Add EventSource plugin

Author: Me No Dev

README.md

@@ -18,6 +18,9 @@ To use this library you need to have the latest git versions of either [ESP8266]
 - Easily extendible to handle any type of content
 - Supports Continue 100
 - Async WebSocket plugin offering different locations without extra servers or ports
+- Async EventSource (ServerSideEvents) plugin to send events to the browser
+- URL Rewrite plugin for conditional and permanent url rewrites
+- ServeStatic plugin that supports cache, Last-Modified, default index and more
 
 ## Important things to remember
 - This is fully asynchronous server and as such does not run on the loop thread.
@@ -65,13 +68,13 @@ To use this library you need to have the latest git versions of either [ESP8266]
 - Two filter callbacks are provided: ```ON_AP_FILTER``` to execute the rewrite when request is made to the AP interface,
   ```ON_SAT_FILTER``` to execute the rewrite when request is made to the STA interface.
 - The ```canHandle``` method is used for handler specific control on whether the requests can be handled
-  and for declaring any interesting headers that the ```Request``` should parse. Decision can be based on request 
+  and for declaring any interesting headers that the ```Request``` should parse. Decision can be based on request
   method, request url, http version, request host/port/target host and get parameters
 - Once a ```Handler``` is attached to given ```Request``` (```canHandle``` returned true)
   that ```Handler``` takes care to receive any file/data upload and attach a ```Response```
   once the ```Request``` has been fully parsed
-- ```Handlers``` are evaluated in the order they are attached to the server. The ```canHandle``` is called only 
-  if the ```Filter``` that was set to the ```Handler``` return true. 
+- ```Handlers``` are evaluated in the order they are attached to the server. The ```canHandle``` is called only
+  if the ```Filter``` that was set to the ```Handler``` return true.
 - The first ```Handler``` that can handle the request is selected, not further ```Filter``` and ```canHandle``` are called.
 
 ### Responses and how do they work
@@ -199,6 +202,14 @@ void handleBody(AsyncWebServerRequest *request, uint8_t *data, size_t len, size_
 ```
 
 ## Responses
+### Redirect to another URL
+```cpp
+//to local url
+request->redirect("/login");
+
+//to external url
+request->redirect("http://esp8266.com");
+```
 
 ### Basic response with HTTP Code
 ```cpp
@@ -417,7 +428,7 @@ request->send(response);
 
 ## Serving static files
 In addition to serving files from SPIFFS as described above, the server provide a dedicated handler that optimize the
-performance of serving files from SPIFFS - ```AsyncStaticWebHandler```. Use ```server.serveStatic()``` function to 
+performance of serving files from SPIFFS - ```AsyncStaticWebHandler```. Use ```server.serveStatic()``` function to
 initialize and add a new instance of ```AsyncStaticWebHandler``` to the server.
 The Handler will not handle the request if the file does not exists, e.g. the server will continue to look for another
 handler that can handle the request.
@@ -656,6 +667,10 @@ const uint8_t flash_binary[] PROGMEM = { 0x01, 0x02, 0x03, 0x04 };
 client->binary(flash_binary, 4);
 ```
 
+## Async Event Source Plugin
+The server includes EventSource (ServerSideEvents) plugin which can be used to send short text events to the browser.
+Difference between EventSource and WebSockets is that EventSource is single direction, text-only protocol.
+
 
 ## Setting up the server
 ```cpp
@@ -664,6 +679,7 @@ client->binary(flash_binary, 4);
 
 AsyncWebServer server(80);
 AsyncWebSocket ws("/ws"); // access at ws://[esp ip]/ws
+AsyncEventSource events("/events"); // event source (server side events)
 
 const char* ssid = "your-ssid";
 const char* password = "your-pass";
@@ -700,6 +716,9 @@ void setup(){
   ws.onEvent(onEvent);
   server.addHandler(&ws);
 
+  // attach AsyncEventSource
+  server.addHandler(&events);
+
   // respond to GET requests on URL /heap
   server.on("/heap", HTTP_GET, [](AsyncWebServerRequest *request){
     request->send(200, "text/plain", String(ESP.getFreeHeap()));
@@ -735,7 +754,11 @@ void setup(){
   server.begin();
 }
 
-void loop(){}
+void loop(){
+  static char temp[128];
+  sprintf(temp, "Seconds since boot: %u", millis()/1000);
+  events.send(temp, "time"); //send event "time"
+}
 ```
 
 ### Methods for controlling websocket connections
@@ -750,7 +773,7 @@ void loop(){}
     ws.enable(true);
 ```
 
-Example of OTA code 
+Example of OTA code
 
 ```arduino
   // OTA callbacks

src/AsyncEventSource.cpp

@@ -0,0 +1,250 @@
+/*
+  Asynchronous WebServer library for Espressif MCUs
+
+  Copyright (c) 2016 Hristo Gochkov. All rights reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+#include "Arduino.h"
+#include "AsyncEventSource.h"
+
+// Client
+
+AsyncEventSourceClient::AsyncEventSourceClient(AsyncWebServerRequest *request, AsyncEventSource *server){
+  _client = request->client();
+  _server = server;
+  next = NULL;
+  //_client->onError([](void *r, AsyncClient* c, int8_t error){ ((AsyncEventSourceClient*)(r))->_onError(error); }, this);
+  //_client->onAck([](void *r, AsyncClient* c, size_t len, uint32_t time){ ((AsyncEventSourceClient*)(r))->_onAck(len, time); }, this);
+  //_client->onPoll([](void *r, AsyncClient* c){ ((AsyncEventSourceClient*)(r))->_onPoll(); }, this);
+  _client->onError(NULL, NULL);
+  _client->onAck(NULL, NULL);
+  _client->onPoll(NULL, NULL);
+  _client->onData(NULL, NULL);
+  _client->onTimeout([](void *r, AsyncClient* c, uint32_t time){ ((AsyncEventSourceClient*)(r))->_onTimeout(time); }, this);
+  _client->onDisconnect([](void *r, AsyncClient* c){ ((AsyncEventSourceClient*)(r))->_onDisconnect(); }, this);
+  _server->_addClient(this);
+  delete request;
+}
+
+AsyncEventSourceClient::~AsyncEventSourceClient(){
+  close();
+}
+
+//void AsyncEventSourceClient::_onAck(size_t len, uint32_t time){}
+//void AsyncEventSourceClient::_onPoll(){}
+//void AsyncEventSourceClient::_onError(int8_t){}
+void AsyncEventSourceClient::_onTimeout(uint32_t time){
+  _client->close(true);
+}
+
+void AsyncEventSourceClient::_onDisconnect(){
+  AsyncClient* cl = _client;
+  _client = NULL;
+  cl->free();
+  delete cl;
+  _server->_handleDisconnect(this);
+}
+
+void AsyncEventSourceClient::close(){
+  if(_client != NULL)
+    _client->close(true);
+}
+
+void AsyncEventSourceClient::send(const char * message, size_t len){
+  if(!_client->canSend()){
+    return;
+  }
+  if(_client->space() < len){
+    return;
+  }
+  _client->write(message, len);
+}
+
+
+// Handler
+
+AsyncEventSource::AsyncEventSource(String url):_url(url){}
+
+AsyncEventSource::~AsyncEventSource(){
+  close();
+}
+
+void AsyncEventSource::_addClient(AsyncEventSourceClient * client){
+  if(_clients == NULL){
+    _clients = client;
+    return;
+  }
+  AsyncEventSourceClient * c = _clients;
+  while(c->next != NULL) c = c->next;
+  c->next = client;
+}
+
+void AsyncEventSource::_handleDisconnect(AsyncEventSourceClient * client){
+  if(_clients == NULL){
+    return;
+  }
+  if(_clients == client){
+    _clients = client->next;
+    delete client;
+    return;
+  }
+  AsyncEventSourceClient * c = _clients;
+  while(c->next != NULL && c->next != client) c = c->next;
+  if(c->next == NULL){
+    return;
+  }
+  c->next = client->next;
+  delete client;
+}
+
+void AsyncEventSource::close(){
+  AsyncEventSourceClient * c = _clients;
+  while(c != NULL){
+    if(c->connected())
+      c->close();
+    c = c->next;
+  }
+}
+
+void AsyncEventSource::send(const char *message, const char *event, uint32_t id, uint32_t reconnect){
+  if(_clients == NULL)
+    return;
+
+  String ev = "";
+
+  if(reconnect){
+    ev += "retry: ";
+    ev += String(reconnect);
+    ev += "\r\n";
+  }
+
+  if(id){
+    ev += "id: ";
+    ev += String(reconnect);
+    ev += "\r\n";
+  }
+
+  if(event != NULL){
+    ev += "event: ";
+    ev += String(event);
+    ev += "\r\n";
+  }
+
+  if(message != NULL){
+    size_t messageLen = strlen(message);
+    char * lineStart = (char *)message;
+    char * lineEnd;
+    do {
+      char * nextN = strchr(lineStart, '\n');
+      char * nextR = strchr(lineStart, '\r');
+      if(nextN == NULL && nextR == NULL){
+        //last line
+        size_t llen = ((char *)message + messageLen) - lineStart;
+        char * ldata = (char *)malloc(llen+1);
+        if(ldata != NULL){
+          memcpy(ldata, lineStart, llen);
+          ldata[llen] = 0;
+          ev += "data: ";
+          ev += ldata;
+          ev += "\r\n\r\n";
+          free(ldata);
+        }
+        lineStart = (char *)message + messageLen;
+      } else {
+        char * nextLine = NULL;
+        if(nextN != NULL && nextR != NULL){
+          if(nextR < nextN){
+            lineEnd = nextR;
+            if(nextN == (nextR + 1))
+              nextLine = nextN + 1;
+            else
+              nextLine = nextR + 1;
+          } else {
+            lineEnd = nextN;
+            if(nextR == (nextN + 1))
+              nextLine = nextR + 1;
+            else
+              nextLine = nextN + 1;
+          }
+        } else if(nextN != NULL){
+          lineEnd = nextN;
+          nextLine = nextN + 1;
+        } else {
+          lineEnd = nextR;
+          nextLine = nextR + 1;
+        }
+
+        size_t llen = lineEnd - lineStart;
+        char * ldata = (char *)malloc(llen+1);
+        if(ldata != NULL){
+          memcpy(ldata, lineStart, llen);
+          ldata[llen] = 0;
+          ev += "data: ";
+          ev += ldata;
+          ev += "\r\n";
+          free(ldata);
+        }
+        lineStart = nextLine;
+        if(lineStart == ((char *)message + messageLen))
+          ev += "\r\n";
+      }
+    } while(lineStart < ((char *)message + messageLen));
+  }
+
+  //os_printf("EVENT_SOURCE:\n%s", ev.c_str());
+
+  AsyncEventSourceClient * c = _clients;
+  while(c != NULL){
+    if(c->connected())
+      c->send(ev.c_str(), ev.length());
+    c = c->next;
+  }
+  ev = String();
+}
+
+bool AsyncEventSource::canHandle(AsyncWebServerRequest *request){
+  if(request->method() != HTTP_GET || !request->url().equals(_url))
+    return false;
+  return true;
+}
+
+void AsyncEventSource::handleRequest(AsyncWebServerRequest *request){
+  request->send(new AsyncEventSourceResponse(this));
+}
+
+// Response
+
+AsyncEventSourceResponse::AsyncEventSourceResponse(AsyncEventSource *server){
+  _server = server;
+  _code = 200;
+  _contentType = "text/event-stream";
+  _sendContentLength = false;
+  addHeader("Cache-Control", "no-cache");
+  addHeader("Connection","keep-alive");
+}
+
+void AsyncEventSourceResponse::_respond(AsyncWebServerRequest *request){
+  String out = _assembleHead(request->version());
+  request->client()->write(out.c_str(), _headLength);
+  _state = RESPONSE_WAIT_ACK;
+}
+
+size_t AsyncEventSourceResponse::_ack(AsyncWebServerRequest *request, size_t len, uint32_t time){
+  if(len){
+    new AsyncEventSourceClient(request, _server);
+  }
+  return 0;
+}