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570 lines
17 KiB
Text
570 lines
17 KiB
Text
##! The summary statistics framework provides a way to
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##! summarize large streams of data into simple reduced
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##! measurements.
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module SumStats;
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export {
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## Type to represent the calculations that are available. The calculations
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## are all defined as plugins.
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type Calculation: enum {
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PLACEHOLDER
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};
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## Represents a thing which is having summarization
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## results collected for it.
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type Key: record {
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## A non-address related summarization or a sub-key for
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## an address based summarization. An example might be
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## successful SSH connections by client IP address
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## where the client string would be the key value.
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## Another example might be number of HTTP requests to
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## a particular value in a Host header. This is an
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## example of a non-host based metric since multiple
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## IP addresses could respond for the same Host
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## header value.
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str: string &optional;
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## Host is the value to which this metric applies.
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host: addr &optional;
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};
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## Represents data being added for a single observation.
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## Only supply a single field at a time!
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type Observation: record {
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## Count value.
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num: count &optional;
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## Double value.
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dbl: double &optional;
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## String value.
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str: string &optional;
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};
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## Represents a reducer.
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type Reducer: record {
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## Observation stream identifier for the reducer
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## to attach to.
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stream: string;
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## The calculations to perform on the data points.
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apply: set[Calculation];
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## A predicate so that you can decide per key if you
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## would like to accept the data being inserted.
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pred: function(key: SumStats::Key, obs: SumStats::Observation): bool &optional;
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## A function to normalize the key. This can be used to
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## aggregate or normalize the entire key.
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normalize_key: function(key: SumStats::Key): Key &optional;
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};
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## Result calculated for an observation stream fed into a reducer.
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## Most of the fields are added by plugins.
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type ResultVal: record {
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## The time when the first observation was added to
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## this result value.
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begin: time;
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## The time when the last observation was added to
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## this result value.
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end: time;
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## The number of observations received.
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num: count &default=0;
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};
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## Type to store a table of results for multiple reducers indexed by
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## observation stream identifier.
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type Result: table[string] of ResultVal;
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## Type to store a table of sumstats results indexed by keys.
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type ResultTable: table[Key] of Result;
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## Represents a SumStat, which consists of an aggregation of reducers along
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## with mechanisms to handle various situations like the epoch ending
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## or thresholds being crossed.
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##
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## It's best to not access any global state outside
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## of the variables given to the callbacks because there
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## is no assurance provided as to where the callbacks
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## will be executed on clusters.
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type SumStat: record {
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## An arbitrary name for the sumstat so that it can
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## be referred to later.
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name: string;
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## The interval at which this sumstat should be "broken"
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## and the *epoch_result* callback called. The
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## results are also reset at this time so any threshold
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## based detection needs to be set to a
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## value that should be expected to happen within
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## this epoch.
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##
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## Passing an epoch of zero (e.g. ``0 secs``) causes this
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## sumstat to be set to manual epochs. You will have to manually
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## end the epoch by calling :zeek:see:`SumStats::next_epoch`.
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epoch: interval;
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## The reducers for the SumStat.
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reducers: set[Reducer];
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## A function that will be called once for each observation in order
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## to calculate a value from the :zeek:see:`SumStats::Result` structure
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## which will be used for thresholding.
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## This function is required if a *threshold* value or
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## a *threshold_series* is given.
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threshold_val: function(key: SumStats::Key, result: SumStats::Result): double &optional;
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## The threshold value for calling the *threshold_crossed* callback.
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## If you need more than one threshold value, then use
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## *threshold_series* instead.
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threshold: double &optional;
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## A series of thresholds for calling the *threshold_crossed*
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## callback. These thresholds must be listed in ascending order,
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## because a threshold is not checked until the preceding one has
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## been crossed.
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threshold_series: vector of double &optional;
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## A callback that is called when a threshold is crossed.
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## A threshold is crossed when the value returned from *threshold_val*
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## is greater than or equal to the threshold value, but only the first
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## time this happens within an epoch.
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threshold_crossed: function(key: SumStats::Key, result: SumStats::Result) &optional;
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## A callback that receives each of the results at the
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## end of the analysis epoch. The function will be
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## called once for each key.
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epoch_result: function(ts: time, key: SumStats::Key, result: SumStats::Result) &optional;
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## A callback that will be called when a single collection
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## interval is completed. The *ts* value will be the time of
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## when the collection started.
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epoch_finished: function(ts:time) &optional;
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};
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## Create a summary statistic.
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##
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## ss: The SumStat to create.
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global create: function(ss: SumStats::SumStat);
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## Add data into an observation stream. This should be
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## called when a script has measured some point value.
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##
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## id: The observation stream identifier that the data
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## point represents.
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##
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## key: The key that the value is related to.
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##
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## obs: The data point to send into the stream.
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global observe: function(id: string, key: SumStats::Key, obs: SumStats::Observation);
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## Dynamically request a sumstat key. This function should be
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## used sparingly and not as a replacement for the callbacks
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## from the :zeek:see:`SumStats::SumStat` record. The function is only
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## available for use within "when" statements as an asynchronous
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## function.
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##
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## ss_name: SumStat name.
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##
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## key: The SumStat key being requested.
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##
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## Returns: The result for the requested sumstat key.
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global request_key: function(ss_name: string, key: Key): Result;
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## Helper function to represent a :zeek:type:`SumStats::Key` value as
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## a simple string.
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##
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## key: The metric key that is to be converted into a string.
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##
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## Returns: A string representation of the metric key.
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global key2str: function(key: SumStats::Key): string;
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## Manually end the current epoch for a sumstat. Calling this function will
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## cause the end of the epoch processing of sumstats to start. Note that the
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## epoch will not end immediately - especially in a cluster settings, a number
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## of messages need to be exchanged between the cluster nodes.
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##
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## Note that this function only can be called if the sumstat was created with
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## an epoch time of zero (manual epochs).
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##
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## In a cluster, this function must be called on the manager; it will not have
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## any effect when called on workers.
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##
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## ss_name: SumStat name.
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##
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## Returns: true on success, false on failure. Failures can be: sumstat not found,
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## or sumstat not created for manual epochs.
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global next_epoch: function(ss_name: string): bool;
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}
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# The function prototype for plugins to do calculations.
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type ObserveFunc: function(r: Reducer, val: double, data: Observation, rv: ResultVal);
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redef record Reducer += {
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# Internal use only. Provides a reference back to the related SumStats by its name.
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ssname: string &optional;
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calc_funcs: vector of Calculation &optional;
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};
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# Internal use only. For tracking thresholds per sumstat and key.
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# In the case of a single threshold, 0 means the threshold isn't crossed.
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# In the case of a threshold series, the number tracks the threshold offset.
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global threshold_tracker: table[string] of table[Key] of count;
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function increment_threshold_tracker(ss_name: string, key: Key)
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{
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if ( ss_name !in threshold_tracker )
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threshold_tracker[ss_name] = table();
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if ( key !in threshold_tracker[ss_name] )
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threshold_tracker[ss_name][key] = 0;
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++threshold_tracker[ss_name][key];
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}
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function get_threshold_index(ss_name: string, key: Key): count
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{
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if ( ss_name !in threshold_tracker )
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return 0;
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if ( key !in threshold_tracker[ss_name] )
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return 0;
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return threshold_tracker[ss_name][key];
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}
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# Prototype the hook point for plugins to initialize any result values.
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global init_resultval_hook: hook(r: Reducer, rv: ResultVal);
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# Prototype the hook point for plugins to merge Results.
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global compose_resultvals_hook: hook(result: ResultVal, rv1: ResultVal, rv2: ResultVal);
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# Store of sumstats indexed on the sumstat id.
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global stats_store: table[string] of SumStat = table();
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# Store of reducers indexed on the data point stream id.
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global reducer_store: table[string] of set[Reducer] = table();
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# Store of results indexed on the measurement id.
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global result_store: table[string] of ResultTable = table();
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# Store of threshold information.
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global thresholds_store: table[string, Key] of bool = table();
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# Store the calculations.
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global calc_store: table[Calculation] of ObserveFunc = table();
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# Store the dependencies for Calculations.
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global calc_deps: table[Calculation] of vector of Calculation = table();
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# Hook for registering observation calculation plugins.
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global register_observe_plugins: hook();
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# This is called whenever key values are updated and the new val is given as the
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# `val` argument. It's only prototyped here because cluster and non-cluster have
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# separate implementations.
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global data_added: function(ss: SumStat, key: Key, result: Result);
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# Event that is used to "finish" measurements and adapt the measurement
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# framework for clustered or non-clustered usage.
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global finish_epoch: event(ss: SumStat);
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function next_epoch(ss_name: string): bool
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{
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if ( ss_name !in stats_store )
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return F;
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local ss = stats_store[ss_name];
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if ( ss$epoch != 0secs )
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return F;
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event SumStats::finish_epoch(ss);
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return T;
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}
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function key2str(key: Key): string
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{
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local out = "";
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if ( key?$host )
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out = fmt("%shost=%s", out, key$host);
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if ( key?$str )
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out = fmt("%s%sstr=%s", out, |out|==0 ? "" : ", ", key$str);
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return fmt("sumstats_key(%s)", out);
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}
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function register_observe_plugin(calc: Calculation, func: ObserveFunc)
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{
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calc_store[calc] = func;
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}
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function add_observe_plugin_dependency(calc: Calculation, depends_on: Calculation)
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{
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if ( calc !in calc_deps )
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calc_deps[calc] = vector();
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calc_deps[calc] += depends_on;
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}
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event zeek_init() &priority=100000
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{
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# Call all of the plugin registration hooks
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hook register_observe_plugins();
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}
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function init_resultval(r: Reducer): ResultVal
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{
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local rv: ResultVal = [$begin=network_time(), $end=network_time()];
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hook init_resultval_hook(r, rv);
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return rv;
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}
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function compose_resultvals(rv1: ResultVal, rv2: ResultVal): ResultVal
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{
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local result: ResultVal;
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result$begin = (rv1$begin < rv2$begin) ? rv1$begin : rv2$begin;
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result$end = (rv1$end > rv2$end) ? rv1$end : rv2$end;
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result$num = rv1$num + rv2$num;
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# Run the plugin composition hooks.
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hook compose_resultvals_hook(result, rv1, rv2);
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return result;
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}
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function compose_results(r1: Result, r2: Result): Result
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{
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local result: Result = table();
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for ( id, rv in r1 )
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{
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result[id] = rv;
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}
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for ( id, rv in r2 )
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{
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if ( id in r1 )
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result[id] = compose_resultvals(r1[id], rv);
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else
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result[id] = rv;
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}
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return result;
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}
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function reset(ss: SumStat)
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{
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if ( ss$name in result_store )
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delete result_store[ss$name];
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result_store[ss$name] = table();
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if ( ss$name in threshold_tracker )
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{
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delete threshold_tracker[ss$name];
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threshold_tracker[ss$name] = table();
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}
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}
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# This could potentially recurse forever, but plugin authors
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# should be making sure they aren't causing reflexive dependencies.
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function add_calc_deps(calcs: vector of Calculation, c: Calculation)
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{
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#print fmt("Checking for deps for %s", c);
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for ( i in calc_deps[c] )
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{
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local skip_calc=F;
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for ( j in calcs )
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{
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if ( calcs[j] == calc_deps[c][i] )
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skip_calc=T;
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}
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if ( ! skip_calc )
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{
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if ( calc_deps[c][i] in calc_deps )
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add_calc_deps(calcs, calc_deps[c][i]);
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calcs += calc_deps[c][i];
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#print fmt("add dep for %s [%s] ", c, calc_deps[c][i]);
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}
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}
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}
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function create(ss: SumStat)
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{
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if ( (ss?$threshold || ss?$threshold_series) && ! ss?$threshold_val )
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{
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Reporter::error("SumStats given a threshold with no $threshold_val function");
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}
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stats_store[ss$name] = ss;
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if ( ss?$threshold || ss?$threshold_series )
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threshold_tracker[ss$name] = table();
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for ( reducer in ss$reducers )
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{
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reducer$ssname = ss$name;
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reducer$calc_funcs = vector();
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for ( calc in reducer$apply )
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{
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# Add in dependencies recursively.
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if ( calc in calc_deps )
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add_calc_deps(reducer$calc_funcs, calc);
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# Don't add this calculation to the vector if
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# it was already added by something else as a
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# dependency.
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local skip_calc=F;
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for ( j in reducer$calc_funcs )
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{
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if ( calc == reducer$calc_funcs[j] )
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skip_calc=T;
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}
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if ( ! skip_calc )
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reducer$calc_funcs += calc;
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}
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if ( reducer$stream !in reducer_store )
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reducer_store[reducer$stream] = set();
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add reducer_store[reducer$stream][reducer];
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}
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reset(ss);
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# do not schedule epoch if this is set to manual epochs.
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if ( ss$epoch != 0secs )
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schedule ss$epoch { SumStats::finish_epoch(ss) };
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}
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function observe(id: string, orig_key: Key, obs: Observation)
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{
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if ( id !in reducer_store )
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return;
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# Try to add the data to all of the defined reducers.
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for ( r in reducer_store[id] )
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{
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local key = r?$normalize_key ? r$normalize_key(copy(orig_key)) : orig_key;
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# If this reducer has a predicate, run the predicate
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# and skip this key if the predicate return false.
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if ( r?$pred && ! r$pred(key, obs) )
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next;
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local ss = stats_store[r$ssname];
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# If there is a threshold and no epoch_result callback
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# we don't need to continue counting since the data will
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# never be accessed. This was leading
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# to some state management issues when measuring
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# uniqueness.
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# NOTE: this optimization could need removed in the
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# future if on demand access is provided to the
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# SumStats results.
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if ( ! ss?$epoch_result &&
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r$ssname in threshold_tracker &&
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( ss?$threshold &&
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key in threshold_tracker[r$ssname] &&
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threshold_tracker[r$ssname][key] != 0 ) ||
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( ss?$threshold_series &&
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key in threshold_tracker[r$ssname] &&
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threshold_tracker[r$ssname][key] == |ss$threshold_series| ) )
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{
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next;
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}
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if ( r$ssname !in result_store )
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result_store[r$ssname] = table();
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local results = result_store[r$ssname];
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if ( key !in results )
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results[key] = table();
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local result = results[key];
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if ( id !in result )
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result[id] = init_resultval(r);
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local result_val = result[id];
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++result_val$num;
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# Continually update the $end field.
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result_val$end=network_time();
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# If a string was given, fall back to 1.0 as the value.
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local val = 1.0;
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if ( obs?$num )
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val = obs$num;
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else if ( obs?$dbl )
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val = obs$dbl;
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for ( i in r$calc_funcs )
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calc_store[r$calc_funcs[i]](r, val, obs, result_val);
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data_added(ss, key, result);
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}
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}
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# This function checks if a threshold has been crossed. It is also used as a method to implement
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# mid-break-interval threshold crossing detection for cluster deployments.
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function check_thresholds(ss: SumStat, key: Key, result: Result, modify_pct: double): bool
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{
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if ( ! (ss?$threshold || ss?$threshold_series || ss?$threshold_crossed) )
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return F;
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# Add in the extra ResultVals to make threshold_vals easier to write.
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# This length comparison should work because we just need to make
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# sure that we have the same number of reducers and results.
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if ( |ss$reducers| != |result| )
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{
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for ( reducer in ss$reducers )
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{
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if ( reducer$stream !in result )
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result[reducer$stream] = init_resultval(reducer);
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}
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}
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local watch = ss$threshold_val(key, result);
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if ( modify_pct < 1.0 && modify_pct > 0.0 )
|
|
watch = watch/modify_pct;
|
|
|
|
local t_index = get_threshold_index(ss$name, key);
|
|
|
|
if ( ss?$threshold &&
|
|
t_index == 0 && # Check that the threshold hasn't already been crossed.
|
|
watch >= ss$threshold )
|
|
{
|
|
# Value crossed the threshold.
|
|
return T;
|
|
}
|
|
|
|
if ( ss?$threshold_series &&
|
|
|ss$threshold_series| > t_index && # Check if there are more thresholds.
|
|
watch >= ss$threshold_series[t_index] )
|
|
{
|
|
# A threshold series was given and the value crossed the next
|
|
# value in the series.
|
|
return T;
|
|
}
|
|
|
|
return F;
|
|
}
|
|
|
|
function threshold_crossed(ss: SumStat, key: Key, result: Result)
|
|
{
|
|
# If there is no callback, there is no point in any of this.
|
|
if ( ! ss?$threshold_crossed )
|
|
return;
|
|
|
|
increment_threshold_tracker(ss$name,key);
|
|
|
|
# Add in the extra ResultVals to make threshold_crossed callbacks easier to write.
|
|
if ( |ss$reducers| != |result| )
|
|
{
|
|
for ( reducer in ss$reducers )
|
|
{
|
|
if ( reducer$stream !in result )
|
|
result[reducer$stream] = init_resultval(reducer);
|
|
}
|
|
}
|
|
|
|
ss$threshold_crossed(key, result);
|
|
}
|