new: added events.on (and other related commands) to trigger specific actions when an events happens

modules/events_stream/trigger_list.go

@@ -0,0 +1,136 @@
+package events_stream
+
+import (
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strings"
+	"sync"
+
+	"github.com/bettercap/bettercap/session"
+
+	"github.com/antchfx/jsonquery"
+	"github.com/evilsocket/islazy/str"
+	"github.com/evilsocket/islazy/tui"
+)
+
+var reQueryCapture = regexp.MustCompile(`{{([^}]+)}}`)
+
+type Trigger struct {
+	For    string
+	Action string
+}
+
+type TriggerList struct {
+	sync.Mutex
+	triggers map[string]Trigger
+}
+
+func NewTriggerList() *TriggerList {
+	return &TriggerList{
+		triggers: make(map[string]Trigger),
+	}
+}
+
+func (l *TriggerList) Add(tag string, command string) (error, string) {
+	l.Lock()
+	defer l.Unlock()
+
+	idNum := 0
+	command = str.Trim(command)
+
+	for id, t := range l.triggers {
+		if t.For == tag {
+			if t.Action == command {
+				return fmt.Errorf("duplicate: trigger '%s' found for action '%s'", tui.Bold(id), command), ""
+			}
+			idNum++
+		}
+	}
+
+	id := fmt.Sprintf("%s-%d", tag, idNum)
+	l.triggers[id] = Trigger{
+		For:    tag,
+		Action: command,
+	}
+
+	return nil, id
+}
+
+func (l *TriggerList) Del(id string) (err error) {
+	l.Lock()
+	defer l.Unlock()
+	if _, found := l.triggers[id]; found {
+		delete(l.triggers, id)
+	} else {
+		err = fmt.Errorf("trigger '%s' not found", tui.Bold(id))
+	}
+	return err
+}
+
+func (l *TriggerList) Each(cb func(id string, t Trigger)) {
+	l.Lock()
+	defer l.Unlock()
+	for id, t := range l.triggers {
+		cb(id, t)
+	}
+}
+
+func (l *TriggerList) Completer(prefix string) []string {
+	ids := []string{}
+	l.Each(func(id string, t Trigger) {
+		if prefix == "" || strings.HasPrefix(id, prefix) {
+			ids = append(ids, id)
+		}
+	})
+	return ids
+}
+
+func (l *TriggerList) Dispatch(e session.Event) (ident string, cmd string, err error, found bool) {
+	l.Lock()
+	defer l.Unlock()
+
+	for id, t := range l.triggers {
+		if e.Tag == t.For {
+			found = true
+			ident = id
+			// this is ugly but it's also the only way to allow
+			// the user to do this easily - since each event Data
+			// field is an interface and type casting is not possible
+			// via golang default text/template system, we transform
+			// the field to JSON, parse it again and then allow the
+			// user to access it in the command via JSON-Query, example:
+			//
+			// events.on wifi.client.new "wifi.deauth {{Client\mac}}"
+			buf := ([]byte)(nil)
+			doc := (*jsonquery.Node)(nil)
+			cmd = t.Action
+			// parse each {EXPR}
+			for _, m := range reQueryCapture.FindAllString(t.Action, -1) {
+				// parse the event Data field as a JSON objects once
+				if doc == nil {
+					if buf, err = json.Marshal(e.Data); err != nil {
+						err = fmt.Errorf("error while encoding event for trigger %s: %v", tui.Bold(id), err)
+						return
+					} else if doc, err = jsonquery.Parse(strings.NewReader(string(buf))); err != nil {
+						err = fmt.Errorf("error while parsing event for trigger %s: %v", tui.Bold(id), err)
+						return
+					}
+				}
+				// {EXPR} -> EXPR
+				expr := strings.Trim(m, "{}")
+				// use EXPR as a JSON query
+				if node := jsonquery.FindOne(doc, expr); node != nil {
+					cmd = strings.Replace(cmd, m, node.InnerText(), -1)
+				} else {
+					err = fmt.Errorf("error while parsing expressionfor trigger %s: '%s' doesn't resolve any object", tui.Bold(id), expr, expr, err)
+					return
+				}
+			}
+
+			return
+		}
+	}
+
+	return
+}