Changed default WhoIs to be Broadcast after seeing problems of unicast I-Am through some BACnet routers. Split out WhoIs into 2 handlers - one for unicast I-Am and one for Broadcast I-Am. Developer can choose which one to use for their default handler.

bacnet-stack/demo/handler/h_whois.c

@@ -40,7 +40,6 @@
 /** @file h_whois.c  Handles Who-Is requests. */
 
 /** Handler for Who-Is requests.
- * @note: Now using Unicast to send I-Am response.
  * @param service_request [in] The received message to be handled.
  * @param service_len [in] Length of the service_request message.
  * @param src [in] The BACNET_ADDRESS of the message's source.
@@ -59,7 +58,7 @@ void handler_who_is(
         whois_decode_service_request(service_request, service_len, &low_limit,
         &high_limit);
     if (len == 0)
-    	Send_I_Am_Unicast(&Handler_Transmit_Buffer[0], src);
+        Send_I_Am(&Handler_Transmit_Buffer[0], src);
     else if (len != -1) {
         /* is my device id within the limits? */
         if (((Device_Object_Instance_Number() >= (uint32_t) low_limit) &&
@@ -68,7 +67,41 @@ void handler_who_is(
             /* BACnet wildcard is the max instance number - everyone responds */
             ((BACNET_MAX_INSTANCE >= (uint32_t) low_limit) &&
                 (BACNET_MAX_INSTANCE <= (uint32_t) high_limit)))
-        	Send_I_Am_Unicast(&Handler_Transmit_Buffer[0], src);
+            Send_I_Am(&Handler_Transmit_Buffer[0], src);
+    }
+
+    return;
+}
+
+/** Handler for Who-Is requests - Unicast (per Addendum 135-2004q).
+ * @param service_request [in] The received message to be handled.
+ * @param service_len [in] Length of the service_request message.
+ * @param src [in] The BACNET_ADDRESS of the message's source.
+ */
+void handler_who_is_unicast(
+    uint8_t * service_request,
+    uint16_t service_len,
+    BACNET_ADDRESS * src)
+{
+    int len = 0;
+    int32_t low_limit = 0;
+    int32_t high_limit = 0;
+
+    (void) src;
+    len =
+        whois_decode_service_request(service_request, service_len, &low_limit,
+        &high_limit);
+    if (len == 0)
+        Send_I_Am_Unicast(&Handler_Transmit_Buffer[0], src);
+    else if (len != -1) {
+        /* is my device id within the limits? */
+        if (((Device_Object_Instance_Number() >= (uint32_t) low_limit) &&
+                (Device_Object_Instance_Number() <= (uint32_t) high_limit))
+            ||
+            /* BACnet wildcard is the max instance number - everyone responds */
+            ((BACNET_MAX_INSTANCE >= (uint32_t) low_limit) &&
+                (BACNET_MAX_INSTANCE <= (uint32_t) high_limit)))
+            Send_I_Am_Unicast(&Handler_Transmit_Buffer[0], src);
     }
 
     return;

bacnet-stack/demo/handler/s_iam.c

@@ -107,7 +107,7 @@ void Send_I_Am(
  * If the src address is not given, the dest address will be
  * a broadcast address.
  * @param buffer [in,out] The buffer to use for building the message.
- * @param src [in] The source address information, if any (may be NULL).
+ * @param src [in] The source address information.
  * @param dest [out] The destination address information.
  * @param npdu_data [out] The NPDU structure describing the message.
  * @return The length of the message in buffer[].

bacnet-stack/include/handlers.h

@@ -59,6 +59,11 @@ extern "C" {
         uint16_t service_len,
         BACNET_ADDRESS * src);
 
+    void handler_who_is_whois(
+        uint8_t * service_request,
+        uint16_t service_len,
+        BACNET_ADDRESS * src);
+    
     void handler_who_has(
         uint8_t * service_request,
         uint16_t service_len,