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LSA checksum works. But it's very uneficient on little endian systems.

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This commit is contained in:
Ondrej Filip 2000-04-01 02:45:49 +00:00
parent ac4b4683ae
commit 499cb346f6
3 changed files with 69 additions and 4 deletions
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69
proto/ospf/lsalib.c
View file

@ -44,16 +44,18 @@ htonlsab(void *h, void *n, u8 type, u16 len)
{
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<hrt->links;i++)
for(i=0;i<links;i++)
{
(nrtl+i)->id=htonl((hrtl+i)->id);
(nrtl+i)->data=htonl((hrtl+i)->data);
@ -137,16 +139,17 @@ ntohlsab(void *n, void *h, u8 type, u16 len)
{
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;
hrt->links=ntohs(nrt->links);
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<hrt->links;i++)
for(i=0;i<links;i++)
{
(hrtl+i)->id=ntohl((nrtl+i)->id);
(hrtl+i)->data=ntohl((nrtl+i)->data);
@ -220,3 +223,63 @@ ntohlsab(void *n, void *h, u8 type, u16 len)
}
};
#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)
{
u8 *sp, *ep, *p, *q, *b;
int c0 = 0, c1 = 0;
int x, y;
u16 length;
h->checksum = 0;
b=body;
length = h->length-2;
sp = (char *) &h->options;
htonlsah(h,h);
htonlsab(b,b,h->type,length+2);
for (ep = sp + length; sp < ep; sp = q)
{
q = sp + MODX;
if (q > ep)
q = ep;
for (p = sp; p < q; p++)
{
if(p<(u8 *)(h+1))
{
c0 += *p;
/*DBG("XXXXXX: %u\t%u\n", p-sp, *p);*/
}
else
{
c0 += *(b+(p-sp)-sizeof(struct ospf_lsa_header)+2);
/*DBG("YYYYYY: %u\t%u\n", p-sp,*(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;
h->checksum = x + (y << 8);
ntohlsah(h,h);
ntohlsab(b,b,h->type,length+2);
}

1
proto/ospf/lsalib.h
View file

@ -14,5 +14,6 @@ void htonlsah(struct ospf_lsa_header *h, struct ospf_lsa_header *n);
void ntohlsah(struct ospf_lsa_header *n, struct ospf_lsa_header *h);
void htonlsab(void *h, void *n, u8 type, u16 len);
void ntohlsab(void *n, void *h, u8 type, u16 len);
void lsasum_calculate(struct ospf_lsa_header *header, void *body, struct proto_ospf *p);
#endif /* _BIRD_OSPF_LSALIB_H_ */

3
proto/ospf/topology.c
View file

@ -195,7 +195,8 @@ addifa_rtlsa(struct ospf_iface *ifa)
}
oa->rt->lsa.length=make_rt_lsa(oa, po)+sizeof(struct ospf_lsa_header);
oa->rt->lsa.checksum=0;
oa->rt->lsa.checksum=ipsum_calculate(&(oa->rt->lsa.options),sizeof(struct ospf_lsa_header)-2,oa->rt->lsa_body,oa->rt->lsa.length-sizeof(struct ospf_lsa_header),NULL);
/*oa->rt->lsa.checksum=ipsum_calculate(&(oa->rt->lsa.options),sizeof(struct ospf_lsa_header)-2,oa->rt->lsa_body,oa->rt->lsa.length-sizeof(struct ospf_lsa_header),NULL);*/
lsasum_calculate(&(oa->rt->lsa),oa->rt->lsa_body,po);
/*FIXME lsa_flood(oa->rt) */
}