packet_test.go

package main

import (
	"encoding/binary"
	"math/rand"
	"net/netip"
	"testing"
)

func TestBuildIPv4UDPHeader(t *testing.T) {
	header, err := buildPacketHeader(PacketSpec{
		Internal:    netip.MustParseAddr("10.0.0.42"),
		Peer:        netip.MustParseAddr("198.18.0.1"),
		Direction:   DirectionIncoming,
		Protocol:    ProtocolUDP,
		FrameLength: 900,
	}, rand.New(rand.NewSource(1)))
	if err != nil {
		t.Fatal(err)
	}
	if got := binary.BigEndian.Uint16(header[12:14]); got != 0x0800 {
		t.Fatalf("EtherType=%#x, expected IPv4", got)
	}
	if header[23] != 17 {
		t.Fatalf("IPv4 protocol=%d, expected UDP", header[23])
	}
	if got := netip.AddrFrom4([4]byte{header[26], header[27], header[28], header[29]}); got.String() != "198.18.0.1" {
		t.Fatalf("source=%s", got)
	}
	if got := netip.AddrFrom4([4]byte{header[30], header[31], header[32], header[33]}); got.String() != "10.0.0.42" {
		t.Fatalf("destination=%s", got)
	}
}

func TestBuildIPv6TCPHeader(t *testing.T) {
	header, err := buildPacketHeader(PacketSpec{
		Internal:    netip.MustParseAddr("2001:db8:10::42"),
		Peer:        netip.MustParseAddr("2001:db8:ffff::1"),
		Direction:   DirectionIncoming,
		Protocol:    ProtocolTCP,
		FrameLength: 900,
		TCPFlags:    "syn",
	}, rand.New(rand.NewSource(1)))
	if err != nil {
		t.Fatal(err)
	}
	if got := binary.BigEndian.Uint16(header[12:14]); got != 0x86dd {
		t.Fatalf("EtherType=%#x, expected IPv6", got)
	}
	if header[20] != 6 {
		t.Fatalf("IPv6 next header=%d, expected TCP", header[20])
	}
	if header[67] != 0x02 {
		t.Fatalf("TCP flags=%#x, expected SYN", header[67])
	}
}

func TestCisternSourceIDWorkaround(t *testing.T) {
	typeValue, indexValue := cisternSourceIDWorkaround(2)
	// This is the expression used by pinned upstream code.
	encoded := uint32(typeValue) | indexValue<<24
	var wire [4]byte
	binary.BigEndian.PutUint32(wire[:], encoded)
	if wire != [4]byte{0, 0, 0, 2} {
		t.Fatalf("workaround encoded %v, expected ifIndex source ID", wire)
	}
}