bird/proto/ospf/lsalib.c
Ondrej Zajicek (work) 4a3f5b3617 OSPF: Basic support for DN-bit handling (RFC 4576)
External LSAs originated by OSPF routers with VPN-PE behavior enabled are
marked by DN flag and they are ignored by other OSPF routers with VPN-PE
enabled.
2019-02-13 15:53:36 +01:00

685 lines
15 KiB
C

/*
* BIRD -- OSPF
*
* (c) 1999--2004 Ondrej Filip <feela@network.cz>
* (c) 2009--2015 Ondrej Zajicek <santiago@crfreenet.org>
* (c) 2009--2015 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "ospf.h"
#include "lib/fletcher16.h"
#ifndef CPU_BIG_ENDIAN
void
lsa_hton_hdr(struct ospf_lsa_header *h, struct ospf_lsa_header *n)
{
n->age = htons(h->age);
n->type_raw = htons(h->type_raw);
n->id = htonl(h->id);
n->rt = htonl(h->rt);
n->sn = htonl(h->sn);
n->checksum = htons(h->checksum);
n->length = htons(h->length);
}
void
lsa_ntoh_hdr(struct ospf_lsa_header *n, struct ospf_lsa_header *h)
{
h->age = ntohs(n->age);
h->type_raw = ntohs(n->type_raw);
h->id = ntohl(n->id);
h->rt = ntohl(n->rt);
h->sn = ntohl(n->sn);
h->checksum = ntohs(n->checksum);
h->length = ntohs(n->length);
}
void
lsa_hton_body(void *h, void *n, u16 len)
{
u32 *hid = h;
u32 *nid = n;
uint i;
for (i = 0; i < (len / sizeof(u32)); i++)
nid[i] = htonl(hid[i]);
}
void
lsa_ntoh_body(void *n, void *h, u16 len)
{
u32 *nid = n;
u32 *hid = h;
uint i;
for (i = 0; i < (len / sizeof(u32)); i++)
hid[i] = ntohl(nid[i]);
}
#endif /* little endian */
int
lsa_flooding_allowed(u32 type, u32 domain, struct ospf_iface *ifa)
{
/* Handle inactive vlinks */
if (ifa->state == OSPF_IS_DOWN)
return 0;
/* 4.5.2 (Case 2) */
switch (LSA_SCOPE(type))
{
case LSA_SCOPE_LINK:
return ifa->iface_id == domain;
case LSA_SCOPE_AREA:
return ifa->oa->areaid == domain;
case LSA_SCOPE_AS:
if (ifa->type == OSPF_IT_VLINK)
return 0;
if (!oa_is_ext(ifa->oa))
return 0;
return 1;
default:
log(L_ERR "OSPF: LSA with invalid scope");
return 0;
}
}
int
lsa_is_acceptable(u32 type, struct ospf_neighbor *n, struct ospf_proto *p)
{
if (ospf_is_v2(p))
{
if (type == LSA_T_NSSA)
return !!(n->options & OPT_N);
if (lsa_is_opaque(type))
return !!(n->options & OPT_O);
return 1;
}
else
{
/*
* There should be check whether receiving router understands that type
* of LSA (for LSA types with U-bit == 0). But as we do not support any
* optional LSA types, this is not needed yet.
*/
return 1;
}
}
static int
unknown_lsa_type(u32 type)
{
switch (type)
{
case LSA_T_RT:
case LSA_T_NET:
case LSA_T_SUM_NET:
case LSA_T_SUM_RT:
case LSA_T_EXT:
case LSA_T_NSSA:
case LSA_T_LINK:
case LSA_T_PREFIX:
case LSA_T_RI_LINK:
case LSA_T_RI_AREA:
case LSA_T_RI_AS:
return 0;
default:
return 1;
}
}
/* Maps OSPFv2 types to OSPFv3 types */
static const u16 lsa_v2_types[] = {
0, LSA_T_RT, LSA_T_NET, LSA_T_SUM_NET, LSA_T_SUM_RT, LSA_T_EXT, 0, LSA_T_NSSA,
0, LSA_T_OPAQUE_LINK, LSA_T_OPAQUE_AREA, LSA_T_OPAQUE_AS
};
/* Maps OSPFv2 opaque types to OSPFv3 function codes */
static const u16 opaque_lsa_types[] = {
[LSA_OT_RI] = LSA_T_RI_,
};
/* Maps (subset of) OSPFv3 function codes to OSPFv2 opaque types */
static const u8 opaque_lsa_types_inv[] = {
[LSA_T_RI_] = LSA_OT_RI,
};
#define LOOKUP(a, i) ({ uint _i = (i); (_i < ARRAY_SIZE(a)) ? a[_i] : 0; })
void
lsa_get_type_domain_(u32 type, u32 id, struct ospf_iface *ifa, u32 *otype, u32 *domain)
{
if (ospf_is_v2(ifa->oa->po))
{
type = type & LSA_T_V2_MASK;
type = LOOKUP(lsa_v2_types, type);
uint code;
if (LSA_FUNCTION(type) == LSA_T_OPAQUE_)
if (code = LOOKUP(opaque_lsa_types, id >> 24))
type = code | LSA_UBIT | LSA_SCOPE(type);
}
else
{
/* For unkown LSAs without U-bit change scope to LSA_SCOPE_LINK */
if (unknown_lsa_type(type) && !(type & LSA_UBIT))
type = type & ~LSA_SCOPE_MASK;
}
*otype = type;
switch (LSA_SCOPE(type))
{
case LSA_SCOPE_LINK:
*domain = ifa->iface_id;
return;
case LSA_SCOPE_AREA:
*domain = ifa->oa->areaid;
return;
case LSA_SCOPE_AS:
default:
*domain = 0;
return;
}
}
u32
lsa_get_opaque_type(u32 type)
{
return LOOKUP(opaque_lsa_types_inv, LSA_FUNCTION(type));
}
void
lsa_generate_checksum(struct ospf_lsa_header *lsa, const u8 *body)
{
struct fletcher16_context ctx;
struct ospf_lsa_header hdr;
u16 len = lsa->length;
/*
* lsa and body are in the host order, we need to compute Fletcher-16 checksum
* for data in the network order. We also skip the initial age field.
*/
lsa_hton_hdr(lsa, &hdr);
hdr.checksum = 0;
fletcher16_init(&ctx);
fletcher16_update(&ctx, (u8 *) &hdr + 2, sizeof(struct ospf_lsa_header) - 2);
fletcher16_update_n32(&ctx, body, len - sizeof(struct ospf_lsa_header));
lsa->checksum = fletcher16_final(&ctx, len, OFFSETOF(struct ospf_lsa_header, checksum));
}
u16
lsa_verify_checksum(const void *lsa_n, int lsa_len)
{
struct fletcher16_context ctx;
/* The whole LSA is at lsa_n in net order, we just skip initial age field */
fletcher16_init(&ctx);
fletcher16_update(&ctx, (u8 *) lsa_n + 2, lsa_len - 2);
return fletcher16_compute(&ctx) == 0;
}
int
lsa_comp(struct ospf_lsa_header *l1, struct ospf_lsa_header *l2)
/* Return codes from point of view of l1 */
{
u32 sn1, sn2;
sn1 = l1->sn - LSA_INITSEQNO + 1;
sn2 = l2->sn - LSA_INITSEQNO + 1;
if (sn1 > sn2)
return CMP_NEWER;
if (sn1 < sn2)
return CMP_OLDER;
if (l1->checksum != l2->checksum)
return l1->checksum < l2->checksum ? CMP_OLDER : CMP_NEWER;
if ((l1->age == LSA_MAXAGE) && (l2->age != LSA_MAXAGE))
return CMP_NEWER;
if ((l2->age == LSA_MAXAGE) && (l1->age != LSA_MAXAGE))
return CMP_OLDER;
if (ABS(l1->age - l2->age) > LSA_MAXAGEDIFF)
return l1->age < l2->age ? CMP_NEWER : CMP_OLDER;
return CMP_SAME;
}
static inline int
lsa_walk_rt2(struct ospf_lsa_rt_walk *rt)
{
if (rt->buf >= rt->bufend)
return 0;
struct ospf_lsa_rt2_link *l = rt->buf;
rt->buf += sizeof(struct ospf_lsa_rt2_link) + l->no_tos * sizeof(struct ospf_lsa_rt2_tos);
rt->type = l->type;
rt->metric = l->metric;
rt->id = l->id;
rt->data = l->data;
return 1;
}
static inline int
lsa_walk_rt3(struct ospf_lsa_rt_walk *rt)
{
while (rt->buf >= rt->bufend)
{
rt->en = ospf_hash_find_rt3_next(rt->en);
if (!rt->en)
return 0;
rt->buf = rt->en->lsa_body;
rt->bufend = rt->buf + rt->en->lsa.length - sizeof(struct ospf_lsa_header);
rt->buf += sizeof(struct ospf_lsa_rt);
}
struct ospf_lsa_rt3_link *l = rt->buf;
rt->buf += sizeof(struct ospf_lsa_rt3_link);
rt->type = l->type;
rt->metric = l->metric;
rt->lif = l->lif;
rt->nif = l->nif;
rt->id = l->id;
return 1;
}
void
lsa_walk_rt_init(struct ospf_proto *p, struct top_hash_entry *act, struct ospf_lsa_rt_walk *rt)
{
rt->ospf2 = ospf_is_v2(p);
rt->id = rt->data = rt->lif = rt->nif = 0;
if (rt->ospf2)
rt->en = act;
else
rt->en = ospf_hash_find_rt3_first(p->gr, act->domain, act->lsa.rt);
rt->buf = rt->en->lsa_body;
rt->bufend = rt->buf + rt->en->lsa.length - sizeof(struct ospf_lsa_header);
rt->buf += sizeof(struct ospf_lsa_rt);
}
int
lsa_walk_rt(struct ospf_lsa_rt_walk *rt)
{
return rt->ospf2 ? lsa_walk_rt2(rt) : lsa_walk_rt3(rt);
}
void
lsa_parse_sum_net(struct top_hash_entry *en, int ospf2, int af, net_addr *net, u8 *pxopts, u32 *metric)
{
if (ospf2)
{
uint opts = lsa_get_options(&en->lsa);
struct ospf_lsa_sum2 *ls = en->lsa_body;
net_fill_ip4(net, ip4_from_u32(en->lsa.id & ls->netmask), u32_masklen(ls->netmask));
*pxopts = (opts & OPT_DN) ? OPT_PX_DN : 0;
*metric = ls->metric & LSA_METRIC_MASK;
}
else
{
struct ospf_lsa_sum3_net *ls = en->lsa_body;
ospf3_get_prefix(ls->prefix, af, net, pxopts, NULL);
*metric = ls->metric & LSA_METRIC_MASK;
}
}
void
lsa_parse_sum_rt(struct top_hash_entry *en, int ospf2, u32 *drid, u32 *metric, u32 *options)
{
if (ospf2)
{
struct ospf_lsa_sum2 *ls = en->lsa_body;
*drid = en->lsa.id;
*metric = ls->metric & LSA_METRIC_MASK;
*options = 0;
}
else
{
struct ospf_lsa_sum3_rt *ls = en->lsa_body;
*drid = ls->drid;
*metric = ls->metric & LSA_METRIC_MASK;
*options = ls->options & LSA_OPTIONS_MASK;
}
}
void
lsa_parse_ext(struct top_hash_entry *en, int ospf2, int af, struct ospf_lsa_ext_local *rt)
{
if (ospf2)
{
struct ospf_lsa_ext2 *ext = en->lsa_body;
net_fill_ip4(&rt->net,
ip4_from_u32(en->lsa.id & ext->netmask),
u32_masklen(ext->netmask));
rt->pxopts = 0;
rt->metric = ext->metric & LSA_METRIC_MASK;
rt->ebit = ext->metric & LSA_EXT2_EBIT;
rt->fbit = ext->fwaddr;
rt->fwaddr = ipa_from_u32(ext->fwaddr);
rt->tag = ext->tag;
rt->propagate = lsa_get_options(&en->lsa) & OPT_P;
rt->downwards = lsa_get_options(&en->lsa) & OPT_DN;
}
else
{
struct ospf_lsa_ext3 *ext = en->lsa_body;
u32 *buf = ospf3_get_prefix(ext->rest, af, &rt->net, &rt->pxopts, NULL);
rt->metric = ext->metric & LSA_METRIC_MASK;
rt->ebit = ext->metric & LSA_EXT3_EBIT;
rt->fbit = ext->metric & LSA_EXT3_FBIT;
if (rt->fbit)
buf = ospf3_get_addr(buf, af, &rt->fwaddr);
else
rt->fwaddr = IPA_NONE;
rt->tag = (ext->metric & LSA_EXT3_TBIT) ? *buf++ : 0;
rt->propagate = rt->pxopts & OPT_PX_P;
rt->downwards = rt->pxopts & OPT_PX_DN;
}
}
#define HDRLEN sizeof(struct ospf_lsa_header)
static int
lsa_validate_rt2(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_rt)))
return 0;
uint i = 0;
void *buf = body;
void *bufend = buf + lsa->length - HDRLEN;
buf += sizeof(struct ospf_lsa_rt);
while (buf < bufend)
{
struct ospf_lsa_rt2_link *l = buf;
buf += sizeof(struct ospf_lsa_rt2_link) + l->no_tos * sizeof(struct ospf_lsa_rt2_tos);
i++;
if (buf > bufend)
return 0;
if (!((l->type == LSART_PTP) ||
(l->type == LSART_NET) ||
(l->type == LSART_STUB) ||
(l->type == LSART_VLNK)))
return 0;
}
if ((body->options & LSA_RT2_LINKS) != i)
return 0;
return 1;
}
static int
lsa_validate_rt3(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_rt)))
return 0;
void *buf = body;
void *bufend = buf + lsa->length - HDRLEN;
buf += sizeof(struct ospf_lsa_rt);
while (buf < bufend)
{
struct ospf_lsa_rt3_link *l = buf;
buf += sizeof(struct ospf_lsa_rt3_link);
if (buf > bufend)
return 0;
if (!((l->type == LSART_PTP) ||
(l->type == LSART_NET) ||
(l->type == LSART_VLNK)))
return 0;
}
return 1;
}
static int
lsa_validate_net(struct ospf_lsa_header *lsa, struct ospf_lsa_net *body UNUSED)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_net)))
return 0;
return 1;
}
static int
lsa_validate_sum2(struct ospf_lsa_header *lsa, struct ospf_lsa_sum2 *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum2)))
return 0;
/* First field should have TOS = 0, we ignore other TOS fields */
if ((body->metric & LSA_SUM2_TOS) != 0)
return 0;
return 1;
}
static inline int
pxlen(u32 *buf)
{
return *buf >> 24;
}
static int
lsa_validate_sum3_net(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_net *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum3_net) + 4))
return 0;
u8 pxl = pxlen(body->prefix);
if (pxl > IP6_MAX_PREFIX_LENGTH)
return 0;
if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_net) +
IPV6_PREFIX_SPACE(pxl)))
return 0;
return 1;
}
static int
lsa_validate_sum3_rt(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_rt *body UNUSED)
{
if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_rt)))
return 0;
return 1;
}
static int
lsa_validate_ext2(struct ospf_lsa_header *lsa, struct ospf_lsa_ext2 *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_ext2)))
return 0;
/* First field should have TOS = 0, we ignore other TOS fields */
if ((body->metric & LSA_EXT2_TOS) != 0)
return 0;
return 1;
}
static int
lsa_validate_ext3(struct ospf_lsa_header *lsa, struct ospf_lsa_ext3 *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_ext3) + 4))
return 0;
u8 pxl = pxlen(body->rest);
if (pxl > IP6_MAX_PREFIX_LENGTH)
return 0;
int len = IPV6_PREFIX_SPACE(pxl);
if (body->metric & LSA_EXT3_FBIT) // forwarding address
len += 16;
if (body->metric & LSA_EXT3_TBIT) // route tag
len += 4;
if (*body->rest & 0xFFFF) // referenced LS type field
len += 4;
if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_ext3) + len))
return 0;
return 1;
}
static int
lsa_validate_pxlist(struct ospf_lsa_header *lsa, u32 pxcount, uint offset, u8 *pbuf)
{
uint bound = lsa->length - HDRLEN - 4;
u32 i;
for (i = 0; i < pxcount; i++)
{
if (offset > bound)
return 0;
u8 pxl = pxlen((u32 *) (pbuf + offset));
if (pxl > IP6_MAX_PREFIX_LENGTH)
return 0;
offset += IPV6_PREFIX_SPACE(pxl);
}
if (lsa->length != (HDRLEN + offset))
return 0;
return 1;
}
static int
lsa_validate_link(struct ospf_lsa_header *lsa, struct ospf_lsa_link *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_link)))
return 0;
return lsa_validate_pxlist(lsa, body->pxcount, sizeof(struct ospf_lsa_link), (u8 *) body);
}
static int
lsa_validate_prefix(struct ospf_lsa_header *lsa, struct ospf_lsa_prefix *body)
{
if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_prefix)))
return 0;
return lsa_validate_pxlist(lsa, body->pxcount, sizeof(struct ospf_lsa_prefix), (u8 *) body);
}
static int
lsa_validate_ri(struct ospf_lsa_header *lsa UNUSED, struct ospf_lsa_net *body UNUSED)
{
/*
* There should be proper validation. But we do not really process RI LSAs, so
* we can just accept them like another unknown opaque LSAs.
*/
return 1;
}
/**
* lsa_validate - check whether given LSA is valid
* @lsa: LSA header
* @lsa_type: internal LSA type (%LSA_T_xxx)
* @ospf2: %true for OSPFv2, %false for OSPFv3
* @body: pointer to LSA body
*
* Checks internal structure of given LSA body (minimal length,
* consistency). Returns true if valid.
*/
int
lsa_validate(struct ospf_lsa_header *lsa, u32 lsa_type, int ospf2, void *body)
{
if (ospf2)
{
switch (lsa_type)
{
case LSA_T_RT:
return lsa_validate_rt2(lsa, body);
case LSA_T_NET:
return lsa_validate_net(lsa, body);
case LSA_T_SUM_NET:
return lsa_validate_sum2(lsa, body);
case LSA_T_SUM_RT:
return lsa_validate_sum2(lsa, body);
case LSA_T_EXT:
case LSA_T_NSSA:
return lsa_validate_ext2(lsa, body);
case LSA_T_RI_LINK:
case LSA_T_RI_AREA:
case LSA_T_RI_AS:
return lsa_validate_ri(lsa, body);
case LSA_T_OPAQUE_LINK:
case LSA_T_OPAQUE_AREA:
case LSA_T_OPAQUE_AS:
return 1; /* Unknown Opaque LSAs */
default:
return 0; /* Should not happen, unknown LSAs are already rejected */
}
}
else
{
switch (lsa_type)
{
case LSA_T_RT:
return lsa_validate_rt3(lsa, body);
case LSA_T_NET:
return lsa_validate_net(lsa, body);
case LSA_T_SUM_NET:
return lsa_validate_sum3_net(lsa, body);
case LSA_T_SUM_RT:
return lsa_validate_sum3_rt(lsa, body);
case LSA_T_EXT:
case LSA_T_NSSA:
return lsa_validate_ext3(lsa, body);
case LSA_T_LINK:
return lsa_validate_link(lsa, body);
case LSA_T_PREFIX:
return lsa_validate_prefix(lsa, body);
case LSA_T_RI_LINK:
case LSA_T_RI_AREA:
case LSA_T_RI_AS:
return lsa_validate_ri(lsa, body);
default:
return 1; /* Unknown LSAs are OK in OSPFv3 */
}
}
}