added parsing and handling of the alt-svc header/frame, and emitting it as a parser event

lib/httpx/channel/http1.rb

@@ -126,6 +126,20 @@ module HTTPX
         response << @parser.upgrade_data
         throw(:called)
       end
+
+      # Alt-Svc
+      if response.headers.key?("alt-svc")
+        origin = request.authority
+        alt_uri, *params = response.headers["alt-svc"].split(/ *; */)
+        alt_proto, alt_uri = alt_uri.split("=")
+        alt_uri = alt_uri[1..-2] if alt_uri.start_with?("\"") && alt_uri.end_with?("\"")
+        alt_uri = URI.parse("#{alt_proto}://#{alt_uri}")
+        alt_uri.host ||= request.authority
+        params = Hash[params.split(/ *, */).map { |field| field.split("=") }]
+        log(level: 1) { "#{origin} alt-svc: #{alt_uri}" }
+        emit(:alternative_service, alt_uri, origin, params)
+      end
+
       reset
       send(@pending.shift) unless @pending.empty?
       return unless response.headers["connection"] == "close"

lib/httpx/channel/http2.rb

@@ -105,7 +105,7 @@ module HTTPX
       stream.on(:half_close) do
         log(level: 2, label: "#{stream.id}: ") { "waiting for response..." }
       end
-      # stream.on(:altsvc)
+      stream.on(:altsvc, &method(:on_altsvc).curry[request.authority])
       stream.on(:headers, &method(:on_stream_headers).curry[stream, request])
       stream.on(:data, &method(:on_stream_data).curry[stream, request])
     end
@@ -225,9 +225,17 @@ module HTTPX
       end
     end
 
-    def on_altsvc(frame)
+    def on_altsvc(origin, frame)
       log(level: 2, label: "#{frame[:stream]}: ") { "altsvc frame was received" }
       log(level: 2, label: "#{frame[:stream]}: ") { frame.inspect }
+      origin ||= frame[:origin]
+      alt_proto = frame[:proto]
+      alt_host = frame[:host]
+      alt_port = frame[:port]
+      alt_uri = URI.parse("#{alt_proto}://#{alt_host}:#{alt_port}")
+      log(level: 1, label: "#{frame[:stream]} ") { "#{origin} alt-svc: #{alt_uri}" }
+      params = { "ma" => frame[:max_age] }
+      emit(:alternate_service, alt_uri, origin, params)
     end
 
     def on_promise(stream)