Setting Cache-Control: for three types of content

At this point the ETag value for ZIM content is still generated from the
timestamp of the server start-up time.

src/server/etag.cpp

@@ -37,7 +37,7 @@ namespace {
 // into the ETag for ETag::Option opt.
 // IMPORTANT: The characters in all_options must come in sorted order (so that
 // IMPORTANT: isValidOptionsString() works correctly).
-const char all_options[] = "cz";
+const char all_options[] = "Zz";
 
 static_assert(ETag::OPTION_COUNT == sizeof(all_options) - 1, "");
 

src/server/etag.h

@@ -51,7 +51,7 @@ class ETag
 {
   public: // types
     enum Option {
-      CACHEABLE_ENTITY,
+      ZIM_CONTENT,
       COMPRESSED_CONTENT,
       OPTION_COUNT
     };

src/server/internalServer.cpp

@@ -606,11 +606,8 @@ MustacheData InternalServer::get_default_data() const
 bool InternalServer::etag_not_needed(const RequestContext& request) const
 {
   const std::string url = request.get_url();
-  return kiwix::startsWith(url, "/catalog")
-      || url == "/search"
-      || url == "/suggest"
-      || url == "/random"
-      || url == "/catch/external";
+  return kiwix::startsWith(url, "/skin")
+      || url == "/random";
 }
 
 ETag
@@ -761,7 +758,7 @@ std::unique_ptr<Response> InternalServer::handle_skin(const RequestContext& requ
         *this,
         getResource(resourceName),
         getMimeTypeForFile(resourceName));
-    response->set_cacheable();
+    response->set_kind(Response::STATIC_RESOURCE);
     return std::move(response);
   } catch (const ResourceNotFound& e) {
     return HTTP404Response(*this, request)

src/server/response.cpp

@@ -102,6 +102,14 @@ bool compress(std::string &content) {
 }
 
 
+const char* getCacheControlHeader(Response::Kind k)
+{
+  switch(k) {
+    case Response::STATIC_RESOURCE: return "max-age=31536000, immutable";
+    case Response::ZIM_CONTENT:     return "max-age=3600, must-revalidate";
+    default:                        return "max-age=0, must-revalidate";
+  }
+}
 
 } // unnamed namespace
 
@@ -112,6 +120,13 @@ Response::Response(bool verbose)
   add_header(MHD_HTTP_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN, "*");
 }
 
+void Response::set_kind(Kind k)
+{
+  m_kind = k;
+  if ( k == ZIM_CONTENT )
+    m_etag.set_option(ETag::ZIM_CONTENT);
+}
+
 std::unique_ptr<Response> Response::build(const InternalServer& server)
 {
   return std::unique_ptr<Response>(new Response(server.m_verbose.load()));
@@ -122,6 +137,9 @@ std::unique_ptr<Response> Response::build_304(const InternalServer& server, cons
   auto response = Response::build(server);
   response->set_code(MHD_HTTP_NOT_MODIFIED);
   response->m_etag = etag;
+  if ( etag.get_option(ETag::ZIM_CONTENT) ) {
+    response->set_kind(Response::ZIM_CONTENT);
+  }
   if ( etag.get_option(ETag::COMPRESSED_CONTENT) ) {
     response->add_header(MHD_HTTP_HEADER_VARY, "Accept-Encoding");
   }
@@ -355,7 +373,7 @@ MHD_Result Response::send(const RequestContext& request, MHD_Connection* connect
   MHD_Response* response = create_mhd_response(request);
 
   MHD_add_response_header(response, MHD_HTTP_HEADER_CACHE_CONTROL,
-    m_etag.get_option(ETag::CACHEABLE_ENTITY) ? "max-age=2723040, public" : "no-cache, no-store, must-revalidate");
+                          getCacheControlHeader(m_kind));
   const std::string etag = m_etag.get_etag();
   if ( ! etag.empty() )
     MHD_add_response_header(response, MHD_HTTP_HEADER_ETAG, etag.c_str());
@@ -411,7 +429,7 @@ ItemResponse::ItemResponse(bool verbose, const zim::Item& item, const std::strin
   m_mimeType(mimetype)
 {
   m_byteRange = byterange;
-  set_cacheable();
+  set_kind(Response::ZIM_CONTENT);
   add_header(MHD_HTTP_HEADER_CONTENT_TYPE, m_mimeType);
 }
 
@@ -423,14 +441,14 @@ std::unique_ptr<Response> ItemResponse::build(const InternalServer& server, cons
   if (noRange && is_compressible_mime_type(mimetype)) {
     // Return a contentResponse
     auto response = ContentResponse::build(server, item.getData(), mimetype);
-    response->set_cacheable();
+    response->set_kind(Response::ZIM_CONTENT);
     response->m_byteRange = byteRange;
     return std::move(response);
   }
 
   if (byteRange.kind() == ByteRange::RESOLVED_UNSATISFIABLE) {
     auto response = Response::build_416(server, item.getSize());
-    response->set_cacheable();
+    response->set_kind(Response::ZIM_CONTENT);
     return response;
   }
 

src/server/response.h

@@ -45,6 +45,14 @@ class InternalServer;
 class RequestContext;
 
 class Response {
+  public:
+    enum Kind
+    {
+      STATIC_RESOURCE,
+      ZIM_CONTENT,
+      DYNAMIC_CONTENT
+    };
+
   public:
     Response(bool verbose);
     virtual ~Response() = default;
@@ -57,7 +65,7 @@ class Response {
     MHD_Result send(const RequestContext& request, MHD_Connection* connection);
 
     void set_code(int code) { m_returnCode = code; }
-    void set_cacheable() { m_etag.set_option(ETag::CACHEABLE_ENTITY); }
+    void set_kind(Kind k);
     void set_server_id(const std::string& id) { m_etag.set_server_id(id); }
     void add_header(const std::string& name, const std::string& value) { m_customHeaders[name] = value; }
 
@@ -68,6 +76,7 @@ class Response {
     MHD_Response* create_error_response(const RequestContext& request) const;
 
   protected: // data
+    Kind m_kind = DYNAMIC_CONTENT;
     bool m_verbose;
     int m_returnCode;
     ByteRange m_byteRange;

test/server.cpp

@@ -35,7 +35,7 @@ struct Resource
   ResourceKind kind;
   const char* url;
 
-  bool etag_expected() const { return kind != DYNAMIC_CONTENT; }
+  bool etag_expected() const { return kind != STATIC_CONTENT; }
 };
 
 std::ostream& operator<<(std::ostream& out, const Resource& r)
@@ -47,7 +47,7 @@ std::ostream& operator<<(std::ostream& out, const Resource& r)
 typedef std::vector<Resource> ResourceCollection;
 
 const ResourceCollection resources200Compressible{
-  { STATIC_CONTENT,  "/ROOT/" },
+  { DYNAMIC_CONTENT, "/ROOT/" },
 
   { STATIC_CONTENT,  "/ROOT/skin/autoComplete.min.js" },
   { STATIC_CONTENT,  "/ROOT/skin/css/autoComplete.css" },