bird/proto/ospf/lsalib.c

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/*
* BIRD -- OSPF
*
* (c) 1999--2004 Ondrej Filip <feela@network.cz>
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* (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>
* (c) 2009--2014 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "ospf.h"
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#ifndef CPU_BIG_ENDIAN
void
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lsa_hton_hdr(struct ospf_lsa_header *h, struct ospf_lsa_header *n)
{
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n->age = htons(h->age);
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n->type_raw = htons(h->type_raw);
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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);
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}
void
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lsa_ntoh_hdr(struct ospf_lsa_header *n, struct ospf_lsa_header *h)
{
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h->age = ntohs(n->age);
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h->type_raw = ntohs(n->type_raw);
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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);
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}
void
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lsa_hton_body(void *h, void *n, u16 len)
{
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u32 *hid = h;
u32 *nid = n;
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uint i;
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for (i = 0; i < (len / sizeof(u32)); i++)
nid[i] = htonl(hid[i]);
}
void
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lsa_ntoh_body(void *n, void *h, u16 len)
{
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u32 *nid = n;
u32 *hid = h;
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uint i;
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for (i = 0; i < (len / sizeof(u32)); i++)
hid[i] = ntohl(nid[i]);
}
#endif /* little endian */
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int
lsa_flooding_allowed(u32 type, u32 domain, struct ospf_iface *ifa)
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{
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/* Handle inactive vlinks */
if (ifa->state == OSPF_IS_DOWN)
return 0;
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/* 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;
}
}
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:
return 0;
default:
return 1;
}
}
#define LSA_V2_TMAX 8
static const u16 lsa_v2_types[LSA_V2_TMAX] =
{0, LSA_T_RT, LSA_T_NET, LSA_T_SUM_NET, LSA_T_SUM_RT, LSA_T_EXT, 0, LSA_T_NSSA};
void
lsa_get_type_domain_(u32 itype, struct ospf_iface *ifa, u32 *otype, u32 *domain)
{
if (ospf_is_v2(ifa->oa->po))
{
itype = itype & LSA_T_V2_MASK;
itype = (itype < LSA_V2_TMAX) ? lsa_v2_types[itype] : 0;
}
else
{
/* For unkown LSAs without U-bit change scope to LSA_SCOPE_LINK */
if (unknown_lsa_type(itype) && !(itype & LSA_UBIT))
itype = itype & ~LSA_SCOPE_MASK;
}
*otype = itype;
switch (LSA_SCOPE(itype))
{
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;
}
}
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/*
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void
buf_dump(const char *hdr, const byte *buf, int blen)
{
char b2[1024];
char *bp;
int first = 1;
int i;
const char *lhdr = hdr;
bp = b2;
for(i = 0; i < blen; i++)
{
if ((i > 0) && ((i % 16) == 0))
{
*bp = 0;
log(L_WARN "%s\t%s", lhdr, b2);
lhdr = "";
bp = b2;
}
bp += snprintf(bp, 1022, "%02x ", buf[i]);
}
*bp = 0;
log(L_WARN "%s\t%s", lhdr, b2);
}
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*/
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#define MODX 4102 /* larges signed value without overflow */
/* Fletcher Checksum -- Refer to RFC1008. */
#define MODX 4102
#define LSA_CHECKSUM_OFFSET 15
/* FIXME This is VERY uneficient, I have huge endianity problems */
void
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lsasum_calculate(struct ospf_lsa_header *h, void *body)
{
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u16 length = h->length;
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// log(L_WARN "Checksum %R %R %d start (len %d)", h->id, h->rt, h->type, length);
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lsa_hton_hdr(h, h);
lsa_hton_body1(body, length - sizeof(struct ospf_lsa_header));
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/*
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char buf[1024];
memcpy(buf, h, sizeof(struct ospf_lsa_header));
memcpy(buf + sizeof(struct ospf_lsa_header), body, length - sizeof(struct ospf_lsa_header));
buf_dump("CALC", buf, length);
*/
(void) lsasum_check(h, body, 1);
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// log(L_WARN "Checksum result %4x", h->checksum);
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lsa_ntoh_hdr(h, h);
lsa_ntoh_body1(body, length - sizeof(struct ospf_lsa_header));
}
/*
* Calculates the Fletcher checksum of an OSPF LSA.
*
* If 'update' is non-zero, the checkbytes (X and Y in RFC905) are calculated
* and the checksum field in the header is updated. The return value is the
* checksum as placed in the header (in network byte order).
*
* If 'update' is zero, only C0 and C1 are calculated and the header is kept
* intact. The return value is a combination of C0 and C1; if the return value
* is exactly zero the checksum is considered valid, any non-zero value is
* invalid.
*
* Note that this function expects the input LSA to be in network byte order.
*/
u16
lsasum_check(struct ospf_lsa_header *h, void *body, int update)
{
u8 *sp, *ep, *p, *q, *b;
int c0 = 0, c1 = 0;
int x, y;
u16 length;
b = body;
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sp = (char *) h;
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sp += 2; /* Skip Age field */
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length = ntohs(h->length) - 2;
if (update) h->checksum = 0;
for (ep = sp + length; sp < ep; sp = q)
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{ /* Actually MODX is very large, do we need the for-cyclus? */
q = sp + MODX;
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if (q > ep)
q = ep;
for (p = sp; p < q; p++)
{
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/*
* I count with bytes from header and than from body
* but if there is no body, it's appended to header
* (probably checksum in update receiving) and I go on
* after header
*/
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if ((b == NULL) || (p < (u8 *) (h + 1)))
{
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c0 += *p;
}
else
{
c0 += *(b + (p - (u8 *) (h + 1)));
}
c1 += c0;
}
c0 %= 255;
c1 %= 255;
}
if (!update) {
/*
* When testing the checksum, we don't need to calculate x and y. The
* checksum passes if c0 and c1 are both 0.
*/
return (c0 << 8) | (c1 & 0xff);
}
x = (int)((length - LSA_CHECKSUM_OFFSET) * c0 - c1) % 255;
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if (x <= 0)
x += 255;
y = 510 - c0 - x;
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if (y > 255)
y -= 255;
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((u8 *) & h->checksum)[0] = x;
((u8 *) & h->checksum)[1] = y;
return h->checksum;
}
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int
lsa_comp(struct ospf_lsa_header *l1, struct ospf_lsa_header *l2)
/* Return codes from point of view of l1 */
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{
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u32 sn1, sn2;
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sn1 = l1->sn - LSA_INITSEQNO + 1;
sn2 = l2->sn - LSA_INITSEQNO + 1;
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if (sn1 > sn2)
return CMP_NEWER;
if (sn1 < sn2)
return CMP_OLDER;
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if (l1->checksum != l2->checksum)
return l1->checksum < l2->checksum ? CMP_OLDER : CMP_NEWER;
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if ((l1->age == LSA_MAXAGE) && (l2->age != LSA_MAXAGE))
return CMP_NEWER;
if ((l2->age == LSA_MAXAGE) && (l1->age != LSA_MAXAGE))
return CMP_OLDER;
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if (ABS(l1->age - l2->age) > LSA_MAXAGEDIFF)
return l1->age < l2->age ? CMP_NEWER : CMP_OLDER;
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return CMP_SAME;
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}
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static inline int
lsa_walk_rt2(struct ospf_lsa_rt_walk *rt)
{
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if (rt->buf >= rt->bufend)
return 0;
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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);
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rt->type = l->type;
rt->metric = l->metric;
rt->id = l->id;
rt->data = l->data;
return 1;
}
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static inline int
lsa_walk_rt3(struct ospf_lsa_rt_walk *rt)
{
while (rt->buf >= rt->bufend)
{
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rt->en = ospf_hash_find_rt3_next(rt->en);
if (!rt->en)
return 0;
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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);
}
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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;
}
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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, ip_addr *ip, int *pxlen, u8 *pxopts, u32 *metric)
{
if (ospf2)
{
struct ospf_lsa_sum2 *ls = en->lsa_body;
*ip = ipa_from_u32(en->lsa.id & ls->netmask);
*pxlen = u32_masklen(ls->netmask);
*pxopts = 0;
*metric = ls->metric & LSA_METRIC_MASK;
}
else
{
struct ospf_lsa_sum3_net *ls = en->lsa_body;
u16 rest;
lsa_get_ipv6_prefix(ls->prefix, ip, pxlen, pxopts, &rest);
*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, struct ospf_lsa_ext_local *rt)
{
if (ospf2)
{
struct ospf_lsa_ext2 *ext = en->lsa_body;
rt->ip = ipa_from_u32(en->lsa.id & ext->netmask);
rt->pxlen = 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;
u16 rest;
u32 *buf = lsa_get_ipv6_prefix(ext->rest, &rt->ip, &rt->pxlen, &rt->pxopts, &rest);
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 = lsa_get_ipv6_addr(buf, &rt->fwaddr);
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else
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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
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lsa_validate_rt2(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
{
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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
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lsa_validate_rt3(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
{
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if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_rt)))
return 0;
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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
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lsa_validate_sum2(struct ospf_lsa_header *lsa, struct ospf_lsa_sum2 *body)
{
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if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum2)))
return 0;
/* First field should have TOS = 0, we ignore other TOS fields */
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if ((body->metric & LSA_SUM2_TOS) != 0)
return 0;
return 1;
}
static inline int
pxlen(u32 *buf)
{
return *buf >> 24;
}
static int
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lsa_validate_sum3_net(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_net *body)
{
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if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum3_net) + 4))
return 0;
u8 pxl = pxlen(body->prefix);
if (pxl > MAX_PREFIX_LENGTH)
return 0;
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if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_net) +
IPV6_PREFIX_SPACE(pxl)))
return 0;
return 1;
}
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static int
lsa_validate_sum3_rt(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_rt *body)
{
if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_rt)))
return 0;
return 1;
}
static int
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lsa_validate_ext2(struct ospf_lsa_header *lsa, struct ospf_lsa_ext2 *body)
{
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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
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lsa_validate_ext3(struct ospf_lsa_header *lsa, struct ospf_lsa_ext3 *body)
{
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if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_ext3) + 4))
return 0;
u8 pxl = pxlen(body->rest);
if (pxl > MAX_PREFIX_LENGTH)
return 0;
int len = IPV6_PREFIX_SPACE(pxl);
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if (body->metric & LSA_EXT3_FBIT) // forwardinf address
len += 16;
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if (body->metric & LSA_EXT3_TBIT) // route tag
len += 4;
if (*body->rest & 0xFFFF) // referenced LS type field
len += 4;
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if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_ext3) + len))
return 0;
return 1;
}
static int
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lsa_validate_pxlist(struct ospf_lsa_header *lsa, u32 pxcount, uint offset, u8 *pbuf)
{
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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 > MAX_PREFIX_LENGTH)
return 0;
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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);
}
/**
* lsa_validate - check whether given LSA is valid
* @lsa: LSA header
* @body: pointer to LSA body
*
* Checks internal structure of given LSA body (minimal length,
* consistency). Returns true if valid.
*/
int
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lsa_validate(struct ospf_lsa_header *lsa, u32 lsa_type, int ospf2, void *body)
{
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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);
default:
return 0; /* Should not happen, unknown LSAs are already rejected */
}
}
else
{
switch (lsa_type)
{
case LSA_T_RT:
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return lsa_validate_rt3(lsa, body);
case LSA_T_NET:
return lsa_validate_net(lsa, body);
case LSA_T_SUM_NET:
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return lsa_validate_sum3_net(lsa, body);
case LSA_T_SUM_RT:
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return lsa_validate_sum3_rt(lsa, body);
case LSA_T_EXT:
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case LSA_T_NSSA:
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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);
default:
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return 1; /* Unknown LSAs are OK in OSPFv3 */
}
}
}