Added binary data type detection (#631)

* Added binary data type detection
Added base64 encoding for binary data types

* Update utils.go

Co-authored-by: Artur Souza <artursouza.ms@outlook.com>

contenttype/utils.go

@@ -24,6 +24,15 @@ func IsJSONContentType(contentType string) bool {
 	return isContentType(contentType, JSONContentType)
 }
 
+// IsStringContentType determines if content type is string
+func IsStringContentType(contentType string) bool {
+	if strings.HasPrefix(strings.ToLower(contentType), "text/") {
+		return true
+	}
+
+	return isContentType(contentType, "application/xml")
+}
+
 func isContentType(contentType string, expected string) bool {
 	lowerContentType := strings.ToLower(contentType)
 	if lowerContentType == expected {

pubsub/envelope.go

@@ -6,6 +6,7 @@
 package pubsub
 
 import (
+	"encoding/base64"
 	"fmt"
 	"time"
 
@@ -57,8 +58,10 @@ func NewCloudEventsEnvelope(id, source, eventType, subject string, topic string,
 	var err error
 	if contrib_contenttype.IsJSONContentType(dataContentType) {
 		err = jsoniter.Unmarshal(data, &ceData)
-	} else {
+	} else if contrib_contenttype.IsStringContentType(dataContentType) {
 		ceData = string(data)
+	} else {
+		ceData = base64.StdEncoding.EncodeToString(data)
 	}
 
 	if err != nil {

pubsub/envelope_test.go

@@ -6,6 +6,7 @@
 package pubsub
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"math"
@@ -198,3 +199,9 @@ func TestNewFromExisting(t *testing.T) {
 		assert.Error(t, err)
 	})
 }
+
+func TestCreateFromBinaryPayload(t *testing.T) {
+	base64Encoding := base64.StdEncoding.EncodeToString([]byte{0x1})
+	envelope := NewCloudEventsEnvelope("", "", "", "", "", "", "application/octet-stream", []byte{0x1}, "trace")
+	assert.Equal(t, base64Encoding, envelope[DataField])
+}