Fix CORS issues.

* Handle OPTIONS requests in ESP port.
* Add Access-Control-Allow-Headers to all ports.

Author: mrstegeman

ESPWebThingAdapter.h

@@ -58,10 +58,17 @@ class WebThingAdapter {
     DefaultHeaders::Instance().addHeader("Access-Control-Allow-Origin", "*");
     DefaultHeaders::Instance().addHeader("Access-Control-Allow-Methods",
                                          "GET, POST, PUT, DELETE, OPTIONS");
+    DefaultHeaders::Instance().addHeader(
+      "Access-Control-Allow-Headers",
+      "Origin, X-Requested-With, Content-Type, Accept"
+    );
 
     this->server.onNotFound(std::bind(&WebThingAdapter::handleUnknown, this,
                                       std::placeholders::_1));
 
+    this->server.on("/*", HTTP_OPTIONS,
+                    std::bind(&WebThingAdapter::handleOptions, this,
+                              std::placeholders::_1));
     this->server.on("/", HTTP_GET,
                     std::bind(&WebThingAdapter::handleThings, this,
                               std::placeholders::_1));
@@ -333,6 +340,13 @@ class WebThingAdapter {
     request->send(404);
   }
 
+  void handleOptions(AsyncWebServerRequest *request) {
+    if (!verifyHost(request)) {
+      return;
+    }
+    request->send(204);
+  }
+
   void handleThings(AsyncWebServerRequest *request) {
     if (!verifyHost(request)) {
       return;

EthernetWebThingAdapter.h

@@ -411,6 +411,10 @@ class WebThingAdapter {
     client.println("Access-Control-Allow-Origin: *");
     client.println(
         "Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS");
+    client.println(
+      "Access-Control-Allow-Headers: "
+      "Origin, X-Requested-With, Content-Type, Accept"
+    );
     client.println("Content-Type: application/json");
     client.println("Connection: close");
     client.println();

WiFi101WebThingAdapter.h

@@ -397,6 +397,10 @@ class WebThingAdapter {
     client.println("Access-Control-Allow-Origin: *");
     client.println(
         "Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS");
+    client.println(
+      "Access-Control-Allow-Headers: "
+      "Origin, X-Requested-With, Content-Type, Accept"
+    );
     client.println("Content-Type: application/json");
     client.println("Connection: close");
     client.println();

library.json

@@ -2,7 +2,7 @@
     "name": "webthing-arduino",
     "description": "A library for creating Web Things using the Web of Things API. Runs on ESP8266, ESP32, Ethernet, and WiFi101-compatible boards. Compatible with the Mozilla WebThings Gateway.",
     "keywords": "Communication",
-    "version": "0.11.1",
+    "version": "0.11.2",
     "authors": {
         "name": "Mozilla IoT <iot@mozilla.com>"
     },
@@ -14,7 +14,7 @@
     "license": "Mozilla Public License Version 2.0",
     "platforms": "espressif8266,espressif32,atmelavr",
     "dependencies": {
-        "ArduinoJson": "6.13.0"
+        "ArduinoJson": "6.15.0"
     },
     "export": {
         "include":

library.properties

@@ -1,5 +1,5 @@
 name=webthing-arduino
-version=0.11.1
+version=0.11.2
 author=Mozilla IoT <iot@mozilla.com>
 maintainer=James Hobin <hobinjk@gmail.com>
 sentence=A library for creating Web Things using the Web of Things API