bird/proto/radv/packets.c
Ondrej Zajicek 36da2857bc Implements router advertisements activated by received routes.
The RAdv protocol could be configured to change its behavior based on
availability of routes, e.g., do not announce router lifetime when a
default route is not available.
2013-02-08 23:58:27 +01:00

441 lines
9.3 KiB
C

/*
* BIRD -- RAdv Packet Processing
*
*
* 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_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;
ip_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_rdnss
{
u8 type;
u8 length;
u16 reserved;
u32 lifetime;
ip_addr servers[];
};
struct radv_opt_dnssl
{
u8 type;
u8 length;
u16 reserved;
u32 lifetime;
char domain[];
};
static struct radv_prefix_config default_prefix = {
.onlink = 1,
.autonomous = 1,
.valid_lifetime = DEFAULT_VALID_LIFETIME,
.preferred_lifetime = DEFAULT_PREFERRED_LIFETIME
};
static struct radv_prefix_config *
radv_prefix_match(struct radv_iface *ifa, struct ifa *a)
{
struct proto *p = &ifa->ra->p;
struct radv_config *cf = (struct radv_config *) (p->cf);
struct radv_prefix_config *pc;
if (a->scope <= SCOPE_LINK)
return NULL;
WALK_LIST(pc, ifa->cf->pref_list)
if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
return pc;
WALK_LIST(pc, cf->pref_list)
if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
return pc;
return &default_prefix;
}
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(ip_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] = rcf->server;
ipa_hton(op->servers[i]);
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 */
char *dom = cf->domain;
char *dom_end = dom; /* Just to */
u8 *dlen_save = &cf->dlen_first;
int len;
while (dom_end)
{
dom_end = strchr(dom, '.');
len = dom_end ? (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 void
radv_prepare_ra(struct radv_iface *ifa)
{
struct proto_radv *ra = ifa->ra;
struct radv_config *cf = (struct radv_config *) (ra->p.cf);
struct radv_iface_config *ic = ifa->cf;
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->flags = (ic->managed ? OPT_RA_MANAGED : 0) |
(ic->other_config ? OPT_RA_OTHER_CFG : 0);
pkt->router_lifetime = (ra->active || !ic->default_lifetime_sensitive) ?
htons(ic->default_lifetime) : 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);
}
struct ifa *addr;
WALK_LIST(addr, ifa->iface->addrs)
{
struct radv_prefix_config *pc;
pc = radv_prefix_match(ifa, addr);
if (!pc || pc->skip)
continue;
if (buf + sizeof(struct radv_opt_prefix) > bufend)
{
log(L_WARN "%s: Too many prefixes on interface %s", ra->p.name, ifa->iface->name);
goto done;
}
struct radv_opt_prefix *op = (void *) buf;
op->type = OPT_PREFIX;
op->length = 4;
op->pxlen = addr->pxlen;
op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) |
(pc->autonomous ? OPT_PX_AUTONOMOUS : 0);
op->valid_lifetime = (ra->active || !pc->valid_lifetime_sensitive) ?
htonl(pc->valid_lifetime) : 0;
op->preferred_lifetime = (ra->active || !pc->preferred_lifetime_sensitive) ?
htonl(pc->preferred_lifetime) : 0;
op->reserved = 0;
op->prefix = addr->prefix;
ipa_hton(op->prefix);
buf += sizeof(*op);
}
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;
done:
ifa->plen = buf - bufstart;
}
void
radv_send_ra(struct radv_iface *ifa, int shutdown)
{
struct proto_radv *ra = ifa->ra;
/* We store prepared RA in tbuf */
if (!ifa->plen)
radv_prepare_ra(ifa);
if (shutdown)
{
/* Modify router lifetime to 0, it is not restored because
we suppose that the iface will be removed */
struct radv_ra_packet *pkt = (void *) ifa->sk->tbuf;
pkt->router_lifetime = 0;
}
RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name);
sk_send_to(ifa->sk, ifa->plen, AllNodes, 0);
}
static int
radv_rx_hook(sock *sk, int size)
{
struct radv_iface *ifa = sk->data;
struct proto_radv *ra = ifa->ra;
/* We want just packets from sk->iface */
if (sk->lifindex != sk->iface->index)
return 1;
if (ipa_equal(sk->faddr, ifa->addr->ip))
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_TRACE(D_PACKETS, "Received RS from %I via %s",
sk->faddr, ifa->iface->name);
radv_iface_notify(ifa, RA_EV_RS);
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_WARN "%s: TX hook called", ifa->ra->p.name);
}
static void
radv_err_hook(sock *sk, int err)
{
struct radv_iface *ifa = sk->data;
log(L_ERR "%s: Socket error: %m", ifa->ra->p.name, err);
}
int
radv_sk_open(struct radv_iface *ifa)
{
sock *sk = sk_new(ifa->ra->p.pool);
sk->type = SK_IP;
sk->dport = ICMPV6_PROTO;
sk->saddr = IPA_NONE;
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;
sk->saddr = ifa->addr->ip;
/* We want listen just to ICMPv6 messages of type RS and RA */
if (sk_set_icmp_filter(sk, ICMPV6_RS, ICMPV6_RA) < 0)
goto err;
if (sk_setup_multicast(sk) < 0)
goto err;
if (sk_join_group(sk, AllRouters) < 0)
goto err;
ifa->sk = sk;
return 1;
err:
rfree(sk);
return 0;
}