Author: rrs
Date: Mon Jun 7 18:29:10 2010
New Revision: 208897
URL: http://svn.freebsd.org/changeset/base/208897
Log:
This fixes a BUG in the handling of the cum-ack calculation.
We were only paying attention to the nr-mapping-array. Which
seems to make sense on the surface, by definition things
up to the cum-ack should be deliverable thus in the nr-mapping-array.
However (there is always a gotcha) thats not true when it
comes to large messages. The stack may hold the message
while re-assembling it not not deliver it based on several
thresholds. If that happens (which it would for smaller
large messages) then the cum-ack is figured wrong. We
now properly use both arrays in the cum-ack calculation.
MFC after: 1 week.
Modified:
head/sys/netinet/sctp_indata.c
Modified: head/sys/netinet/sctp_indata.c
==============================================================================
--- head/sys/netinet/sctp_indata.c Mon Jun 7 17:41:34 2010
(r208896)
+++ head/sys/netinet/sctp_indata.c Mon Jun 7 18:29:10 2010
(r208897)
@@ -2245,15 +2245,19 @@ sctp_slide_mapping_arrays(struct sctp_tc
/*
* Now we also need to check the mapping array in a couple of ways.
* 1) Did we move the cum-ack point?
+ *
+ * When you first glance at this you might think that all entries that
+ * make up the postion of the cum-ack would be in the nr-mapping
+ * array only.. i.e. things up to the cum-ack are always
+ * deliverable. Thats true with one exception, when its a fragmented
+ * message we may not deliver the data until some threshold (or all
+ * of it) is in place. So we must OR the nr_mapping_array and
+ * mapping_array to get a true picture of the cum-ack.
*/
struct sctp_association *asoc;
int at;
+ uint8_t val;
int slide_from, slide_end, lgap, distance;
-
- /* EY nr_mapping array variables */
- /* int nr_at; */
- /* int nr_last_all_ones = 0; */
- /* int nr_slide_from, nr_slide_end, nr_lgap, nr_distance; */
uint32_t old_cumack, old_base, old_highest, highest_tsn;
asoc = &stcb->asoc;
@@ -2268,11 +2272,12 @@ sctp_slide_mapping_arrays(struct sctp_tc
*/
at = 0;
for (slide_from = 0; slide_from < stcb->asoc.mapping_array_size;
slide_from++) {
- if (asoc->nr_mapping_array[slide_from] == 0xff) {
+ val = asoc->nr_mapping_array[slide_from] |
asoc->mapping_array[slide_from];
+ if (val == 0xff) {
at += 8;
} else {
/* there is a 0 bit */
- at +=
sctp_map_lookup_tab[asoc->nr_mapping_array[slide_from]];
+ at += sctp_map_lookup_tab[val];
break;
}
}
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