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improve performance of dns policy

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defer allocating various tables until at least 2 pending queries are
seen.
This commit is contained in:
Justin Azoff 2019-01-03 13:51:50 -05:00
parent aff3f4b3fd
commit a97cf10d03
1 changed files with 28 additions and 7 deletions
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35
scripts/base/protocols/dns/main.bro
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@ -128,13 +128,16 @@ export {
## A record type which tracks the status of DNS queries for a given
## :bro:type:`connection`.
type State: record {
## a single query that hasn't been matched with a response yet.
pending_query: Info &optional;
## Indexed by query id, returns Info record corresponding to
## queries that haven't been matched with a response yet.
pending_queries: PendingMessages;
pending_queries: PendingMessages &optional;
## Indexed by query id, returns Info record corresponding to
## replies that haven't been matched with a query yet.
pending_replies: PendingMessages;
pending_replies: PendingMessages &optional;
};
}
@ -230,7 +233,7 @@ hook set_session(c: connection, msg: dns_msg, is_query: bool) &priority=5
if ( is_query )
{
if ( msg$id in c$dns_state$pending_replies &&
if ( c$dns_state?$pending_replies && msg$id in c$dns_state$pending_replies &&
Queue::len(c$dns_state$pending_replies[msg$id]) > 0 )
{
# Match this DNS query w/ what's at head of pending reply queue.
@ -241,12 +244,24 @@ hook set_session(c: connection, msg: dns_msg, is_query: bool) &priority=5
# Create a new DNS session and put it in the query queue so
# we can wait for a matching reply.
c$dns = new_session(c, msg$id);
enqueue_new_msg(c$dns_state$pending_queries, msg$id, c$dns);
if(!c$dns_state?$pending_query)
c$dns_state$pending_query = c$dns;
else
{
if(!c$dns_state?$pending_queries)
c$dns_state$pending_queries = table();
enqueue_new_msg(c$dns_state$pending_queries, msg$id, c$dns);
}
}
}
else
{
if ( msg$id in c$dns_state$pending_queries &&
if (c$dns_state?$pending_query && c$dns_state$pending_query$trans_id == msg$id)
{
c$dns = c$dns_state$pending_query;
delete c$dns_state$pending_query;
}
else if (c$dns_state?$pending_queries && msg$id in c$dns_state$pending_queries &&
Queue::len(c$dns_state$pending_queries[msg$id]) > 0 )
{
# Match this DNS reply w/ what's at head of pending query queue.
@ -257,6 +272,8 @@ hook set_session(c: connection, msg: dns_msg, is_query: bool) &priority=5
# Create a new DNS session and put it in the reply queue so
# we can wait for a matching query.
c$dns = new_session(c, msg$id);
if(!c$dns_state?$pending_replies)
c$dns_state$pending_replies = table();
enqueue_new_msg(c$dns_state$pending_replies, msg$id, c$dns);
}
}
@ -511,6 +528,10 @@ event connection_state_remove(c: connection) &priority=-5
# If Bro is expiring state, we should go ahead and log all unmatched
# queries and replies now.
log_unmatched_msgs(c$dns_state$pending_queries);
log_unmatched_msgs(c$dns_state$pending_replies);
if(c$dns_state?$pending_query)
Log::write(DNS::LOG, c$dns_state$pending_query);
if(c$dns_state?$pending_queries)
log_unmatched_msgs(c$dns_state$pending_queries);
if(c$dns_state?$pending_replies)
log_unmatched_msgs(c$dns_state$pending_replies);
}