ETag support for WebServer (#7709)

* implemented with native md5
* testing locals variables
* less memory used, partil refactoring
* reworked serveStatic logic, different handler for File and Directory

Author: imwhocodes

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 {
 
@@ -254,7 +255,18 @@ void ESP8266WebServerTemplate<ServerType>::_addRequestHandler(RequestHandlerType
 
 template <typename ServerType>
 void ESP8266WebServerTemplate<ServerType>::serveStatic(const char* uri, FS& fs, const char* path, const char* cache_header) {
-    _addRequestHandler(new StaticRequestHandler<ServerType>(fs, path, uri, cache_header));
+  bool is_file = false;
+
+  if (fs.exists(path)) {
+    File file = fs.open(path, "r");
+    is_file = file && file.isFile();
+    file.close();
+  }
+
+  if(is_file)
+    _addRequestHandler(new StaticFileRequestHandler<ServerType>(fs, path, uri, cache_header));
+  else
+    _addRequestHandler(new StaticDirectoryRequestHandler<ServerType>(fs, path, uri, cache_header));  
 }
 
 template <typename ServerType>
@@ -606,15 +618,18 @@ const String& ESP8266WebServerTemplate<ServerType>::header(const String& name) c
   return emptyString;
 }
 
-template <typename ServerType>
+
+template<typename ServerType>
 void ESP8266WebServerTemplate<ServerType>::collectHeaders(const char* headerKeys[], const size_t headerKeysCount) {
-  _headerKeysCount = headerKeysCount + 1;
-  if (_currentHeaders)
-     delete[]_currentHeaders;
+  _headerKeysCount = headerKeysCount + 2;
+  if (_currentHeaders){
+    delete[] _currentHeaders;
+  }
   _currentHeaders = new RequestArgument[_headerKeysCount];
   _currentHeaders[0].key = FPSTR(AUTHORIZATION_HEADER);
-  for (int i = 1; i < _headerKeysCount; i++){
-    _currentHeaders[i].key = headerKeys[i-1];
+  _currentHeaders[1].key = FPSTR(ETAG_HEADER);
+  for (int i = 2; i < _headerKeysCount; i++){
+      _currentHeaders[i].key = headerKeys[i-2];
   }
 }
 

libraries/ESP8266WebServer/src/ESP8266WebServer.h

@@ -308,5 +308,4 @@ class ESP8266WebServerTemplate
 using ESP8266WebServer = esp8266webserver::ESP8266WebServerTemplate<WiFiServer>;
 using RequestHandler = esp8266webserver::RequestHandler<WiFiServer>;
 
-
-#endif //ESP8266WEBSERVER_H
+#endif //ESP8266WEBSERVER_H

libraries/ESP8266WebServer/src/detail/RequestHandlersImpl.h

@@ -72,70 +72,82 @@ class StaticRequestHandler : public RequestHandler<ServerType> {
     , _path(path)
     , _cache_header(cache_header)
     {
-        if (fs.exists(path)) {
-            File file = fs.open(path, "r");
-            _isFile = file && file.isFile();
-            file.close();
-        }
-        else {
-            _isFile = false;
-        }
+        DEBUGV("StaticRequestHandler: path=%s uri=%s, cache_header=%s\r\n", path, uri, cache_header == __null ? "" : cache_header);
+    }
 
-        DEBUGV("StaticRequestHandler: path=%s uri=%s isFile=%d, cache_header=%s\r\n", path, uri, _isFile, cache_header == __null ? "" : cache_header);
-        _baseUriLength = _uri.length();
+    bool validMethod(HTTPMethod requestMethod){
+        return (requestMethod == HTTP_GET) || (requestMethod == HTTP_HEAD);
     }
 
-    bool canHandle(HTTPMethod requestMethod, const String& requestUri) override  {
-        if ((requestMethod != HTTP_GET) && (requestMethod != HTTP_HEAD))
-            return false;
+    /* Deprecated version. Please use mime::getContentType instead */
+    static String getContentType(const String& path) __attribute__((deprecated)) {
+        return mime::getContentType(path);
+    }
 
-        if ((_isFile && requestUri != _uri) || !requestUri.startsWith(_uri))
-            return false;
+protected:
+    FS _fs;
+    String _uri;
+    String _path;
+    String _cache_header;
+};
 
-        return true;
+
+template<typename ServerType>
+class StaticDirectoryRequestHandler : public StaticRequestHandler<ServerType> {
+
+    using SRH = StaticRequestHandler<ServerType>;
+    using WebServerType = ESP8266WebServerTemplate<ServerType>;
+
+public:
+    StaticDirectoryRequestHandler(FS& fs, const char* path, const char* uri, const char* cache_header)
+        :
+    SRH(fs, path, uri, cache_header),
+    _baseUriLength{SRH::_uri.length()}
+    {}
+
+    bool canHandle(HTTPMethod requestMethod, const String& requestUri) override {
+        return SRH::validMethod(requestMethod) && requestUri.startsWith(SRH::_uri);
     }
 
     bool handle(WebServerType& server, HTTPMethod requestMethod, const String& requestUri) override {
 
         if (!canHandle(requestMethod, requestUri))
             return false;
 
-        DEBUGV("StaticRequestHandler::handle: request=%s _uri=%s\r\n", requestUri.c_str(), _uri.c_str());
+        DEBUGV("DirectoryRequestHandler::handle: request=%s _uri=%s\r\n", requestUri.c_str(), SRH::_uri.c_str());
 
         String path;
-        path.reserve(_path.length() + requestUri.length() + 32);
-        path = _path;
+        path.reserve(SRH::_path.length() + requestUri.length() + 32);
+        path = SRH::_path;
 
-        if (!_isFile) {
+        // Append whatever follows this URI in request to get the file path.
+        path += requestUri.substring(_baseUriLength);
 
-            // Append whatever follows this URI in request to get the file path.
-            path += requestUri.substring(_baseUriLength);
+        // Base URI doesn't point to a file.
+        // If a directory is requested, look for index file.
+        if (path.endsWith("/"))
+            path += F("index.htm");
 
-            // Base URI doesn't point to a file.
-            // If a directory is requested, look for index file.
-            if (path.endsWith("/"))
-                path += F("index.htm");
-
-            // If neither <blah> nor <blah>.gz exist, and <blah> is a file.htm, try it with file.html instead
-            // For the normal case this will give a search order of index.htm, index.htm.gz, index.html, index.html.gz
-            if (!_fs.exists(path) && !_fs.exists(path + ".gz") && path.endsWith(".htm")) {
-                path += 'l';
-            }
+        // If neither <blah> nor <blah>.gz exist, and <blah> is a file.htm, try it with file.html instead
+        // For the normal case this will give a search order of index.htm, index.htm.gz, index.html, index.html.gz
+        if (!SRH::_fs.exists(path) && !SRH::_fs.exists(path + ".gz") && path.endsWith(".htm")) {
+            path += 'l';
         }
-        DEBUGV("StaticRequestHandler::handle: path=%s, isFile=%d\r\n", path.c_str(), _isFile);
+
+        DEBUGV("DirectoryRequestHandler::handle: path=%s\r\n", path.c_str());
 
         String contentType = mime::getContentType(path);
 
         using namespace mime;
         // look for gz file, only if the original specified path is not a gz.  So part only works to send gzip via content encoding when a non compressed is asked for
         // if you point the the path to gzip you will serve the gzip as content type "application/x-gzip", not text or javascript etc...
-        if (!path.endsWith(FPSTR(mimeTable[gz].endsWith)) && !_fs.exists(path))  {
+        if (!path.endsWith(FPSTR(mimeTable[gz].endsWith)) && !SRH::_fs.exists(path))  {
             String pathWithGz = path + FPSTR(mimeTable[gz].endsWith);
-            if(_fs.exists(pathWithGz))
+            if(SRH::_fs.exists(pathWithGz))
                 path += FPSTR(mimeTable[gz].endsWith);
         }
 
-        File f = _fs.open(path, "r");
+        File f = SRH::_fs.open(path, "r");
         if (!f)
             return false;
 
@@ -144,27 +156,77 @@ class StaticRequestHandler : public RequestHandler<ServerType> {
             return false;
         }
 
-        if (_cache_header.length() != 0)
-            server.sendHeader("Cache-Control", _cache_header);
+        if (SRH::_cache_header.length() != 0)
+            server.sendHeader("Cache-Control", SRH::_cache_header);
 
         server.streamFile(f, contentType, requestMethod);
         return true;
     }
 
-    /* Deprecated version. Please use mime::getContentType instead */
-    static String getContentType(const String& path) __attribute__((deprecated)) {
-        return mime::getContentType(path);
+protected:
+    size_t _baseUriLength;
+};
+
+template<typename ServerType>
+class StaticFileRequestHandler
+    :
+public StaticRequestHandler<ServerType> {
+
+    using SRH = StaticRequestHandler<ServerType>;
+    using WebServerType = ESP8266WebServerTemplate<ServerType>;
+
+public:
+    StaticFileRequestHandler(FS& fs, const char* path, const char* uri, const char* cache_header)
+        :
+    StaticRequestHandler<ServerType>{fs, path, uri, cache_header}
+    {
+        File f = SRH::_fs.open(path, "r");
+        MD5Builder calcMD5;
+        calcMD5.begin();
+        calcMD5.addStream(f, f.size());
+        calcMD5.calculate();
+        calcMD5.getBytes(_ETag_md5);
+        f.close();
+    }
+
+    bool canHandle(HTTPMethod requestMethod, const String& requestUri) override  {
+        return SRH::validMethod(requestMethod) && requestUri == SRH::_uri;
+    }
+
+    bool handle(WebServerType& server, HTTPMethod requestMethod, const String & requestUri) override {
+        if (!canHandle(requestMethod, requestUri))
+            return false;
+
+        const String etag = "\"" + base64::encode(_ETag_md5, 16, false) + "\"";
+
+        if(server.header("If-None-Match") == etag){
+            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("Cache-Control", SRH::_cache_header);
+
+        server.sendHeader("ETag", etag);
+
+        server.streamFile(f, mime::getContentType(SRH::_path), requestMethod);
+        return true;
     }
 
 protected:
-    FS _fs;
-    String _uri;
-    String _path;
-    String _cache_header;
-    bool _isFile;
-    size_t _baseUriLength;
+    uint8_t _ETag_md5[16];       
 };
 
 } // namespace
 
-#endif //REQUESTHANDLERSIMPL_H
+#endif //REQUESTHANDLERSIMPL_H