Use http header ETag caching for all static content.

Using the md5sum as ETag http header value should enable caching on all static http content.

include/WebApi_webapp.h

@@ -10,4 +10,5 @@ public:
 
 private:
     AsyncWebServer* _server;
+    void responseBinaryDataWithETagCache(AsyncWebServerRequest* request, const String &contentType, const String &contentEncoding, const uint8_t *content, size_t len);
 };

src/WebApi_webapp.cpp

@@ -3,6 +3,7 @@
  * Copyright (C) 2022-2024 Thomas Basler and others
  */
 #include "WebApi_webapp.h"
+#include <MD5Builder.h>
 
 extern const uint8_t file_index_html_start[] asm("_binary_webapp_dist_index_html_gz_start");
 extern const uint8_t file_favicon_ico_start[] asm("_binary_webapp_dist_favicon_ico_start");
@@ -18,62 +19,22 @@ extern const uint8_t file_zones_json_end[] asm("_binary_webapp_dist_zones_json_g
 extern const uint8_t file_app_js_end[] asm("_binary_webapp_dist_js_app_js_gz_end");
 extern const uint8_t file_site_webmanifest_end[] asm("_binary_webapp_dist_site_webmanifest_end");
 
-#ifdef AUTO_GIT_HASH
+void WebApiWebappClass::responseBinaryDataWithETagCache(AsyncWebServerRequest *request, const String &contentType, const String &contentEncoding, const uint8_t *content, size_t len)
-#define ETAG_HTTP_HEADER_VAL "\"" AUTO_GIT_HASH "\"" // ETag value must be between quotes
-#endif
-
-void WebApiWebappClass::init(AsyncWebServer& server, Scheduler& scheduler)
 {
-    _server = &server;
+    auto _md5 = MD5Builder();
+    _md5.begin();
+    _md5.add(const_cast<uint8_t *>(content), len);
+    _md5.calculate();
 
-    _server->on("/", HTTP_GET, [](AsyncWebServerRequest* request) {
+    String expectedEtag;
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "text/html", file_index_html_start, file_index_html_end - file_index_html_start);
+    expectedEtag = "\"";
-        response->addHeader("Content-Encoding", "gzip");
+    expectedEtag += _md5.toString();
-        request->send(response);
+    expectedEtag += "\"";
-    });
 
-    _server->onNotFound([](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "text/html", file_index_html_start, file_index_html_end - file_index_html_start);
-        response->addHeader("Content-Encoding", "gzip");
-        request->send(response);
-    });
-
-    _server->on("/index.html", HTTP_GET, [](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "text/html", file_index_html_start, file_index_html_end - file_index_html_start);
-        response->addHeader("Content-Encoding", "gzip");
-        request->send(response);
-    });
-
-    _server->on("/favicon.ico", HTTP_GET, [](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "image/x-icon", file_favicon_ico_start, file_favicon_ico_end - file_favicon_ico_start);
-        request->send(response);
-    });
-
-    _server->on("/favicon.png", HTTP_GET, [](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "image/png", file_favicon_png_start, file_favicon_png_end - file_favicon_png_start);
-        request->send(response);
-    });
-
-    _server->on("/zones.json", HTTP_GET, [](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "application/json", file_zones_json_start, file_zones_json_end - file_zones_json_start);
-        response->addHeader("Content-Encoding", "gzip");
-        request->send(response);
-    });
-
-    _server->on("/site.webmanifest", HTTP_GET, [](AsyncWebServerRequest* request) {
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "application/json", file_site_webmanifest_start, file_site_webmanifest_end - file_site_webmanifest_start);
-        request->send(response);
-    });
-
-    _server->on("/js/app.js", HTTP_GET, [](AsyncWebServerRequest* request) {
-#ifdef ETAG_HTTP_HEADER_VAL
-        // check client If-None-Match header vs ETag/AUTO_GIT_HASH
     bool eTagMatch = false;
     if (request->hasHeader("If-None-Match")) {
         const AsyncWebHeader* h = request->getHeader("If-None-Match");
-            if (strncmp(ETAG_HTTP_HEADER_VAL, h->value().c_str(), strlen(ETAG_HTTP_HEADER_VAL)) == 0) {
+        eTagMatch = h->value().equals(expectedEtag);
-                eTagMatch = true;
-            }
     }
 
     // begin response 200 or 304
@@ -81,16 +42,57 @@ void WebApiWebappClass::init(AsyncWebServer& server, Scheduler& scheduler)
     if (eTagMatch) {
         response = request->beginResponse(304);
     } else {
-            response = request->beginResponse_P(200, "text/javascript", file_app_js_start, file_app_js_end - file_app_js_start);
+        response = request->beginResponse_P(200, contentType, content, len);
-            response->addHeader("Content-Encoding", "gzip");
+        if (contentEncoding.length() > 0) {
+            response->addHeader("Content-Encoding", contentEncoding);
         }
+    }
+
     // HTTP requires cache headers in 200 and 304 to be identical
     response->addHeader("Cache-Control", "public, must-revalidate");
-        response->addHeader("ETag", ETAG_HTTP_HEADER_VAL);
+    response->addHeader("ETag", expectedEtag);
-#else
+
-        AsyncWebServerResponse* response = request->beginResponse_P(200, "text/javascript", file_app_js_start, file_app_js_end - file_app_js_start);
-        response->addHeader("Content-Encoding", "gzip");
-#endif
     request->send(response);
+}
+
+void WebApiWebappClass::init(AsyncWebServer& server, Scheduler& scheduler)
+{
+    _server = &server;
+
+    /*
+       We don't validate the request header "Accept-Encoding" if gzip compression is supported!
+       We just have the gzipped data available - so we ship them!
+    */
+
+    _server->on("/", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "text/html", "gzip", file_index_html_start, file_index_html_end - file_index_html_start);
+    });
+
+    _server->onNotFound([&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "text/html", "gzip", file_index_html_start, file_index_html_end - file_index_html_start);
+    });
+
+    _server->on("/index.html", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "text/html", "gzip", file_index_html_start, file_index_html_end - file_index_html_start);
+    });
+
+    _server->on("/favicon.ico", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "image/x-icon", "", file_favicon_ico_start, file_favicon_ico_end - file_favicon_ico_start);
+    });
+
+    _server->on("/favicon.png", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "image/png", "", file_favicon_png_start, file_favicon_png_end - file_favicon_png_start);
+    });
+
+    _server->on("/zones.json", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "application/json", "gzip", file_zones_json_start, file_zones_json_end - file_zones_json_start);
+    });
+
+    _server->on("/site.webmanifest", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "application/json", "", file_site_webmanifest_start, file_site_webmanifest_end - file_site_webmanifest_start);
+    });
+
+    _server->on("/js/app.js", HTTP_GET, [&](AsyncWebServerRequest* request) {
+        responseBinaryDataWithETagCache(request, "text/javascript", "gzip", file_app_js_start, file_app_js_end - file_app_js_start);
     });
 }