From 13579acd8f0f51f2070a7db2fcd4965e97df442a Mon Sep 17 00:00:00 2001
From: Mutzi <root@mattv.de>
Date: Mon, 23 Oct 2023 17:33:19 +0200
Subject: [PATCH] Implemented caching for index.html

---
 lib/CMakeLists.txt |  2 +-
 src/main.cxx       | 41 ++++++++++++++++++++++++++++++++---------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index a990a13..37cce15 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -2,7 +2,7 @@ add_subdirectory(spdlog-1.12.0)
 add_subdirectory(restbed-4.8)
 
 add_custom_command(
-    COMMAND ./configure.py ARGS --amalgamation --disable-shared --minimized-build --enable-modules=argon2fmt,hotp,base32,auto_rng,system_rng,tls13,certstor_system,certstor_flatfile
+    COMMAND ./configure.py ARGS --amalgamation --disable-shared --minimized-build --enable-modules=argon2fmt,hotp,base32,auto_rng,system_rng,tls13,certstor_system,certstor_flatfile,md5
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/Botan-3.2.0
     OUTPUT ${CMAKE_CURRENT_SOURCE_DIR}/Botan-3.2.0/botan_all.cpp ${CMAKE_CURRENT_SOURCE_DIR}/Botan-3.2.0/botan_all.h
 )
diff --git a/src/main.cxx b/src/main.cxx
index d3366bd..d84237a 100644
--- a/src/main.cxx
+++ b/src/main.cxx
@@ -1,5 +1,7 @@
 #include <memory>
 #include <csignal>
+#include <botan_all.h>
+#include <corvusoft/restbed/request.hpp>
 #include <corvusoft/restbed/resource.hpp>
 #include <corvusoft/restbed/session.hpp>
 #include <corvusoft/restbed/settings.hpp>
@@ -26,6 +28,13 @@ int main() {
     spdlog::default_logger()->sinks().push_back(file_sink);
     spdlog::set_level(spdlog::level::trace);
 
+    std::string index_etag;
+    {
+        auto md5_hash = Botan::HashFunction::create_or_throw("MD5");
+        md5_hash->update(index_html_bytes);
+        index_etag = Botan::hex_encode(md5_hash->final());
+    }
+
     auto mrpc_resource = std::make_shared<restbed::Resource>();
     mrpc_resource->set_path("/mrpc");
     Server server{mrpc_resource};
@@ -41,15 +50,29 @@ int main() {
 
     auto index_resource = std::make_shared<restbed::Resource>();
     index_resource->set_path("/");
-    index_resource->set_method_handler("GET", [](const std::shared_ptr<restbed::Session>& s){
-        s->yield(
-            200,
-            index_html_bytes,
-            std::multimap<std::string, std::string>{
-                {"Content-Type", "text/html"},
-                {"Content-Length", std::to_string(index_html_len)}
-            }
-        );
+    index_resource->set_method_handler("GET", [&index_etag](const std::shared_ptr<restbed::Session>& s){
+        auto req = s->get_request();
+        if (req->get_header("If-None-Match", "") == index_etag) {
+            s->yield(
+                304,
+                "",
+                std::multimap<std::string, std::string>{
+                    {"Cache-Control", "no-cache"},
+                    {"ETag", index_etag}
+                }
+            );
+        } else {
+            s->yield(
+                200,
+                index_html_bytes,
+                std::multimap<std::string, std::string>{
+                    {"Content-Type",   "text/html"},
+                    {"Content-Length", std::to_string(index_html_len)},
+                    {"Cache-Control",  "no-cache"},
+                    {"ETag",           index_etag}
+                }
+            );
+        }
     });
 
     auto favicon_resource = std::make_shared<restbed::Resource>();