zeek/scripts/base/protocols/conn/polling.bro
Robin Sommer 5e12a53ae5 Merge remote-tracking branch 'origin/topic/jsiwek/gridftp'
* origin/topic/jsiwek/gridftp:
  Add memory leak unit test for GridFTP.
  Enable GridFTP detection by default.  Track/log SSL client certs.
  Add analyzer for GSI mechanism of GSSAPI FTP AUTH method.
  Add an example of a GridFTP data channel detection script.
2012-10-12 10:43:16 -07:00

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##! Implements a generic way to poll connections looking for certain features
##! (e.g. monitor bytes transferred). The specific feature of a connection
##! to look for, the polling interval, and the code to execute if the feature
##! is found are all controlled by user-defined callback functions.
module ConnPolling;
export {
## Starts monitoring a given connection.
##
## c: The connection to watch.
##
## callback: A callback function that takes as arguments the monitored
## *connection*, and counter *cnt* that increments each time the
## callback is called. It returns an interval indicating how long
## in the future to schedule an event which will call the
## callback. A negative return interval causes polling to stop.
##
## cnt: The initial value of a counter which gets passed to *callback*.
##
## i: The initial interval at which to schedule the next callback.
## May be ``0secs`` to poll right away.
global watch: function(c: connection,
callback: function(c: connection, cnt: count): interval,
cnt: count, i: interval);
}
event ConnPolling::check(c: connection,
callback: function(c: connection, cnt: count): interval,
cnt: count)
{
if ( ! connection_exists(c$id) )
return;
lookup_connection(c$id); # updates the conn val
local next_interval = callback(c, cnt);
if ( next_interval < 0secs )
return;
watch(c, callback, cnt + 1, next_interval);
}
function watch(c: connection,
callback: function(c: connection, cnt: count): interval,
cnt: count, i: interval)
{
schedule i { ConnPolling::check(c, callback, cnt) };
}