Verify permissions to run Inno Setup installer online - inno-setup

Question

I am looking for a code for Inno Setup, that I can use to make my setup verify my permission to install the program. This code must check a text file on a web server.
If the file has the value "False", the setup has to cancel an installation and save the value in a registry file to cancel it always when Internet connection is not available.
If the file has the value "True", the setup will continue to install, and it will delete the registry file value if it exists.
If there is no Internet and the registry value does not exist the setup will continue to install.

Answer 1

Use InitializeSetup event function to trigger your check using HTTP request.
[Code]
const
SubkeyName = 'Software\My Program';
AllowInstallationValue = 'Allow Installation';
function IsInstallationAllowed: Boolean;
var
Url: string;
WinHttpReq: Variant;
S: string;
ResultDWord: Cardinal;
begin
try
WinHttpReq := CreateOleObject('WinHttp.WinHttpRequest.5.1');
Url := 'https://www.example.com/can_install.txt';
WinHttpReq.Open('GET', Url, False);
WinHttpReq.Send('');
if WinHttpReq.Status <> 200 then
begin
RaiseException(
'HTTP Error: ' + IntToStr(WinHttpReq.Status) + ' ' + WinHttpReq.StatusText);
end
else
begin
S := Trim(WinHttpReq.ResponseText);
Log('HTTP Response: ' + S);
Result := (CompareText(S, 'true') = 0);
if RegWriteDWordValue(
HKLM, SubkeyName, AllowInstallationValue, Integer(Result)) then
Log('Cached response to registry')
else
Log('Error caching response to registry');
end;
except
Log('Error: ' + GetExceptionMessage);
if RegQueryDWordValue(HKLM, SubkeyName, AllowInstallationValue, ResultDWord) then
begin
Log('Online check failed, using cached result');
Result := (ResultDWord <> 0);
end
else
begin
Log('Online check failed, no cached result, allowing installation by default');
Result := True;
end;
end;
if Result then Log('Can install')
else Log('Cannot install');
end;
function InitializeSetup(): Boolean;
begin
Result := True;
if not IsInstallationAllowed then
begin
MsgBox('You cannot install this', mbError, MB_OK);
Result := False;
end;
end;