Added the ability to ask for the BVLC Function Code in the lower layers; particular need was to recognize bcasts and not respond with Reject-Message-to-Network.

bacnet-stack/src/bip.c

@@ -234,6 +234,7 @@ uint16_t bip_receive(
     struct sockaddr_in sin = { 0 };
     socklen_t sin_len = sizeof(sin);
     uint16_t i = 0;
+    int function = 0;
 
     /* Make sure the socket is open */
     if (BIP_Socket < 0)
@@ -273,8 +274,19 @@ uint16_t bip_receive(
     /* the signature of a BACnet/IP packet */
     if (pdu[0] != BVLL_TYPE_BACNET_IP)
         return 0;
-    if ((pdu[1] == BVLC_ORIGINAL_UNICAST_NPDU) ||
-        (pdu[1] == BVLC_ORIGINAL_BROADCAST_NPDU)) {
+    
+    if ( bvlc_for_non_bbmd(&sin, pdu, received_bytes) > 0 )
+    {
+        /* Handled, usually with a NACK. */
+#if PRINT_ENABLED
+        fprintf(stderr, "BIP: BVLC discarded!\n");
+#endif
+        return 0;
+    }
+    
+    function = bvlc_get_function_code();        /* aka, pdu[1] */
+    if ((function == BVLC_ORIGINAL_UNICAST_NPDU) ||
+        (function == BVLC_ORIGINAL_BROADCAST_NPDU)) {
         /* ignore messages from me */
         if ((sin.sin_addr.s_addr == BIP_Address.s_addr) &&
             (sin.sin_port == BIP_Port)) {
@@ -327,7 +339,7 @@ uint16_t bip_receive(
 #endif
             }
         }
-    } else if (pdu[1] == BVLC_FORWARDED_NPDU) {
+    } else if (function == BVLC_FORWARDED_NPDU) {
         memcpy(&sin.sin_addr.s_addr, &pdu[4], 4);
         memcpy(&sin.sin_port, &pdu[8], 2);
         if ((sin.sin_addr.s_addr == BIP_Address.s_addr) &&
@@ -356,14 +368,7 @@ uint16_t bip_receive(
                 pdu_len = 0;
             }
         }
-    } else {
-        /* Handle, usually with a NACK. */
-        bvlc_for_non_bbmd(&sin, pdu, received_bytes);
-#if PRINT_ENABLED
-        fprintf(stderr, "BIP: BVLC discarded!\n");
-#endif
-        pdu_len = 0;
-    }
+    } 
 
     return pdu_len;
 }

bacnet-stack/src/bvlc.c

@@ -51,13 +51,15 @@
  * Foreign Device Registration. 
  */
 
-/* if we are a foreign device, store the
+/** if we are a foreign device, store the
    remote BBMD address/port here in network byte order */
 static struct sockaddr_in Remote_BBMD;
 
-/* result from a client request */
+/** result from a client request */
 BACNET_BVLC_RESULT BVLC_Result_Code = BVLC_RESULT_SUCCESSFUL_COMPLETION;
 
+/** The current BVLC Function Code being handled. */
+BACNET_BVLC_FUNCTION BVLC_Function_Code = BVLC_RESULT;    /* A safe default */
 
 /* Define BBMD_ENABLED to get the functions that a
  * BBMD needs to handle its services.
@@ -823,7 +825,6 @@ uint16_t bvlc_receive(
     struct sockaddr_in original_sin = { 0 };
     struct sockaddr_in dest = { 0 };
     socklen_t sin_len = sizeof(sin);
-    int function_type = 0;
     int received_bytes = 0;
     uint16_t result_code = 0;
     uint16_t i = 0;
@@ -869,12 +870,12 @@ uint16_t bvlc_receive(
     if (npdu[0] != BVLL_TYPE_BACNET_IP) {
         return 0;
     }
-    function_type = npdu[1];
+    BVLC_Function_Code = npdu[1];
     /* decode the length of the PDU - length is inclusive of BVLC */
     (void) decode_unsigned16(&npdu[2], &npdu_len);
     /* subtract off the BVLC header */
     npdu_len -= 4;
-    switch (function_type) {
+    switch (BVLC_Function_Code) {
         case BVLC_RESULT:
             /* Upon receipt of a BVLC-Result message containing a result code
                of X'0000' indicating the successful completion of the
@@ -1234,18 +1235,22 @@ int bvlc_register_with_bbmd(
 
 /** Note any BVLC_RESULT code, or NAK the BVLL message in the unsupported cases.
  * Use this handler when you are not a BBMD.
+ * Sets the BVLC_Function_Code in case it is needed later.
+ * 
  * @param sout  [in] Socket address to send any NAK back to.
  * @param npdu  [in] The received buffer.
  * @param received_bytes [in] How many bytes in npdu[].
+ * @return Non-zero BVLC_RESULT_ code if we sent a response (NAK) to this
+ *      BVLC message.  If zero, may need further processing.
  */ 
-void bvlc_for_non_bbmd(     
+int bvlc_for_non_bbmd(     
         struct sockaddr_in * sout,      
         uint8_t * npdu,     
         uint16_t received_bytes)
 {
     uint16_t result_code = 0; /* aka, BVLC_RESULT_SUCCESSFUL_COMPLETION */
-    uint8_t function_type = npdu[1];    /* The BVLC function */
-    switch (function_type) {
+    BVLC_Function_Code = npdu[1];    /* The BVLC function */
+    switch (BVLC_Function_Code) {
         case BVLC_RESULT:
             if ( received_bytes >= 6) {
                 /* This is the result of our foreign device registration */
@@ -1276,6 +1281,7 @@ void bvlc_for_non_bbmd(
         case BVLC_DISTRIBUTE_BROADCAST_TO_NETWORK:
         	result_code = BVLC_RESULT_DISTRIBUTE_BROADCAST_TO_NETWORK_NAK;
             break;
+        /* case BVLC_FORWARDED_NPDU: */
         /* case BVLC_ORIGINAL_UNICAST_NPDU: */
         /* case BVLC_ORIGINAL_BROADCAST_NPDU: */
         default:
@@ -1300,6 +1306,21 @@ BACNET_BVLC_RESULT bvlc_get_last_result()
     return BVLC_Result_Code;
 }
 
+/** Returns the current BVLL Function Code we are processing.
+ * We have to store this higher layer code for when the lower layers
+ * need to know what it is, especially to differentiate between
+ * BVLC_ORIGINAL_UNICAST_NPDU and BVLC_ORIGINAL_BROADCAST_NPDU.
+ * 
+ * @return A BVLC_ code, such as BVLC_ORIGINAL_UNICAST_NPDU.
+ */
+BACNET_BVLC_FUNCTION bvlc_get_function_code()
+{
+    return BVLC_Function_Code;
+}
+
+
+
+
 #ifdef TEST
 #include <assert.h>
 #include <string.h>