Add optional support for CORS headers (espressif#2688)

* add support for CORS headers * remove accidental function impl * rename setCORS to enableCORS, and add aliased function enableCrossOrigin

Author: vicatcu

libraries/WebServer/src/WebServer.cpp

@@ -55,6 +55,7 @@ WebServer::WebServer(IPAddress addr, int port)
 , _currentHeaders(nullptr)
 , _contentLength(0)
 , _chunked(false)
+, _corsEnabled(false)
 {
 }
 
@@ -75,6 +76,7 @@ WebServer::WebServer(int port)
 , _currentHeaders(nullptr)
 , _contentLength(0)
 , _chunked(false)
+, _corsEnabled(false)
 {
 }
 
@@ -104,7 +106,7 @@ void WebServer::begin(uint16_t port) {
 
 String WebServer::_extractParam(String& authReq,const String& param,const char delimit){
  int _begin = authReq.indexOf(param);
- if (_begin == -1) 
+ if (_begin == -1)
  return "";
  return authReq.substring(_begin+param.length(),authReq.indexOf(delimit,_begin+param.length()));
 }
@@ -366,6 +368,14 @@ void WebServer::setContentLength(const size_t contentLength) {
  _contentLength = contentLength;
 }
 
+void WebServer::enableCORS(boolean value) {
+ _corsEnabled = value;
+}
+
+void WebServer::enableCrossOrigin(boolean value) {
+ enableCORS(value);
+}
+
 void WebServer::_prepareHeader(String& response, int code, const char* content_type, size_t contentLength) {
  response = String(F("HTTP/1.")) + String(_currentVersion) + ' ';
  response += String(code);
@@ -388,6 +398,9 @@ void WebServer::_prepareHeader(String& response, int code, const char* content_t
  sendHeader(String(F("Accept-Ranges")),String(F("none")));
  sendHeader(String(F("Transfer-Encoding")),String(F("chunked")));
  }
+ if (_corsEnabled) {
+ sendHeader(String(FPSTR("Access-Control-Allow-Origin")), String("*"));
+ }
  sendHeader(String(F("Connection")), String(F("close")));
 
  response += _responseHeaders;
@@ -494,7 +507,7 @@ void WebServer::_streamFileCore(const size_t fileSize, const String & fileName,
  send(200, contentType, "");
 }
 
-String WebServer::pathArg(unsigned int i) { 
+String WebServer::pathArg(unsigned int i) {
  if (_currentHandler != nullptr)
  return _currentHandler->pathArg(i);
  return "";

libraries/WebServer/src/WebServer.h

@@ -122,6 +122,9 @@ class WebServer
  void send_P(int code, PGM_P content_type, PGM_P content);
  void send_P(int code, PGM_P content_type, PGM_P content, size_t contentLength);
 
+ void enableCORS(boolean value = true);
+ void enableCrossOrigin(boolean value = true);
+
  void setContentLength(const size_t contentLength);
  void sendHeader(const String& name, const String& value, bool first = false);
  void sendContent(const String& content);
@@ -130,12 +133,12 @@ class WebServer
 
  static String urlDecode(const String& text);
 
- template<typename T> 
+ template<typename T>
  size_t streamFile(T &file, const String& contentType) {
  _streamFileCore(file.size(), file.name(), contentType);
  return _currentClient.write(file);
  }
- 
+
 protected:
  virtual size_t _currentClientWrite(const char* b, size_t l) { return _currentClient.write( b, l ); }
  virtual size_t _currentClientWrite_P(PGM_P b, size_t l) { return _currentClient.write_P( b, l ); }
@@ -151,7 +154,7 @@ class WebServer
  int _uploadReadByte(WiFiClient& client);
  void _prepareHeader(String& response, int code, const char* content_type, size_t contentLength);
  bool _collectHeader(const char* headerName, const char* headerValue);
- 
+
  void _streamFileCore(const size_t fileSize, const String & fileName, const String & contentType);
 
  String _getRandomHexString();
@@ -163,6 +166,7 @@ class WebServer
  String value;
  };
 
+ boolean _corsEnabled;
  WiFiServer _server;
 
  WiFiClient _currentClient;