From 5ec367b2a1830d04d39459e6dd7023e996624165 Mon Sep 17 00:00:00 2001
From: Klaus Deissner <klaus.deissner@sap.com>
Date: Tue, 13 Apr 2021 18:39:53 +0200
Subject: [PATCH] By default, do not restrict the length of extension attribute
 names

Signed-off-by: Klaus Deissner <klaus.deissner@sap.com>
---
 v2/event/eventcontext_v1.go |  5 ++---
 v2/event/extensions.go      | 25 ++++++++++++++++++++++---
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/v2/event/eventcontext_v1.go b/v2/event/eventcontext_v1.go
index 01f1774eb..6695e1509 100644
--- a/v2/event/eventcontext_v1.go
+++ b/v2/event/eventcontext_v1.go
@@ -1,7 +1,6 @@
 package event
 
 import (
-	"errors"
 	"fmt"
 	"mime"
 	"sort"
@@ -72,8 +71,8 @@ func (ec EventContextV1) ExtensionAs(name string, obj interface{}) error {
 // SetExtension adds the extension 'name' with value 'value' to the CloudEvents context.
 // This function fails if the name doesn't respect the regex ^[a-zA-Z0-9]+$
 func (ec *EventContextV1) SetExtension(name string, value interface{}) error {
-	if !IsExtensionNameValid(name) {
-		return errors.New("bad key, CloudEvents attribute names MUST consist of lower-case letters ('a' to 'z') or digits ('0' to '9') from the ASCII character set")
+	if err := validateExtensionName(name); err != nil {
+		return err
 	}
 
 	name = strings.ToLower(name)
diff --git a/v2/event/extensions.go b/v2/event/extensions.go
index ff19f5cb2..3d0210fb0 100644
--- a/v2/event/extensions.go
+++ b/v2/event/extensions.go
@@ -1,6 +1,8 @@
 package event
 
 import (
+	"errors"
+	"fmt"
 	"strings"
 )
 
@@ -10,6 +12,12 @@ const (
 	DataContentEncodingKey = "datacontentencoding"
 )
 
+var (
+	// This determines the behavior of validateExtensionName(). For MaxExtensionNameLength > 0, an error will be returned,
+	// if len(key) > MaxExtensionNameLength
+	MaxExtensionNameLength = 0
+)
+
 func caseInsensitiveSearch(key string, space map[string]interface{}) (interface{}, bool) {
 	lkey := strings.ToLower(key)
 	for k, v := range space {
@@ -21,13 +29,24 @@ func caseInsensitiveSearch(key string, space map[string]interface{}) (interface{
 }
 
 func IsExtensionNameValid(key string) bool {
-	if len(key) < 1 || len(key) > 20 {
+	if err := validateExtensionName(key); err != nil {
 		return false
 	}
+	return true
+}
+
+func validateExtensionName(key string) error {
+	if len(key) < 1 {
+		return errors.New("bad key, CloudEvents attribute names MUST NOT be empty")
+	}
+	if MaxExtensionNameLength > 0 && len(key) > MaxExtensionNameLength {
+		return fmt.Errorf("bad key, CloudEvents attribute name '%s' is longer than %d characters", key, MaxExtensionNameLength)
+	}
+
 	for _, c := range key {
 		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9')) {
-			return false
+			return errors.New("bad key, CloudEvents attribute names MUST consist of lower-case letters ('a' to 'z') or digits ('0' to '9') from the ASCII character set")
 		}
 	}
-	return true
+	return nil
 }