feat: observe HTTP2 reset and goaway frames

transport/http2/server.go

@@ -59,6 +59,8 @@ type Server struct {
 	rejectedReqs   atomic.Uint64
 	protocolErrors atomic.Uint64
 	goAwaySent     atomic.Uint64
+	rstStreams     atomic.Uint64
+	goAwayFrames   atomic.Uint64
 	activeConns    atomic.Int64
 	activeRequests atomic.Int64
 	wg             sync.WaitGroup
@@ -72,6 +74,8 @@ type Stats struct {
 	RejectedRequests    uint64 `json:"rejectedRequests"`
 	ProtocolErrors      uint64 `json:"protocolErrors"`
 	GoAwaySent          uint64 `json:"goAwaySent"`
+	RSTStreams          uint64 `json:"rstStreams"`
+	GoAwayFrames        uint64 `json:"goAwayFrames"`
 	ActiveConnections   int64  `json:"activeConnections"`
 	ActiveRequests      int64  `json:"activeRequests"`
 }
@@ -97,6 +101,8 @@ func (s *Server) Stats() Stats {
 		RejectedRequests:    s.rejectedReqs.Load(),
 		ProtocolErrors:      s.protocolErrors.Load(),
 		GoAwaySent:          s.goAwaySent.Load(),
+		RSTStreams:          s.rstStreams.Load(),
+		GoAwayFrames:        s.goAwayFrames.Load(),
 		ActiveConnections:   s.activeConns.Load(),
 		ActiveRequests:      s.activeRequests.Load(),
 	}
@@ -356,7 +362,23 @@ func (s *Server) serveConn(ctx context.Context, protocolServer *xhttp2.Server, b
 	}
 	s.protocolConns[conn] = struct{}{}
 	s.mu.Unlock()
-	protocolServer.ServeConn(conn, &xhttp2.ServeConnOpts{
+	observed := &observedConn{
+		Conn:       conn,
+		readParser: frameParser{prefaceRemain: 24},
+		onFrame: func(direction frameDirection, frameType byte) {
+			if direction == frameRead && frameType == frameTypeRSTStream {
+				s.rstStreams.Add(1)
+			}
+			if direction == frameWrite && frameType == frameTypeGoAway {
+				s.goAwayFrames.Add(1)
+			}
+		},
+	}
+	var protocolConn net.Conn = observed
+	if tlsConn, ok := conn.(*tls.Conn); ok {
+		protocolConn = &observedTLSConn{observedConn: observed, state: tlsConn.ConnectionState()}
+	}
+	protocolServer.ServeConn(protocolConn, &xhttp2.ServeConnOpts{
 		Context: ctx, Handler: handler, BaseConfig: baseConfig,
 	})
 }