crowdsec/pkg/parser/runtime.go

package parser

/*
 This file contains
 - the runtime parsing routines
*/

import (
	"errors"
	"fmt"
	"reflect"
	"strings"

	"github.com/crowdsecurity/crowdsec/pkg/exprhelpers"
	"github.com/crowdsecurity/crowdsec/pkg/types"

	"strconv"

	"github.com/davecgh/go-spew/spew"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/sirupsen/logrus"
	log "github.com/sirupsen/logrus"

	"github.com/antonmedv/expr"
)

//ECTX : DID YOU SEE THAT GLOBAL, ISN'T IT HUGLY
var ECTX []EnricherCtx

type Parser interface {
	Init(map[string]interface{}) (interface{}, error)
	IsParsable(types.Line) (bool, error)
	Parse(interface{}, types.Line) (map[string]interface{}, error)
}

/* ok, this is kinda experimental, I don't know how bad of an idea it is .. */
func SetTargetByName(target string, value string, evt *types.Event) bool {

	if evt == nil {
		return false
	}

	//it's a hack, we do it for the user
	target = strings.TrimPrefix(target, "evt.")

	log.Debugf("setting target %s to %s", target, value)
	defer func() {
		if r := recover(); r != nil {
			log.Errorf("Runtime error while trying to set '%s' in %s : %+v", target, spew.Sdump(evt), r)
			return
		}
	}()

	iter := reflect.ValueOf(evt).Elem()
	if (iter == reflect.Value{}) || iter.IsZero() {
		log.Tracef("event is nill")
		//event is nill
		return false
	}
	for _, f := range strings.Split(target, ".") {
		/*
		** According to current Event layout we only have to handle struct and map
		 */
		switch iter.Kind() {
		case reflect.Map:
			tmp := iter.MapIndex(reflect.ValueOf(f))
			/*if we're in a map and the field doesn't exist, the user wants to add it :) */
			if (tmp == reflect.Value{}) || tmp.IsZero() {
				log.Debugf("map entry is zero in '%s'", target)
			}
			iter.SetMapIndex(reflect.ValueOf(f), reflect.ValueOf(value))
			return true
		case reflect.Struct:
			tmp := iter.FieldByName(f)
			if !tmp.IsValid() {
				log.Debugf("%s IsValid false", f)
				return false
			}
			iter = tmp
			break
		default:
			log.Errorf("unexpected type %s in '%s'", iter.Kind(), target)
			return false
		}
	}
	//now we should have the final member :)
	if !iter.CanSet() {
		log.Errorf("'%s' can't be set", target)
		return false
	}
	if iter.Kind() != reflect.String {
		log.Errorf("Expected string, got %v when handling '%s'", iter.Kind(), target)
		return false
	}
	iter.Set(reflect.ValueOf(value))
	return true
}

func printStaticTarget(static types.ExtraField) string {

	if static.Method != "" {
		return static.Method
	} else if static.Parsed != "" {
		return fmt.Sprintf(".Parsed[%s]", static.Parsed)
	} else if static.Meta != "" {
		return fmt.Sprintf(".Meta[%s]", static.Meta)
	} else if static.Enriched != "" {
		return fmt.Sprintf(".Enriched[%s]", static.Enriched)
	} else if static.TargetByName != "" {
		return static.TargetByName
	} else {
		return "?"
	}
}

func ProcessStatics(statics []types.ExtraField, p *types.Event, clog *logrus.Entry) error {
	//we have a few cases :
	//(meta||key) + (static||reference||expr)
	var value string

	for _, static := range statics {
		value = ""
		if static.Value != "" {
			value = static.Value
		} else if static.RunTimeValue != nil {
			output, err := expr.Run(static.RunTimeValue, exprhelpers.GetExprEnv(map[string]interface{}{"evt": p}))
			if err != nil {
				clog.Warningf("failed to run RunTimeValue : %v", err)
				continue
			}
			switch out := output.(type) {
			case string:
				value = out
			case int:
				value = strconv.Itoa(out)
			default:
				clog.Fatalf("unexpected return type for RunTimeValue : %T", output)
				return errors.New("unexpected return type for RunTimeValue")
			}
		}

		if value == "" {
			clog.Debugf("Empty value for %s, skip.", printStaticTarget(static))
			continue
		}

		if static.Method != "" {
			processed := false
			/*still way too hackish, but : inject all the results in enriched, and */
			for _, x := range ECTX {
				if fptr, ok := x.Funcs[static.Method]; ok {
					clog.Tracef("Found method '%s'", static.Method)
					ret, err := fptr(value, p, x.RuntimeCtx)
					if err != nil {
						clog.Fatalf("plugin function error : %v", err)
					}
					processed = true
					clog.Debugf("+ Method %s('%s') returned %d entries to merge in .Enriched\n", static.Method, value, len(ret))
					if len(ret) == 0 {
						clog.Debugf("+ Method '%s' empty response on '%s'", static.Method, value)
					}
					for k, v := range ret {
						clog.Debugf("\t.Enriched[%s] = '%s'\n", k, v)
						p.Enriched[k] = v
					}
					break
				} else {
					clog.Warningf("method '%s' doesn't exist", static.Method)
				}
			}
			if !processed {
				clog.Warningf("method '%s' doesn't exist", static.Method)
			}
		} else if static.Parsed != "" {
			clog.Debugf(".Parsed[%s] = '%s'", static.Parsed, value)
			p.Parsed[static.Parsed] = value
		} else if static.Meta != "" {
			clog.Debugf(".Meta[%s] = '%s'", static.Meta, value)
			p.Meta[static.Meta] = value
		} else if static.Enriched != "" {
			clog.Debugf(".Enriched[%s] = '%s'", static.Enriched, value)
			p.Enriched[static.Enriched] = value
		} else if static.TargetByName != "" {
			if !SetTargetByName(static.TargetByName, value, p) {
				clog.Errorf("Unable to set value of '%s'", static.TargetByName)
			} else {
				clog.Debugf("%s = '%s'", static.TargetByName, value)
			}
		} else {
			clog.Fatalf("unable to process static : unknown tartget")
		}

	}
	return nil
}

var NodesHits = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_node_hits",
		Help: "How many time an event entered this node.",
	},
	[]string{"source", "name"},
)

var NodesHitsOk = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_node_hits_ok",
		Help: "How many time an event successfuly exited this node.",
	},
	[]string{"source", "name"},
)

var NodesHitsKo = prometheus.NewCounterVec(
	prometheus.CounterOpts{
		Name: "cs_node_hits_ko",
		Help: "How many time an event unsuccessfuly exited this node.",
	},
	[]string{"source", "name"},
)

func stageidx(stage string, stages []string) int {
	for i, v := range stages {
		if stage == v {
			return i
		}
	}
	return -1
}

func /*(u types.UnixParser)*/ Parse(ctx UnixParserCtx, xp types.Event, nodes []Node) (types.Event, error) {
	var event types.Event = xp

	/* the stage is undefined, probably line is freshly acquired, set to first stage !*/
	if event.Stage == "" && len(ctx.Stages) > 0 {
		event.Stage = ctx.Stages[0]
		log.Debugf("no stage, set to : %s", event.Stage)
	}
	event.Process = false

	if event.Parsed == nil {
		event.Parsed = make(map[string]string)
	}
	if event.Enriched == nil {
		event.Enriched = make(map[string]string)
	}
	if event.Meta == nil {
		event.Meta = make(map[string]string)
	}
	if event.Type == types.LOG {
		log.Tracef("INPUT '%s'", event.Line.Raw)
	}

	for _, stage := range ctx.Stages {
		/* if the node is forward in stages, seek to its stage */
		/* this is for example used by testing system to inject logs in post-syslog-parsing phase*/
		if stageidx(event.Stage, ctx.Stages) > stageidx(stage, ctx.Stages) {
			log.Tracef("skipping stage, we are already at [%s] expecting [%s]", event.Stage, stage)
			continue
		}
		log.Tracef("node stage : %s, current stage : %s", event.Stage, stage)

		/* if the stage is wrong, it means that the log didn't manage "pass" a stage with a onsuccess: next_stage tag */
		if event.Stage != stage {
			log.Debugf("Event not parsed, expected stage '%s' got '%s', abort", stage, event.Stage)
			return types.Event{Process: false}, nil
		}

		isStageOK := false
		for idx, node := range nodes {
			clog := log.WithFields(log.Fields{
				"node-name": node.rn,
				"stage":     event.Stage,
			})
			//Only process current stage's nodes
			if event.Stage != node.Stage {
				continue
			}
			clog.Tracef("Processing node %d/%d -> %s", idx, len(nodes), node.rn)
			if ctx.Profiling {
				node.Profiling = true
			}
			ret, err := node.process(&event, ctx)
			if err != nil {
				clog.Fatalf("Error while processing node : %v", err)
			}
			clog.Tracef("node (%s) ret : %v", node.rn, ret)
			if ret {
				isStageOK = true
			}
			if ret && node.OnSuccess == "next_stage" {
				clog.Debugf("node successful, stop end stage %s", stage)
				break
			}
			//the parsed object moved onto the next phase
			if event.Stage != stage {
				clog.Tracef("node moved stage, break and redo")
				break
			}
		}
		if !isStageOK {
			log.Debugf("Log didn't finish stage %s", event.Stage)
			event.Process = false
			return event, nil
		}

	}

	event.Process = true
	return event, nil

}