76 lines
2.8 KiB
Go
76 lines
2.8 KiB
Go
package leakybucket
|
|
|
|
import (
|
|
"github.com/antonmedv/expr"
|
|
"github.com/antonmedv/expr/vm"
|
|
|
|
"github.com/crowdsecurity/crowdsec/pkg/exprhelpers"
|
|
"github.com/crowdsecurity/crowdsec/pkg/types"
|
|
)
|
|
|
|
// ResetFilter allows to kill the bucket (without overflowing), if a particular condition is met.
|
|
// An example would be a scenario to detect aggressive crawlers that *do not* fetch any static resources :
|
|
// type : leaky
|
|
// filter: filter: "evt.Meta.log_type == 'http_access-log'
|
|
// reset_filter: evt.Parsed.request endswith '.css'
|
|
// ....
|
|
// Thus, if the bucket receives a request that matches fetching a static resource (here css), it cancels itself
|
|
|
|
type CancelOnFilter struct {
|
|
CancelOnFilter *vm.Program
|
|
CancelOnFilterDebug *exprhelpers.ExprDebugger
|
|
}
|
|
|
|
func (u *CancelOnFilter) OnBucketPour(bucketFactory *BucketFactory) func(types.Event, *Leaky) *types.Event {
|
|
return func(msg types.Event, leaky *Leaky) *types.Event {
|
|
var condition, ok bool
|
|
if u.CancelOnFilter != nil {
|
|
leaky.logger.Tracef("running cancel_on filter")
|
|
output, err := expr.Run(u.CancelOnFilter, exprhelpers.GetExprEnv(map[string]interface{}{"evt": &msg}))
|
|
if err != nil {
|
|
leaky.logger.Warningf("cancel_on error : %s", err)
|
|
return &msg
|
|
}
|
|
//only run debugger expression if condition is false
|
|
if u.CancelOnFilterDebug != nil {
|
|
u.CancelOnFilterDebug.Run(leaky.logger, condition, exprhelpers.GetExprEnv(map[string]interface{}{"evt": &msg}))
|
|
}
|
|
if condition, ok = output.(bool); !ok {
|
|
leaky.logger.Warningf("cancel_on, unexpected non-bool return : %T", output)
|
|
return &msg
|
|
}
|
|
if condition {
|
|
leaky.logger.Debugf("reset_filter matched, kill bucket")
|
|
leaky.Suicide <- true
|
|
return nil //counter intuitively, we need to keep the message so that it doesn't trigger an endless loop
|
|
}
|
|
leaky.logger.Debugf("reset_filter didn't match")
|
|
}
|
|
return &msg
|
|
}
|
|
}
|
|
|
|
func (u *CancelOnFilter) OnBucketOverflow(bucketFactory *BucketFactory) func(*Leaky, types.RuntimeAlert, *Queue) (types.RuntimeAlert, *Queue) {
|
|
return func(leaky *Leaky, alert types.RuntimeAlert, queue *Queue) (types.RuntimeAlert, *Queue) {
|
|
return alert, queue
|
|
}
|
|
}
|
|
|
|
func (u *CancelOnFilter) OnBucketInit(bucketFactory *BucketFactory) error {
|
|
var err error
|
|
|
|
u.CancelOnFilter, err = expr.Compile(bucketFactory.CancelOnFilter, expr.Env(exprhelpers.GetExprEnv(map[string]interface{}{"evt": &types.Event{}})))
|
|
if err != nil {
|
|
bucketFactory.logger.Errorf("reset_filter compile error : %s", err)
|
|
return err
|
|
}
|
|
if bucketFactory.Debug {
|
|
u.CancelOnFilterDebug, err = exprhelpers.NewDebugger(bucketFactory.CancelOnFilter, expr.Env(exprhelpers.GetExprEnv(map[string]interface{}{"evt": &types.Event{}})))
|
|
if err != nil {
|
|
bucketFactory.logger.Errorf("reset_filter debug error : %s", err)
|
|
return err
|
|
}
|
|
}
|
|
return err
|
|
}
|