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// 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
}
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