GetIpNetTable

  • Thread starter Thread starter James Jenkins
  • Start date Start date
J

James Jenkins

does anyone know how to implement the following? - I am very new to using
Marshalling and could really do with some help - it's late and I am tired -
I have spent all day on this and the net comes up with very little help - I
have followed lots of tutorials and looked at many peoples source - I am in
need of enlightenment ;) - thanks
[DllImport("iphlpapi.dll", EntryPoint="GetIpNetTable", SetLastError=true)]

public static extern int GetIpNetTable(IntPtr buffer,ref int Size, bool
Order);



I have got this far in the calling it- as below



IntPtr lpBuffer = IntPtr.Zero;

int size = 0;

int result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Debug.WriteLine("NO ERROR");

lpBuffer = Marshal.AllocHGlobal(size);

result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Marshal.FreeHGlobal(lpBuffer);

lpBuffer = IntPtr.Zero;

Debug.WriteLine("RETURN ERROR");

return;

}

Debug.WriteLine("I GOT THIS FAR");

// But canot allocate the structures from here - I hope someone out there
can pointer me in the right direction - good night all;;;



JJ
 
James,

Here is how I would do it:

using System;
using System.Runtime.InteropServices;
using System.ComponentModel;

namespace ConsoleApplication5
{
class Program
{
// The max number of physical addresses.
const int MAXLEN_PHYSADDR = 8;

// Define the MIB_IPNETROW structure.
[StructLayout(LayoutKind.Sequential)]
struct MIB_IPNETROW
{
[MarshalAs(UnmanagedType.U4)]
public int dwIndex;
[MarshalAs(UnmanagedType.U4)]
public int dwPhysAddrLen;
[MarshalAs(UnmanagedType.ByValArray, SizeConst =
MAXLEN_PHYSADDR)]
byte[] bPhysAddr;
[MarshalAs(UnmanagedType.U4)]
public int dwAddr;
[MarshalAs(UnmanagedType.U4)]
public int dwType;
}

// Declare the GetIpNetTable function.
[DllImport("IpHlpApi.dll")]
[return: MarshalAs(UnmanagedType.U4)]
static extern int GetIpNetTable(
IntPtr pIpNetTable,
[MarshalAs(UnmanagedType.U4)]
ref int pdwSize,
bool bOrder);

// The insufficient buffer error.
const int ERROR_INSUFFICIENT_BUFFER = 122;

static void Main(string[] args)
{
// The number of bytes needed.
int bytesNeeded = 0;

// The result from the API call.
int result = GetIpNetTable(IntPtr.Zero, ref bytesNeeded, false);

// Call the function, expecting an insufficient buffer.
if (result != ERROR_INSUFFICIENT_BUFFER)
{
// Throw an exception.
throw new Win32Exception(result);
}

// Allocate the memory, do it in a try/finally block, to ensure
// that it is released.
IntPtr buffer = IntPtr.Zero;

// Try/finally.
try
{
// Allocate the memory.
buffer = Marshal.AllocCoTaskMem(bytesNeeded);

// Make the call again. If it did not succeed, then
// raise an error.
result = GetIpNetTable(buffer, ref bytesNeeded, false);

// If the result is not 0 (no error), then throw an
exception.
if (result != 0)
{
// Throw an exception.
throw new Win32Exception(result);
}

// Now we have the buffer, we have to marshal it. We can
read
// the first 4 bytes to get the length of the buffer.
int entries = Marshal.ReadInt32(buffer);

// Increment the memory pointer by the size of the int.
IntPtr currentBuffer = new IntPtr(buffer.ToInt64() +
sizeof(int));

// Allocate an array of entries.
MIB_IPNETROW[] table = new MIB_IPNETROW[entries];

// Cycle through the entries.
for (int index = 0; index < entries; index++)
{
// Call PtrToStructure, getting the structure
information.
table[index] = (MIB_IPNETROW) Marshal.PtrToStructure(new
IntPtr(currentBuffer.ToInt64() + (index *
Marshal.SizeOf(typeof(MIB_IPNETROW)))), typeof(MIB_IPNETROW));
}
}
finally
{
// Release the memory.
Marshal.FreeCoTaskMem(buffer);
}
}
}
}

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

James Jenkins said:
does anyone know how to implement the following? - I am very new to using
Marshalling and could really do with some help - it's late and I am
tired - I have spent all day on this and the net comes up with very little
help - I have followed lots of tutorials and looked at many peoples
source - I am in need of enlightenment ;) - thanks
[DllImport("iphlpapi.dll", EntryPoint="GetIpNetTable", SetLastError=true)]

public static extern int GetIpNetTable(IntPtr buffer,ref int Size, bool
Order);



I have got this far in the calling it- as below



IntPtr lpBuffer = IntPtr.Zero;

int size = 0;

int result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Debug.WriteLine("NO ERROR");

lpBuffer = Marshal.AllocHGlobal(size);

result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Marshal.FreeHGlobal(lpBuffer);

lpBuffer = IntPtr.Zero;

Debug.WriteLine("RETURN ERROR");

return;

}

Debug.WriteLine("I GOT THIS FAR");

// But canot allocate the structures from here - I hope someone out there
can pointer me in the right direction - good night all;;;



JJ
Click to expand...
 
Nicholas Paldino said:
James,

Here is how I would do it:

using System;
using System.Runtime.InteropServices;
using System.ComponentModel;

namespace ConsoleApplication5
{
class Program
{
// The max number of physical addresses.
const int MAXLEN_PHYSADDR = 8;

// Define the MIB_IPNETROW structure.
[StructLayout(LayoutKind.Sequential)]
struct MIB_IPNETROW
{
[MarshalAs(UnmanagedType.U4)]
public int dwIndex;
[MarshalAs(UnmanagedType.U4)]
public int dwPhysAddrLen;
[MarshalAs(UnmanagedType.ByValArray, SizeConst =
MAXLEN_PHYSADDR)]
byte[] bPhysAddr;
[MarshalAs(UnmanagedType.U4)]
public int dwAddr;
[MarshalAs(UnmanagedType.U4)]
public int dwType;
}

// Declare the GetIpNetTable function.
[DllImport("IpHlpApi.dll")]
[return: MarshalAs(UnmanagedType.U4)]
static extern int GetIpNetTable(
IntPtr pIpNetTable,
[MarshalAs(UnmanagedType.U4)]
ref int pdwSize,
bool bOrder);

// The insufficient buffer error.
const int ERROR_INSUFFICIENT_BUFFER = 122;

static void Main(string[] args)
{
// The number of bytes needed.
int bytesNeeded = 0;

// The result from the API call.
int result = GetIpNetTable(IntPtr.Zero, ref bytesNeeded,
false);

// Call the function, expecting an insufficient buffer.
if (result != ERROR_INSUFFICIENT_BUFFER)
{
// Throw an exception.
throw new Win32Exception(result);
}

// Allocate the memory, do it in a try/finally block, to ensure
// that it is released.
IntPtr buffer = IntPtr.Zero;

// Try/finally.
try
{
// Allocate the memory.
buffer = Marshal.AllocCoTaskMem(bytesNeeded);

// Make the call again. If it did not succeed, then
// raise an error.
result = GetIpNetTable(buffer, ref bytesNeeded, false);

// If the result is not 0 (no error), then throw an
exception.
if (result != 0)
{
// Throw an exception.
throw new Win32Exception(result);
}

// Now we have the buffer, we have to marshal it. We can
read
// the first 4 bytes to get the length of the buffer.
int entries = Marshal.ReadInt32(buffer);

// Increment the memory pointer by the size of the int.
IntPtr currentBuffer = new IntPtr(buffer.ToInt64() +
sizeof(int));

// Allocate an array of entries.
MIB_IPNETROW[] table = new MIB_IPNETROW[entries];

// Cycle through the entries.
for (int index = 0; index < entries; index++)
{
// Call PtrToStructure, getting the structure
information.
table[index] = (MIB_IPNETROW)
Marshal.PtrToStructure(new IntPtr(currentBuffer.ToInt64() + (index *
Marshal.SizeOf(typeof(MIB_IPNETROW)))), typeof(MIB_IPNETROW));
}
}
finally
{
// Release the memory.
Marshal.FreeCoTaskMem(buffer);
}
}
}
}

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

James Jenkins said:
does anyone know how to implement the following? - I am very new to using
Marshalling and could really do with some help - it's late and I am
tired - I have spent all day on this and the net comes up with very
little help - I have followed lots of tutorials and looked at many
peoples source - I am in need of enlightenment ;) - thanks
[DllImport("iphlpapi.dll", EntryPoint="GetIpNetTable",
SetLastError=true)]

public static extern int GetIpNetTable(IntPtr buffer,ref int Size, bool
Order);



I have got this far in the calling it- as below



IntPtr lpBuffer = IntPtr.Zero;

int size = 0;

int result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Debug.WriteLine("NO ERROR");

lpBuffer = Marshal.AllocHGlobal(size);

result = IPHelperAPI.GetIpNetTable(lpBuffer,ref size,true);

if(result != NO_ERROR)

{

Marshal.FreeHGlobal(lpBuffer);

lpBuffer = IntPtr.Zero;

Debug.WriteLine("RETURN ERROR");

return;

}

Debug.WriteLine("I GOT THIS FAR");

// But canot allocate the structures from here - I hope someone out there
can pointer me in the right direction - good night all;;;



JJ
Click to expand...
Click to expand...


Excellent - I will take a close look at this code and hopefully learn from
it - As I have to implement many IP Helper functions - thanks again - any
more tips would be appreciated
 
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