// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Isovalent */
#include <stdbool.h>

#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/stddef.h>
#include <linux/if_packet.h>
#include <bpf/bpf_endian.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>

char LICENSE[] SEC("license") = "GPL";

bool seen_tc1;
bool seen_tc2;
bool seen_tc3;
bool seen_tc4;
bool seen_tc5;
bool seen_tc6;
bool seen_tc7;
bool seen_tc8;

bool set_type;

bool seen_eth;
bool seen_host;
bool seen_mcast;

int mark, prio;
unsigned short headroom, tailroom;

SEC("tc/ingress")
int tc1(struct __sk_buff *skb)
{
	struct ethhdr eth = {};

	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
		goto out;
	if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
		goto out;
	seen_eth = eth.h_proto == bpf_htons(ETH_P_IP);
	seen_host = skb->pkt_type == PACKET_HOST;
	if (seen_host && set_type) {
		eth.h_dest[0] = 4;
		if (bpf_skb_store_bytes(skb, 0, &eth, sizeof(eth), 0))
			goto fail;
		bpf_skb_change_type(skb, PACKET_MULTICAST);
	}
out:
	seen_tc1 = true;
fail:
	return TCX_NEXT;
}

SEC("tc/egress")
int tc2(struct __sk_buff *skb)
{
	seen_tc2 = true;
	return TCX_NEXT;
}

SEC("tc/egress")
int tc3(struct __sk_buff *skb)
{
	seen_tc3 = true;
	return TCX_NEXT;
}

SEC("tc/egress")
int tc4(struct __sk_buff *skb)
{
	seen_tc4 = true;
	return TCX_NEXT;
}

SEC("tc/egress")
int tc5(struct __sk_buff *skb)
{
	seen_tc5 = true;
	return TCX_PASS;
}

SEC("tc/egress")
int tc6(struct __sk_buff *skb)
{
	seen_tc6 = true;
	return TCX_PASS;
}

SEC("tc/ingress")
int tc7(struct __sk_buff *skb)
{
	struct ethhdr eth = {};

	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
		goto out;
	if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
		goto out;
	if (eth.h_dest[0] == 4 && set_type) {
		seen_mcast = skb->pkt_type == PACKET_MULTICAST;
		bpf_skb_change_type(skb, PACKET_HOST);
	}
out:
	seen_tc7 = true;
	return TCX_PASS;
}

struct sk_buff {
	struct net_device *dev;
};

struct net_device {
	unsigned short needed_headroom;
	unsigned short needed_tailroom;
};

SEC("tc/egress")
int tc8(struct __sk_buff *skb)
{
	struct net_device *dev = BPF_CORE_READ((struct sk_buff *)skb, dev);

	seen_tc8 = true;
	mark = skb->mark;
	prio = skb->priority;
	headroom = BPF_CORE_READ(dev, needed_headroom);
	tailroom = BPF_CORE_READ(dev, needed_tailroom);
	return TCX_PASS;
}