package vpnruntime

import (
	"encoding/binary"
	"testing"
)

func TestNormalizeIPv4PacketChecksumsRepairsTCP(t *testing.T) {
	packet := []byte{
		0x45, 0x00, 0x00, 0x28, 0x00, 0x00, 0x40, 0x00, 0x40, 0x06, 0x12, 0x34, 192, 168, 200, 61, 10, 77, 0, 2,
		0x46, 0xa0, 0xdd, 0x78, 0, 0, 0, 1, 0, 0, 0, 0, 0x50, 0x12, 0x72, 0x10, 0xab, 0xcd, 0, 0,
	}
	if !normalizeIPv4PacketChecksums(packet) {
		t.Fatal("normalize returned false")
	}
	if got := checksum(packet[:20]); got != 0 {
		t.Fatalf("ip checksum verification = %#x, want 0", got)
	}
	tcp := packet[20:]
	pseudo := make([]byte, 12+len(tcp))
	copy(pseudo[0:4], packet[12:16])
	copy(pseudo[4:8], packet[16:20])
	pseudo[9] = 6
	binary.BigEndian.PutUint16(pseudo[10:12], uint16(len(tcp)))
	copy(pseudo[12:], tcp)
	if got := checksum(pseudo); got != 0 {
		t.Fatalf("tcp checksum verification = %#x, want 0", got)
	}
}

func TestNormalizeIPv4PacketChecksumsRepairsUDP(t *testing.T) {
	packet := []byte{
		0x45, 0x00, 0x00, 0x20, 0, 0, 0x40, 0, 0x40, 0x11, 0x12, 0x34, 10, 77, 0, 2, 192, 168, 200, 210,
		0x30, 0x39, 0x00, 0x35, 0x00, 0x0c, 0xab, 0xcd, 0xde, 0xad, 0xbe, 0xef,
	}
	if !normalizeIPv4PacketChecksums(packet) {
		t.Fatal("normalize returned false")
	}
	if got := checksum(packet[:20]); got != 0 {
		t.Fatalf("ip checksum verification = %#x, want 0", got)
	}
	udp := packet[20:]
	pseudo := make([]byte, 12+len(udp))
	copy(pseudo[0:4], packet[12:16])
	copy(pseudo[4:8], packet[16:20])
	pseudo[9] = 17
	binary.BigEndian.PutUint16(pseudo[10:12], uint16(len(udp)))
	copy(pseudo[12:], udp)
	if got := checksum(pseudo); got != 0 {
		t.Fatalf("udp checksum verification = %#x, want 0", got)
	}
}