ArraySegment<T>(arraySegment.Array, arraySegment.Offset + index, arraySegment.Count - index);
}

internal static ArraySegment<T> Slice<T>(this ArraySegment<T> arraySegment, int index, int count)
{
return new ArraySegment<T>(arraySegment.Array, arraySegment.Offset + index, count);
}

internal static T[] ToArray<T>(this ArraySegment<T> arraySegment)
{
if (arraySegment.Count == 0)
{
return Array.Empty<T>();
}

var array = new T[arraySegment.Count];
Array.Copy(arraySegment.Array, arraySegment.Offset, array, 0, arraySegment.Count);
return array;
}
#endif
}
}
111 changes: 56 additions & 55 deletions src/Renci.SshNet/Common/SshDataStream.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
using System;
using System.Buffers.Binary;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Numerics;
Expand Down Expand Up @@ -27,7 +29,7 @@ public SshDataStream(int capacity)
/// <param name="buffer">The array of unsigned bytes from which to create the current stream.</param>
/// <exception cref="ArgumentNullException"><paramref name="buffer"/> is <see langword="null"/>.</exception>
public SshDataStream(byte[] buffer)
: base(buffer)
: base(buffer ?? throw new ArgumentNullException(nameof(buffer)), 0, buffer.Length, writable: true, publiclyVisible: true)
{
}

Expand All @@ -39,7 +41,7 @@ public SshDataStream(byte[] buffer)
/// <param name="count">The number of bytes to load.</param>
/// <exception cref="ArgumentNullException"><paramref name="buffer"/> is <see langword="null"/>.</exception>
public SshDataStream(byte[] buffer, int offset, int count)
: base(buffer, offset, count)
: base(buffer, offset, count, writable: true, publiclyVisible: true)
{
}

Expand All @@ -58,19 +60,6 @@ public bool IsEndOfData
}

#if NETFRAMEWORK || NETSTANDARD2_0
private int Read(Span<byte> buffer)
{
var sharedBuffer = System.Buffers.ArrayPool<byte>.Shared.Rent(buffer.Length);

var numRead = Read(sharedBuffer, 0, buffer.Length);

sharedBuffer.AsSpan(0, numRead).CopyTo(buffer);

System.Buffers.ArrayPool<byte>.Shared.Return(sharedBuffer);

return numRead;
}

private void Write(ReadOnlySpan<byte> buffer)
{
var sharedBuffer = System.Buffers.ArrayPool<byte>.Shared.Rent(buffer.Length);
Expand All @@ -90,7 +79,7 @@ private void Write(ReadOnlySpan<byte> buffer)
public void Write(uint value)
{
Span<byte> bytes = stackalloc byte[4];
System.Buffers.Binary.BinaryPrimitives.WriteUInt32BigEndian(bytes, value);
BinaryPrimitives.WriteUInt32BigEndian(bytes, value);
Write(bytes);
}

Expand All @@ -101,7 +90,7 @@ public void Write(uint value)
public void Write(ulong value)
{
Span<byte> bytes = stackalloc byte[8];
System.Buffers.Binary.BinaryPrimitives.WriteUInt64BigEndian(bytes, value);
BinaryPrimitives.WriteUInt64BigEndian(bytes, value);
Write(bytes);
}

Expand Down Expand Up @@ -137,6 +126,7 @@ public void Write(byte[] data)
/// <exception cref="ArgumentNullException"><paramref name="encoding"/> is <see langword="null"/>.</exception>
public void Write(string s, Encoding encoding)
{
ThrowHelper.ThrowIfNull(s);
ThrowHelper.ThrowIfNull(encoding);

#if NETSTANDARD2_1 || NET
Expand All @@ -153,12 +143,21 @@ public void Write(string s, Encoding encoding)
}

/// <summary>
/// Reads a byte array from the SSH data stream.
/// Reads a length-prefixed byte array from the SSH data stream.
/// </summary>
/// <returns>
/// The byte array read from the SSH data stream.
/// </returns>
public byte[] ReadBinary()
{
return ReadBinarySegment().ToArray();
}

/// <summary>
/// Reads a length-prefixed byte array from the SSH data stream,
/// returned as a view over the underlying buffer.
/// </summary>
internal ArraySegment<byte> ReadBinarySegment()
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@Rob-Hague Rob-Hague May 3, 2025 •
edited
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later this will be used in SshData to remove large array allocations when reading e.g. ChannelDataMessage (the motivation for this change)

{
var length = ReadUInt32();

Expand All @@ -167,7 +166,23 @@ public byte[] ReadBinary()
throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture, "Data longer than {0} is not supported.", int.MaxValue));
}

return ReadBytes((int)length);
var buffer = GetRemainingBuffer().Slice(0, (int)length);

Position += length;

return buffer;
}

/// <summary>
/// Gets a view over the remaining data in the underlying buffer.
/// </summary>
private ArraySegment<byte> GetRemainingBuffer()
{
var success = TryGetBuffer(out var buffer);

Debug.Assert(success, "Expected buffer to be publicly visible");

return buffer.Slice((int)Position);
}

/// <summary>
Expand Down Expand Up @@ -205,11 +220,11 @@ public void WriteBinary(byte[] buffer, int offset, int count)
/// </returns>
public BigInteger ReadBigInt()
{
var data = ReadBinary();

#if NETSTANDARD2_1 || NET
var data = ReadBinarySegment();
return new BigInteger(data, isBigEndian: true);
#else
var data = ReadBinary();
Array.Reverse(data);
return new BigInteger(data);
#endif
Expand All @@ -223,9 +238,9 @@ public BigInteger ReadBigInt()
/// </returns>
public ushort ReadUInt16()
{
Span<byte> bytes = stackalloc byte[2];
ReadBytes(bytes);
return System.Buffers.Binary.BinaryPrimitives.ReadUInt16BigEndian(bytes);
var ret = BinaryPrimitives.ReadUInt16BigEndian(GetRemainingBuffer());
Position += sizeof(ushort);
return ret;
}

/// <summary>
Expand All @@ -236,9 +251,9 @@ public ushort ReadUInt16()
/// </returns>
public uint ReadUInt32()
{
Span<byte> span = stackalloc byte[4];
ReadBytes(span);
return System.Buffers.Binary.BinaryPrimitives.ReadUInt32BigEndian(span);
var ret = BinaryPrimitives.ReadUInt32BigEndian(GetRemainingBuffer());
Position += sizeof(uint);
return ret;
}

/// <summary>
Expand All @@ -249,9 +264,9 @@ public uint ReadUInt32()
/// </returns>
public ulong ReadUInt64()
{
Span<byte> span = stackalloc byte[8];
ReadBytes(span);
return System.Buffers.Binary.BinaryPrimitives.ReadUInt64BigEndian(span);
var ret = BinaryPrimitives.ReadUInt64BigEndian(GetRemainingBuffer());
Position += sizeof(ulong);
return ret;
}

/// <summary>
Expand All @@ -265,19 +280,13 @@ public string ReadString(Encoding encoding = null)
{
encoding ??= Encoding.UTF8;

var length = ReadUInt32();

if (length > int.MaxValue)
{
throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture, "Strings longer than {0} is not supported.", int.MaxValue));
}
var bytes = ReadBinarySegment();

var bytes = ReadBytes((int)length);
return encoding.GetString(bytes, 0, bytes.Length);
return encoding.GetString(bytes.Array, bytes.Offset, bytes.Count);
}

/// <summary>
/// Writes the stream contents to a byte array, regardless of the <see cref="MemoryStream.Position"/>.
/// Retrieves the stream contents as a byte array, regardless of the <see cref="MemoryStream.Position"/>.
/// </summary>
/// <returns>
/// This method returns the contents of the <see cref="SshDataStream"/> as a byte array.
Expand All @@ -288,9 +297,15 @@ public string ReadString(Encoding encoding = null)
/// </remarks>
public override byte[] ToArray()
{
if (Capacity == Length)
var success = TryGetBuffer(out var buffer);

Debug.Assert(success, "Expected buffer to be publicly visible");

if (buffer.Offset == 0 &&
buffer.Count == buffer.Array.Length &&
buffer.Count == Length)
{
return GetBuffer();
return buffer.Array;
}

return base.ToArray();
Expand All @@ -315,19 +330,5 @@ internal byte[] ReadBytes(int length)

return data;
}

/// <summary>
/// Reads data into the specified <paramref name="buffer" />.
/// </summary>
/// <param name="buffer">The buffer to read into.</param>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="buffer"/> is larger than the total of bytes available.</exception>
private void ReadBytes(Span<byte> buffer)
{
var bytesRead = Read(buffer);
if (bytesRead < buffer.Length)
{
throw new ArgumentOutOfRangeException(nameof(buffer), string.Format(CultureInfo.InvariantCulture, "The requested length ({0}) is greater than the actual number of bytes read ({1}).", buffer.Length, bytesRead));
}
}
}
}
39 changes: 19 additions & 20 deletions src/Renci.SshNet/PrivateKeyFile.OpenSSH.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ public OpenSSH(byte[] data, string? passPhrase)
/// </summary>
public Key Parse()
{
var keyReader = new SshDataReader(_data);
var keyReader = new SshDataStream(_data);

// check magic header
var authMagic = "openssh-key-v1\0"u8;
Expand Down Expand Up @@ -171,7 +171,7 @@ public Key Parse()
// now parse the data we called the private key, it actually contains the public key again
// so we need to parse through it to get the private key bytes, plus there's some
// validation we need to do.
var privateKeyReader = new SshDataReader(privateKeyBytes);
var privateKeyReader = new SshDataStream(privateKeyBytes);

// check ints should match, they wouldn't match for example if the wrong passphrase was supplied
var checkInt1 = (int)privateKeyReader.ReadUInt32();
Expand All @@ -196,33 +196,29 @@ public Key Parse()
// https://datatracker.ietf.org/doc/html/draft-miller-ssh-agent-11#section-3.2.3

// ENC(A)
_ = privateKeyReader.ReadBignum2();
_ = privateKeyReader.ReadBinarySegment();

// k || ENC(A)
unencryptedPrivateKey = privateKeyReader.ReadBignum2();
unencryptedPrivateKey = privateKeyReader.ReadBinary();
parsedKey = new ED25519Key(unencryptedPrivateKey);
break;
case "ecdsa-sha2-nistp256":
case "ecdsa-sha2-nistp384":
case "ecdsa-sha2-nistp521":
// curve
var len = (int)privateKeyReader.ReadUInt32();
var curve = Encoding.ASCII.GetString(privateKeyReader.ReadBytes(len));
var curve = privateKeyReader.ReadString(Encoding.ASCII);

// public key
publicKey = privateKeyReader.ReadBignum2();
publicKey = privateKeyReader.ReadBinary();

// private key
unencryptedPrivateKey = privateKeyReader.ReadBignum2();
unencryptedPrivateKey = privateKeyReader.ReadBinary();
parsedKey = new EcdsaKey(curve, publicKey, unencryptedPrivateKey.TrimLeadingZeros());
break;
case "ssh-rsa":
var modulus = privateKeyReader.ReadBignum(); // n
var exponent = privateKeyReader.ReadBignum(); // e
var d = privateKeyReader.ReadBignum(); // d
var inverseQ = privateKeyReader.ReadBignum(); // iqmp
var p = privateKeyReader.ReadBignum(); // p
var q = privateKeyReader.ReadBignum(); // q
var modulus = privateKeyReader.ReadBigInt();
var exponent = privateKeyReader.ReadBigInt();
var d = privateKeyReader.ReadBigInt();
var inverseQ = privateKeyReader.ReadBigInt();
var p = privateKeyReader.ReadBigInt();
var q = privateKeyReader.ReadBigInt();
parsedKey = new RsaKey(modulus, exponent, d, p, q, inverseQ);
break;
default:
Expand All @@ -233,14 +229,17 @@ public Key Parse()

// The list of privatekey/comment pairs is padded with the bytes 1, 2, 3, ...
// until the total length is a multiple of the cipher block size.
var padding = privateKeyReader.ReadBytes();
for (var i = 0; i < padding.Length; i++)
int b, i = 0;

while ((b = privateKeyReader.ReadByte()) != -1)
{
if ((int)padding[i] != i + 1)
if (b != i + 1)
{
throw new SshException("Padding of openssh key format contained wrong byte at position: " +
i.ToString(CultureInfo.InvariantCulture));
}

i++;
}

return parsedKey;
Expand Down
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