Move network internal code to internal package

Utilities written to be common across IPv4/IPv6 are not planned to be
available for public use.

https://golang.org/doc/go1.4#internalpackages

PiperOrigin-RevId: 356554862

3 files changed, 246 insertions, 0 deletions

diff --git a/pkg/tcpip/network/internal/testutil/BUILD b/pkg/tcpip/network/internal/testutil/BUILD
new file mode 100644
index 000000000..1c4f583c7
--- /dev/null
+++ b/pkg/tcpip/network/internal/testutil/BUILD
@@ -0,0 +1,23 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "testutil",
+    srcs = [
+        "testutil.go",
+        "testutil_unsafe.go",
+    ],
+    visibility = [
+        "//pkg/tcpip/network/arp:__pkg__",
+        "//pkg/tcpip/network/internal/fragmentation:__pkg__",
+        "//pkg/tcpip/network/ipv4:__pkg__",
+        "//pkg/tcpip/network/ipv6:__pkg__",
+    ],
+    deps = [
+        "//pkg/tcpip",
+        "//pkg/tcpip/buffer",
+        "//pkg/tcpip/header",
+        "//pkg/tcpip/stack",
+    ],
+)
diff --git a/pkg/tcpip/network/internal/testutil/testutil.go b/pkg/tcpip/network/internal/testutil/testutil.go
new file mode 100644
index 000000000..f5fa77b65
--- /dev/null
+++ b/pkg/tcpip/network/internal/testutil/testutil.go
@@ -0,0 +1,197 @@
+// 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 defines types and functions used to test Network Layer
+// functionality such as IP fragmentation.
+package testutil
+
+import (
+	"fmt"
+	"math/rand"
+	"reflect"
+	"strings"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+// MockLinkEndpoint is an endpoint used for testing, it stores packets written
+// to it and can mock errors.
+type MockLinkEndpoint struct {
+	// WrittenPackets is where packets written to the endpoint are stored.
+	WrittenPackets []*stack.PacketBuffer
+
+	mtu          uint32
+	err          tcpip.Error
+	allowPackets int
+}
+
+// NewMockLinkEndpoint creates a new MockLinkEndpoint.
+//
+// err is the error that will be returned once allowPackets packets are written
+// to the endpoint.
+func NewMockLinkEndpoint(mtu uint32, err tcpip.Error, allowPackets int) *MockLinkEndpoint {
+	return &MockLinkEndpoint{
+		mtu:          mtu,
+		err:          err,
+		allowPackets: allowPackets,
+	}
+}
+
+// MTU implements LinkEndpoint.MTU.
+func (ep *MockLinkEndpoint) MTU() uint32 { return ep.mtu }
+
+// Capabilities implements LinkEndpoint.Capabilities.
+func (*MockLinkEndpoint) Capabilities() stack.LinkEndpointCapabilities { return 0 }
+
+// MaxHeaderLength implements LinkEndpoint.MaxHeaderLength.
+func (*MockLinkEndpoint) MaxHeaderLength() uint16 { return 0 }
+
+// LinkAddress implements LinkEndpoint.LinkAddress.
+func (*MockLinkEndpoint) LinkAddress() tcpip.LinkAddress { return "" }
+
+// WritePacket implements LinkEndpoint.WritePacket.
+func (ep *MockLinkEndpoint) WritePacket(_ stack.RouteInfo, _ *stack.GSO, _ tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
+	if ep.allowPackets == 0 {
+		return ep.err
+	}
+	ep.allowPackets--
+	ep.WrittenPackets = append(ep.WrittenPackets, pkt)
+	return nil
+}
+
+// WritePackets implements LinkEndpoint.WritePackets.
+func (ep *MockLinkEndpoint) WritePackets(r stack.RouteInfo, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
+	var n int
+
+	for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
+		if err := ep.WritePacket(r, gso, protocol, pkt); err != nil {
+			return n, err
+		}
+		n++
+	}
+
+	return n, nil
+}
+
+// Attach implements LinkEndpoint.Attach.
+func (*MockLinkEndpoint) Attach(stack.NetworkDispatcher) {}
+
+// IsAttached implements LinkEndpoint.IsAttached.
+func (*MockLinkEndpoint) IsAttached() bool { return false }
+
+// Wait implements LinkEndpoint.Wait.
+func (*MockLinkEndpoint) Wait() {}
+
+// ARPHardwareType implements LinkEndpoint.ARPHardwareType.
+func (*MockLinkEndpoint) ARPHardwareType() header.ARPHardwareType { return header.ARPHardwareNone }
+
+// AddHeader implements LinkEndpoint.AddHeader.
+func (*MockLinkEndpoint) AddHeader(_, _ tcpip.LinkAddress, _ tcpip.NetworkProtocolNumber, _ *stack.PacketBuffer) {
+}
+
+// MakeRandPkt generates a randomized packet. transportHeaderLength indicates
+// how many random bytes will be copied in the Transport Header.
+// extraHeaderReserveLength indicates how much extra space will be reserved for
+// the other headers. The payload is made from Views of the sizes listed in
+// viewSizes.
+func MakeRandPkt(transportHeaderLength int, extraHeaderReserveLength int, viewSizes []int, proto tcpip.NetworkProtocolNumber) *stack.PacketBuffer {
+	var views buffer.VectorisedView
+
+	for _, s := range viewSizes {
+		newView := buffer.NewView(s)
+		if _, err := rand.Read(newView); err != nil {
+			panic(fmt.Sprintf("rand.Read: %s", err))
+		}
+		views.AppendView(newView)
+	}
+
+	pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
+		ReserveHeaderBytes: transportHeaderLength + extraHeaderReserveLength,
+		Data:               views,
+	})
+	pkt.NetworkProtocolNumber = proto
+	if _, err := rand.Read(pkt.TransportHeader().Push(transportHeaderLength)); err != nil {
+		panic(fmt.Sprintf("rand.Read: %s", err))
+	}
+	return pkt
+}
+
+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/network/internal/testutil/testutil_unsafe.go b/pkg/tcpip/network/internal/testutil/testutil_unsafe.go
new file mode 100644
index 000000000..5ff764800
--- /dev/null
+++ b/pkg/tcpip/network/internal/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()
+}