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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"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/link/channel"
"gvisor.dev/gvisor/pkg/tcpip/stack"
)
// TestEndpoint is an endpoint used for testing, it stores packets written to it
// and can mock errors.
type TestEndpoint struct {
*channel.Endpoint
// WrittenPackets is where we store packets written via WritePacket().
WrittenPackets []*stack.PacketBuffer
packetCollectorErrors []*tcpip.Error
}
// NewTestEndpoint creates a new TestEndpoint endpoint.
//
// packetCollectorErrors can be used to set error values and each call to
// WritePacket will remove the first one from the slice and return it until
// the slice is empty - at that point it will return nil every time.
func NewTestEndpoint(ep *channel.Endpoint, packetCollectorErrors []*tcpip.Error) *TestEndpoint {
return &TestEndpoint{
Endpoint: ep,
WrittenPackets: make([]*stack.PacketBuffer, 0),
packetCollectorErrors: packetCollectorErrors,
}
}
// WritePacket stores outbound packets and may return an error if one was
// injected.
func (e *TestEndpoint) WritePacket(_ *stack.Route, _ *stack.GSO, _ tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
e.WrittenPackets = append(e.WrittenPackets, pkt)
if len(e.packetCollectorErrors) > 0 {
nextError := e.packetCollectorErrors[0]
e.packetCollectorErrors = e.packetCollectorErrors[1:]
return nextError
}
return nil
}
// 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
}
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