Merge pull request #10 from spark/feature/ack-server-pings

Ack server pings for faster closure of half-open sockets

Author: Zachary Crockett

src/coap.cpp

@@ -35,3 +35,15 @@ CoAPCode::Enum CoAP::code(const unsigned char *message)
     default: return CoAPCode::ERROR;
   }
 }
+
+CoAPType::Enum CoAP::type(const unsigned char *message)
+{
+  switch (message[0] & 0x30)
+  {
+    case 0x00: return CoAPType::CON;
+    case 0x10: return CoAPType::NON;
+    default:
+    case 0x20: return CoAPType::ACK;
+    case 0x30: return CoAPType::RESET;
+  }
+}

src/coap.h

@@ -34,7 +34,8 @@ namespace CoAPMessageType {
     KEY_CHANGE,
     SIGNAL_START,
     SIGNAL_STOP,
-    EMPTY,
+    EMPTY_ACK,
+    PING,
     ERROR
   };
 }
@@ -49,8 +50,18 @@ namespace CoAPCode {
   };
 }
 
+namespace CoAPType {
+  enum Enum {
+    CON,
+    NON,
+    ACK,
+    RESET
+  };
+}
+
 class CoAP
 {
   public:
     static CoAPCode::Enum code(const unsigned char *message);
+    static CoAPType::Enum type(const unsigned char *message);
 };

src/spark_protocol.cpp

@@ -287,7 +287,7 @@ CoAPMessageType::Enum
         case 'u': return CoAPMessageType::UPDATE_BEGIN;
         case 'c': return CoAPMessageType::CHUNK;
         default: break;
-      }  break;
+      } break;
     case CoAPCode::PUT:
       switch (path)
       {
@@ -297,10 +297,13 @@ CoAPMessageType::Enum
           if (buf[8]) return CoAPMessageType::SIGNAL_START;
           else return CoAPMessageType::SIGNAL_STOP;
         default: break;
-      }  break;
+      } break;
     case CoAPCode::EMPTY:
-      return CoAPMessageType::EMPTY;
-      break;
+      switch (CoAP::type(buf))
+      {
+        case CoAPType::CON: return CoAPMessageType::PING;
+        default: return CoAPMessageType::EMPTY_ACK;
+      } break;
     default:
       break;
   }
@@ -449,7 +452,10 @@ int SparkProtocol::variable_value(unsigned char *buf,
 bool SparkProtocol::send_event(const char *event_name, const char *data,
                                int ttl, EventType::Enum event_type)
 {
-  static system_tick_t recent_event_ticks[5] = { -1000, -1000, -1000, -1000, -1000 };
+  static system_tick_t recent_event_ticks[5] = {
+    (system_tick_t) -1000, (system_tick_t) -1000,
+    (system_tick_t) -1000, (system_tick_t) -1000,
+    (system_tick_t) -1000 };
   static int evt_tick_idx = 0;
 
   system_tick_t now = recent_event_ticks[evt_tick_idx] = callback_millis();
@@ -953,6 +959,18 @@ bool SparkProtocol::handle_received_message(void)
       descriptor.ota_upgrade_status_sent();
       break;
 
+    case CoAPMessageType::PING:
+      *msg_to_send = 0;
+      *(msg_to_send + 1) = 16;
+      empty_ack(msg_to_send + 2, queue[2], queue[3]);
+      if (0 > blocking_send(msg_to_send, 18))
+      {
+        // error
+        return false;
+      }
+      break;
+
+    case CoAPMessageType::EMPTY_ACK:
     case CoAPMessageType::ERROR:
     default:
       ; // drop it on the floor