Prominent payload limit error and configurable URL length limit (#27747)

* Added context error handler for MaxBytesError

* Made URL length limit configurable

* Added tests

* Removed an unused function

* Typo

server/public/model/config.go

@@ -112,6 +112,7 @@ const (
 	ServiceSettingsDefaultGiphySdkKeyTest        = "s0glxvzVg9azvPipKxcPLpXV0q1x1fVP"
 	ServiceSettingsDefaultDeveloperFlags         = ""
 	ServiceSettingsDefaultUniqueReactionsPerPost = 50
+	ServiceSettingsDefaultMaxURLLength           = 2048
 	ServiceSettingsMaxUniqueReactionsPerPost     = 500
 
 	TeamSettingsDefaultSiteName              = "Mattermost"
@@ -410,6 +411,7 @@ type ServiceSettings struct {
 	UniqueEmojiReactionLimitPerPost                   *int    `access:"site_posts"`
 	RefreshPostStatsRunTime                           *string `access:"site_users_and_teams"`
 	MaximumPayloadSizeBytes                           *int64  `access:"environment_file_storage,write_restrictable,cloud_restrictable"`
+	MaximumURLLength                                  *int    `access:"environment_file_storage,write_restrictable,cloud_restrictable"`
 }
 
 var MattermostGiphySdkKey string
@@ -921,6 +923,10 @@ func (s *ServiceSettings) SetDefaults(isUpdate bool) {
 	if s.MaximumPayloadSizeBytes == nil {
 		s.MaximumPayloadSizeBytes = NewInt64(300000)
 	}
+
+	if s.MaximumURLLength == nil {
+		s.MaximumURLLength = NewInt(ServiceSettingsDefaultMaxURLLength)
+	}
 }
 
 type ClusterSettings struct {
@@ -4031,6 +4037,10 @@ func (s *ServiceSettings) isValid() *AppError {
 		return NewAppError("Config.IsValid", "model.config.is_valid.max_payload_size.app_error", nil, "", http.StatusBadRequest)
 	}
 
+	if *s.MaximumURLLength <= 0 {
+		return NewAppError("Config.IsValid", "model.config.is_valid.max_url_length.app_error", nil, "", http.StatusBadRequest)
+	}
+
 	if *s.ReadTimeout <= 0 {
 		return NewAppError("Config.IsValid", "model.config.is_valid.read_timeout.app_error", nil, "", http.StatusBadRequest)
 	}