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bird/proto/radv/packets.c
Maria Matejka fd9f0c0640 Configuration strings are constant.
This is merely a const propagation. There was no problem in there.
2020-04-09 15:37:14 +02:00

518 lines
11 KiB
C

/*
* BIRD -- RAdv Packet Processing
*
* (c) 2011--2019 Ondrej Zajicek <santiago@crfreenet.org>
* (c) 2011--2019 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdlib.h>
#include "radv.h"
struct radv_ra_packet
{
u8 type;
u8 code;
u16 checksum;
u8 current_hop_limit;
u8 flags;
u16 router_lifetime;
u32 reachable_time;
u32 retrans_timer;
};
#define OPT_RA_MANAGED 0x80
#define OPT_RA_OTHER_CFG 0x40
#define OPT_PREFIX 3
#define OPT_MTU 5
#define OPT_ROUTE 24
#define OPT_RDNSS 25
#define OPT_DNSSL 31
struct radv_opt_prefix
{
u8 type;
u8 length;
u8 pxlen;
u8 flags;
u32 valid_lifetime;
u32 preferred_lifetime;
u32 reserved;
ip6_addr prefix;
};
#define OPT_PX_ONLINK 0x80
#define OPT_PX_AUTONOMOUS 0x40
struct radv_opt_mtu
{
u8 type;
u8 length;
u16 reserved;
u32 mtu;
};
struct radv_opt_route {
u8 type;
u8 length;
u8 pxlen;
u8 flags;
u32 lifetime;
u8 prefix[];
};
struct radv_opt_rdnss
{
u8 type;
u8 length;
u16 reserved;
u32 lifetime;
ip6_addr servers[];
};
struct radv_opt_dnssl
{
u8 type;
u8 length;
u16 reserved;
u32 lifetime;
char domain[];
};
static int
radv_prepare_route(struct radv_iface *ifa, struct radv_route *rt,
char **buf, char *bufend)
{
struct radv_proto *p = ifa->ra;
u8 px_blocks = (net6_pxlen(rt->n.addr) + 63) / 64;
u8 opt_len = 8 * (1 + px_blocks);
if (*buf + opt_len > bufend)
{
log(L_WARN, "%s: Too many RA options on interface %s",
p->p.name, ifa->iface->name);
return -1;
}
uint preference = rt->preference_set ? rt->preference : ifa->cf->route_preference;
uint lifetime = rt->lifetime_set ? rt->lifetime : ifa->cf->route_lifetime;
uint valid = rt->valid && p->valid && (p->active || !ifa->cf->route_lifetime_sensitive);
struct radv_opt_route *opt = (void *) *buf;
*buf += opt_len;
opt->type = OPT_ROUTE;
opt->length = 1 + px_blocks;
opt->pxlen = net6_pxlen(rt->n.addr);
opt->flags = preference;
opt->lifetime = valid ? htonl(lifetime) : 0;
/* Copy the relevant part of the prefix */
ip6_addr px_addr = ip6_hton(net6_prefix(rt->n.addr));
memcpy(opt->prefix, &px_addr, 8 * px_blocks);
/* Keeping track of first linger timeout */
if (!rt->valid)
ifa->valid_time = MIN(ifa->valid_time, rt->changed + ifa->cf->route_linger_time S);
return 0;
}
static int
radv_prepare_rdnss(struct radv_iface *ifa, list *rdnss_list, char **buf, char *bufend)
{
struct radv_rdnss_config *rcf = HEAD(*rdnss_list);
while(NODE_VALID(rcf))
{
struct radv_rdnss_config *rcf_base = rcf;
struct radv_opt_rdnss *op = (void *) *buf;
int max_i = (bufend - *buf - sizeof(struct radv_opt_rdnss)) / sizeof(ip6_addr);
int i = 0;
if (max_i < 1)
goto too_much;
op->type = OPT_RDNSS;
op->reserved = 0;
if (rcf->lifetime_mult)
op->lifetime = htonl(rcf->lifetime_mult * ifa->cf->max_ra_int);
else
op->lifetime = htonl(rcf->lifetime);
while(NODE_VALID(rcf) &&
(rcf->lifetime == rcf_base->lifetime) &&
(rcf->lifetime_mult == rcf_base->lifetime_mult))
{
if (i >= max_i)
goto too_much;
op->servers[i] = ip6_hton(rcf->server);
i++;
rcf = NODE_NEXT(rcf);
}
op->length = 1+2*i;
*buf += 8 * op->length;
}
return 0;
too_much:
log(L_WARN "%s: Too many RA options on interface %s",
ifa->ra->p.name, ifa->iface->name);
return -1;
}
int
radv_process_domain(struct radv_dnssl_config *cf)
{
/* Format of domain in search list is <size> <label> <size> <label> ... 0 */
const char *dom = cf->domain;
const char *dom_end = dom; /* Just to */
u8 *dlen_save = &cf->dlen_first;
uint len;
while (dom_end)
{
dom_end = strchr(dom, '.');
len = dom_end ? (uint)(dom_end - dom) : strlen(dom);
if (len < 1 || len > 63)
return -1;
*dlen_save = len;
dlen_save = (u8 *) dom_end;
dom += len + 1;
}
len = dom - cf->domain;
if (len > 254)
return -1;
cf->dlen_all = len;
return 0;
}
static int
radv_prepare_dnssl(struct radv_iface *ifa, list *dnssl_list, char **buf, char *bufend)
{
struct radv_dnssl_config *dcf = HEAD(*dnssl_list);
while(NODE_VALID(dcf))
{
struct radv_dnssl_config *dcf_base = dcf;
struct radv_opt_dnssl *op = (void *) *buf;
int bsize = bufend - *buf - sizeof(struct radv_opt_dnssl);
int bpos = 0;
if (bsize < 0)
goto too_much;
bsize = bsize & ~7; /* Round down to multiples of 8 */
op->type = OPT_DNSSL;
op->reserved = 0;
if (dcf->lifetime_mult)
op->lifetime = htonl(dcf->lifetime_mult * ifa->cf->max_ra_int);
else
op->lifetime = htonl(dcf->lifetime);
while(NODE_VALID(dcf) &&
(dcf->lifetime == dcf_base->lifetime) &&
(dcf->lifetime_mult == dcf_base->lifetime_mult))
{
if (bpos + dcf->dlen_all + 1 > bsize)
goto too_much;
op->domain[bpos++] = dcf->dlen_first;
memcpy(op->domain + bpos, dcf->domain, dcf->dlen_all);
bpos += dcf->dlen_all;
dcf = NODE_NEXT(dcf);
}
int blen = (bpos + 7) / 8;
bzero(op->domain + bpos, 8 * blen - bpos);
op->length = 1 + blen;
*buf += 8 * op->length;
}
return 0;
too_much:
log(L_WARN "%s: Too many RA options on interface %s",
ifa->ra->p.name, ifa->iface->name);
return -1;
}
static int
radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix *px,
char **buf, char *bufend)
{
struct radv_prefix_config *pc = px->cf;
if (*buf + sizeof(struct radv_opt_prefix) > bufend)
{
log(L_WARN "%s: Too many prefixes on interface %s",
ifa->ra->p.name, ifa->iface->name);
return -1;
}
struct radv_opt_prefix *op = (void *) *buf;
op->type = OPT_PREFIX;
op->length = 4;
op->pxlen = px->prefix.pxlen;
op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) |
(pc->autonomous ? OPT_PX_AUTONOMOUS : 0);
op->valid_lifetime = (ifa->ra->active || !pc->valid_lifetime_sensitive) ?
htonl(pc->valid_lifetime) : 0;
op->preferred_lifetime = (ifa->ra->active || !pc->preferred_lifetime_sensitive) ?
htonl(pc->preferred_lifetime) : 0;
op->reserved = 0;
op->prefix = ip6_hton(px->prefix.prefix);
*buf += sizeof(*op);
/* Keeping track of first linger timeout */
if (!px->valid)
ifa->valid_time = MIN(ifa->valid_time, px->changed + ifa->cf->prefix_linger_time S);
return 0;
}
static void
radv_prepare_ra(struct radv_iface *ifa)
{
struct radv_proto *p = ifa->ra;
struct radv_config *cf = (struct radv_config *) (p->p.cf);
struct radv_iface_config *ic = ifa->cf;
btime now = current_time();
char *buf = ifa->sk->tbuf;
char *bufstart = buf;
char *bufend = buf + ifa->sk->tbsize;
struct radv_ra_packet *pkt = (void *) buf;
pkt->type = ICMPV6_RA;
pkt->code = 0;
pkt->checksum = 0;
pkt->current_hop_limit = ic->current_hop_limit;
pkt->router_lifetime = (p->valid && (p->active || !ic->default_lifetime_sensitive)) ?
htons(ic->default_lifetime) : 0;
pkt->flags = (ic->managed ? OPT_RA_MANAGED : 0) |
(ic->other_config ? OPT_RA_OTHER_CFG : 0) |
(pkt->router_lifetime ? ic->default_preference : 0);
pkt->reachable_time = htonl(ic->reachable_time);
pkt->retrans_timer = htonl(ic->retrans_timer);
buf += sizeof(*pkt);
if (ic->link_mtu)
{
struct radv_opt_mtu *om = (void *) buf;
om->type = OPT_MTU;
om->length = 1;
om->reserved = 0;
om->mtu = htonl(ic->link_mtu);
buf += sizeof (*om);
}
/* Keeping track of first linger timeout */
ifa->valid_time = TIME_INFINITY;
struct radv_prefix *px;
WALK_LIST(px, ifa->prefixes)
{
/* Skip invalid prefixes that are past linger timeout but still not pruned */
if (!px->valid && ((px->changed + ic->prefix_linger_time S) <= now))
continue;
if (radv_prepare_prefix(ifa, px, &buf, bufend) < 0)
goto done;
}
if (! ic->rdnss_local)
if (radv_prepare_rdnss(ifa, &cf->rdnss_list, &buf, bufend) < 0)
goto done;
if (radv_prepare_rdnss(ifa, &ic->rdnss_list, &buf, bufend) < 0)
goto done;
if (! ic->dnssl_local)
if (radv_prepare_dnssl(ifa, &cf->dnssl_list, &buf, bufend) < 0)
goto done;
if (radv_prepare_dnssl(ifa, &ic->dnssl_list, &buf, bufend) < 0)
goto done;
if (p->fib_up)
{
FIB_WALK(&p->routes, struct radv_route, rt)
{
/* Skip invalid routes that are past linger timeout but still not pruned */
if (!rt->valid && ((rt->changed + ic->route_linger_time S) <= now))
continue;
if (radv_prepare_route(ifa, rt, &buf, bufend) < 0)
goto done;
}
FIB_WALK_END;
}
done:
ifa->plen = buf - bufstart;
}
void
radv_send_ra(struct radv_iface *ifa, ip_addr to)
{
struct radv_proto *p = ifa->ra;
/* TX queue is already full */
if (!sk_tx_buffer_empty(ifa->sk))
return;
if (ifa->valid_time <= current_time())
radv_invalidate(ifa);
/* We store prepared RA in tbuf */
if (!ifa->plen)
radv_prepare_ra(ifa);
if (ipa_zero(to))
{
to = IP6_ALL_NODES;
RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name);
}
else
{
RADV_TRACE(D_PACKETS, "Sending RA to %I via %s", to, ifa->iface->name);
}
int done = sk_send_to(ifa->sk, ifa->plen, to, 0);
if (!done)
log(L_WARN "%s: TX queue full on %s", p->p.name, ifa->iface->name);
}
static void
radv_receive_rs(struct radv_proto *p, struct radv_iface *ifa, ip_addr from)
{
RADV_TRACE(D_PACKETS, "Received RS from %I via %s",
from, ifa->iface->name);
if (ifa->cf->solicited_ra_unicast && ipa_nonzero(from))
radv_send_ra(ifa, from);
else
radv_iface_notify(ifa, RA_EV_RS);
}
static int
radv_rx_hook(sock *sk, uint size)
{
struct radv_iface *ifa = sk->data;
struct radv_proto *p = ifa->ra;
/* We want just packets from sk->iface */
if (sk->lifindex != sk->iface->index)
return 1;
if (ipa_equal(sk->faddr, sk->saddr))
return 1;
if (size < 8)
return 1;
byte *buf = sk->rbuf;
if (buf[1] != 0)
return 1;
/* Validation is a bit sloppy - Hop Limit is not checked and
length of options is ignored for RS and left to later for RA */
switch (buf[0])
{
case ICMPV6_RS:
radv_receive_rs(p, ifa, sk->faddr);
return 1;
case ICMPV6_RA:
RADV_TRACE(D_PACKETS, "Received RA from %I via %s",
sk->faddr, ifa->iface->name);
/* FIXME - there should be some checking of received RAs, but we just ignore them */
return 1;
default:
return 1;
}
}
static void
radv_tx_hook(sock *sk)
{
struct radv_iface *ifa = sk->data;
log(L_INFO "%s: TX queue ready on %s", ifa->ra->p.name, ifa->iface->name);
/* Some RAs may be missed due to full TX queue */
radv_iface_notify(ifa, RA_EV_RS);
}
static void
radv_err_hook(sock *sk, int err)
{
struct radv_iface *ifa = sk->data;
log(L_ERR "%s: Socket error on %s: %M", ifa->ra->p.name, ifa->iface->name, err);
}
int
radv_sk_open(struct radv_iface *ifa)
{
sock *sk = sk_new(ifa->pool);
sk->type = SK_IP;
sk->subtype = SK_IPV6;
sk->dport = ICMPV6_PROTO;
sk->saddr = ifa->addr->ip;
sk->vrf = ifa->ra->p.vrf;
sk->ttl = 255; /* Mandatory for Neighbor Discovery packets */
sk->rx_hook = radv_rx_hook;
sk->tx_hook = radv_tx_hook;
sk->err_hook = radv_err_hook;
sk->iface = ifa->iface;
sk->rbsize = 1024; // bufsize(ifa);
sk->tbsize = 1024; // bufsize(ifa);
sk->data = ifa;
sk->flags = SKF_LADDR_RX;
if (sk_open(sk) < 0)
goto err;
/* We want listen just to ICMPv6 messages of type RS and RA */
if (sk_set_icmp6_filter(sk, ICMPV6_RS, ICMPV6_RA) < 0)
goto err;
if (sk_setup_multicast(sk) < 0)
goto err;
if (sk_join_group(sk, IP6_ALL_ROUTERS) < 0)
goto err;
ifa->sk = sk;
return 1;
err:
sk_log_error(sk, ifa->ra->p.name);
rfree(sk);
return 0;
}