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#define BFD_FLAG_POLL (1 << 5)
#define BFD_FLAG_FINAL (1 << 4)
#define BFD_FLAG_CPI (1 << 3)
#define BFD_FLAG_AP (1 << 2)
#define BFD_FLAG_DEMAND (1 << 1)
#define BFD_FLAG_MULTIPOINT (1 << 0)
struct bfd_ctl_packet
{
u8 vdiag; /* version and diagnostic */
u8 flags; /* state and flags */
u8 detect_mult;
u8 length;
u32 snd_id; /* sender ID, aka 'my discriminator' */
u32 rcv_id; /* receiver ID, aka 'your discriminator' */
u32 des_min_tx_int;
u32 req_min_rx_int;
u32 req_min_echo_rx_int;
};
static inline void bfd_pack_vdiag(u8 version, u8 diag)
{ return (version << 5) | diag; }
static inline void bfd_pack_flags(u8 state, u8 flags)
{ return (state << 6) | diag; }
static inline u8 bfd_pkt_get_version(struct bfd_ctl_packet *pkt)
{ return pkt->vdiag >> 5; }
static inline u8 bfd_pkt_get_diag(struct bfd_ctl_packet *pkt)
{ return pkt->vdiag && 0x1f; }
static inline u8 bfd_pkt_get_state(struct bfd_ctl_packet *pkt)
{ return pkt->flags >> 6; }
static inline void bfd_pkt_set_state(struct bfd_ctl_packet *pkt, u8 val)
{ pkt->flags = val << 6; }
void
bfd_send_ctl(struct bfd_proto *p, struct bfd_session *s, int final)
{
sock *sk = p->skX;
struct bfd_ctl_packet *pkt = (struct ospf_packet *) sk->tbuf;
pkt->vdiag = bfd_pack_vdiag(1, s->loc_diag);
pkt->flags = bfd_pack_flags(s->loc_state, 0);
pkt->detect_mult = s->detect_mult;
pkt->length = 24;
pkt->snd_id = htonl(s->loc_id);
pkt->rcv_id = htonl(s->rem_id);
pkt->des_min_tx_int = htonl(s->des_min_tx_int);
pkt->req_min_rx_int = htonl(s->req_min_rx_int);
pkt->req_min_echo_rx_int = 0;
if (final)
pkt->flags |= BFD_FLAG_FINAL;
else if (s->poll_active)
pkt->flags |= BFD_FLAG_POLL;
// XXX
sk_send_to(sk, len, dst, 0);
}
int
bfd_ctl_rx_hook(sock *sk, int len)
{
struct bfd_proto *p = sk->data;
struct bfd_ctl_packet *pkt =sk->rbuf;
if (len < BFD_BASE_LEN)
DROP("too short", len);
u8 version = bfd_pkt_get_version(pkt);
if (version != 1)
DROP("version mismatch", version);
if ((pkt->length < BFD_BASE_LEN) || (pkt->length > len))
DROP("length mismatch", pkt->length);
if (pkt->detect_mult == 0)
DROP("invalid detect mult", 0);
if (pkt->flags & BFD_FLAG_MULTIPOINT)
DROP("invalid flags", pkt->flags);
if (pkt->snd_id == 0)
DROP("invalid my discriminator", 0);
struct bfd_session *s;
u32 id = ntohl(pkt->rcv_id);
if (id)
{
s = bfd_find_session_by_id(p, id);
if (!s)
DROP("unknown session", id);
}
else
{
u8 ps = bfd_pkt_get_state(pkt);
if (ps > BFD_STATE_DOWN)
DROP("invalid init state", ps);
s = bfd_find_session_by_ip(p, sk->faddr);
/* FIXME: better session matching and message */
if (!s || !s->opened)
return;
}
/* FIXME: better authentication handling and message */
if (pkt->flags & BFD_FLAG_AP)
DROP("authentication not supported", 0);
u32 old_rx_int = s->des_min_tx_int;
u32 old_tx_int = s->rem_min_rx_int;
s->rem_id = ntohl(pkt->snd_id);
s->rem_state = bfd_pkt_get_state(pkt);
s->rem_demand_mode = pkt->flags & BFD_FLAG_DEMAND;
s->rem_min_tx_int = ntohl(pkt->des_min_tx_int);
s->rem_min_rx_int = ntohl(pkt->req_min_rx_int);
s->rem_detect_mult = pkt->detect_mult;
bfd_session_process_ctl(s, pkt->flags, xxx);
return 1;
drop:
// log(L_WARN "%s: Bad packet from %I - %s (%u)", p->p.name, sk->faddr, err_dsc, err_val);
return 1;
}
sock *
bfd_open_rx_sk(struct bfd_proto *p, int multihop)
{
sock *sk = sk_new(p->p.pool);
sk->type = SK_UDP;
sk->sport = !multihop ? BFD_CONTROL_PORT : BFD_MULTI_CTL_PORT;
sk->data = p;
sk->rbsize = 64; // XXX
sk->rx_hook = bfd_rx_hook;
sk->err_hook = bfd_err_hook;
sk->flags = SKF_LADDR_RX | (!multihop ? SKF_TTL_RX : 0);
if (sk_open(sk) < 0)
goto err;
}
static inline sock *
bfd_open_tx_sk(struct bfd_proto *p, ip_addr local, struct iface *ifa)
{
sock *sk = sk_new(p->p.pool);
sk->type = SK_UDP;
sk->saddr = local;
sk->data = p;
sk->tbsize = 64; // XXX
sk->err_hook = bfd_err_hook;
sk->iface = new;
sk->tos = PATT->tx_tos;
sk->priority = PATT->tx_priority;
sk->ttl = PATT->ttl_security ? 255 : 1;
if (sk_open(sk) < 0)
goto err;
}
struct bfd_socket *
bfd_get_socket(struct bfd_proto *p, ip_addr local, struct iface *ifa)
{
struct bfd_socket *sk;
WALK_LIST(sk, p->sockets)
if (ipa_equal(sk->sk->saddr, local) && (sk->sk->iface == ifa))
return sk->uc++, sk;
sk = mb_allocz(p->p.pool, sizeof(struct bfd_socket));
sk->sk = bfd_open_tx_sk(p, local, ifa);
sk->uc = 1;
add_tail(&p->sockets, &sk->n);
return sk;
}
void
bfd_free_socket(struct bfd_socket *sk)
{
if (!sk || --sk->uc)
return;
rem_node(&sk->n);
sk_stop(sk->sk);
rfree(sk->sk);
mb_free(sk);
}
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