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bird/proto/ospf/lsalib.c
Ondrej Filip 17e29574bc Better algoritmus of LSA aging.
2000-06-07 23:48:33 +00:00

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11 KiB
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/*
* BIRD -- OSPF
*
* (c) 1999 - 2000 Ondrej Filip <feela@network.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "ospf.h"
void
flush_lsa(struct top_hash_entry *en, struct ospf_area *oa)
{
struct proto *p=&oa->po->proto;
OSPF_TRACE(D_EVENTS, "Going to remove node Type: %u, Id: %I, Rt: %I, Age: %u",
en->lsa.type, en->lsa.id, en->lsa.rt, en->lsa.age);
s_rem_node(SNODE en);
ospf_hash_delete(oa->gr,en);
}
/**
* ospf_age
* @oa: ospf area
*
* This function is periodicaly invoked from area_disp(). It computes new
* age of all LSAs and old (@age is higher than %LSA_MAXAGE) are flushed
* when ever possible. If some LSA originated by router itself is older
* than %LSREFRESHTIME new instance is originated.
*
* RFC says, that router should check checksum of every LSA to detect some
* hardware problem. BIRD does not do it to minimalize CPU utilization.
*
* If routing table calculation is scheduled, it also invalidates old routing
* table calculation results.
*/
void
ospf_age(struct ospf_area *oa)
{
struct proto *p=&oa->po->proto;
struct proto_ospf *po=(struct proto_ospf *)p;
struct top_hash_entry *en,*nxt;
int flush=can_flush_lsa(oa);
WALK_SLIST_DELSAFE(en,nxt,oa->lsal)
{
if(oa->calcrt)
{
en->color=OUTSPF;
en->dist=LSINFINITY;
en->nhi=NULL;
en->nh=ipa_from_u32(0);
DBG("Infinitying Type: %u, Id: %I, Rt: %I\n", en->lsa.type, en->lsa.id,
en->lsa.rt);
}
if(en->lsa.age==LSA_MAXAGE)
{
if(flush) flush_lsa(en,oa);
continue;
}
if((en->lsa.rt==p->cf->global->router_id)&&(en->lsa.age>=LSREFRESHTIME))
{
OSPF_TRACE(D_EVENTS, "Refreshing my LSA: Type: %u, Id: %I, Rt: %I",
en->lsa.type, en->lsa.id, en->lsa.rt);
en->lsa.sn++;
en->lsa.age=0;
lsasum_calculate(&en->lsa,en->lsa_body,po);
flood_lsa(NULL,NULL,&en->lsa,po,NULL,oa,1);
continue;
}
if((en->lsa.age=(en->ini_age+(now-en->inst_t)))>=LSA_MAXAGE)
{
if(flush)
{
flush_lsa(en,oa);
schedule_rtcalc(oa);
}
else en->lsa.age=LSA_MAXAGE;
}
}
}
void
htonlsah(struct ospf_lsa_header *h, struct ospf_lsa_header *n)
{
n->age=htons(h->age);
n->options=h->options;
n->type=h->type;
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
ntohlsah(struct ospf_lsa_header *n, struct ospf_lsa_header *h)
{
h->age=ntohs(n->age);
h->options=n->options;
h->type=n->type;
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
htonlsab(void *h, void *n, u8 type, u16 len)
{
unsigned int i;
switch(type)
{
case LSA_T_RT:
{
struct ospf_lsa_rt *hrt, *nrt;
struct ospf_lsa_rt_link *hrtl,*nrtl;
u16 links;
nrt=n;
hrt=h;
links=hrt->links;
nrt->VEB=hrt->VEB;
nrt->padding=0;
nrt->links=htons(hrt->links);
nrtl=(struct ospf_lsa_rt_link *)(nrt+1);
hrtl=(struct ospf_lsa_rt_link *)(hrt+1);
for(i=0;i<links;i++)
{
(nrtl+i)->id=htonl((hrtl+i)->id);
(nrtl+i)->data=htonl((hrtl+i)->data);
(nrtl+i)->type=(hrtl+i)->type;
(nrtl+i)->notos=(hrtl+i)->notos;
(nrtl+i)->metric=htons((hrtl+i)->metric);
}
break;
}
case LSA_T_NET:
{
u32 *hid,*nid;
nid=n;
hid=h;
for(i=0;i<(len/sizeof(u32));i++)
{
*(nid+i)=htonl(*(hid+i));
}
break;
}
case LSA_T_SUM_NET:
case LSA_T_SUM_RT:
{
struct ospf_lsa_summ *hs, *ns;
struct ospf_lsa_summ_net *hn, *nn;
hs=h;
ns=n;
ns->netmask=hs->netmask;
ipa_hton(ns->netmask);
hn=(struct ospf_lsa_summ_net *)(hs+1);
nn=(struct ospf_lsa_summ_net *)(ns+1);
for(i=0;i<((len-sizeof(struct ospf_lsa_summ))/
sizeof(struct ospf_lsa_summ_net));i++)
{
(nn+i)->tos=(hn+i)->tos;
(nn+i)->metric=htons((hn+i)->metric);
(nn+i)->padding=0;
}
break;
}
case LSA_T_EXT:
{
struct ospf_lsa_ext *he, *ne;
struct ospf_lsa_ext_tos *ht, *nt;
he=h;
ne=n;
ne->netmask=he->netmask;
ipa_hton(ne->netmask);
ht=(struct ospf_lsa_ext_tos *)(he+1);
nt=(struct ospf_lsa_ext_tos *)(ne+1);
for(i=0;i<((len-sizeof(struct ospf_lsa_ext))/
sizeof(struct ospf_lsa_ext_tos));i++)
{
(nt+i)->etos=(ht+i)->etos;
(nt+i)->padding=0;
(nt+i)->metric=htons((ht+i)->metric);
(nt+i)->fwaddr=(ht+i)->fwaddr;
ipa_hton((nt+i)->fwaddr);
(nt+i)->tag=htonl((ht+i)->tag);
}
break;
}
default: bug("(hton): Unknown LSA");
}
};
void
ntohlsab(void *n, void *h, u8 type, u16 len)
{
unsigned int i;
switch(type)
{
case LSA_T_RT:
{
struct ospf_lsa_rt *hrt, *nrt;
struct ospf_lsa_rt_link *hrtl,*nrtl;
u16 links;
nrt=n;
hrt=h;
hrt->VEB=nrt->VEB;
hrt->padding=0;
links=hrt->links=ntohs(nrt->links);
nrtl=(struct ospf_lsa_rt_link *)(nrt+1);
hrtl=(struct ospf_lsa_rt_link *)(hrt+1);
for(i=0;i<links;i++)
{
(hrtl+i)->id=ntohl((nrtl+i)->id);
(hrtl+i)->data=ntohl((nrtl+i)->data);
(hrtl+i)->type=(nrtl+i)->type;
(hrtl+i)->notos=(nrtl+i)->notos;
(hrtl+i)->metric=ntohs((nrtl+i)->metric);
}
break;
}
case LSA_T_NET:
{
u32 *hid,*nid;
hid=h;
nid=n;
for(i=0;i<(len/sizeof(u32));i++)
{
*(hid+i)=ntohl(*(nid+i));
}
break;
}
case LSA_T_SUM_NET:
case LSA_T_SUM_RT:
{
struct ospf_lsa_summ *hs, *ns;
struct ospf_lsa_summ_net *hn, *nn;
hs=h;
ns=n;
hs->netmask=ns->netmask;
ipa_ntoh(hs->netmask);
hn=(struct ospf_lsa_summ_net *)(hs+1);
nn=(struct ospf_lsa_summ_net *)(ns+1);
for(i=0;i<((len-sizeof(struct ospf_lsa_summ))/
sizeof(struct ospf_lsa_summ_net));i++)
{
(hn+i)->tos=(nn+i)->tos;
(hn+i)->metric=ntohs((nn+i)->metric);
(hn+i)->padding=0;
}
break;
}
case LSA_T_EXT:
{
struct ospf_lsa_ext *he, *ne;
struct ospf_lsa_ext_tos *ht, *nt;
he=h;
ne=n;
he->netmask=ne->netmask;
ipa_ntoh(he->netmask);
ht=(struct ospf_lsa_ext_tos *)(he+1);
nt=(struct ospf_lsa_ext_tos *)(ne+1);
for(i=0;i<((len-sizeof(struct ospf_lsa_ext))/
sizeof(struct ospf_lsa_ext_tos));i++)
{
(ht+i)->etos=(nt+i)->etos;
(ht+i)->padding=0;
(ht+i)->metric=ntohs((nt+i)->metric);
(ht+i)->fwaddr=(nt+i)->fwaddr;
ipa_ntoh((ht+i)->fwaddr);
(ht+i)->tag=ntohl((nt+i)->tag);
}
break;
}
default: bug("(ntoh): Unknown LSA");
}
};
#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
lsasum_calculate(struct ospf_lsa_header *h,void *body,struct proto_ospf *po)
{
u16 length;
length=h->length;
htonlsah(h,h);
htonlsab(body,body,h->type,length-sizeof(struct ospf_lsa_header));
(void)lsasum_check(h,body,po);
ntohlsah(h,h);
ntohlsab(body,body,h->type,length-sizeof(struct ospf_lsa_header));
}
/*
* Note, that this function expects that LSA is in big endianity
* It also returns value in big endian
*/
u16
lsasum_check(struct ospf_lsa_header *h,void *body,struct proto_ospf *po)
{
u8 *sp, *ep, *p, *q, *b;
int c0 = 0, c1 = 0;
int x, y;
u16 length,chsum;
b=body;
sp = (char *) &h->options;
length=ntohs(h->length)-2;
h->checksum = 0;
for (ep = sp + length; sp < ep; sp = q)
{ /* Actually MODX is very large, do we need the for-cyclus? */
q = sp + MODX;
if (q > ep) q = ep;
for (p = sp; p < q; p++)
{
/*
* 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
*/
if((b==NULL) || (p<(u8 *)(h+1)))
{
c0 += *p;
}
else
{
c0 += *(b+(p-sp)-sizeof(struct ospf_lsa_header)+2);
}
c1 += c0;
}
c0 %= 255;
c1 %= 255;
}
x = ((length - LSA_CHECKSUM_OFFSET) * c0 - c1) % 255;
if (x <= 0) x += 255;
y = 510 - c0 - x;
if (y > 255) y -= 255;
chsum= x + (y << 8);
h->checksum = chsum;
return chsum;
}
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;
}
/**
* lsa_install_new - install new LSA into database
* @lsa: LSA header
* @body pointer to LSA body
* @oa: current ospf_area
*
* This function ensures installing new LSA into LSA database. Old instance is
* replaced. Several actions are taken to detec if new routing table
* calculation is necessary. This is described in 13.2 of RFC 2328.
*/
struct top_hash_entry *
lsa_install_new(struct ospf_lsa_header *lsa, void *body, struct ospf_area *oa)
{
/* LSA can be temporarrily, but body must be mb_alloced. */
struct proto *p=&oa->po->proto;
int change=0;
unsigned i;
struct top_hash_entry *en;
if((en=ospf_hash_find_header(oa->gr,lsa))==NULL)
{
en=ospf_hash_get_header(oa->gr,lsa);
change=1;
}
else
{
if((en->lsa.length!=lsa->length)||(en->lsa.options!=lsa->options)||
((en->lsa.age==LSA_MAXAGE)||(lsa->age==LSA_MAXAGE))) change=1;
else
{
u8 *k=en->lsa_body,*l=body;
for(i=0;i<(lsa->length-sizeof(struct ospf_lsa_header));i++)
{
if(*(k+i)!=*(l+i))
{
change=1;
break;
}
}
}
s_rem_node(SNODE en);
}
DBG("Inst lsa: Id: %I, Rt: %I, Type: %u, Age: %u, Sum: %u, Sn: 0x%x\n",
lsa->id, lsa->rt, lsa->type, lsa->age, lsa->checksum, lsa->sn);
s_add_tail(&oa->lsal, SNODE en);
en->inst_t=now;
if(en->lsa_body!=NULL) mb_free(en->lsa_body);
en->lsa_body=body;
memcpy(&en->lsa,lsa,sizeof(struct ospf_lsa_header));
en->ini_age=en->lsa.age;
if(change)
{
schedule_rtcalc(oa);
}
return en;
}
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