Move multicounter testutil functions out of network/ip

This is in preparation of having aggregated NIC stats at the stack
level. These validation functions will be needed outside of the
network layer packages to test aggregated NIC stats.

PiperOrigin-RevId: 373180565

3 files changed, 98 insertions, 1 deletions

diff --git a/pkg/tcpip/testutil/BUILD b/pkg/tcpip/testutil/BUILD
index 472545a5d..02ee86ff1 100644
--- a/pkg/tcpip/testutil/BUILD
+++ b/pkg/tcpip/testutil/BUILD
@@ -5,7 +5,10 @@ package(licenses = ["notice"])
 go_library(
     name = "testutil",
     testonly = True,
-    srcs = ["testutil.go"],
+    srcs = [
+        "testutil.go",
+        "testutil_unsafe.go",
+    ],
     visibility = ["//visibility:public"],
     deps = ["//pkg/tcpip"],
 )
diff --git a/pkg/tcpip/testutil/testutil.go b/pkg/tcpip/testutil/testutil.go
index 1aaed590f..f84d399fb 100644
--- a/pkg/tcpip/testutil/testutil.go
+++ b/pkg/tcpip/testutil/testutil.go
@@ -18,6 +18,8 @@ package testutil
 import (
 	"fmt"
 	"net"
+	"reflect"
+	"strings"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 )
@@ -41,3 +43,69 @@ func MustParse6(addr string) tcpip.Address {
 	}
 	return tcpip.Address(ip)
 }
+
+func checkFieldCounts(ref, multi reflect.Value) error {
+	refTypeName := ref.Type().Name()
+	multiTypeName := multi.Type().Name()
+	refNumField := ref.NumField()
+	multiNumField := multi.NumField()
+
+	if refNumField != multiNumField {
+		return fmt.Errorf("type %s has an incorrect number of fields: got = %d, want = %d (same as type %s)", multiTypeName, multiNumField, refNumField, refTypeName)
+	}
+
+	return nil
+}
+
+func validateField(ref reflect.Value, refName string, m tcpip.MultiCounterStat, multiName string) error {
+	s, ok := ref.Addr().Interface().(**tcpip.StatCounter)
+	if !ok {
+		return fmt.Errorf("expected ref type's to be *StatCounter, but its type is %s", ref.Type().Elem().Name())
+	}
+
+	// The field names are expected to match (case insensitive).
+	if !strings.EqualFold(refName, multiName) {
+		return fmt.Errorf("wrong field name: got = %s, want = %s", multiName, refName)
+	}
+
+	base := (*s).Value()
+	m.Increment()
+	if (*s).Value() != base+1 {
+		return fmt.Errorf("updates to the '%s MultiCounterStat' counters are not reflected in the '%s CounterStat'", multiName, refName)
+	}
+
+	return nil
+}
+
+// ValidateMultiCounterStats verifies that every counter stored in multi is
+// correctly tracking its counterpart in the given counters.
+func ValidateMultiCounterStats(multi reflect.Value, counters []reflect.Value) error {
+	for _, c := range counters {
+		if err := checkFieldCounts(c, multi); err != nil {
+			return err
+		}
+	}
+
+	for i := 0; i < multi.NumField(); i++ {
+		multiName := multi.Type().Field(i).Name
+		multiUnsafe := unsafeExposeUnexportedFields(multi.Field(i))
+
+		if m, ok := multiUnsafe.Addr().Interface().(*tcpip.MultiCounterStat); ok {
+			for _, c := range counters {
+				if err := validateField(unsafeExposeUnexportedFields(c.Field(i)), c.Type().Field(i).Name, *m, multiName); err != nil {
+					return err
+				}
+			}
+		} else {
+			var countersNextField []reflect.Value
+			for _, c := range counters {
+				countersNextField = append(countersNextField, c.Field(i))
+			}
+			if err := ValidateMultiCounterStats(multi.Field(i), countersNextField); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
diff --git a/pkg/tcpip/testutil/testutil_unsafe.go b/pkg/tcpip/testutil/testutil_unsafe.go
new file mode 100644
index 000000000..5ff764800
--- /dev/null
+++ b/pkg/tcpip/testutil/testutil_unsafe.go
@@ -0,0 +1,26 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// unsafeExposeUnexportedFields takes a Value and returns a version of it in
+// which even unexported fields can be read and written.
+func unsafeExposeUnexportedFields(a reflect.Value) reflect.Value {
+	return reflect.NewAt(a.Type(), unsafe.Pointer(a.UnsafeAddr())).Elem()
+}