ETag support for WebServer

libraries/ESP8266WebServer/src/ESP8266WebServer-impl.h

@@ -34,6 +34,7 @@ static const char qop_auth[] PROGMEM = "qop=auth";
 static const char qop_auth_quoted[] PROGMEM = "qop=\"auth\"";
 static const char WWW_Authenticate[] PROGMEM = "WWW-Authenticate";
 static const char Content_Length[] PROGMEM = "Content-Length";
+static const char ETAG_HEADER[] PROGMEM = "If-None-Match";
 
 namespace esp8266webserver {
 
@@ -618,6 +619,20 @@ void ESP8266WebServerTemplate<ServerType>::collectHeaders(const char* headerKeys
   }
 }
 
+template<typename ServerType>
+void ESP8266WebServerETagTemplate<ServerType>::collectHeaders(const char* headerKeys[], const size_t headerKeysCount) {
+  WST::_headerKeysCount = headerKeysCount + 2;
+  if (WST::_currentHeaders){
+    delete[] WST::_currentHeaders;
+  }
+  WST::_currentHeaders = new typename WST::RequestArgument[WST::_headerKeysCount];
+  WST::_currentHeaders[0].key = FPSTR(AUTHORIZATION_HEADER);
+  WST::_currentHeaders[1].key = FPSTR(ETAG_HEADER);
+  for (int i = 2; i < WST::_headerKeysCount; i++){
+      WST::_currentHeaders[i].key = headerKeys[i-2];
+  }
+}
+
 template <typename ServerType>
 const String& ESP8266WebServerTemplate<ServerType>::header(int i) const {
   if (i < _headerKeysCount)
@@ -831,4 +846,37 @@ String ESP8266WebServerTemplate<ServerType>::responseCodeToString(const int code
     return String(r);
 }
 
+template<typename ServerType>
+void ESP8266WebServerETagTemplate<ServerType>::serveStaticETag(const char* uri, FS& fs, const char* path, const char* cache_header){
+  WST::_addRequestHandler(new StaticRequestETagHandler<ServerType>(fs, path, uri, cache_header));
+}
+
+template<typename ServerType>
+void ESP8266WebServerETagTemplate<ServerType>::serveStaticETag(const char* uri, FS& fs, const char * path) {
+
+  File toHash = fs.open(path, "r");
+
+  if(toHash){
+
+    MD5Builder calcMD5;
+    calcMD5.begin();
+
+    calcMD5.addStream(toHash, toHash.size());
+
+    toHash.close();
+
+    calcMD5.calculate();
+
+    uint8_t buff[16];
+
+    calcMD5.getBytes(buff);
+
+    const String etag = "\"" + base64::encode(buff, 16, false) + "\"";
+
+    serveStaticETag(uri, fs, path, etag.c_str());
+
+  }
+
+}
+
 } // namespace

libraries/ESP8266WebServer/src/ESP8266WebServer.h

@@ -300,6 +300,20 @@ class ESP8266WebServerTemplate
   HookFunction     _hook;
 };
 
+
+template<typename ServerType>
+class ESP8266WebServerETagTemplate : public ESP8266WebServerTemplate<ServerType>
+{
+  using WST = ESP8266WebServerTemplate<ServerType>;
+
+  using WST::WST;
+
+  public:
+  void collectHeaders(const char* headerKeys[], const size_t headerKeysCount);
+  void serveStaticETag(const char* uri, FS& fs, const char* path, const char* cache_header);
+  void serveStaticETag(const char* uri, FS& fs, const char* path);
+};
+
 } // namespace
 
 #include "ESP8266WebServer-impl.h"
@@ -308,5 +322,6 @@ class ESP8266WebServerTemplate
 using ESP8266WebServer = esp8266webserver::ESP8266WebServerTemplate<WiFiServer>;
 using RequestHandler = esp8266webserver::RequestHandler<WiFiServer>;
 
+using  ESP8266WebServerETag = esp8266webserver::ESP8266WebServerETagTemplate<WiFiServer>;
 
-#endif //ESP8266WEBSERVER_H
+#endif //ESP8266WEBSERVER_H

libraries/ESP8266WebServer/src/detail/RequestHandlersImpl.h

@@ -165,6 +165,51 @@ class StaticRequestHandler : public RequestHandler<ServerType> {
     size_t _baseUriLength;
 };
 
+template<typename ServerType>
+class StaticRequestETagHandler
+    :
+public StaticRequestHandler<ServerType> {
+
+    using SRH = StaticRequestHandler<ServerType>;
+
+    using SRH::SRH;
+
+    using WebServerType = ESP8266WebServerTemplate<ServerType>;
+
+    public:
+    bool handle(WebServerType& server, HTTPMethod requestMethod, const String & requestUri) override {
+        if (!SRH::canHandle(requestMethod, requestUri)){
+            return false;
+        }
+
+        if(server.header("If-None-Match") == SRH::_cache_header){
+            // Serial.println("Sending 304!!!");
+            server.send(304);
+            return true;
+        }
+
+
+        File f = SRH::_fs.open(SRH::_path, "r");
+
+        if (!f){
+            return false;
+        }
+
+        if (!f.isFile()) {
+            f.close();
+            return false;
+        }
+
+        if (SRH::_cache_header.length() != 0){
+            server.sendHeader("ETag", SRH::_cache_header);
+        }
+
+        server.streamFile(f, SRH::getContentType(SRH::_path), requestMethod);
+        return true;
+    }
+
+};
+
 } // namespace
 
-#endif //REQUESTHANDLERSIMPL_H
+#endif //REQUESTHANDLERSIMPL_H