voidio 0.1.12

VOID I/O - High-performance Cross-platform I/O for Rust.
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#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <bpf/bpf_helpers.h>

#define MAX_PORTS 64


struct bpf_map_def {
    unsigned int type;
    unsigned int key_size;
    unsigned int value_size;
    unsigned int max_entries;
    unsigned int map_flags;
};

struct bpf_map_def SEC(".maps") xsks_map = {
    .type = BPF_MAP_TYPE_XSKMAP,
    .key_size = sizeof(__u32),
    .value_size = sizeof(__u32),
    .max_entries = 64,
    .map_flags = 0,
};

struct bpf_map_def SEC(".maps") port_filter = {
    .type = BPF_MAP_TYPE_HASH,
    .key_size = sizeof(__u16),
    .value_size = sizeof(__u8),
    .max_entries = MAX_PORTS,
    .map_flags = 0,
};


SEC("xdp_sock")
int xdp_udp_filter(struct xdp_md *ctx) {
    void *data_end = (void *)(long)ctx->data_end;
    void *data = (void *)(long)ctx->data;

    struct ethhdr *eth = data;
    if ((void *)(eth + 1) > data_end)
        return XDP_PASS;

    if (eth->h_proto != __constant_htons(ETH_P_IP))
        return XDP_PASS;

    struct iphdr *ip = (void *)(eth + 1);
    if ((void *)(ip + 1) > data_end)
        return XDP_PASS;

    if (ip->protocol != IPPROTO_UDP)
        return XDP_PASS;

    struct udphdr *udp = (void *)ip + ip->ihl * 4;
    if ((void *)(udp + 1) > data_end)
        return XDP_PASS;

    __u16 dport = udp->dest;
    __u8 *accept = bpf_map_lookup_elem(&port_filter, &dport);
    if (!accept)
        return XDP_PASS;

    __u32 qid = ctx->rx_queue_index;
    if (bpf_map_lookup_elem(&xsks_map, &qid))
        return bpf_redirect_map(&xsks_map, qid, 0);

    return XDP_PASS;
}

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