Home How to release and renew a lease on an IP address previously obtained through Dynamic Host Configuration Protocol (DHCP)
This is an equivalent of two DOS commands
IPCONFIG /release
IPCONFIG /renew
*|typedef struct _IP_INTERFACE_INFO {
*| LONG NumAdapters;
*| IP_ADAPTER_INDEX_MAP Adapter[1];
*|} IP_INTERFACE_INFO, *PIP_INTERFACE_INFO;
#DEFINE ERROR_SUCCESS 0
#DEFINE MAX_ADAPTER_NAME 128
#DEFINE INTERFACE_INFO_SIZE (MAX_ADAPTER_NAME+4)
DO declare
LOCAL cBuffer, nBufsize, nAdapterCount
nBufsize = 0
cBuffer = ""
* this call usually returns the 122=ERROR_INSUFFICIENT_BUFFER
* with nBufsize set to the required amount of memory
= GetInterfaceInfo(@cBuffer, @nBufsize)
cBuffer = REPLICATE(Chr(0), nBufsize)
IF GetInterfaceInfo(@cBuffer, @nBufsize) <> ERROR_SUCCESS
* failed to obtain the list of the network adapters
RETURN
ENDIF
LOCAL nIndex, cBuffer1, cBuffer2, nAdapterIndex, cAdapterName
* the following works if the number of adapters installed
* on your computer is less than 15 :)
nAdapterCount = ASC(SUBSTR(cBuffer, 1,1))
? "Network adapters found:", nAdapterCount
* proceed with the first adapter found,
* otherwise a cycle should be programmed
cBuffer1 = SUBSTR(cBuffer, 1, INTERFACE_INFO_SIZE)
nAdapterIndex = buf2dword(SUBSTR(cBuffer1, 5,1))
cAdapterName = STRCONV(SUBSTR(cBuffer1, 9),6) && unicode
cAdapterName = STRTRAN(m.cAdapterName, CHR(0), "")
? nAdapterIndex, cAdapterName
cBuffer2 = SUBSTR(cBuffer1, 5)
* the following code is intentionally commented out
* presuming that you are aware of what is going to happen
* uncomment either Release or Renew call
*? IpReleaseAddress(@cBuffer2)
*? IpRenewAddress(@cBuffer2)
* end of main
PROCEDURE declare
DECLARE INTEGER GetInterfaceInfo IN iphlpapi;
STRING @pIfTable, LONG @dwOutBufLen
DECLARE INTEGER IpRenewAddress IN iphlpapi STRING @AdapterInfo
DECLARE INTEGER IpReleaseAddress IN iphlpapi STRING @AdapterInfo
FUNCTION buf2dword(cBuffer)
RETURN Asc(SUBSTR(cBuffer, 1,1)) + ;
BitLShift(Asc(SUBSTR(cBuffer, 2,1)), 8) +;
BitLShift(Asc(SUBSTR(cBuffer, 3,1)), 16) +;
BitLShift(Asc(SUBSTR(cBuffer, 4,1)), 24)