Validate Event Body for Json Format

Throw Error Message and Bad Request Code if event Body isn't json.

cmd/eventlistenersink/main.go

@@ -118,7 +118,8 @@ func main() {
 	// Listen and serve
 	logger.Infof("Listen and serve on port %s", sinkArgs.Port)
 	mux := http.NewServeMux()
-	mux.HandleFunc("/", r.HandleEvent)
+	eventHandler := http.HandlerFunc(r.HandleEvent)
+	mux.Handle("/", r.IsValidPayload(eventHandler))
 
 	// For handling Liveness Probe
 	// TODO(dibyom): Livness, metrics etc. should be on a separate port

pkg/sink/sink.go

@@ -71,6 +71,8 @@ type Response struct {
 	Namespace string `json:"namespace,omitempty"`
 	// EventID is a uniqueID that gets assigned to each incoming request
 	EventID string `json:"eventID,omitempty"`
+	// ErrorMessage gives message about Error which occurs during event processing
+	ErrorMessage string `json:"errorMessage,omitempty"`
 }
 
 // HandleEvent processes an incoming HTTP event for the event listener.

pkg/sink/validate_payload.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2021 The Tekton Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package sink
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+func (r Sink) IsValidPayload(eventHandler http.Handler) http.Handler {
+	return http.HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
+		payload, err := ioutil.ReadAll(request.Body)
+		request.Body = ioutil.NopCloser(bytes.NewBuffer(payload))
+		if err != nil {
+			r.Logger.Errorf("Error reading event body: %s", err)
+			response.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		var event map[string]interface{}
+		if err := json.Unmarshal([]byte(payload), &event); err != nil {
+			errMsg := fmt.Sprintf("Invalid event body format format: %s", err)
+			r.Logger.Error(errMsg)
+			response.WriteHeader(http.StatusBadRequest)
+			response.Header().Set("Content-Type", "application/json")
+			body := Response{
+				EventListener: r.EventListenerName,
+				Namespace:     r.EventListenerNamespace,
+				ErrorMessage:  errMsg,
+			}
+			if err := json.NewEncoder(response).Encode(body); err != nil {
+				r.Logger.Errorf("failed to write back sink response: %v", err)
+			}
+			return
+		}
+		eventHandler.ServeHTTP(response, request)
+	})
+}

pkg/sink/validate_payload_test.go

@@ -0,0 +1,92 @@
+/*
+Copyright 2021 The Tekton Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package sink
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	triggersv1 "github.com/tektoncd/triggers/pkg/apis/triggers/v1alpha1"
+	"github.com/tektoncd/triggers/test"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestSink_IsValidPayload(t *testing.T) {
+	const defaultELName = "test-el"
+	for _, tc := range []struct {
+		name           string
+		testResources  test.Resources
+		eventBody      []byte
+		wantStatusCode int
+	}{{
+		name: "event with Json Body",
+		testResources: test.Resources{
+			EventListeners: []*triggersv1.EventListener{{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      defaultELName,
+					Namespace: namespace,
+				},
+				Spec: triggersv1.EventListenerSpec{
+					Triggers: []triggersv1.EventListenerTrigger{{
+						TriggerRef: "test",
+					}},
+				},
+			}},
+		},
+		eventBody:      json.RawMessage(`{"head_commit": {"id": "testrevision"}, "repository": {"url": "testurl"}}`),
+		wantStatusCode: http.StatusAccepted,
+	}, {
+		name: "event with non Json Body",
+		testResources: test.Resources{
+			EventListeners: []*triggersv1.EventListener{{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      defaultELName,
+					Namespace: namespace,
+				},
+				Spec: triggersv1.EventListenerSpec{
+					Triggers: []triggersv1.EventListenerTrigger{{
+						TriggerRef: "test",
+					}},
+				},
+			}},
+		},
+		eventBody:      []byte(`<test>xml</test>`),
+		wantStatusCode: http.StatusBadRequest,
+	}} {
+		t.Run(tc.name, func(t *testing.T) {
+			elName := defaultELName
+			if len(tc.testResources.EventListeners) > 0 {
+				elName = tc.testResources.EventListeners[0].Name
+			}
+			sink, _ := getSinkAssets(t, tc.testResources, elName, nil)
+
+			ts := httptest.NewServer(sink.IsValidPayload(http.HandlerFunc(sink.HandleEvent)))
+			defer ts.Close()
+
+			resp, err := http.Post(ts.URL, "application/json", bytes.NewReader(tc.eventBody))
+			if err != nil {
+				t.Fatalf("error making request to eventListener: %s", err)
+			}
+			if resp.StatusCode != tc.wantStatusCode {
+				t.Fatalf("Status code mismatch: got %d, want %d", resp.StatusCode, http.StatusInternalServerError)
+			}
+		})
+	}
+}