From 7c546e9606fb7b6c5ff1417bfa11a80ac57fa1c1 Mon Sep 17 00:00:00 2001
From: Tindy X <49061470+tindy2013@users.noreply.github.com>
Date: Thu, 30 Jan 2020 11:10:19 +0800
Subject: [PATCH] Fix a potential loop request bug which may cause server to
 overload

---
 src/webget.cpp             | 2 +-
 src/webserver_libevent.cpp | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/webget.cpp b/src/webget.cpp
index 02cad2f..5add36c 100644
--- a/src/webget.cpp
+++ b/src/webget.cpp
@@ -8,7 +8,7 @@
 extern bool print_debug_info;
 
 //std::string user_agent_str = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36";
-static std::string user_agent_str = "subconverter/latest cURL/7.xx-DEV";
+std::string user_agent_str = "subconverter/latest cURL/7.xx-DEV";
 
 static int writer(char *data, size_t size, size_t nmemb, std::string *writerData)
 {
diff --git a/src/webserver_libevent.cpp b/src/webserver_libevent.cpp
index 353b80e..5bb153b 100644
--- a/src/webserver_libevent.cpp
+++ b/src/webserver_libevent.cpp
@@ -16,6 +16,8 @@
 #include "webserver.h"
 #include "socket.h"
 
+extern std::string user_agent_str;
+
 struct responseRoute
 {
     std::string method;
@@ -76,6 +78,12 @@ void OnReq(evhttp_request *req, void *args)
     int retVal;
     std::string postdata, content_type, return_data;
 
+    if(user_agent_str.compare(evhttp_find_header(req->input_headers, "User-Agent")) == 0)
+    {
+        evhttp_send_error(req, 500, "Loop request detected!");
+        return;
+    }
+
     if(EVBUFFER_LENGTH(req->input_buffer) != 0)
     {
         postdata.assign((char *)EVBUFFER_DATA(req->input_buffer), EVBUFFER_LENGTH(req->input_buffer));