Add hook to webserver based on @d-a-v code

libraries/WebServer/examples/HelloServer/HelloServer.ino

@@ -63,7 +63,64 @@ void setup(void) {
   });
 
   server.onNotFound(handleNotFound);
+   /////////////////////////////////////////////////////////
+  // Hook examples
 
+  server.addHook([](const String & method, const String & url, WiFiClient * client, WebServer::ContentTypeFunction contentType) {
+    (void)method;      // GET, PUT, ...
+    (void)url;         // example: /root/myfile.html
+    (void)client;      // the webserver tcp client connection
+    (void)contentType; // contentType(".html") => "text/html"
+    Serial.printf("A useless web hook has passed\n");
+    return CLIENT_REQUEST_CAN_CONTINUE;
+  });
+
+  server.addHook([](const String&, const String & url, WiFiClient*, WebServer::ContentTypeFunction) {
+    if (url.startsWith("/fail")) {
+      Serial.printf("An always failing web hook has been triggered\n");
+      return CLIENT_MUST_STOP;
+    }
+    return CLIENT_REQUEST_CAN_CONTINUE;
+  });
+
+  server.addHook([](const String&, const String & url, WiFiClient * client, WebServer::ContentTypeFunction) {
+    if (url.startsWith("/dump")) {
+      Serial.printf("The dumper web hook is on the run\n");
+
+      // Here the request is not interpreted, so we cannot for sure
+      // swallow the exact amount matching the full request+content,
+      // hence the tcp connection cannot be handled anymore by the
+      // webserver.
+#ifdef STREAMTO_API
+      // we are lucky
+      client->toWithTimeout(Serial, 500);
+#else
+      auto last = millis();
+      while ((millis() - last) < 500) {
+        char buf[32];
+        size_t len = client->read((uint8_t*)buf, sizeof(buf));
+        if (len > 0) {
+          Serial.printf("(<%d> chars)", (int)len);
+          Serial.write(buf, len);
+          last = millis();
+        }
+      }
+#endif
+      // Two choices: return MUST STOP and webserver will close it
+      //                       (we already have the example with '/fail' hook)
+      // or                  IS GIVEN and webserver will forget it
+      // trying with IS GIVEN and storing it on a dumb WiFiClient.
+      // check the client connection: it should not immediately be closed
+      // (make another '/dump' one to close the first)
+      Serial.printf("\nTelling server to forget this connection\n");
+      static WiFiClient forgetme = *client; // stop previous one if present and transfer client refcounter
+      return CLIENT_IS_GIVEN;
+    }
+    return CLIENT_REQUEST_CAN_CONTINUE;
+  });
+
+  // Hook examples
+  /////////////////////////////////////////////////////////
   server.begin();
   Serial.println("HTTP server started");
 }

libraries/WebServer/src/Parsing.cpp

@@ -65,13 +65,13 @@ static char* readBytesWithTimeout(WiFiClient& client, size_t maxLength, size_t&
   return buf;
 }
 
-bool WebServer::_parseRequest(WiFiClient& client) {
+ClientFuture WebServer::_parseRequest(WiFiClient& client) {
   // Read the first line of HTTP request
   String req = client.readStringUntil('\r');
   client.readStringUntil('\n');
   //reset header value
   for (int i = 0; i < _headerKeysCount; ++i) {
-    _currentHeaders[i].value =String();
+    _currentHeaders[i].value.clear();
    }
 
   // First line of HTTP request looks like "GET /path HTTP/1.1"
@@ -80,7 +80,7 @@ bool WebServer::_parseRequest(WiFiClient& client) {
   int addr_end = req.indexOf(' ', addr_start + 1);
   if (addr_start == -1 || addr_end == -1) {
     log_e("Invalid request: %s", req.c_str());
-    return false;
+    return CLIENT_MUST_STOP;
   }
 
   String methodStr = req.substring(0, addr_start);
@@ -95,7 +95,12 @@ bool WebServer::_parseRequest(WiFiClient& client) {
   }
   _currentUri = url;
   _chunked = false;
-
+  if (_hook)
+  {
+    auto whatNow = _hook(methodStr, url, &client, mime::getContentType);
+    if (whatNow != CLIENT_REQUEST_CAN_CONTINUE)
+        return whatNow;
+  }
   HTTPMethod method = HTTP_GET;
   if (methodStr == F("POST")) {
     method = HTTP_POST;
@@ -170,7 +175,7 @@ bool WebServer::_parseRequest(WiFiClient& client) {
       char* plainBuf = readBytesWithTimeout(client, contentLength, plainLength, HTTP_MAX_POST_WAIT);
       if (plainLength < contentLength) {
       	free(plainBuf);
-      	return false;
+      	 return CLIENT_MUST_STOP;
       }
       if (contentLength > 0) {
         if(isEncoded){
@@ -197,7 +202,7 @@ bool WebServer::_parseRequest(WiFiClient& client) {
     if (isForm){
       _parseArguments(searchStr);
       if (!_parseForm(client, boundaryStr, contentLength)) {
-        return false;
+         return CLIENT_MUST_STOP;
       }
     }
   } else {
@@ -230,7 +235,7 @@ bool WebServer::_parseRequest(WiFiClient& client) {
   log_v("Request: %s", url.c_str());
   log_v(" Arguments: %s", searchStr.c_str());
 
-  return true;
+  return CLIENT_REQUEST_CAN_CONTINUE;
 }
 
 bool WebServer::_collectHeader(const char* headerName, const char* headerValue) {

libraries/WebServer/src/WebServer.cpp

@@ -306,34 +306,53 @@ void WebServer::handleClient() {
     case HC_WAIT_READ:
       // Wait for data from client to become available
       if (_currentClient.available()) {
-        if (_parseRequest(_currentClient)) {
+        switch (_parseRequest(_currentClient))
+            {
+            case CLIENT_REQUEST_CAN_CONTINUE:
           // because HTTP_MAX_SEND_WAIT is expressed in milliseconds,
           // it must be divided by 1000
-          _currentClient.setTimeout(HTTP_MAX_SEND_WAIT / 1000);
-          _contentLength = CONTENT_LENGTH_NOT_SET;
-          _handleRequest();
-
-// Fix for issue with Chrome based browsers: https://github.com/espressif/arduino-esp32/issues/3652
-//           if (_currentClient.connected()) {
-//             _currentStatus = HC_WAIT_CLOSE;
-//             _statusChange = millis();
-//             keepCurrentClient = true;
-//           }
-        }
+              _currentClient.setTimeout(HTTP_MAX_SEND_WAIT / 1000);
+              _contentLength = CONTENT_LENGTH_NOT_SET;
+              _handleRequest();
+              /* fallthrough */
+             case CLIENT_REQUEST_IS_HANDLED://log_v
+                if (_currentClient.connected() || _currentClient.available()) {
+                   _currentStatus = HC_WAIT_CLOSE;
+                    _statusChange = millis();
+                    keepCurrentClient = true;
+                } else
+                log_v("webserver: peer has closed after served");
+                break;
+              case CLIENT_MUST_STOP:
+                log_v("Close client\n");
+                _currentClient.stop();
+                break;
+              case CLIENT_IS_GIVEN:
+                // client must not be stopped but must not be handled here anymore
+                // (example: tcp connection given to websocket)
+                log_v("Give client\n");
+                break;
+            } // switch _parseRequest()
       } else { // !_currentClient.available()
         if (millis() - _statusChange <= HTTP_MAX_DATA_WAIT) {
           keepCurrentClient = true;
         }
-        callYield = true;
+         else
+          log_v("webserver: closing after read timeout\n");
+          callYield = true;
       }
       break;
     case HC_WAIT_CLOSE:
       // Wait for client to close the connection
-      if (millis() - _statusChange <= HTTP_MAX_CLOSE_WAIT) {
+      if (!_server.available() && (millis() - _statusChange <= HTTP_MAX_CLOSE_WAIT)) {
         keepCurrentClient = true;
         callYield = true;
+        if (_currentClient.available())
+            // continue serving current client
+            _currentStatus = HC_WAIT_READ;
       }
-    }
+      break;
+    } // switch _currentStatus
   }
 
   if (!keepCurrentClient) {

libraries/WebServer/src/WebServer.h

@@ -34,6 +34,7 @@ enum HTTPUploadStatus { UPLOAD_FILE_START, UPLOAD_FILE_WRITE, UPLOAD_FILE_END,
                         UPLOAD_FILE_ABORTED };
 enum HTTPClientStatus { HC_NONE, HC_WAIT_READ, HC_WAIT_CLOSE };
 enum HTTPAuthMethod { BASIC_AUTH, DIGEST_AUTH };
+enum ClientFuture { CLIENT_REQUEST_CAN_CONTINUE, CLIENT_REQUEST_IS_HANDLED, CLIENT_MUST_STOP, CLIENT_IS_GIVEN };
 
 #define HTTP_DOWNLOAD_UNIT_SIZE 1436
 
@@ -49,6 +50,8 @@ enum HTTPAuthMethod { BASIC_AUTH, DIGEST_AUTH };
 #define CONTENT_LENGTH_UNKNOWN ((size_t) -1)
 #define CONTENT_LENGTH_NOT_SET ((size_t) -2)
 
+#define WEBSERVER_HAS_HOOK 1
+
 class WebServer;
 
 typedef struct {
@@ -73,7 +76,8 @@ class WebServer
   WebServer(IPAddress addr, int port = 80);
   WebServer(int port = 80);
   virtual ~WebServer();
-
+  typedef String (*ContentTypeFunction) (const String&);
+  using HookFunction = std::function<ClientFuture(const String& method, const String& url, WiFiClient* client, ContentTypeFunction contentType)>;
   virtual void begin();
   virtual void begin(uint16_t port);
   virtual void handleClient();
@@ -141,14 +145,26 @@ class WebServer
     _streamFileCore(file.size(), file.name(), contentType);
     return _currentClient.write(file);
   }
-
+  void addHook (HookFunction hook) {
+    if (_hook) {
+      auto previousHook = _hook;
+      _hook = [previousHook, hook](const String& method, const String& url, WiFiClient* client, ContentTypeFunction contentType) {
+          auto whatNow = previousHook(method, url, client, contentType);
+          if (whatNow == CLIENT_REQUEST_CAN_CONTINUE)
+            return hook(method, url, client, contentType);
+          return whatNow;
+        };
+    } else {
+      _hook = hook;
+    }
+  }
 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 ); }
   void _addRequestHandler(RequestHandler* handler);
   void _handleRequest();
   void _finalizeResponse();
-  bool _parseRequest(WiFiClient& client);
+  ClientFuture  _parseRequest(WiFiClient& client);
   void _parseArguments(String data);
   static String _responseCodeToString(int code);
   bool _parseForm(WiFiClient& client, String boundary, uint32_t len);
@@ -159,7 +175,7 @@ class WebServer
   bool _collectHeader(const char* headerName, const char* headerValue);
 
   void _streamFileCore(const size_t fileSize, const String & fileName, const String & contentType);
-
+  
   String _getRandomHexString();
   // for extracting Auth parameters
   String _extractParam(String& authReq,const String& param,const char delimit = '"');
@@ -204,7 +220,7 @@ class WebServer
   String           _snonce;  // Store noance and opaque for future comparison
   String           _sopaque;
   String           _srealm;  // Store the Auth realm between Calls
-
+  HookFunction     _hook;
 };
 
 

libraries/WebServer/src/detail/RequestHandlersImpl.h

@@ -102,7 +102,7 @@ class StaticRequestHandler : public RequestHandler {
         }
         log_v("StaticRequestHandler::handle: path=%s, isFile=%d\r\n", path.c_str(), _isFile);
 
-        String contentType = getContentType(path);
+        String contentType = mime::getContentType(path);
 
         // 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...
@@ -123,21 +123,6 @@ class StaticRequestHandler : public RequestHandler {
         return true;
     }
 
-    static String getContentType(const String& path) {
-        char buff[sizeof(mimeTable[0].mimeType)];
-        // Check all entries but last one for match, return if found
-        for (size_t i=0; i < sizeof(mimeTable)/sizeof(mimeTable[0])-1; i++) {
-            strcpy_P(buff, mimeTable[i].endsWith);
-            if (path.endsWith(buff)) {
-                strcpy_P(buff, mimeTable[i].mimeType);
-                return String(buff);
-            }
-        }
-        // Fall-through and just return default type
-        strcpy_P(buff, mimeTable[sizeof(mimeTable)/sizeof(mimeTable[0])-1].mimeType);
-        return String(buff);
-    }
-
 protected:
     FS _fs;
     String _uri;

libraries/WebServer/src/detail/mimetable.cpp

@@ -1,5 +1,6 @@
 #include "mimetable.h"
 #include "pgmspace.h"
+#include "WString.h"
 
 namespace mime
 {
@@ -32,4 +33,19 @@ const Entry mimeTable[maxType] =
     { "", "application/octet-stream" } 
 };
 
+    String getContentType(const String& path) {
+        char buff[sizeof(mimeTable[0].mimeType)];
+        // Check all entries but last one for match, return if found
+        for (size_t i=0; i < sizeof(mimeTable)/sizeof(mimeTable[0])-1; i++) {
+            strcpy_P(buff, mimeTable[i].endsWith);
+            if (path.endsWith(buff)) {
+                strcpy_P(buff, mimeTable[i].mimeType);
+                return String(buff);
+            }
+        }
+        // Fall-through and just return default type
+        strcpy_P(buff, mimeTable[sizeof(mimeTable)/sizeof(mimeTable[0])-1].mimeType);
+        return String(buff);
+    }
+
 }

libraries/WebServer/src/detail/mimetable.h

@@ -1,6 +1,6 @@
 #ifndef __MIMETABLE_H__
 #define __MIMETABLE_H__
-
+class String;
 
 namespace mime
 {
@@ -41,6 +41,7 @@ struct Entry
 
 
 extern const Entry mimeTable[maxType];
+String getContentType(const String& path);
 }