Oh boy...I am still struggling with this.
Now I'm at the stage that I created a WIN32 project in my solution, and
created the C++ file below. The code from the 'createIpForwardEntry()'
method is from an online example that I found. The code compiles, but
it doesn't create a DLL or so, so I wouldn't know how to invoke this
DLL and test it.
Still, I really wonder what I'm doing wrong when invoking iphlpapi.dll
directly from C# as discussed here:
http://groups-beta.google.com/group/...9e27fc9415d06e
There must be others that have tried this...
What are the other places to search for info on these matters?
====== C++ FILE =======
#include "stdafx.h"
#ifdef _MANAGED
#pragma managed(push, off)
#endif
#ifdef __cplusplus
extern "C" {
#endif
typedef DWORD (*getIpForwardTableFunction)(PMIB_IPFORWARDTABLE, PULONG,
BOOL);
typedef DWORD (*createIpForwardEntryFunction)(PMIB_IPFORWARDROW) ;
typedef DWORD (*setIpForwardEntryFunction)(PMIB_IPFORWARDROW);
typedef DWORD (*deleteIpForwardEntryFunction)(PMIB_IPFORWARDROW) ;
HINSTANCE hinstLib;
getIpForwardTableFunction myGetIpForwardTable = NULL;
createIpForwardEntryFunction myCreateIpForwardEntry = NULL;
setIpForwardEntryFunction mySetIpForwardEntry = NULL;
deleteIpForwardEntryFunction myDeleteIpForwardEntry = NULL;
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
) {
LPCWSTR dllName = LPCWSTR("Iphlpapi.dll");
hinstLib = LoadLibrary(dllName);
if (hinstLib == NULL) {
printf("Error: could not load Iphlpapi.dll\n");
return FALSE;
}
myGetIpForwardTable = (getIpForwardTableFunction)
GetProcAddress(hinstLib, "GetIpForwardTable");
if (myGetIpForwardTable == NULL) {
printf("Error: could not find function getipforwardtable");
return FALSE;
}
myCreateIpForwardEntry = (createIpForwardEntryFunction)
GetProcAddress(hinstLib, "CreateIpForwardEntry");
if (myCreateIpForwardEntry == NULL) {
printf("Error: could not find function createipforwardentry");
return FALSE;
}
mySetIpForwardEntry = (setIpForwardEntryFunction)
GetProcAddress(hinstLib, "SetIpForwardEntry");
if (mySetIpForwardEntry == NULL) {
printf("Error: could not find function setipforwardentry");
return FALSE;
}
myDeleteIpForwardEntry = (deleteIpForwardEntryFunction)
GetProcAddress(hinstLib, "DeleteIpForwardEntry");
if (myDeleteIpForwardEntry == NULL) {
printf("Error: could not find function deleteipforwardentry");
return FALSE;
}
return TRUE;
}
__declspec(dllexport) void __stdcall createIpForwardEntry() {
PMIB_IPFORWARDTABLE pIpForwardTable = NULL;
PMIB_IPFORWARDROW pRow = NULL;
DWORD dwSize = 0;
BOOL bOrder = FALSE;
DWORD dwStatus = 0;
DWORD NewGateway = 0xDDBBCCAA; // this is in host order Ip Address
AA.BB.CC.DD is DDCCBBAA
// Find out how big our buffer needs to be.
dwStatus = myGetIpForwardTable(pIpForwardTable, &dwSize, bOrder);
if (dwStatus == ERROR_INSUFFICIENT_BUFFER) {
// Allocate the memory for the table
if (!(pIpForwardTable = (PMIB_IPFORWARDTABLE)malloc(dwSize))) {
printf("Malloc failed. Out of memory.\n");
exit(1);
}
// Now get the table.
dwStatus = myGetIpForwardTable(pIpForwardTable, &dwSize, bOrder);
}
if (dwStatus != ERROR_SUCCESS) {
printf("getIpForwardTable failed.\n");
if (pIpForwardTable)
free(pIpForwardTable);
exit(1);
}
// Search for the row in the table we want. The default gateway has a
destination
// of 0.0.0.0. Notice that we continue looking through the table, but
copy only
// one row. This is so that if there happen to be multiple default
gateways, we can
// be sure to delete them all.
for (unsigned long int i=0; i < pIpForwardTable->dwNumEntries; i++) {
if (pIpForwardTable->table[i].dwForwardDest == 0) {
// We have found the default gateway.
if (!pRow) {
// Allocate some memory to store the row in; this is easier than
filling
// in the row structure ourselves, and we can be sure we change
only the
// gateway address.
pRow = (PMIB_IPFORWARDROW)malloc(sizeof(MIB_IPFORWARDROW) );
if (!pRow) {
printf("Malloc failed. Out of memory.\n");
exit(1);
}
// Copy the row
memcpy(pRow, &(pIpForwardTable->table[i]),
sizeof(MIB_IPFORWARDROW));
}
// Delete the old default gateway entry.
dwStatus = myDeleteIpForwardEntry(&(pIpForwardTable->table[i]));
if (dwStatus != ERROR_SUCCESS) {
printf("Could not delete old gateway\n");
exit(1);
}
}
}
// Set the nexthop field to our new gateway - all the other properties
of the route will
// be the same as they were previously.
pRow->dwForwardNextHop = NewGateway;
// Create a new route entry for the default gateway.
dwStatus = myCreateIpForwardEntry(pRow);
if (dwStatus == NO_ERROR)
printf("Gateway changed successfully\n");
else if (dwStatus == ERROR_INVALID_PARAMETER)
printf("Invalid parameter.\n");
else
printf("Error: %d\n", dwStatus);
// Free resources
if (pIpForwardTable)
free(pIpForwardTable);
if (pRow)
free(pRow);
}
#ifdef __cplusplus
}
#endif
#ifdef _MANAGED
#pragma managed(pop)
#endif
