Adding WebTransport Handshake to Kestrel (#41877)

Author: Daniel-Genkin-MS-2

src/Http/Headers/src/HeaderNames.cs

@@ -189,6 +189,9 @@ public static class HeaderNames
     /// <summary>Gets the <c>Pragma</c> HTTP header name.</summary>
     public static readonly string Pragma = "Pragma";
 
+    /// <summary>Gets the <c>Protocol</c> HTTP header name.</summary>
+    public static readonly string Protocol = ":protocol";
+
     /// <summary>Gets the <c>Proxy-Authenticate</c> HTTP header name.</summary>
     public static readonly string ProxyAuthenticate = "Proxy-Authenticate";
 

src/Http/Headers/src/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+static readonly Microsoft.Net.Http.Headers.HeaderNames.Protocol -> string!

src/Servers/Kestrel/Core/src/CoreStrings.resx

@@ -668,4 +668,13 @@ For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?l
   <data name="Http3ControlStreamErrorInitializingOutbound" xml:space="preserve">
     <value>Error initializing outbound control stream.</value>
   </data>
-</root>
+  <data name="Http3DatagramStatusMismatch" xml:space="preserve">
+    <value>HTTP/3 datagrams negotiation mismatch. Currently client has it '{clientStatus}' and server has it '{serverStatus}'</value>
+  </data>
+  <data name="Http3MethodMustBeConnectWhenUsingProtocolPseudoHeader" xml:space="preserve">
+    <value>Method must be CONNECT when using the :protocol pseudo-header.</value>
+  </data>
+  <data name="Http3MissingAuthorityOrPathPseudoHeaders" xml:space="preserve">
+    <value>The :authority and/or :path pseudo-headers are missing.</value>
+  </data>
+</root>