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Use http header ETag caching for all static content.
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Using the md5sum as ETag http header value should enable caching on all static http content.
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@StefanOberhumer
StefanOberhumer committed Jan 29, 2024
1 parent 21ec72f commit e752c43
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Showing 2 changed files with 58 additions and 55 deletions.
1 change: 1 addition & 0 deletions include/WebApi_webapp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,4 +10,5 @@ class WebApiWebappClass {

private:
AsyncWebServer* _server;
void responseBinaryDataWithETagCache(AsyncWebServerRequest* request, const String &contentType, const String &contentEncoding, const uint8_t *content, size_t len);
};
112 changes: 57 additions & 55 deletions src/WebApi_webapp.cpp
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Expand Up @@ -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");
Expand All @@ -18,79 +19,80 @@ 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
#define ETAG_HTTP_HEADER_VAL "\"" AUTO_GIT_HASH "\"" // ETag value must be between quotes
#endif
void WebApiWebappClass::responseBinaryDataWithETagCache(AsyncWebServerRequest *request, const String &contentType, const String &contentEncoding, const uint8_t *content, size_t len)
{
auto _md5 = MD5Builder();
_md5.begin();
_md5.add(const_cast<uint8_t *>(content), len);
_md5.calculate();

String expectedEtag;
expectedEtag = "\"";
expectedEtag += _md5.toString();
expectedEtag += "\"";

bool eTagMatch = false;
if (request->hasHeader("If-None-Match")) {
const AsyncWebHeader* h = request->getHeader("If-None-Match");
eTagMatch = h->value().equals(expectedEtag);
}

// begin response 200 or 304
AsyncWebServerResponse* response;
if (eTagMatch) {
response = request->beginResponse(304);
} else {
response = request->beginResponse_P(200, contentType, content, len);
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", expectedEtag);

request->send(response);
}

void WebApiWebappClass::init(AsyncWebServer& server, Scheduler& scheduler)
{
_server = &server;

_server->on("/", 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);
});
/*
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->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("/", HTTP_GET, [&](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) {
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->onNotFound([&](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) {
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("/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.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("/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("/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("/favicon.png", HTTP_GET, [&](AsyncWebServerRequest* request) {
responseBinaryDataWithETagCache(request, "image/png", "", file_favicon_png_start, file_favicon_png_end - file_favicon_png_start);
});

_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("/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("/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 = true;
}
}
_server->on("/site.webmanifest", HTTP_GET, [&](AsyncWebServerRequest* request) {
responseBinaryDataWithETagCache(request, "application/json", "", file_site_webmanifest_start, file_site_webmanifest_end - file_site_webmanifest_start);
});

// begin response 200 or 304
AsyncWebServerResponse* response;
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->addHeader("Content-Encoding", "gzip");
}
// 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);
#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);
_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);
});
}

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