send proper max stream ID in graceful goaway (#254)

src/frame/stream_id.rs

@@ -14,8 +14,6 @@ impl StreamId {
 
     pub const MAX: StreamId = StreamId(u32::MAX >> 1);
 
-    pub const MAX_CLIENT: StreamId = StreamId((u32::MAX >> 1) - 1);
-
     /// Parse the stream ID
     #[inline]
     pub fn parse(buf: &[u8]) -> (StreamId, bool) {

src/proto/connection.rs

@@ -383,14 +383,14 @@ where
         //
         // > A server that is attempting to gracefully shut down a connection
         // > SHOULD send an initial GOAWAY frame with the last stream
-        // > identifier set to 231-1 and a NO_ERROR code. This signals to the
+        // > identifier set to 2^31-1 and a NO_ERROR code. This signals to the
         // > client that a shutdown is imminent and that initiating further
         // > requests is prohibited. After allowing time for any in-flight
         // > stream creation (at least one round-trip time), the server can
         // > send another GOAWAY frame with an updated last stream identifier.
         // > This ensures that a connection can be cleanly shut down without
         // > losing requests.
-        self.go_away(StreamId::MAX_CLIENT, Reason::NO_ERROR);
+        self.go_away(StreamId::MAX, Reason::NO_ERROR);
 
         // We take the advice of waiting 1 RTT literally, and wait
         // for a pong before proceeding.

src/proto/go_away.rs

@@ -103,7 +103,7 @@ impl GoAway {
     pub fn should_close_on_idle(&self) -> bool {
         !self.close_now && self.going_away
             .as_ref()
-            .map(|g| g.last_processed_id != StreamId::MAX_CLIENT)
+            .map(|g| g.last_processed_id != StreamId::MAX)
             .unwrap_or(false)
     }
 

tests/server.rs

@@ -245,7 +245,10 @@ fn graceful_shutdown() {
                 .request("GET", "https://example.com/")
                 .eos(),
         )
-        .recv_frame(frames::go_away(StreamId::MAX_CLIENT))
+        // 2^31 - 1 = 2147483647
+        // Note: not using a constant in the library because library devs
+        // can be unsmart.
+        .recv_frame(frames::go_away(2147483647))
         .recv_frame(frames::ping(frame::Ping::SHUTDOWN))
         .recv_frame(frames::headers(1).response(200).eos())
         // Pretend this stream was sent while the GOAWAY was in flight