public SocketSshConnection(ILogger logger, SequencePool sequencePool, Socket socket) :
base(sequencePool)
{
_logger = logger;
_socket = socket;
_receiveBuffer = sequencePool.RentSequence();
_sendBuffer = sequencePool.RentSequence();
_decoder = new PacketDecoder(SequencePool);
_encoder = new PacketEncoder();
}
private byte[] CalculateExchangeHash(SequencePool sequencePool, SshConnectionInfo connectionInfo, Packet clientKexInitMsg, Packet serverKexInitMsg, ReadOnlySequence <byte> public_host_key, ECPoint q_c, ECPoint q_s, BigInteger sharedSecret)
{
/*
* string V_C, client's identification string (CR and LF excluded)
* string V_S, server's identification string (CR and LF excluded)
* string I_C, payload of the client's SSH_MSG_KEXINIT
* string I_S, payload of the server's SSH_MSG_KEXINIT
* string K_S, server's public host key
* string Q_C, client's ephemeral public key octet string
* string Q_S, server's ephemeral public key octet string
* mpint K, shared secret
*/
using Sequence sequence = sequencePool.RentSequence();
var writer = new SequenceWriter(sequence);
writer.WriteString(connectionInfo.ClientIdentificationString !);
writer.WriteString(connectionInfo.ServerIdentificationString !);
writer.WriteString(clientKexInitMsg.Payload);
writer.WriteString(serverKexInitMsg.Payload);
writer.WriteString(public_host_key);
writer.WriteString(q_c);
writer.WriteString(q_s);
writer.WriteMPInt(sharedSecret);
using IncrementalHash hash = IncrementalHash.CreateHash(_hashAlgorithmName);
foreach (var segment in sequence.AsReadOnlySequence())
{
hash.AppendData(segment.Span);
}
return(hash.GetHashAndReset());
}
private byte[] Hash(SequencePool sequencePool, BigInteger sharedSecret, byte[] exchangeHash, byte c, byte[] sessionId, int hashLength)
{
// https://tools.ietf.org/html/rfc4253#section-7.2
byte[] hashRv = new byte[hashLength];
int hashOffset = 0;
// TODO: handle 'If the key length needed is longer than the output of the HASH'
// HASH(K || H || c || session_id)
using Sequence sequence = sequencePool.RentSequence();
var writer = new SequenceWriter(sequence);
writer.WriteMPInt(sharedSecret);
writer.Write(exchangeHash);
writer.WriteByte(c);
writer.Write(sessionId);
using IncrementalHash hash = IncrementalHash.CreateHash(_hashAlgorithmName);
foreach (var segment in sequence.AsReadOnlySequence())
{
hash.AppendData(segment.Span);
}
byte[] K1 = hash.GetHashAndReset();
Append(hashRv, K1, ref hashOffset);
while (hashOffset != hashRv.Length)
{
// TODO: handle 'If the key length needed is longer than the output of the HASH'
// K3 = HASH(K || H || K1 || K2)
throw new NotSupportedException();
}
return(hashRv);
private static Packet CreatePublicKeyRequestMessage(SequencePool sequencePool, string userName, byte[] sessionId, PrivateKey privateKey)
{
/*
* byte SSH_MSG_USERAUTH_REQUEST
* string user name
* string service name
* string "publickey"
* boolean TRUE
* string public key algorithm name
* string public key to be used for authentication
* string signature
*/
using var packet = sequencePool.RentPacket();
var writer = packet.GetWriter();
writer.WriteByte(MessageNumber.SSH_MSG_USERAUTH_REQUEST);
writer.WriteString(userName);
writer.WriteString("ssh-connection");
writer.WriteString("publickey");
writer.WriteBoolean(true);
writer.WriteString(privateKey.Format);
privateKey.AppendPublicKey(ref writer);
{
/*
* string session identifier
* byte SSH_MSG_USERAUTH_REQUEST
* string user name
* string service name
* string "publickey"
* boolean TRUE
* string public key algorithm name
* string public key to be used for authentication
*/
using var signatureData = sequencePool.RentSequence();
var signatureWriter = new SequenceWriter(signatureData);
signatureWriter.WriteString(sessionId);
signatureWriter.WriteByte(MessageNumber.SSH_MSG_USERAUTH_REQUEST);
signatureWriter.WriteString(userName);
signatureWriter.WriteString("ssh-connection");
signatureWriter.WriteString("publickey");
signatureWriter.WriteBoolean(true);
signatureWriter.WriteString(privateKey.Format);
privateKey.AppendPublicKey(ref signatureWriter);
privateKey.AppendSignature(ref writer, signatureData.AsReadOnlySequence());
}
return(packet.Move());
}
public bool TryDecodePacket(Sequence receiveBuffer, int maxLength, out Packet packet)
{
// Binary Packet Protocol: https://tools.ietf.org/html/rfc4253#section-6.
/*
* uint32 packet_length
* byte padding_length
* byte[n1] payload; n1 = packet_length - padding_length - 1
* byte[n2] random padding; n2 = padding_length
* byte[m] mac (Message Authentication Code - MAC); m = mac_length
*/
if (_decodedPacket == null)
{
_decodedPacket = _sequencePool.RentSequence();
}
// We can't decode past the packet, because the mac is not encrypted.
// We need to know the packet length to know how much we can decrypt.
while (_decodedPacket.Length < 4 && receiveBuffer.Length >= _decode.BlockSize)
{
_decode.Transform(receiveBuffer.AsReadOnlySequence().Slice(0, _decode.BlockSize), _decodedPacket);
receiveBuffer.Remove(_decode.BlockSize);
}
var decodedReader = new SequenceReader(_decodedPacket);
if (decodedReader.Length >= 4)
{
// Read the packet length.
uint packet_length = decodedReader.ReadUInt32();
if (packet_length > maxLength)
{
ThrowHelper.ThrowProtocolPacketTooLong();
}
// Decode the entire packet.
uint concatenated_length = 4 + packet_length;
// TODO: verify contatenated_length is a multiple of the cipher block size or 8, whichever is larger.
long remaining = concatenated_length - decodedReader.Length;
if (remaining > 0 && receiveBuffer.Length >= remaining)
{
_decode.Transform(receiveBuffer.AsReadOnlySequence().Slice(0, remaining), _decodedPacket);
receiveBuffer.Remove(remaining);
remaining = 0;
}
if (remaining == 0)
{
if (_decodedPacket.Length != concatenated_length)
{
ThrowHelper.ThrowInvalidOperation("Complete packet expected.");
}
// TODO: verify mac
receiveBuffer.Remove(_mac.HashSize);
packet = new Packet(_decodedPacket);
_decodedPacket = null;
return(true);
}
}
packet = new Packet(null);
return(false);
}
public static Packet RentPacket(this SequencePool sequencePool)
{
Sequence sequence = sequencePool.RentSequence();
return(new Packet(sequence));
}
