WIP on GPIO example

src/mesh/MeshPlugin.cpp

@@ -1,5 +1,6 @@
 #include "MeshPlugin.h"
 #include "NodeDB.h"
+#include "MeshService.h"
 #include <assert.h>
 
 std::vector<MeshPlugin *> *MeshPlugin::plugins;
@@ -31,7 +32,7 @@ void MeshPlugin::callPlugins(const MeshPacket &mp)
 
             // Possibly send replies (unless we are handling a locally generated message)
             if (mp.decoded.want_response && mp.from != nodeDB.getNodeNum())
-                pi.sendResponse(mp.from);
+                pi.sendResponse(mp);
 
             DEBUG_MSG("Plugin %s handled=%d\n", pi.name, handled);
             if (handled)
@@ -41,4 +42,28 @@ void MeshPlugin::callPlugins(const MeshPacket &mp)
             DEBUG_MSG("Plugin %s not interested\n", pi.name);
         }
     }
+}
+
+/** Messages can be received that have the want_response bit set.  If set, this callback will be invoked
+ * so that subclasses can (optionally) send a response back to the original sender.  Implementing this method
+ * is optional
+ */
+void MeshPlugin::sendResponse(const MeshPacket &req) {
+    auto r = allocReply();
+    if(r) {
+        DEBUG_MSG("Sending response\n");
+        setReplyTo(r, req);
+        service.sendToMesh(r);
+    }
+    else {
+        DEBUG_MSG("WARNING: Client requested response but this plugin did not provide\n");
+    }
+}
+
+/** set the destination and packet parameters of packet p intended as a reply to a particular "to" packet 
+ * This ensures that if the request packet was sent reliably, the reply is sent that way as well.
+*/
+void setReplyTo(MeshPacket *p, const MeshPacket &to) {
+    p->to = to.from;
+    p->want_ack = to.want_ack;
 }