Add nounce processing to HTTP/2 WebSockets for HTTP/1 proxy compatibi…

…lity.

lib/async/websocket/connect_response.rb

@@ -19,6 +19,11 @@ def initialize(request, headers = nil, protocol: nil, &block)
 					headers.add(SEC_WEBSOCKET_PROTOCOL, protocol)
 				end
 
+				# For compatibility with HTTP/1 websockets proxied over HTTP/2, we process the accept nounce here:
+				if accept_nounce = request.headers[SEC_WEBSOCKET_KEY]&.first
+					headers.add(SEC_WEBSOCKET_ACCEPT, Nounce.accept_digest(accept_nounce))
+				end
+
 				body = Async::HTTP::Body::Hijack.wrap(request, &block)
 
 				super(request.version, 200, headers, body)

lib/async/websocket/upgrade_request.rb

@@ -81,6 +81,7 @@ def call(connection)
 						raise ProtocolError, "Invalid accept digest, expected #{expected_accept_digest.inspect}, got #{accept_digest.inspect}!"
 					end
 				end
+
 				verified = accept_digest && Array(response.protocol).map(&:downcase) == %w(websocket) && response.headers['connection']&.include?('upgrade')
 
 				return Wrapper.new(response, verified: verified)