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