#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include "bridge_xdp.h"

// Definição local para struct vlan_hdr (caso não esteja disponível)
#ifndef VLAN_HLEN
#define VLAN_HLEN 4
#endif

struct vlan_hdr {
    __be16 h_vlan_TCI;
    __be16 h_vlan_encapsulated_proto;
};

struct {
    __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
    __uint(max_entries, 1);
    __type(key, __u32);
    __type(value, struct packet_stats);
} stats_map SEC(".maps");

SEC("xdp")
int bridge_filter(struct xdp_md *ctx)
{
    void *data_end = (void *)(long)ctx->data_end;
    void *data = (void *)(long)ctx->data;
    struct ethhdr *eth = data;
    __u16 h_proto;
    struct iphdr *iph;
    int action = XDP_PASS;
    __u32 key = 0;
    struct packet_stats *stats;

    if ((void*)(eth + 1) > data_end)
        return XDP_ABORTED;

    h_proto = eth->h_proto;

    // Tráfego broadcast/multicast: libera imediatamente
    if (eth->h_dest[0] & 1)
        goto stats;

    // VLAN
    if (h_proto == bpf_htons(ETH_P_8021Q) || h_proto == bpf_htons(ETH_P_8021AD)) {
        struct vlan_hdr *vhdr = (void *)(eth + 1);
        if ((void *)(vhdr + 1) > data_end)
            return XDP_ABORTED;
        h_proto = vhdr->h_vlan_encapsulated_proto;
        iph = (void *)(vhdr + 1);
    } else {
        iph = (void *)(eth + 1);
    }

    // IPv4 local: libera imediatamente
    if (h_proto == bpf_htons(ETH_P_IP)) {
        if ((void*)(iph + 1) > data_end)
            goto stats;
        if ((iph->daddr & bpf_htonl(0xffff0000)) == bpf_htonl(0x0a0f0000))
            goto stats;
    }

    // ...outros filtros podem ser adicionados aqui...

stats:
    // Atualizar estatísticas apenas uma vez
    stats = bpf_map_lookup_elem(&stats_map, &key);
    if (stats) {
        stats->packets++;
        stats->bytes += (data_end - data);
    }
    return action;
}

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