From fb3870d68cf0f36fc198d9ed01459fd4950997ec Mon Sep 17 00:00:00 2001
From: Leonid Bugaev <leonsbox@gmail.com>
Date: Thu, 24 Jan 2019 23:47:14 +0100
Subject: [PATCH] Fix --http-allow-header to filter non existent headers

Fix https://github.com/buger/goreplay/issues/604
---
 http_modifier.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/http_modifier.go b/http_modifier.go
index 8ed611e..c9c3cdc 100644
--- a/http_modifier.go
+++ b/http_modifier.go
@@ -98,7 +98,11 @@ func (m *HTTPModifier) Rewrite(payload []byte) (response []byte) {
 		for _, f := range m.config.headerFilters {
 			value := proto.Header(payload, f.name)
 
-			if len(value) > 0 && !f.regexp.Match(value) {
+			if len(value) == 0 {
+                return
+            }
+
+            if !f.regexp.Match(value) {
 				return
 			}
 		}