handler_test.go

/*
Copyright (c) 2014 VMware, Inc. All Rights Reserved.

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 dhcpv4

import (
	"errors"
	"io"
	"net"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/mock"
)

type testPacketConn struct {
	mock.Mock
}

func (pc *testPacketConn) ReadFrom(b []byte) (n int, addr net.Addr, ifindex int, err error) {
	args := pc.Called(b)

	switch arg0 := args.Get(0).(type) {
	case []byte:
		copy(b, arg0)
		n = len(arg0)
	}

	switch arg1 := args.Get(1).(type) {
	case net.Addr:
		addr = arg1
	default:
		addr = &net.UDPAddr{IP: net.IPv4zero, Port: 67}
	}

	switch arg2 := args.Get(2).(type) {
	case int:
		ifindex = arg2
	}

	switch arg3 := args.Get(3).(type) {
	case error:
		err = arg3
	}

	return n, addr, ifindex, err
}

func (pc *testPacketConn) WriteTo(b []byte, addr net.Addr, ifindex int) (n int, err error) {
	args := pc.Called(b, addr, ifindex)
	return args.Int(0), args.Error(1)
}

func (pc *testPacketConn) Close() error {
	return nil
}

func (pc *testPacketConn) LocalAddr() net.Addr {
	return &net.IPAddr{IP: net.IPv4zero}
}

func (pc *testPacketConn) ReadError(err error) {
	pc.On("ReadFrom", mock.Anything).Return(nil, nil, -1, io.EOF).Once()
}

func (pc *testPacketConn) ReadSuccess(b []byte) {
	pc.On("ReadFrom", mock.Anything).Return(b, nil, -1, nil).Once()
}

type testReply struct {
	mock.Mock

	// Embed OptionMap so this struct implements the Reply interface.
	OptionMap
}

func (r *testReply) Validate() error {
	args := r.Called()
	return args.Error(0)
}

func (r *testReply) ToBytes() (b []byte, err error) {
	args := r.Called()

	switch arg0 := args.Get(0).(type) {
	case []byte:
		b = arg0
	}

	switch arg1 := args.Get(1).(type) {
	case error:
		err = arg1
	}

	return b, err
}

func (r *testReply) Request() Request {
	args := r.Called()
	return args.Get(0).(Packet)
}

func (r *testReply) SetCIAddr(ip net.IP) {}
func (r *testReply) SetYIAddr(ip net.IP) {}
func (r *testReply) SetSIAddr(ip net.IP) {}
func (r *testReply) SetGIAddr(ip net.IP) {}

func TestReplyWriterReturnsValidationError(t *testing.T) {
	validationError := errors.New("some validation error")

	r := testReply{}
	r.On("Validate").Return(validationError)

	rw := replyWriter{
		pw: &testPacketConn{},
	}

	err := rw.WriteReply(&r)
	assert.Equal(t, validationError, err)
}

func TestReplyWriterReturnsSerializationError(t *testing.T) {
	serializationError := errors.New("some serialization error")

	r := testReply{}
	r.On("Validate").Return(nil)
	r.On("ToBytes").Return(nil, serializationError)

	rw := replyWriter{
		pw: &testPacketConn{},
	}

	err := rw.WriteReply(&r)
	assert.Equal(t, serializationError, err)
}

func TestReplyWriterDestinationAddress(t *testing.T) {
	withBcast := NewPacket(BootRequest)
	withBcast.Flags()[0] |= 128 // Set MSB

	withoutBcast := NewPacket(BootRequest)
	withoutBcast.Flags()[0] &= 127 // Clear MSB

	zeroIP := net.IP{0, 0, 0, 0}
	someIP := net.IP{1, 2, 3, 4}

	testCases := []struct {
		req Packet
		src net.UDPAddr
		dst net.IP
	}{
		// Broadcast flag trumps everything
		{withBcast, net.UDPAddr{IP: zeroIP}, net.IPv4bcast},
		{withBcast, net.UDPAddr{IP: someIP}, net.IPv4bcast},

		// Without broadcast flag, only broadcast without a destination IP
		{withoutBcast, net.UDPAddr{IP: zeroIP}, net.IPv4bcast},
		{withoutBcast, net.UDPAddr{IP: someIP}, someIP},
	}

	for _, testCase := range testCases {
		r := testReply{}
		r.On("Validate").Return(nil)
		r.On("ToBytes").Return([]byte("xyz"), nil)
		r.On("Request").Return(testCase.req)

		pw := &testPacketConn{}
		pw.On("WriteTo", mock.Anything, mock.Anything, mock.Anything).Return(3, nil)

		rw := replyWriter{
			pw:   pw,
			addr: testCase.src,
		}

		err := rw.WriteReply(&r)
		assert.NoError(t, err)

		expected := net.UDPAddr{IP: testCase.dst}
		actual := *pw.Calls[0].Arguments[1].(*net.UDPAddr)
		assert.Equal(t, expected, actual)
	}
}

type testHandler struct {
	mock.Mock
}

func (h *testHandler) ServeDHCP(req Request) {
	h.Called(req)
}

func TestServeReturnsReadError(t *testing.T) {
	pc := &testPacketConn{}
	pc.ReadError(io.EOF)

	err := Serve(pc, &testHandler{})
	assert.Equal(t, io.EOF, err)
}

func TestServeFiltersNonRequests(t *testing.T) {
	var err error
	var buf []byte
	var bufs [3][]byte

	bufs[0] = []byte("this is a garbage packet")

	p1 := NewPacket(OpCode(2)) // BootReply
	if buf, err = PacketToBytes(p1, nil); err != nil {
		panic(err)
	}

	bufs[1] = buf

	p2 := NewPacket(OpCode(2)) // Undefined opcode
	if buf, err = PacketToBytes(p2, nil); err != nil {
		panic(err)
	}

	bufs[2] = buf

	// Test that none of these buffers result in a call to ServeDHCP
	for _, buf := range bufs {
		pc := &testPacketConn{}
		pc.ReadSuccess(buf)
		pc.ReadError(io.EOF)

		h := &testHandler{}
		Serve(pc, h)

		h.AssertNotCalled(t, "ServeDHCP", mock.Anything)
	}
}

func TestServeRequestDispatch(t *testing.T) {
	testCases := []struct {
		t MessageType
		a mock.AnythingOfTypeArgument
	}{
		{MessageTypeDHCPDiscover, mock.AnythingOfType("DHCPDiscover")},
		{MessageTypeDHCPRequest, mock.AnythingOfType("DHCPRequest")},
		{MessageTypeDHCPDecline, mock.AnythingOfType("DHCPDecline")},
		{MessageTypeDHCPRelease, mock.AnythingOfType("DHCPRelease")},
		{MessageTypeDHCPInform, mock.AnythingOfType("DHCPInform")},
	}

	for _, testCase := range testCases {
		var buf []byte
		var err error

		p := NewPacket(BootRequest)
		p.SetMessageType(testCase.t)

		if buf, err = PacketToBytes(p, nil); err != nil {
			panic(err)
		}

		pc := &testPacketConn{}
		pc.ReadSuccess(buf)
		pc.ReadError(io.EOF)

		h := &testHandler{}
		h.On("ServeDHCP", mock.Anything).Return()

		Serve(pc, h)

		h.AssertCalled(t, "ServeDHCP", testCase.a)
	}
}