max_error_reason_size limit error reason

config/config.go

@@ -48,6 +48,8 @@ var (
 
 	defaultMaxPayloadSize = ByteSize(1 << 50)
 
+	defaultMaxErrorReasonSize = ByteSize(1 << 50)
+
 	defaultRetryNumber = 0
 )
 
@@ -67,6 +69,9 @@ type Config struct {
 
 	NetworkGroups []NetworkGroups `yaml:"network_groups,omitempty"`
 
+	// Maximum size of error payload
+	MaxErrorReasonSize ByteSize `yaml:"max_error_reason_size,omitempty"`
+
 	Caches []Cache `yaml:"caches,omitempty"`
 
 	ParamGroups []ParamGroup `yaml:"param_groups,omitempty"`
@@ -188,6 +193,10 @@ func (cfg *Config) setDefaults() error {
 		c.setDefaults()
 	}
 
+	if cfg.MaxErrorReasonSize <= 0 {
+		cfg.MaxErrorReasonSize = defaultMaxErrorReasonSize
+	}
+
 	cfg.setServerMaxResponseTime(maxResponseTime)
 
 	return nil

proxy.go

@@ -48,6 +48,7 @@ type reverseProxy struct {
 	hasWildcarded       bool
 	maxIdleConns        int
 	maxIdleConnsPerHost int
+	maxErrorReasonSize  int64
 }
 
 func newReverseProxy(cfgCp *config.ConnectionPool) *reverseProxy {
@@ -451,12 +452,18 @@ func (rp *reverseProxy) serveFromCache(s *scope, srw *statResponseWriter, req *h
 			tmpFileRespWriter.WriteHeader(srw.statusCode)
 		}
 
-		errString, err := toString(reader)
-		if err != nil {
-			log.Errorf("%s failed to get error reason: %s", s, err.Error())
+		var errReason string
+		if contentLength > rp.maxErrorReasonSize {
+			log.Infof("%s: Error reason length (%d) is greater than max error reason size (%d)", s, contentLength, rp.maxErrorReasonSize)
+		} else {
+			errString, err := toString(reader)
+			if err != nil {
+				log.Errorf("%s failed to get error reason: %s", s, err.Error())
+			}
+
+			errReason = fmt.Sprintf("%s %s", failedTransactionPrefix, errString)
 		}
 
-		errReason := fmt.Sprintf("%s %s", failedTransactionPrefix, errString)
 		rp.completeTransaction(s, statusCode, userCache, key, q, errReason)
 
 		// we need to reset the offset since the reader of tmpFileRespWriter was already
@@ -622,6 +629,8 @@ func (rp *reverseProxy) applyConfig(cfg *config.Config) error {
 		return err
 	}
 
+	rp.maxErrorReasonSize = int64(cfg.MaxErrorReasonSize)
+
 	caches := make(map[string]*cache.AsyncCache, len(cfg.Caches))
 	defer func() {
 		// caches is swapped with old caches from rp.caches