//***************************************************************
// From the book "Win32 System Services: The Heart of Windows 98
// and Windows 2000"
// by Marshall Brain
// Published by Prentice Hall
//
// Copyright 1995, by Prentice Hall.
//
// This code allows a client to connect, and then impersonates
// that client until it disconnects.
//***************************************************************

// imprecv.cpp

#include <windows.h>
#include <iostream.h>

int main(void)
{
  char toDisptxt[80];
  HANDLE ssnpPipe;
  DWORD NumBytesRead;
  char buffer[80];
  DWORD bufferLen;
  SECURITY_ATTRIBUTES sa;
  SECURITY_DESCRIPTOR sd;

  InitializeSecurityDescriptor(&sd,
    SECURITY_DESCRIPTOR_REVISION);
  SetSecurityDescriptorDacl(&sd, TRUE, NULL,
    FALSE);
  sa.nLength= sizeof(SECURITY_ATTRIBUTES);
  sa.bInheritHandle = FALSE;
  sa.lpSecurityDescriptor = &sd;

  /* Create a named pipe for receiving messages */
  ssnpPipe=CreateNamedPipe("\\\\.\\pipe\\ssnp",
    PIPE_ACCESS_INBOUND, 
    PIPE_TYPE_MESSAGE | PIPE_WAIT,
    1, 0, 0, 150, &sa);

  /* Check and see if the named pipe was created */
  if (ssnpPipe == INVALID_HANDLE_VALUE)
  {
    cerr << "ERROR: Unable to create a named pipe."
      << endl;
    return (1);
  }

  bufferLen = 80;
  GetUserName(buffer, &bufferLen);
  cout << "Right now my user is: "
    << buffer
    << endl;
  cout << "Waiting for connection..." << endl;

  /* Allow a client to connect to the name pipe, 
     terminate if unsuccessful */
  if(!ConnectNamedPipe(ssnpPipe, 
    (LPOVERLAPPED) NULL))
  {
    cerr << "ERROR: Unable to connect a pipe "
      << GetLastError() << endl;
    CloseHandle(ssnpPipe);
    return (1);
  }

  cout << "Beginning impersonation...\n";

  if (!ImpersonateNamedPipeClient(ssnpPipe))
  {
    cerr << "ERROR: Cannot impersonate, " 
      << GetLastError() << endl;
    CloseHandle(ssnpPipe);
    return(1);
  }

  bufferLen = 80;
  GetUserName(buffer, &bufferLen);
  cout << "Now my user is: "
    << buffer << endl;

  /* Repeatedly check for messages until 
     the program is terminated */
  while(1)
  {
    /* Read the message and check to see if read
       was successful */
    if (!ReadFile(ssnpPipe, toDisptxt,
      sizeof(toDisptxt),
      &NumBytesRead, (LPOVERLAPPED) NULL))
    {
      cerr << "ERROR: Unable to read from pipe"
        << endl;
      CloseHandle(ssnpPipe);
      break;
    }

    /* Display the Message */
    cout << toDisptxt << endl;

  } /* while */

  cout << "Reverting back to original user.\n";
  RevertToSelf();

  bufferLen = 80;
  GetUserName(buffer, &bufferLen);
  cout << "Now my user is: "
    << buffer
    << endl;
}