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/* Benjamin DELPY `gentilkiwi`
https://blog.gentilkiwi.com
benjamin@gentilkiwi.com
Licence : https://creativecommons.org/licenses/by/4.0/
*/
#include "kdhcp.h"
HMODULE kdhcp_nextLibrary = NULL;
LPDHCP_NEWPKT kdhcp_nextLibraryCalloutNewPkt = NULL;
BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
if((ul_reason_for_call == DLL_PROCESS_DETACH) && kdhcp_nextLibrary)
FreeLibrary(kdhcp_nextLibrary);
return TRUE;
}
DWORD CALLBACK kdhcp_DhcpServerCalloutEntry(IN LPWSTR ChainDlls, IN DWORD CalloutVersion, IN OUT LPDHCP_CALLOUT_TABLE CalloutTbl)
{
LPDHCP_ENTRY_POINT_FUNC nextEntry;
RtlZeroMemory(CalloutTbl, sizeof(DHCP_CALLOUT_TABLE));
if(ChainDlls)
if(kdhcp_nextLibrary = LoadLibrary(ChainDlls))
if(nextEntry = (LPDHCP_ENTRY_POINT_FUNC) GetProcAddress(kdhcp_nextLibrary, DHCP_CALLOUT_ENTRY_POINT))
nextEntry(ChainDlls + lstrlenW(ChainDlls) + 1, CalloutVersion, CalloutTbl);
if(CalloutTbl->DhcpNewPktHook)
kdhcp_nextLibraryCalloutNewPkt = CalloutTbl->DhcpNewPktHook;
CalloutTbl->DhcpNewPktHook = kdhcp_DhcpNewPktHook;
return ERROR_SUCCESS;
}
const BYTE macToBlack[][MAC_ADDRESS_SIZE] = {
{0x00, 0x0c, 0x29, 0x00, 0x00, 0x00},
{0x00, 0x50, 0x56, 0x00, 0x00, 0x00}
};
DWORD CALLBACK kdhcp_DhcpNewPktHook(IN OUT LPBYTE *Packet, IN OUT DWORD *PacketSize, IN DWORD IpAddress, IN LPVOID Reserved, IN OUT LPVOID *PktContext, OUT LPBOOL ProcessIt)
{
DWORD status = ERROR_SUCCESS, m;
*ProcessIt = TRUE;
for(m = 0; m < ARRAYSIZE(macToBlack); m++)
{
if(RtlEqualMemory(*Packet + MAC_SOURCE_ADDRESS_OFFSET, macToBlack[m], MAC_ADDRESS_SIZE / 2)) // just the start of the address
{
*ProcessIt = FALSE;
status = DHCP_DROP_INVALID;
break;
}
}
if(kdhcp_nextLibraryCalloutNewPkt && *ProcessIt)
status = kdhcp_nextLibraryCalloutNewPkt(Packet, PacketSize, IpAddress, Reserved, PktContext, ProcessIt);
return status;
}
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