examples/networking/distributed_bridge/tunnel.c

// Copyright (c) PLUMgrid, Inc.
// Licensed under the Apache License, Version 2.0 (the "License")
#include <bcc/proto.h>

BPF_TABLE("hash", u32, int, vni2if, 1024);

struct vni_key {
  u64 mac;
  int ifindex;
  int pad;
};
struct host {
  u32 tunnel_id;
  u32 remote_ipv4;
  u64 rx_pkts;
  u64 tx_pkts;
};
BPF_TABLE("hash", struct vni_key, struct host, mac2host, 10240);

struct config {
  int tunnel_ifindex;
};
BPF_TABLE("hash", int, struct config, conf, 1);

// Handle packets from the encap device, demux into the dest tenant
int handle_ingress(struct __sk_buff *skb) {
  u8 *cursor = 0;

  struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));

  struct bpf_tunnel_key tkey = {};
  bpf_skb_get_tunnel_key(skb, &tkey, sizeof(tkey), 0);

  int *ifindex = vni2if.lookup(&tkey.tunnel_id);
  if (ifindex) {
    //bpf_trace_printk("ingress tunnel_id=%d ifindex=%d\n", tkey.tunnel_id, *ifindex);
    struct vni_key vk = {ethernet->src, *ifindex, 0};
    struct host *src_host = mac2host.lookup_or_init(&vk,
        &(struct host){tkey.tunnel_id, tkey.remote_ipv4, 0, 0});
    lock_xadd(&src_host->rx_pkts, 1);
    bpf_clone_redirect(skb, *ifindex, 1/*ingress*/);
  } else {
    bpf_trace_printk("ingress invalid tunnel_id=%d\n", tkey.tunnel_id);
  }

  return 1;
}

// Handle packets from the tenant, mux into the encap device
int handle_egress(struct __sk_buff *skb) {
  u8 *cursor = 0;

  int one = 1;
  struct config *cfg = conf.lookup(&one);
  if (!cfg) return 1;

  struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet));

  struct vni_key vk = {ethernet->dst, skb->ifindex, 0};
  struct host *dst_host = mac2host.lookup(&vk);
  struct bpf_tunnel_key tkey = {};
  if (dst_host) {
    u32 zero = 0;
    tkey.tunnel_id = dst_host->tunnel_id;
    tkey.remote_ipv4 = dst_host->remote_ipv4;
    bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), 0);
    lock_xadd(&dst_host->tx_pkts, 1);
  } else {
    struct bpf_tunnel_key tkey = {};
    vk.mac = 0xFFFFFFFFFFFFull;
    dst_host = mac2host.lookup(&vk);
    if (!dst_host)
      return 1;
    tkey.tunnel_id = dst_host->tunnel_id;
    tkey.remote_ipv4 = dst_host->remote_ipv4;
    bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), 0);
  }
  bpf_clone_redirect(skb, cfg->tunnel_ifindex, 0/*egress*/);
  return 1;
}