dashboard: introduce an emergency stop mode

Add an emergency stop button that can be used by any admin. After it's
clicked two times, syzbot stops all reporting and recoding of new bugs.

It's assumed that the stop mode is revoked by manually deleting an entry
from the database.

1 files changed, 29 insertions, 0 deletions

diff --git a/dashboard/app/api.go b/dashboard/app/api.go
index 2dce92d55..6a84c758b 100644
--- a/dashboard/app/api.go
+++ b/dashboard/app/api.go
@@ -30,6 +30,7 @@ import (
 	"google.golang.org/appengine/v2"
 	db "google.golang.org/appengine/v2/datastore"
 	"google.golang.org/appengine/v2/log"
+	"google.golang.org/appengine/v2/user"
 )
 
 func initAPIHandlers() {
@@ -363,6 +364,10 @@ func addCommitInfoToBugImpl(c context.Context, bug *Bug, com dashapi.Commit) (bo
 }
 
 func apiJobPoll(c context.Context, r *http.Request, payload []byte) (interface{}, error) {
+	if stop, err := emergentlyStopped(c); err != nil || stop {
+		// The bot's operation was aborted. Don't accept new crash reports.
+		return &dashapi.JobPollResp{}, err
+	}
 	req := new(dashapi.JobPollReq)
 	if err := json.Unmarshal(payload, req); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal request: %w", err)
@@ -699,6 +704,10 @@ const (
 )
 
 func apiReportCrash(c context.Context, ns string, r *http.Request, payload []byte) (interface{}, error) {
+	if stop, err := emergentlyStopped(c); err != nil || stop {
+		// The bot's operation was aborted. Don't accept new crash reports.
+		return &dashapi.ReportCrashResp{}, err
+	}
 	req := new(dashapi.Crash)
 	if err := json.Unmarshal(payload, req); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal request: %w", err)
@@ -1632,3 +1641,23 @@ func apiSaveDiscussion(c context.Context, r *http.Request, payload []byte) (inte
 	}
 	return nil, mergeDiscussion(c, d)
 }
+
+func emergentlyStopped(c context.Context) (bool, error) {
+	keys, err := db.NewQuery("EmergencyStop").
+		Limit(1).
+		KeysOnly().
+		GetAll(c, nil)
+	if err != nil {
+		return false, err
+	}
+	return len(keys) > 0, nil
+}
+
+func recordEmergencyStop(c context.Context) error {
+	key := db.NewKey(c, "EmergencyStop", "all", 0, nil)
+	_, err := db.Put(c, key, &EmergencyStop{
+		Time: timeNow(c),
+		User: user.Current(c).Email,
+	})
+	return err
+}