Feature(restapi): add netstats

restapi/errors.go

@@ -1,8 +1,9 @@
 package restapi
 
 var (
-	ErrUnauthorized = newError("Unauthorized")
-	ErrBadRequest   = newError("Body invalid")
+	ErrBadRequest    = newError("Body invalid")
+	ErrUnauthorized  = newError("Unauthorized")
+	ErrUninitialized = newError("Uninitialized")
 )
 
 var _ error = (*HTTPError)(nil)

restapi/netstats.go

@@ -1,4 +1,84 @@
 package restapi
 
-// TODO: Network statistic support.
-func init() {}
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"reflect"
+	"time"
+
+	"github.com/go-chi/render"
+	"github.com/gorilla/websocket"
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+var _statsFunc func() tcpip.Stats
+
+func SetStatsFunc(s func() tcpip.Stats) {
+	_statsFunc = s
+}
+
+func getNetStats(w http.ResponseWriter, r *http.Request) {
+	if _statsFunc == nil {
+		render.Status(r, http.StatusInternalServerError)
+		render.JSON(w, r, ErrUninitialized)
+		return
+	}
+
+	snapshot := func() any {
+		s := _statsFunc()
+		return dump(reflect.ValueOf(&s).Elem())
+	}
+
+	if !websocket.IsWebSocketUpgrade(r) {
+		render.JSON(w, r, snapshot())
+		return
+	}
+
+	conn, err := _upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		return
+	}
+
+	tick := time.NewTicker(time.Second)
+	defer tick.Stop()
+
+	buf := &bytes.Buffer{}
+	for range tick.C {
+		buf.Reset()
+
+		if err = json.NewEncoder(buf).Encode(snapshot()); err != nil {
+			break
+		}
+
+		if err = conn.WriteMessage(websocket.TextMessage, buf.Bytes()); err != nil {
+			break
+		}
+	}
+}
+
+func dump(value reflect.Value) map[string]any {
+	numField := value.NumField()
+	structure := make(map[string]any, numField)
+
+	for i := 0; i < numField; i++ {
+		field := value.Type().Field(i)
+		value := value.Field(i)
+
+		switch v := value.Addr().Interface().(type) {
+		case **tcpip.StatCounter:
+			structure[field.Name] = (*v).Value()
+		case **tcpip.IntegralStatCounterMap:
+			counterMap := make(map[uint64]uint64)
+			for _, k := range (*v).Keys() {
+				if counter, ok := (*v).Get(k); ok {
+					counterMap[k] = counter.Value()
+				}
+			}
+			structure[field.Name] = counterMap
+		default:
+			structure[field.Name] = dump(value)
+		}
+	}
+	return structure
+}

restapi/server.go

@@ -43,6 +43,7 @@ func Start(addr, token string) error {
 		r.Get("/logs", getLogs)
 		r.Get("/traffic", traffic)
 		r.Get("/version", version)
+		r.Get("/netstats", getNetStats)
 		r.Mount("/connections", connectionRouter())
 	})