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bird/proto/ospf/lsalib.c
Ondrej Zajicek (work) a30b9d2800 OSPF: Opaque LSAs and Router Information LSA
Add support for OSPFv2 Opaque LSAs (RFC 5250) and for Router Information
LSA (RFC 7770). The second part is here mainly for testing opaque LSAs.
2019-02-17 23:02:05 +01:00

683 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)
{
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 = 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;
}
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;
}
}
#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 */
}
}
}