added initialization to the src and dest address when portions of it were not decoded. This corrects a bug preventing proper communication on Ethernet.

bacnet-stack/npdu.c

@@ -211,7 +211,9 @@ int npdu_decode(
     // 1 = DNET, DLEN, and Hop Count present
     // DLEN = 0 denotes broadcast MAC DADR and DADR field is absent
     // DLEN > 0 specifies length of DADR field
-    if (dest && (npdu[1] & BIT5))
+    if (dest)
+    {
+      if (npdu[1] & BIT5)
       {
         len += decode_unsigned16(&npdu[len], &dest->net);
         // DLEN = 0 denotes broadcast MAC DADR and DADR field is absent
@@ -225,12 +227,24 @@ int npdu_decode(
           }
         }
       }
+      else
+      {
+        dest->net = 0;
+        dest->len = 0;
+        for (i = 0; i < MAX_MAC_LEN; i++)
+        {
+          dest->adr[i] = 0;
+        }
+      }
+    }
     // Bit 3: Source specifier where:
     // 0 =  SNET, SLEN, and SADR absent
     // 1 =  SNET, SLEN, and SADR present
     // SLEN = 0 Invalid
     // SLEN > 0 specifies length of SADR field
-    if (src && (npdu[1] & BIT3))
+    if (src)
+    {
+      if (npdu[1] & BIT3)
       {
         len += decode_unsigned16(&npdu[len], &src->net);
         // SLEN = 0 denotes broadcast MAC SADR and SADR field is absent
@@ -244,11 +258,23 @@ int npdu_decode(
           }
         }
       }
+      else
+      {
+        src->net = 0;
+        src->len = 0;
+        for (i = 0; i < MAX_MAC_LEN; i++)
+        {
+          src->adr[i] = 0;
+        }
+      }
+    }
     // The Hop Count field shall be present only if the message is
     // destined for a remote network, i.e., if DNET is present.
     // This is a one-octet field that is initialized to a value of 0xff.
     if (dest && dest->net)
       npdu_data->hop_count = npdu[len++];
+    else
+      npdu_data->hop_count = 0;
     // Indicates that the NSDU conveys a network layer message.
     // Message Type field is present.
     if (npdu_data->network_layer_message)
@@ -259,6 +285,8 @@ int npdu_decode(
       if (npdu_data->network_message_type >= 0x80)
         len += decode_unsigned16(&npdu[len], &npdu_data->vendor_id);
     }
+    else
+      npdu_data->network_message_type = 0;
   }
 
   return len;