re: DHCP Server Callout API usage

Aki Tuomi — Sun, 26 Jul 2009 19:25:43 GMT

Few hints for using this:

1. It's easiest if you install Visual Studio C++ Express 2008.

2. Make a project under 'Win32', 'Win32 Project'. Application type = DLL, [x] Export Symbols.

3. Put this stuff into <project name>.cpp

- you can move the includes into "stdafx.h"

4. Compile

If you get error:

error C2065: 'CalloutFile' : undeclared identifier

You need to add

FILE * CalloutFile = NULL;

at the top of the code, after include lines.

If you get error:

error C2065: 'DHCP_OPTION_82' : undeclared identifier

You need to add

#define DHCP_OPTION_82 0x52

at the top of the code, after include lines.

If you get warning:

warning C4996: 'fopen': This function or variable may be unsafe.

You can either remove/comment out line

CalloutFile = fopen("callout.txt", "w");

Or you can change it to

fopen_s(&CalloutFile, "callout.txt", "w");

4. To use it in your DHCP server, you will have to use the 'release' version (in folder release). You'll also have to install C++ Runtime libs. It will not work otherwise.

5. To enable, you'll have to edit your registry

http://msdn.microsoft.com/en-us/library/aa363389%28VS.85%29.aspx

6. Stop, and start DHCP service. Monitor event viewer to see if it failed.

re: DHCP Server Callout API usage

Aki Tuomi — Mon, 27 Jul 2009 10:52:44 GMT

In case you get problems while loading the DLL about not finding the entry point, try adding this to your headers. Please change the OPT82_API into whatever you've used...

#ifdef OPT82_EXPORTS

#define OPT82_API __declspec(dllexport)

#else

#define OPT82_API __declspec(dllimport)

#endif

extern "C" {

OPT82_API DWORD CALLBACK Opt82DhcpAddressDelHook(LPBYTE Packet,DWORD PacketSize,DWORD ControlCode,DWORD IpAddress,DWORD AltAddress,LPVOID Reserved,LPVOID PktContext);

OPT82_API DWORD CALLBACK Opt82DhcpAddressOfferHook(LPBYTE Packet,DWORD PacketSize,DWORD ControlCode, DWORD IpAddress,DWORD AltAddress,DWORD AddrType,DWORD LeaseTime,LPVOID Reserved,LPVOID PktContext);

OPT82_API DWORD CALLBACK Opt82DhcpControlHook(DWORD dwControlCode,LPVOID lpReserved);

OPT82_API DWORD CALLBACK Opt82DhcpDeleteClientHook(DWORD IpAddress, LPBYTE HwAddress,ULONG HwAddressLength, DWORD Reserved,DWORD ClientType);

OPT82_API DWORD CALLBACK Opt82DhcpNewPktHook(LPBYTE* Packet,DWORD* PacketSize,DWORD IpAddress,LPVOID Reserved,LPVOID* PktContext,LPBOOL ProcessIt);

OPT82_API DWORD CALLBACK Opt82DhcpPktDropHook(LPBYTE* Packet,DWORD* PacketSize,DWORD ControlCode, DWORD IpAddress,LPVOID Reserved,LPVOID PktContext);

OPT82_API DWORD CALLBACK Opt82DhcpPktSendHook(LPBYTE* Packet,DWORD* PacketSize,DWORD ControlCode,DWORD IpAddress,LPVOID Reserved,LPVOID PktContext);

OPT82_API DWORD DhcpServerCalloutEntry(LPWSTR ChainDlls,DWORD CalloutVersion,LPDHCP_CALLOUT_TABLE CalloutTbl);

};