Detect an internet connection activation with Delp

Question

I've been using a 3G wireless card for a while and every time I connect, my anti-virus fires up the updates.

I'm wondering what is the Win32 API set of functions that I can use to, either, get notified or query about the event of an Internet Connection coming up?

And is there already a set of ported headers for Delphi?

Answer 1

Look at InternetGetConnectedState in WinINet.

Some applications might also poll for a known server and not do anything until they get a valid connection.

Answer 2

uses WinInet;

function IsConnected: boolean;
const
  // local system uses a modem to connect to the Internet.
  INTERNET_CONNECTION_MODEM      = 1;
  // local system uses a local area network to connect to the Internet.
  INTERNET_CONNECTION_LAN        = 2;
  // local system uses a proxy server to connect to the Internet.
  INTERNET_CONNECTION_PROXY      = 4;
  // local system's modem is busy with a non-Internet connection.
  INTERNET_CONNECTION_MODEM_BUSY = 8;

var
  dwConnectionTypes : DWORD;
begin
  dwConnectionTypes := INTERNET_CONNECTION_MODEM +
                       INTERNET_CONNECTION_LAN +
                       INTERNET_CONNECTION_PROXY;
  Result := InternetGetConnectedState(@dwConnectionTypes,0);
end;

Answer 3

I worked on a project to run a user's logon script whenever they connected our network over VPN. To do this, I wrote a helper unit that retrieves adapter info and stores it into a simple record.

I then setup up a registry notification, see here for how to do that in Delphi

The registry notification was on HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces. This notification event fires every time Windows obtains a new IP address, or makes any type of change to an adapters connection information. When this event fired, I called the function (in the code below) to retrieve updated information about the adapter. I compared this new information to my previously recorded information...meaning I had to save the previous adapter info query in order to know if something had changed.

Anyhow, here is my helper unit:

unit uAdapterInfo;

interface

uses
  Classes,
  SysUtils;

const
  MAX_INTERFACE_NAME_LEN = $100;
  ERROR_SUCCESS   = 0;
  MAXLEN_IFDESCR  = $100;
  MAXLEN_PHYSADDR = 8;

  MIB_IF_OPER_STATUS_NON_OPERATIONAL = 0;
  MIB_IF_OPER_STATUS_UNREACHABLE = 1;
  MIB_IF_OPER_STATUS_DISCONNECTED = 2;
  MIB_IF_OPER_STATUS_CONNECTING  = 3;
  MIB_IF_OPER_STATUS_CONNECTED   = 4;
  MIB_IF_OPER_STATUS_OPERATIONAL = 5;

  MIB_IF_TYPE_OTHER    = 1;
  MIB_IF_TYPE_ETHERNET = 6;
  MIB_IF_TYPE_TOKENRING = 9;
  MIB_IF_TYPE_FDDI     = 15;
  MIB_IF_TYPE_PPP      = 23;
  MIB_IF_TYPE_LOOPBACK = 24;
  MIB_IF_TYPE_SLIP     = 28;

  MIB_IF_ADMIN_STATUS_UP      = 1;
  MIB_IF_ADMIN_STATUS_DOWN    = 2;
  MIB_IF_ADMIN_STATUS_TESTING = 3;

  _MAX_ROWS_ = 20;
  ANY_SIZE   = 1;


type
  MIB_IFROW = record
    wszName:    array[0 .. (MAX_INTERFACE_NAME_LEN * 2 - 1)] of ansichar;
    dwIndex:    longint;
    dwType:     longint;
    dwMtu:      longint;
    dwSpeed:    longint;
    dwPhysAddrLen: longint;
    bPhysAddr:  array[0 .. (MAXLEN_PHYSADDR - 1)] of byte;
    dwAdminStatus: longint;
    dwOperStatus: longint;
    dwLastChange: longint;
    dwInOctets: longint;
    dwInUcastPkts: longint;
    dwInNUcastPkts: longint;
    dwInDiscards: longint;
    dwInErrors: longint;
    dwInUnknownProtos: longint;
    dwOutOctets: longint;
    dwOutUcastPkts: longint;
    dwOutNUcastPkts: longint;
    dwOutDiscards: longint;
    dwOutErrors: longint;
    dwOutQLen:  longint;
    dwDescrLen: longint;
    bDescr:     array[0 .. (MAXLEN_IFDESCR - 1)] of ansichar;
  end;

type
  MIB_IPADDRROW = record
    dwAddr:      longint;
    dwIndex:     longint;
    dwMask:      longint;
    dwBCastAddr: longint;
    dwReasmSize: longint;
    unused1:     word;
    unused2:     word;
  end;

type
  _IfTable = record
    nRows: longint;
    ifRow: array[1.._MAX_ROWS_] of MIB_IFROW;
  end;

type
  _IpAddrTable = record
    dwNumEntries: longint;
    table: array[1..ANY_SIZE] of MIB_IPADDRROW;
  end;



function GetIfTable(pIfTable: Pointer; var pdwSize: longint; bOrder: longint): longint;
  stdcall;
function GetIpAddrTable(pIpAddrTable: Pointer; var pdwSize: longint;
  bOrder: longint): longint; stdcall;

function Get_if_type(iType: integer): string;
function Get_if_admin_status(iStatus: integer): string;
function Get_if_oper_status(iStatus: integer): string;


implementation

function GetIfTable; stdcall; external 'IPHLPAPI.DLL';
function GetIpAddrTable; stdcall; external 'IPHLPAPI.DLL';

function Get_if_type(iType: integer): string;
var
  sResult: string;
begin
  sResult := 'UNKNOWN';
  case iType of
    1: sResult   := 'Other';
    6: sResult   := 'Ethernet';
    9: sResult   := 'Tokenring';
    15: sResult  := 'FDDI';
    23: sResult  := 'PPP';
    24: sResult  := 'Local loopback';
    28: sResult  := 'SLIP';
    37: sResult  := 'ATM';
    71: sResult  := 'IEEE 802.11';
    131: sResult := 'Tunnel';
    144: sResult := 'IEEE 1394 (Firewire)';
  end;

  Result := sResult;
end;

function Get_if_admin_status(iStatus: integer): string;
var
  sResult: string;
begin
  sResult := 'UNKNOWN';

  case iStatus of
    1: sResult := 'UP';
    2: sResult := 'DOWN';
    3: sResult := 'TESTING';
  end;

  Result := sResult;
end;

function Get_if_oper_status(iStatus: integer): string;
var
  sResult: string;
begin
  sResult := 'UNKNOWN';

  case iStatus of
    0: sResult := 'NON_OPERATIONAL';
    1: sResult := 'UNREACHABLE';
    2: sResult := 'DISCONNECTED';
    3: sResult := 'CONNECTING';
    4: sResult := 'CONNECTED';
    5: sResult := 'OPERATIONAL';
  end;

  Result := sResult;
end;

end.

To use this unit from another unit, I created the following function, which populated a custom type called TAdapterInfo (declared in my main unit):

type
  TAdapterInfo = array of record
    dwIndex:    longint;
    dwType:     longint;
    dwMtu:      longint;
    dwSpeed:    extended;
    dwPhysAddrLen: longint;
    bPhysAddr:  string;
    dwAdminStatus: longint;
    dwOperStatus: longint;
    dwLastChange: longint;
    dwInOctets: longint;
    dwInUcastPkts: longint;
    dwInNUcastPkts: longint;
    dwInDiscards: longint;
    dwInErrors: longint;
    dwInUnknownProtos: longint;
    dwOutOctets: longint;
    dwOutUcastPkts: longint;
    dwOutNUcastPkts: longint;
    dwOutDiscards: longint;
    dwOutErrors: longint;
    dwOutQLen:  longint;
    dwDescrLen: longint;
    bDescr:     string;
    sIpAddress: string;
    sIpMask:    string;
  end;

//////////

function Get_EthernetAdapterDetail(var AdapterDataFound: TAdapterInfo): boolean;
var
  pIfTable: ^_IfTable;
  pIpTable: ^_IpAddrTable;
  ifTableSize, ipTableSize: longint;
  tmp:      string;
  i, j, k, m: integer;
  ErrCode:  longint;
  sAddr, sMask: in_addr;
  IPAddresses, IPMasks: TStringList;
  sIPAddressLine, sIPMaskLine: string;
  bResult:  boolean;
begin
  bResult  := True; //default return value
  pIfTable := nil;
  pIpTable := nil;

  IPAddresses := TStringList.Create;
  IPMasks     := TStringList.Create;

  try
    // First: just get the buffer size.
    // TableSize returns the size needed.
    ifTableSize := 0; // Set to zero so the GetIfTabel function
    // won't try to fill the buffer yet,
    // but only return the actual size it needs.
    GetIfTable(pIfTable, ifTableSize, 1);
    if (ifTableSize < SizeOf(MIB_IFROW) + Sizeof(longint)) then
    begin
      bResult := False;
      Result  := bResult;
      Exit; // less than 1 table entry?!
    end;

    ipTableSize := 0;
    GetIpAddrTable(pIpTable, ipTableSize, 1);
    if (ipTableSize < SizeOf(MIB_IPADDRROW) + Sizeof(longint)) then
    begin
      bResult := False;
      Result  := bResult;
      Exit; // less than 1 table entry?!
    end;

    // Second:
    // allocate memory for the buffer and retrieve the
    // entire table.
    GetMem(pIfTable, ifTableSize);
    ErrCode := GetIfTable(pIfTable, ifTableSize, 1);

    if ErrCode <> ERROR_SUCCESS then
    begin
      bResult := False;
      Result  := bResult;
      Exit; // OK, that did not work. 
      // Not enough memory i guess.
    end;

    GetMem(pIpTable, ipTableSize);
    ErrCode := GetIpAddrTable(pIpTable, ipTableSize, 1);

    if ErrCode <> ERROR_SUCCESS then
    begin
      bResult := False;
      Result  := bResult;
      Exit;
    end;

    for k := 1 to pIpTable^.dwNumEntries do
    begin
      sAddr.S_addr := pIpTable^.table[k].dwAddr;
      sMask.S_addr := pIpTable^.table[k].dwMask;

      sIPAddressLine := Format('0x%8.8x', [(pIpTable^.table[k].dwIndex)]) +
        '=' + Format('%s', [inet_ntoa(sAddr)]);
      sIPMaskLine    := Format('0x%8.8x', [(pIpTable^.table[k].dwIndex)]) +
        '=' + Format('%s', [inet_ntoa(sMask)]);

      IPAddresses.Add(sIPAddressLine);
      IPMasks.Add(sIPMaskLine);
    end;

    SetLength(AdapterDataFound, pIfTable^.nRows); //initialize the array or records
    for i := 1 to pIfTable^.nRows do
      try
        //if pIfTable^.ifRow[i].dwType=MIB_IF_TYPE_ETHERNET then
        //begin
        m := i - 1;
        AdapterDataFound[m].dwIndex := 4;//(pIfTable^.ifRow[i].dwIndex);
        AdapterDataFound[m].dwType := (pIfTable^.ifRow[i].dwType);
        AdapterDataFound[m].dwIndex := (pIfTable^.ifRow[i].dwIndex);
        AdapterDataFound[m].sIpAddress :=
          IPAddresses.Values[Format('0x%8.8x', [(pIfTable^.ifRow[i].dwIndex)])];
        AdapterDataFound[m].sIpMask :=
          IPMasks.Values[Format('0x%8.8x', [(pIfTable^.ifRow[i].dwIndex)])];
        AdapterDataFound[m].dwMtu := (pIfTable^.ifRow[i].dwMtu);
        AdapterDataFound[m].dwSpeed := (pIfTable^.ifRow[i].dwSpeed);
        AdapterDataFound[m].dwAdminStatus := (pIfTable^.ifRow[i].dwAdminStatus);
        AdapterDataFound[m].dwOperStatus := (pIfTable^.ifRow[i].dwOperStatus);
        AdapterDataFound[m].dwInUcastPkts := (pIfTable^.ifRow[i].dwInUcastPkts);
        AdapterDataFound[m].dwInNUcastPkts := (pIfTable^.ifRow[i].dwInNUcastPkts);
        AdapterDataFound[m].dwInDiscards := (pIfTable^.ifRow[i].dwInDiscards);
        AdapterDataFound[m].dwInErrors := (pIfTable^.ifRow[i].dwInErrors);
        AdapterDataFound[m].dwInUnknownProtos := (pIfTable^.ifRow[i].dwInUnknownProtos);
        AdapterDataFound[m].dwOutNUcastPkts := (pIfTable^.ifRow[i].dwOutNUcastPkts);
        AdapterDataFound[m].dwOutUcastPkts := (pIfTable^.ifRow[i].dwOutUcastPkts);
        AdapterDataFound[m].dwOutDiscards := (pIfTable^.ifRow[i].dwOutDiscards);
        AdapterDataFound[m].dwOutErrors := (pIfTable^.ifRow[i].dwOutErrors);
        AdapterDataFound[m].dwOutQLen := (pIfTable^.ifRow[i].dwOutQLen);
        AdapterDataFound[m].bDescr := (pIfTable^.ifRow[i].bDescr);

        tmp := '';
        for j := 0 to pIfTable^.ifRow[i].dwPhysAddrLen - 1 do
        begin
          if Length(tmp) > 0 then
            tmp := tmp + '-' + format('%.2x', [pIfTable^.ifRow[i].bPhysAddr[j]])
          else
            tmp := tmp + format('%.2x', [pIfTable^.ifRow[i].bPhysAddr[j]]);
        end;

        if Length(tmp) > 0 then
        begin
          AdapterDataFound[m].bPhysAddr := tmp;
        end;
      except
        bResult := False;
        Result  := bResult;
        Exit;
      end;
  finally
    if Assigned(pIfTable) then
    begin
      FreeMem(pIfTable, ifTableSize);
    end;

    FreeAndNil(IPMasks);
    FreeAndNil(IPAddresses);
  end;

  Result := bResult;
end;

On a completely side note, I also used this unit and almost exact same code to create a duplicate of ifconfig -a, which can be found on github. I mainly did it as an exercise in teaching myself how to accomplish this task.

Answer 4

Here's a working example of how to use the helper unit. It is from a small project I wrote to emulate "ifconfig -a". This is a console application project.

program ifconfig;

{$APPTYPE CONSOLE}

uses
  SysUtils,
  Classes,
  Winsock,
  uAdapterInfo in 'uAdapterInfo.pas';

type
  TAdapterInfo = array of record
    dwIndex:    longint;
    dwType:     longint;
    dwMtu:      longint;
    dwSpeed:    extended;
    dwPhysAddrLen: longint;
    bPhysAddr:  string;
    dwAdminStatus: longint;
    dwOperStatus: longint;
    dwLastChange: longint;
    dwInOctets: longint;
    dwInUcastPkts: longint;
    dwInNUcastPkts: longint;
    dwInDiscards: longint;
    dwInErrors: longint;
    dwInUnknownProtos: longint;
    dwOutOctets: longint;
    dwOutUcastPkts: longint;
    dwOutNUcastPkts: longint;
    dwOutDiscards: longint;
    dwOutErrors: longint;
    dwOutQLen:  longint;
    dwDescrLen: longint;
    bDescr:     string;
    sIpAddress: string;
    sIpMask:    string;
  end;




  function Get_EthernetAdapterDetail(var AdapterDataFound: TAdapterInfo): boolean;
  var
    pIfTable: ^_IfTable;
    pIpTable: ^_IpAddrTable;
    ifTableSize, ipTableSize: longint;
    tmp:      string;
    i, j, k, m: integer;
    ErrCode:  longint;
    sAddr, sMask: in_addr;
    IPAddresses, IPMasks: TStringList;
    sIPAddressLine, sIPMaskLine: string;
    bResult:  boolean;
  begin
    bResult  := True; //default return value
    pIfTable := nil;
    pIpTable := nil;

    IPAddresses := TStringList.Create;
    IPMasks     := TStringList.Create;

    try
      // First: just get the buffer size.
      // TableSize returns the size needed.
      ifTableSize := 0; // Set to zero so the GetIfTabel function
      // won't try to fill the buffer yet, 
      // but only return the actual size it needs.
      GetIfTable(pIfTable, ifTableSize, 1);
      if (ifTableSize < SizeOf(MIB_IFROW) + Sizeof(longint)) then
      begin
        bResult := False;
        Result := bResult;
        Exit; // less than 1 table entry?!
      end;

      ipTableSize := 0;
      GetIpAddrTable(pIpTable, ipTableSize, 1);
      if (ipTableSize < SizeOf(MIB_IPADDRROW) + Sizeof(longint)) then
      begin
        bResult := False;
        Result := bResult;
        Exit; // less than 1 table entry?!
      end;

      // Second:
      // allocate memory for the buffer and retrieve the 
      // entire table.
      GetMem(pIfTable, ifTableSize);
      ErrCode := GetIfTable(pIfTable, ifTableSize, 1);

      if ErrCode <> ERROR_SUCCESS then
      begin
        bResult := False;
        Result := bResult;
        Exit; // OK, that did not work. 
        // Not enough memory i guess.
      end;

      GetMem(pIpTable, ipTableSize);
      ErrCode := GetIpAddrTable(pIpTable, ipTableSize, 1);

      if ErrCode <> ERROR_SUCCESS then
      begin
        bResult := False;
        Result := bResult;
        Exit;
      end;

      for k := 1 to pIpTable^.dwNumEntries do
      begin
        sAddr.S_addr := pIpTable^.table[k].dwAddr;
        sMask.S_addr := pIpTable^.table[k].dwMask;

        sIPAddressLine := Format('0x%8.8x', [(pIpTable^.table[k].dwIndex)]) +
          '=' + Format('%s', [inet_ntoa(sAddr)]);
        sIPMaskLine    := Format('0x%8.8x', [(pIpTable^.table[k].dwIndex)]) +
          '=' + Format('%s', [inet_ntoa(sMask)]);

        IPAddresses.Add(sIPAddressLine);
        IPMasks.Add(sIPMaskLine);
      end;

      SetLength(AdapterDataFound, pIfTable^.nRows); //initialize the array or records
      for i := 1 to pIfTable^.nRows do
        try
          //if pIfTable^.ifRow[i].dwType=MIB_IF_TYPE_ETHERNET then
          //begin
          m := i - 1;
          AdapterDataFound[m].dwIndex := 4;//(pIfTable^.ifRow[i].dwIndex);
          AdapterDataFound[m].dwType := (pIfTable^.ifRow[i].dwType);
          AdapterDataFound[m].dwIndex := (pIfTable^.ifRow[i].dwIndex);
          AdapterDataFound[m].sIpAddress :=
            IPAddresses.Values[Format('0x%8.8x', [(pIfTable^.ifRow[i].dwIndex)])];
          AdapterDataFound[m].sIpMask :=
            IPMasks.Values[Format('0x%8.8x', [(pIfTable^.ifRow[i].dwIndex)])];
          AdapterDataFound[m].dwMtu := (pIfTable^.ifRow[i].dwMtu);
          AdapterDataFound[m].dwSpeed := (pIfTable^.ifRow[i].dwSpeed);
          AdapterDataFound[m].dwAdminStatus := (pIfTable^.ifRow[i].dwAdminStatus);
          AdapterDataFound[m].dwOperStatus := (pIfTable^.ifRow[i].dwOperStatus);
          AdapterDataFound[m].dwInUcastPkts := (pIfTable^.ifRow[i].dwInUcastPkts);
          AdapterDataFound[m].dwInNUcastPkts := (pIfTable^.ifRow[i].dwInNUcastPkts);
          AdapterDataFound[m].dwInDiscards := (pIfTable^.ifRow[i].dwInDiscards);
          AdapterDataFound[m].dwInErrors := (pIfTable^.ifRow[i].dwInErrors);
          AdapterDataFound[m].dwInUnknownProtos := (pIfTable^.ifRow[i].dwInUnknownProtos);
          AdapterDataFound[m].dwOutNUcastPkts := (pIfTable^.ifRow[i].dwOutNUcastPkts);
          AdapterDataFound[m].dwOutUcastPkts := (pIfTable^.ifRow[i].dwOutUcastPkts);
          AdapterDataFound[m].dwOutDiscards := (pIfTable^.ifRow[i].dwOutDiscards);
          AdapterDataFound[m].dwOutErrors := (pIfTable^.ifRow[i].dwOutErrors);
          AdapterDataFound[m].dwOutQLen := (pIfTable^.ifRow[i].dwOutQLen);
          AdapterDataFound[m].bDescr := (pIfTable^.ifRow[i].bDescr);

          tmp := '';
          for j := 0 to pIfTable^.ifRow[i].dwPhysAddrLen - 1 do
          begin
            if Length(tmp) > 0 then
              tmp := tmp + '-' + format('%.2x', [pIfTable^.ifRow[i].bPhysAddr[j]])
            else
              tmp := tmp + format('%.2x', [pIfTable^.ifRow[i].bPhysAddr[j]]);
          end;

          if Length(tmp) > 0 then
          begin
            AdapterDataFound[m].bPhysAddr := tmp;
          end;
        except
          bResult := False;
          Result := bResult;
          Exit;
        end;
    finally
      if Assigned(pIfTable) then
      begin
        FreeMem(pIfTable, ifTableSize);
      end;

      FreeAndNil(IPMasks);
      FreeAndNil(IPAddresses);
    end;

    Result := bResult;
  end;



var
  AdapterData: TAdapterInfo;
  i: integer;
begin
  try
    WriteLn('');
    if Get_EthernetAdapterDetail(AdapterData) then
    begin
      for i := 0 to Length(AdapterData) - 1 do
      begin
        WriteLn(Format('0x%8.8x', [AdapterData[i].dwIndex]));
        WriteLn('"' + AdapterData[i].bDescr + '"');
        Write(Format(#9 + 'Link encap: %s ', [Get_if_type(AdapterData[i].dwType)]));

        if Length(AdapterData[i].bPhysAddr) > 0 then
          Write('HWaddr: ' + AdapterData[i].bPhysAddr);

        Write(#13 + #10 + #9 + 'inet addr:' + AdapterData[i].sIpAddress);
        WriteLn(' Mask: ' + AdapterData[i].sIpMask);
        WriteLn(Format(#9 + 'MTU: %d Speed:%.2f Mbps', [AdapterData[i].dwMtu,
          (AdapterData[i].dwSpeed) / 1000 / 1000]));
        Write(#9 + 'Admin status:' + Get_if_admin_status(AdapterData[i].dwAdminStatus));
        WriteLn(' Oper status:' + Get_if_oper_status(AdapterData[i].dwOperStatus));
        WriteLn(#9 + Format('RX packets:%d dropped:%d errors:%d unkown:%d',
          [AdapterData[i].dwInUcastPkts + AdapterData[i].dwInNUcastPkts,
          AdapterData[i].dwInDiscards, AdapterData[i].dwInErrors,
          AdapterData[i].dwInUnknownProtos]));
        WriteLn(#9 + Format('TX packets:%d dropped:%d errors:%d txqueuelen:%d',
          [AdapterData[i].dwOutUcastPkts + AdapterData[i].dwOutNUcastPkts,
          AdapterData[i].dwOutDiscards, AdapterData[i].dwOutErrors,
          AdapterData[i].dwOutQLen]));

        WriteLn('');
      end;
    end
    else
    begin
      WriteLn(#13+#10+'*** Error retrieving adapter information');
    end;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.