/// <summary>
/// <para>
/// Handle the web socket handshake for the web socket specification <a href=
/// "http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00">HyBi version 0</a> and lower. This standard
/// is really a rehash of <a href="http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76" >hixie-76</a> and
/// <a href="http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75" >hixie-75</a>.
/// </para>
///
/// <para>
/// Browser request to the server:
/// </para>
///
/// <![CDATA[
/// GET /demo HTTP/1.1
/// Upgrade: WebSocket
/// Connection: Upgrade
/// Host: example.com
/// Origin: http://example.com
/// Sec-WebSocket-Protocol: chat, sample
/// Sec-WebSocket-Key1: 4 @1 46546xW%0l 1 5
/// Sec-WebSocket-Key2: 12998 5 Y3 1 .P00
///
/// ^n:ds[4U
/// ]]>
///
/// <para>
/// Server response:
/// </para>
///
/// <![CDATA[
/// HTTP/1.1 101 WebSocket Protocol Handshake
/// Upgrade: WebSocket
/// Connection: Upgrade
/// Sec-WebSocket-Origin: http://example.com
/// Sec-WebSocket-Location: ws://example.com/demo
/// Sec-WebSocket-Protocol: sample
///
/// 8jKS'y:G*Co,Wxa-
/// ]]>
/// </summary>
/// <param name="req"></param>
/// <param name="headers"></param>
/// <returns></returns>
protected internal override IFullHttpResponse NewHandshakeResponse(IFullHttpRequest req, HttpHeaders headers)
{
// Serve the WebSocket handshake request.
if (!req.Headers.ContainsValue(HttpHeaderNames.Connection, HttpHeaderValues.Upgrade, true) ||
!req.Headers.TryGet(HttpHeaderNames.Upgrade, out ICharSequence value) ||
!HttpHeaderValues.Websocket.ContentEqualsIgnoreCase(value))
{
ThrowHelper.ThrowWebSocketHandshakeException_MissingUpgrade();
}
// Hixie 75 does not contain these headers while Hixie 76 does
bool isHixie76 = req.Headers.Contains(HttpHeaderNames.SecWebsocketKey1) &&
req.Headers.Contains(HttpHeaderNames.SecWebsocketKey2);
var origin = req.Headers.Get(HttpHeaderNames.Origin, null);
//throw before allocating FullHttpResponse
if (origin is null && !isHixie76)
{
ThrowHelper.ThrowWebSocketHandshakeException_Missing_origin_header(req);
}
// Create the WebSocket handshake response.
var res = new DefaultFullHttpResponse(HttpVersion.Http11, new HttpResponseStatus(101,
new AsciiString(isHixie76 ? "WebSocket Protocol Handshake" : "Web Socket Protocol Handshake")),
req.Content.Allocator.Buffer(0));
if (headers is object)
{
_ = res.Headers.Add(headers);
}
_ = res.Headers.Set(HttpHeaderNames.Upgrade, HttpHeaderValues.Websocket)
.Set(HttpHeaderNames.Connection, HttpHeaderValues.Upgrade);
// Fill in the headers and contents depending on handshake getMethod.
if (isHixie76)
{
// New handshake getMethod with a challenge:
_ = res.Headers.Add(HttpHeaderNames.SecWebsocketOrigin, origin);
_ = res.Headers.Add(HttpHeaderNames.SecWebsocketLocation, this.Uri);
if (req.Headers.TryGet(HttpHeaderNames.SecWebsocketProtocol, out ICharSequence subprotocols))
{
string selectedSubprotocol = this.SelectSubprotocol(subprotocols.ToString());
if (selectedSubprotocol is null)
{
#if DEBUG
if (Logger.DebugEnabled)
{
Logger.RequestedSubprotocolNotSupported(subprotocols);
}
#endif
}
else
{
_ = res.Headers.Add(HttpHeaderNames.SecWebsocketProtocol, selectedSubprotocol);
}
}
// Calculate the answer of the challenge.
value = req.Headers.Get(HttpHeaderNames.SecWebsocketKey1, null);
Debug.Assert(value is object, $"{HttpHeaderNames.SecWebsocketKey1} must exist");
string key1 = value.ToString();
value = req.Headers.Get(HttpHeaderNames.SecWebsocketKey2, null);
Debug.Assert(value is object, $"{HttpHeaderNames.SecWebsocketKey2} must exist");
string key2 = value.ToString();
int a = (int)(long.Parse(BeginningDigit.Replace(key1, "")) /
BeginningSpace.Replace(key1, "").Length);
int b = (int)(long.Parse(BeginningDigit.Replace(key2, "")) /
BeginningSpace.Replace(key2, "").Length);
long c = req.Content.ReadLong();
IByteBuffer input = Unpooled.WrappedBuffer(new byte[16]).SetIndex(0, 0);
_ = input.WriteInt(a);
_ = input.WriteInt(b);
_ = input.WriteLong(c);
_ = res.Content.WriteBytes(WebSocketUtil.Md5(input.Array));
}
else
{
// Old Hixie 75 handshake getMethod with no challenge:
_ = res.Headers.Add(HttpHeaderNames.WebsocketOrigin, origin);
_ = res.Headers.Add(HttpHeaderNames.WebsocketLocation, this.Uri);
if (req.Headers.TryGet(HttpHeaderNames.WebsocketProtocol, out ICharSequence protocol))
{
_ = res.Headers.Add(HttpHeaderNames.WebsocketProtocol, this.SelectSubprotocol(protocol.ToString()));
}
}
return(res);
}
