[ospfd] discount IP header size from a new LSA pkt
diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 5f0d99d..7ebf114 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -2869,7 +2869,7 @@
{
struct ospf_lsa *lsa;
struct listnode *node;
- u_int16_t length = OSPF_LS_UPD_MIN_SIZE;
+ u_int16_t length = 0;
unsigned int size_noauth;
unsigned long delta = stream_get_endp (s);
unsigned long pp;
@@ -2880,6 +2880,7 @@
pp = stream_get_endp (s);
stream_forward_endp (s, OSPF_LS_UPD_MIN_SIZE);
+ length += OSPF_LS_UPD_MIN_SIZE;
/* Calculate amount of packet usable for data. */
size_noauth = stream_get_size(s) - ospf_packet_authspace(oi);
@@ -3298,7 +3299,6 @@
else
size = oi->ifp->mtu;
- /* XXX Should this be - sizeof(struct ip)?? -gdt */
if (size > OSPF_MAX_PACKET_SIZE)
{
zlog_warn ("ospf_ls_upd_packet_new: oversized LSA id:%s too big,"
@@ -3310,7 +3310,16 @@
return NULL;
}
- return ospf_packet_new (size);
+ /* IP header is built up separately by ospf_write(). This means, that we must
+ * reduce the "affordable" size just calculated by length of an IP header.
+ * This makes sure, that even if we manage to fill the payload with LSA data
+ * completely, the final packet (our data plus IP header) still fits into
+ * outgoing interface MTU. This correction isn't really meaningful for an
+ * oversized LSA, but for consistency the correction is done for both cases.
+ *
+ * P.S. OSPF_MAX_PACKET_SIZE above already includes IP header size
+ */
+ return ospf_packet_new (size - sizeof (struct ip));
}
static void