We have a legacy Delphi application which uses IcmpSendEcho
(from iphlpapi.dll) to perform echo requests. As I understand it, this performs the same function as "ping" from the command prompt.
On Windows XP, the code below works fine. When the IPv4 address is correct the response is quick and if not error code 11010 (IP_REQ_TIMED_OUT) is returned as expected.
However, on my 32-bit Windows 10 machine, the error code is 87 (ERROR_INVALID_PARAMETER). I've carefully reviewed the Microsoft documentation for IcmpSendEcho and cannot see anything obvious that is wrong.
"ping 200.1.2.121" (the example IPv4 address I use in the code sample) works as expected from the command prompt in both XP and 10.
type
PIpAddress = ^TIpAddress;
TIpAddress = record
case Integer of
0: (S_un_b: TSunB);
1: (S_un_w: TSunW);
2: (S_addr: LongWord);
end;
IpAddress = TIpAddress;
// Functions imported from external DLLs
function IcmpCreateFile() : THandle; stdcall; external 'iphlpapi.dll';
function IcmpCloseHandle(icmpHandle: THandle) : Boolean; stdcall; external 'iphlpapi.dll';
function IcmpSendEcho(IcmpHandle: THandle; ipDest: IpAddress;
pRequestData: Pointer; nRequestSize: SmallInt; RequestOptions: Pointer;
pReplyBuffer: Pointer; dwReplySize: DWORD; dwTimeout: DWORD) : DWORD; stdcall; external 'iphlpapi.dll';
procedure TranslateStringToIpAddress(strIP: String; var ipAddress);
var
phe: PHostEnt;
pac: PChar;
begin
try
phe := GetHostByName(PChar(strIP));
if (Assigned(phe)) then
begin
pac := phe^.h_addr_list^;
if (Assigned(pac)) then
begin
with TIpAddress(ipAddress).S_un_b do
begin
by1 := Byte(pac[0]);
by2 := Byte(pac[1]);
by3 := Byte(pac[2]);
by4 := Byte(pac[3]);
end;
end
else
begin
raise Exception.Create('Error getting IP from HostName');
end;
end
else
begin
raise Exception.Create('Error getting HostName');
end;
except
FillChar(ipAddress, SizeOf(ipAddress), #0);
end;
end;
function Ping(strIpAddress : String) : Boolean;
const
ICMP_ECHO_BUFFER = 128; // Works as low as 28 on Windows XP (nothing works on Windows 10)
var
address: IpAddress;
dwReplies: DWORD;
{$IFDEF DBG} dwErrorCode: DWORD; {$ENDIF}
abyReplyBuffer: array[1..ICMP_ECHO_BUFFER] of BYTE;
begin
// Use this function to determine if an IPv4 address can be reached
Result := False;
// "m_cache.hPingHandle" is generated earlier with a call to "IcmpCreateFile"
if (m_cache.hPingHandle = INVALID_HANDLE_VALUE) then
Exit;
TranslateStringToIpAddress(strIpAddress, address);
dwReplies := IcmpSendEcho(
m_cache.hPingHandle, address, nil, 0, nil, @abyReplyBuffer, ICMP_ECHO_BUFFER, 0);
{$IFDEF DBG}
if (dwReplies = 0) then
begin
dwErrorCode := GetLastError();
// dwErrorCode = 87 (ERROR_INVALID_PARAMETER, "The parameter is incorrect")
Application.MessageBox(
PAnsiChar(Format('WinError = %d', [dwErrorCode])), 'Ping failed', MB_ICONEXCLAMATION);
end;
{$ENDIF}
// Success?
Result := (dwReplies <> 0);
end;
// Usage elsewhere in the application...
Ping('200.1.2.121'); // Works on Windows XP, but fails on Windows 10
Based on the comment from @FredS (thanks!), the answer is simply to make the last parameter for the IcmpSendEcho
non-zero (eg. "200").
The MSDN documentation for IcmpSendEcho
does not make this clear, so Microsoft have probably changed the internal implementation of this method from the version in Windows XP so that a non-zero Timeout
is now required.