DHCP C++ error LNK2019

Question

Given the follow code I cannot seem to figure out why I am receiving this error if someone could help.

CODE:

#include "StdAfx.h"
#include "WINDOWS.H"
#include "Dhcpcsdk.h"
//#include "Dhcpcsvc.dll"
#include <iostream>

using namespace std;

#define NUMBER_OF_OPTIONS 7


//#define NUMBER_OF_OPTIONS 4
enum OptionArrayPositions
{
   MASK,
   DNS,
   HOSTNAME,
   VENDOR,
   LEASE_TIME,
   MESSAGE_TYPE,
   SERVERIP
};

BOOL RetrieveDHCPInfo(LPWSTR pszAdapterName);
void PrintAsAscii(DHCPCAPI_PARAMS param);
void PrintAsIP(DHCPCAPI_PARAMS param);
void PrintAsInt(DHCPCAPI_PARAMS param);
void PrintMask(DHCPCAPI_PARAMS param);
void PrintDNS(DHCPCAPI_PARAMS param);
void PrintHostName(DHCPCAPI_PARAMS param);
void PrintVendor(DHCPCAPI_PARAMS param);
void PrintLeaseTime(DHCPCAPI_PARAMS param);
void PrintMessageType(DHCPCAPI_PARAMS param);
void PrintServerIP(DHCPCAPI_PARAMS param);

BOOL RetrieveDHCPInfo(LPWSTR pszAdapterName)
{
   DWORD dwError, dwSize;
   CHAR TmpBuffer[1000]; // host name won't be larger than this


   DHCPCAPI_PARAMS DhcpApiMaskParams = {0,
                                    OPTION_SUBNET_MASK,
                                    FALSE,
                                    NULL,
                                    0
                                    };
   DHCPCAPI_PARAMS DhcpApiDNSParams = {0,
                                    OPTION_DOMAIN_NAME_SERVERS,
                                    FALSE,
                                    NULL,
                                    0
                                    };
   DHCPCAPI_PARAMS DhcpApiHostNameParams = {0,                // Flags
                                       OPTION_HOST_NAME, // OptionId
                                       FALSE,            // vendor specific?
                                       NULL,             // data filled in on return
                                       0                 // nBytes
                                       }; 
   DHCPCAPI_PARAMS DhcpApiVendorParams = {0,
                                       OPTION_VENDOR_SPEC_INFO,
                                       FALSE,
                                       NULL,
                                       0
                                    };
   DHCPCAPI_PARAMS DhcpApiLeaseTimeParams = {0,
                                          OPTION_LEASE_TIME,
                                          FALSE,
                                          NULL,
                                          0
                                       };    
   DHCPCAPI_PARAMS DhcpApiMsgTypeParams = {0,
                                       OPTION_MESSAGE_TYPE,
                                       FALSE,
                                       NULL,
                                       0
                                       };

   DHCPCAPI_PARAMS DhcpApiServerNameParams = {0,
                                          OPTION_SERVER_IDENTIFIER,
                                          FALSE,
                                          NULL,
                                          0
                                          };

   DHCPCAPI_PARAMS paramArray[NUMBER_OF_OPTIONS] = { DhcpApiMaskParams, 
                                                DhcpApiDNSParams,
                                                DhcpApiHostNameParams, 
                                                DhcpApiVendorParams, 
                                                DhcpApiLeaseTimeParams,
                                                DhcpApiMsgTypeParams,
                                                DhcpApiServerNameParams
                                                };

   DHCPCAPI_PARAMS_ARRAY DhcpApiParamsArray = {NUMBER_OF_OPTIONS,  // only one option to request
                                          paramArray
                                          };
   DHCPCAPI_PARAMS_ARRAY SendParams = {0, NULL};

   dwSize = sizeof(TmpBuffer);
   dwError = DhcpRequestParams(DHCPCAPI_REQUEST_SYNCHRONOUS, // Flags
                           NULL,                         // Reserved
                           pszAdapterName,               // Adapter Name
                           NULL,                         // not using class id
                           SendParams,                   // nothing to send
                           DhcpApiParamsArray,           // requesting params
                           (PBYTE) TmpBuffer,            // buffer
                           &dwSize,                      // buffer size
                           NULL                          // Request ID
                           );

   cout << "Your Error Code from DhcpRequestParams is " << dwError << endl;
   if( ERROR_MORE_DATA == dwError ) 
   {
      //
      // dwSize is not large enough.
      //
   }

   int success = FALSE;
   if( NO_ERROR == dwError ) 
   {
      for(int i=0; i<NUMBER_OF_OPTIONS; i++)
      {
         if(paramArray[i].nBytesData != 0)
         {
            success = true;
            switch(paramArray[i].OptionId)
            {
               case OPTION_SUBNET_MASK:
                  PrintMask(paramArray[i]);
                  break;
               case OPTION_DOMAIN_NAME_SERVERS:
                  PrintDNS(paramArray[i]);
                  break;
               case OPTION_HOST_NAME:
                  PrintHostName(paramArray[i]);
                  break;
               case OPTION_VENDOR_SPEC_INFO:
                  PrintVendor(paramArray[i]);
                  break;
               case OPTION_LEASE_TIME:
                  PrintLeaseTime(paramArray[i]);
                  break;
               case OPTION_MESSAGE_TYPE:
                  PrintMessageType(paramArray[i]);
                  break;
               case OPTION_SERVER_IDENTIFIER:
                  PrintServerIP(paramArray[i]);
                  break;
            }
         }
      }
      cout << endl;
   }

   if(success == TRUE)
      return TRUE;
   else
      return FALSE;
}

void PrintAsAscii(DHCPCAPI_PARAMS param)
{
   unsigned char temp[260];
   CopyMemory(temp, 
   param.Data,
   param.nBytesData);

   temp[param.nBytesData] = '\0';
   cout << temp;
}

void PrintAsIP(DHCPCAPI_PARAMS param)
{
   unsigned char temp[260];
   CopyMemory(temp, 
   param.Data,
   param.nBytesData);

   temp[param.nBytesData] = '\0';
   for(unsigned int i=0; i<param.nBytesData; i++)
   { 
      if(i%4 == 0)
      {
         cout << endl;
      }
         cout << (int)temp[i]<< ".";
   }
}

void PrintAsInt(DHCPCAPI_PARAMS param)
{
   unsigned char temp[260];
   CopyMemory(temp, 
   param.Data,
   param.nBytesData);

   temp[param.nBytesData] = '\0';
   cout << (unsigned int)*temp;
}

void PrintMask(DHCPCAPI_PARAMS param)
{
   /* Print the subnet mask
   * This is stored as Option 1
   *
   *
   */
   cout << endl << "MASK" << endl;
   cout << "--------------------------------------------";
   PrintAsIP(param);
}

void PrintDNS(DHCPCAPI_PARAMS param)
{
   /* Print the DNS Servers
   * This is stored as Option 6
   *
   *
   */
   cout << endl << "\nDNS SERVERS" << endl;
   cout << "--------------------------------------------";
   PrintAsIP(param);
}

void PrintHostName(DHCPCAPI_PARAMS param)
{
   /* Print the Host name or IP address if 
   * that's what's stored in this option
   * This is stored as Option 12
   *
   */
   cout << endl << "\nHOST NAME" << endl;
   cout << "--------------------------------------------";
   cout << endl << "ANSI String" << endl;
   PrintAsAscii(param);
   cout << endl << "IP FORMAT";
   PrintAsIP(param);
}

void PrintVendor(DHCPCAPI_PARAMS param)
{
   /* Print the Vendor parameter
   * This is stored as Option 43
   *
   *
   */
   cout << endl << "\nVENDOR PARAMETER" << endl;
   cout << "--------------------------------------------";
   cout << endl << "ANSI String" << endl;
   PrintAsAscii(param);
}

void PrintLeaseTime(DHCPCAPI_PARAMS param)
{
   /* Print the Lease Time
   * This is stored as Option 51
   *
   *
   */
   cout << endl << "\nLEASE TIME" << endl;
   cout << "--------------------------------------------" << endl;
   PrintAsInt(param);
   cout << endl;
}

void PrintMessageType(DHCPCAPI_PARAMS param)
{
   /* Print the message type
   * This is stored as Option 53
   *
   *
   */
   cout << endl << "\nMESSAGE TYPE" << endl;
   cout << "--------------------------------------------" << endl;;
   PrintAsInt(param);
}

void PrintServerIP(DHCPCAPI_PARAMS param)
{
   /* Print the DHCP servers IP address
   * This is stored as Option 54
   *
   *
   */
   cout << endl << "\nDHCP SERVER" << endl;
   cout << "--------------------------------------------";
   PrintAsIP(param);
} 






int main(){

    struct DHCPAPI_PARAMS {
    ULONG  Flags;
    ULONG  OptionId;
    BOOL   IsVendor;
    LPBYTE Data;
    DWORD  nBytesData;
    };
    DHCPCAPI_PARAMS DhcpApiMaskParams = {0,
                                         OPTION_SUBNET_MASK,
                                         FALSE,
                                         NULL,
                                         0
                                         };



    char name[26];
    cout<<"Hello World"<< endl;
    cin>>name;  
    PrintAsIP(DhcpApiMaskParams);

    return 0;

}

This is the error code I receive when running this, obviously the hello world and enter cin name are there just for starter purposes.

Here is the errors I receive.

ERRORS:

Error 1 error LNK2019: unresolved external symbol _DhcpRequestParams@44 referenced in function "int __cdecl RetrieveDHCPInfo(wchar_t *)" (?RetrieveDHCPInfo@@YAHPA_W@Z)

Error 2 error LNK1120: 1 unresolved externals

Answer 1

You need to link the import library listed at the bottom of the manual page.

Add Dhcpcsvc.lib to your Additional Libraries.