On Wed, May 06, 2020 at 09:33:11AM +0100, Richard Chivers wrote:
> Hi,
>
> Some progress has been made, we can now replicate this consistently and it
> appears that whenever a LS update exceeds the mtu (1500) we get this issue
> of lsa_check bad age.
>
> When running with the diff Claudio sent we start getting a bunch of errors
> complaining about:
>
> recv_ls_update: bad packet size, neighbor ID x.x.x.x
> lsa_check: bad packet size
>
> We don't ever move to a state of FULL/DR or similar.
>
> Does anyone have any suggestions? We are just starting to look at the wider
> code to see if we can comprehend what may be occurring, but it will
> likely be a steep learning curve :)
>
Just realized that my diff was wrong since ibuf_reserve() would change the
write position of the buffer and so you end up with some empty space in
the buffer.
Here is a better diff. This is using ibuf_size to get the current write
position and then ibuf_seek() to write the age back into the right spot.
Using the position instead of the pointer has the benefit that a realloc()
in ibuf_add() will not result in the stale pointer to lsage that the
current code has.
I have currently no ospf setup so my testing is limited.
--
:wq Claudio
Index: lsupdate.c
===================================================================
RCS file: /cvs/src/usr.sbin/ospfd/lsupdate.c,v
retrieving revision 1.47
diff -u -p -r1.47 lsupdate.c
--- lsupdate.c 19 Nov 2019 09:55:55 -0000 1.47
+++ lsupdate.c 6 May 2020 08:48:19 -0000
@@ -175,8 +175,8 @@ int
add_ls_update(struct ibuf *buf, struct iface *iface, void *data, u_int16_t len,
u_int16_t older)
{
- void *lsage;
- u_int16_t age;
+ size_t ageoff;
+ u_int16_t age;
if ((size_t)iface->mtu < sizeof(struct ip) + sizeof(struct ospf_hdr) +
sizeof(u_int32_t) + ibuf_size(buf) + len + MD5_DIGEST_LENGTH) {
@@ -186,7 +186,7 @@ add_ls_update(struct ibuf *buf, struct i
return (0);
}
- lsage = ibuf_reserve(buf, 0);
+ ageoff = ibuf_size(buf);
if (ibuf_add(buf, data, len)) {
log_warn("add_ls_update");
return (0);
@@ -198,7 +198,7 @@ add_ls_update(struct ibuf *buf, struct i
if ((age += older + iface->transmit_delay) >= MAX_AGE)
age = MAX_AGE;
age = htons(age);
- memcpy(lsage, &age, sizeof(age));
+ memcpy(ibuf_seek(buf, ageoff, sizeof(age)), &age, sizeof(age));
return (1);
}
