add bvlc_delete_from_bbmd to unregister as a foreign device and become normal (not foreign) (#1041)

src/bacnet/basic/bbmd/h_bbmd.c

@@ -1269,6 +1269,30 @@ int bvlc_register_with_bbmd(
     return bip_send_mpdu(bbmd_addr, &BVLC_Buffer[0], BVLC_Buffer_Len);
 }
 
+/** Become a normal (non-foreign) device and delete self from a BBMD if
+ * registered
+ * @return Positive number (of bytes sent) on success,
+ *         0 if no delete request is sent, or
+ *         -1 if delete fails.
+ */
+int bvlc_delete_from_bbmd(void)
+{
+    int status;
+    BACNET_IP_ADDRESS addr;
+    BACNET_IP_ADDRESS bbmd_addr;
+    bip_get_addr(&addr);
+    bvlc_address_copy(&bbmd_addr, &Remote_BBMD);
+    memset(&Remote_BBMD, 0, sizeof(Remote_BBMD));
+    Remote_BBMD_TTL_Seconds = 0;
+    status = 0;
+    if (bbmd_addr.port) {
+        BVLC_Buffer_Len = bvlc_encode_delete_foreign_device(
+            &BVLC_Buffer[0], sizeof(BVLC_Buffer), &addr);
+        status = bip_send_mpdu(&Remote_BBMD, &BVLC_Buffer[0], BVLC_Buffer_Len);
+    }
+    return status;
+}
+
 /** Get the remote BBMD address that was used to Register as a foreign device
  * @param bbmd_addr - IPv4 address of BBMD with which to register
  * @return Positive number (of bytes sent) on success,

src/bacnet/basic/bbmd/h_bbmd.h

@@ -94,6 +94,8 @@ BACNET_STACK_EXPORT
 int bvlc_register_with_bbmd(
     const BACNET_IP_ADDRESS *address, uint16_t time_to_live_seconds);
 BACNET_STACK_EXPORT
+int bvlc_delete_from_bbmd(void);
+BACNET_STACK_EXPORT
 void bvlc_remote_bbmd_address(BACNET_IP_ADDRESS *address);
 BACNET_STACK_EXPORT
 uint16_t bvlc_remote_bbmd_lifetime(void);