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hamakaze/Hamakaze/WebSocket/WsConnection.cs

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using System;
using System.IO;
using System.Net.Security;
using System.Security.Cryptography;
using System.Text;
namespace Hamakaze.WebSocket {
public class WsConnection : IDisposable {
public Stream Stream { get; }
public bool IsSecure { get; }
public bool IsClosed { get; private set; }
private const byte MASK_FLAG = 0x80;
private const int MASK_SIZE = 4;
private WsOpcode FragmentType = 0;
private MemoryStream FragmentStream;
private WsBufferedSend BufferedSend;
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public WsConnection(Stream stream) {
Stream = stream ?? throw new ArgumentNullException(nameof(stream));
IsSecure = stream is SslStream;
}
private static byte[] GenerateMask() {
return RandomNumberGenerator.GetBytes(MASK_SIZE);
}
private void StrictRead(byte[] buffer, int offset, int length) {
int read = Stream.Read(buffer, offset, length);
if(read < length)
throw new Exception(@"Was unable to read the requested amount of data.");
}
private (WsOpcode opcode, int length, bool isFinal, byte[] mask) ReadFrameHeader() {
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byte[] buffer = new byte[8];
StrictRead(buffer, 0, 2);
WsOpcode opcode = (WsOpcode)(buffer[0] & 0x0F);
bool isFinal = (buffer[0] & (byte)WsOpcode.FlagFinal) > 0;
if(opcode >= WsOpcode.CtrlClose && !isFinal)
throw new WsInvalidOpcodeException((WsOpcode)buffer[0]);
bool isControl = (opcode & WsOpcode.CtrlClose) > 0;
if(isControl && !isFinal)
throw new WsInvalidControlFrameException(@"fragmented");
bool isMasked = (buffer[1] & MASK_FLAG) > 0;
// this may look stupid and you'd be correct but it's better than the stack of casts
// i'd otherwise have to do otherwise because c# converts everything back to int32
buffer[1] &= 0x7F;
long length = buffer[1];
if(length == 126) {
StrictRead(buffer, 0, 2);
length = WsUtils.ToU16(buffer);
} else if(length == 127) {
StrictRead(buffer, 0, 8);
length = WsUtils.ToI64(buffer);
}
if(isControl && length > 125)
throw new WsInvalidControlFrameException(@"too large");
// should there be a sanity check on the length of frames?
// i seriously don't understand the rationale behind both
// having a framing system but then also supporting frame lengths
// of 2^63, feels like 2^16 per frame would be a fine max.
// UPDATE: decided to put the max at 2^32-1
// it's still more than you should ever need for a single frame
// and it makes working with the number within a .NET context
// less of a bother.
if(length < 0 || length > int.MaxValue)
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throw new WsInvalidFrameSizeException(length);
byte[] mask = null;
if(isMasked) {
StrictRead(buffer, 0, MASK_SIZE);
mask = buffer;
}
return (opcode, (int)length, isFinal, mask);
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}
private int ReadFrameBody(byte[] target, int length, byte[] mask, int offset = 0) {
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if(target == null)
throw new ArgumentNullException(nameof(target));
bool isMasked = mask != null;
int read;
const int bufferSize = 0x1000;
int take = length > bufferSize ? bufferSize : (int)length;
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while(length > 0) {
read = Stream.Read(target, offset, take);
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if(isMasked)
for(int i = 0; i < read; ++i) {
int o = offset + i;
target[o] ^= mask[o % MASK_SIZE];
}
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length -= read;
offset += read;
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if(take > length)
take = (int)length;
}
return offset;
}
private WsMessage ReadFrame() {
(WsOpcode opcode, int length, bool isFinal, byte[] mask) = ReadFrameHeader();
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if(opcode is not WsOpcode.DataContinue
and not WsOpcode.DataBinary
and not WsOpcode.DataText
and not WsOpcode.CtrlClose
and not WsOpcode.CtrlPing
and not WsOpcode.CtrlPong)
throw new WsUnsupportedOpcodeException(opcode);
bool hasBody = length > 0;
bool isContinue = opcode == WsOpcode.DataContinue;
bool canFragment = (opcode & WsOpcode.CtrlClose) == 0;
byte[] body = length < 1 ? null : new byte[length];
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if(hasBody) {
ReadFrameBody(body, length, mask);
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if(canFragment) {
if(isContinue) {
if(FragmentType == 0)
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throw new WsUnexpectedContinueException();
opcode = FragmentType;
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FragmentStream ??= new();
FragmentStream.Write(body, 0, length);
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} else {
if(FragmentType != 0)
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throw new WsUnexpectedDataException();
if(!isFinal) {
FragmentType = opcode;
FragmentStream = new();
FragmentStream.Write(body, 0, length);
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}
}
}
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}
WsMessage msg;
if(isFinal) {
if(canFragment && isContinue) {
FragmentType = 0;
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body = FragmentStream.ToArray();
FragmentStream.Dispose();
FragmentStream = null;
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}
msg = opcode switch {
WsOpcode.DataText => new WsTextMessage(body),
WsOpcode.DataBinary => new WsBinaryMessage(body),
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WsOpcode.CtrlClose => new WsCloseMessage(body),
WsOpcode.CtrlPing => new WsPingMessage(body),
WsOpcode.CtrlPong => new WsPongMessage(body),
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// fallback, if we end up here something is very fucked
_ => throw new WsUnsupportedOpcodeException(opcode),
};
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} else msg = null;
return msg;
}
public WsMessage Receive() {
WsMessage msg;
while((msg = ReadFrame()) == null);
return msg;
}
private void WriteFrameHeader(WsOpcode opcode, int length, bool isFinal, byte[] mask = null) {
if(length < 0 || length > int.MaxValue)
throw new WsInvalidFrameSizeException(length);
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bool shouldMask = mask != null;
if(isFinal)
opcode |= WsOpcode.FlagFinal;
Stream.WriteByte((byte)opcode);
byte bLen1 = 0;
if(shouldMask)
bLen1 |= MASK_FLAG;
byte[] bLenBuff = WsUtils.FromI64(length);
if(length < 126) {
Stream.WriteByte((byte)(bLen1 | bLenBuff[7]));
} else if(length <= ushort.MaxValue) {
Stream.WriteByte((byte)(bLen1 | 126));
Stream.Write(bLenBuff, 6, 2);
} else {
Stream.WriteByte((byte)(bLen1 | 127));
Stream.Write(bLenBuff, 0, 8);
}
if(shouldMask)
Stream.Write(mask, 0, MASK_SIZE);
Stream.Flush();
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}
private int WriteFrameBody(ReadOnlySpan<byte> body, byte[] mask = null, int offset = 0) {
if(body == null)
throw new ArgumentNullException(nameof(body));
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if(mask != null) {
byte[] masked = new byte[body.Length];
for(int i = 0; i < body.Length; ++i)
masked[i] = (byte)(body[i] ^ mask[offset++ % MASK_SIZE]);
body = masked;
}
Stream.Write(body);
Stream.Flush();
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return offset;
}
internal void WriteFrame(WsOpcode opcode, ReadOnlySpan<byte> body, bool isFinal) {
if(body == null)
throw new ArgumentNullException(nameof(body));
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byte[] mask = GenerateMask();
WriteFrameHeader(opcode, body.Length, isFinal, mask);
if(body.Length > 0)
WriteFrameBody(body, mask);
}
private void WriteData(WsOpcode opcode, ReadOnlySpan<byte> body) {
if(body == null)
throw new ArgumentNullException(nameof(body));
if(BufferedSend != null)
throw new WsBufferedSendInSessionException();
if(body.Length > ushort.MaxValue) {
WriteFrame(opcode, body.Slice(0, ushort.MaxValue), false);
body = body.Slice(ushort.MaxValue);
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while(body.Length > ushort.MaxValue) {
WriteFrame(WsOpcode.DataContinue, body.Slice(0, ushort.MaxValue), false);
body = body.Slice(ushort.MaxValue);
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}
WriteFrame(WsOpcode.DataContinue, body, true);
} else
WriteFrame(opcode, body, true);
}
public void Send(string text)
=> WriteData(WsOpcode.DataText, Encoding.UTF8.GetBytes(text));
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public void Send(ReadOnlySpan<byte> buffer)
=> WriteData(WsOpcode.DataBinary, buffer);
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public WsBufferedSend BeginBufferedSend() {
if(BufferedSend != null)
throw new WsBufferedSendAlreadyActiveException();
return BufferedSend = new(this);
}
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// this method should only be called from within WsBufferedSend.Dispose
internal void EndBufferedSend() {
BufferedSend = null;
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}
private void WriteControl(WsOpcode opcode)
=> WriteFrameHeader(opcode, 0, true, GenerateMask());
private void WriteControl(WsOpcode opcode, ReadOnlySpan<byte> buffer) {
if(buffer == null)
throw new ArgumentNullException(nameof(buffer));
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if(buffer.Length > 125)
throw new ArgumentException(@"Data may not be more than 125 bytes.", nameof(buffer));
byte[] mask = GenerateMask();
WriteFrameHeader(opcode, buffer.Length, true, mask);
WriteFrameBody(buffer, mask);
}
public void Ping()
=> WriteControl(WsOpcode.CtrlPing);
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public void Ping(ReadOnlySpan<byte> buffer)
=> WriteControl(WsOpcode.CtrlPing, buffer);
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public void Pong()
=> WriteControl(WsOpcode.CtrlPong);
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public void Pong(ReadOnlySpan<byte> buffer)
=> WriteControl(WsOpcode.CtrlPong, buffer);
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public void CloseEmpty() {
if(IsClosed)
return;
IsClosed = true;
WriteControl(WsOpcode.CtrlClose);
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}
public void Close(ReadOnlySpan<byte> buffer) {
if(buffer == null)
throw new ArgumentNullException(nameof(buffer));
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if(IsClosed)
return;
IsClosed = true;
WriteControl(WsOpcode.CtrlClose, buffer);
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}
public void Close(WsCloseReason code)
=> Close(WsUtils.FromU16((ushort)code));
public void Close(WsCloseReason code, ReadOnlySpan<byte> reason) {
if(reason == null)
throw new ArgumentNullException(nameof(reason));
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if(reason.Length > 123)
throw new ArgumentException(@"Reason may not be more than 123 bytes.", nameof(reason));
if(IsClosed)
return;
IsClosed = true;
byte[] mask = GenerateMask();
WriteFrameHeader(WsOpcode.CtrlClose, 2 + reason.Length, true, mask);
WriteFrameBody(WsUtils.FromU16((ushort)code), mask);
WriteFrameBody(reason, mask, 2);
}
public void Close(WsCloseReason code, string reason) {
if(reason == null)
throw new ArgumentNullException(nameof(reason));
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int length = Encoding.UTF8.GetByteCount(reason);
if(length > 123)
throw new ArgumentException(@"Reason string may not exceed 123 bytes in length.", nameof(reason));
if(IsClosed)
return;
IsClosed = true;
byte[] mask = GenerateMask();
WriteFrameHeader(WsOpcode.CtrlClose, 2 + reason.Length, true, mask);
WriteFrameBody(WsUtils.FromU16((ushort)code), mask);
WriteFrameBody(Encoding.UTF8.GetBytes(reason), mask, 2);
}
private bool IsDisposed;
~WsConnection() {
DoDispose();
}
public void Dispose() {
DoDispose();
GC.SuppressFinalize(this);
}
private void DoDispose() {
if(IsDisposed)
return;
IsDisposed = true;
BufferedSend?.Dispose();
FragmentStream?.Dispose();
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Stream.Dispose();
}
}
}