Passing values into a procedure from NextButtonClicked method Inno Setup - inno-setup

Question

Currently I'm trying to make an installer utility that sets the static IP for the Wi-Fi on Inno Setup. I'm having trouble finding a way to make the correct command insert when the Next button of custom page is pressed. The NextButtonClick method is called correctly however when I actually hit the next button on my page it merely exits without executing the query.
procedure InitializeWizard();
var
Page: TInputQueryWizardPage;
ipAddress, subnetMask, defaultGateway, prefferredDNSServer: String;
ResultCode: Integer;
begin
Page := CreateInputQueryPage(wpWelcome,
'Set Network Config', 'A window for setting the wifi configuration',
'Please indicate the IP address and press next when finished.');
{ Add items (False means it's not a password edit) }
Page.Add('IP Address:', False);
Page.Add('Subnet mask:', False);
Page.Add('Default gateway:', False);
Page.Add('Preferred DNS server:', False);
{ Set initial values (optional) }
Page.Values[0] := ExpandConstant('0.0.0.0');
ipAddress := Page.Values[0]
Page.Values[1] := ExpandConstant('0.0.0.0');
subnetMask := Page.Values[1]
Page.Values[2] := ExpandConstant('0.0.0.0');
defaultGateway := Page.Values[2]
Page.Values[3] := ExpandConstant('0.0.0.0');
prefferredDNSServer := Page.Values[3]
if NextButtonClick(Page.ID) then
begin
Exec('cmd.exe',
'/k ' + 'netsh interface ip set address "Wi-Fi" static ' + ipAddress + ' ' +
subnetMask + ' ' + defaultGateway + ' ' + prefferredDNSServer,
'', SW_SHOW, ewWaitUntilTerminated, ResultCode)
end;
end;
function NextButtonClick(CurPageID: Integer): Boolean;
var
ipAddress, subnetMask, defaultGateway, prefferredDNSServer: String;
ResultCode: Integer;
begin
Result := True
Log('NextButtonClick(' + IntToStr(CurPageID) + ') called');
case CurPageID of
100:
{ ipAddress := getParams(ipAddress); }
{ setWifi(ipAddress, subnetMask, defaultGateway, prefferredDNSServer); }
Result:= True;
end;
end;

Answer 1

You do not call the NextButtonClick function yourself. It's an event function, so it's called by Inno Setup.
The code should be like:
var
NetPage: TInputQueryWizardPage;
procedure InitializeWizard();
begin
NetPage :=
CreateInputQueryPage(wpWelcome,
'Set Network Config', 'A window for setting the wifi configuration',
'Please indicate the IP address and press next when finished.');
{ Add items (False means it's not a password edit) }
NetPage.Add('IP Address:', False);
NetPage.Add('Subnet mask:', False);
NetPage.Add('Default gateway:', False);
NetPage.Add('Preferred DNS server:', False);
{ Set initial values (optional) }
NetPage.Values[0] := ExpandConstant('0.0.0.0');
NetPage.Values[1] := ExpandConstant('0.0.0.0');
NetPage.Values[2] := ExpandConstant('0.0.0.0');
NetPage.Values[3] := ExpandConstant('0.0.0.0');
end;
function NextButtonClick(CurPageID: Integer): Boolean;
var
ipAddress, subnetMask, defaultGateway, prefferredDNSServer: String;
ResultCode: Integer;
Command: string;
begin
Result := True;
if CurPageID = NetPage.ID then
begin
ipAddress := NetPage.Values[0];
subnetMask := NetPage.Values[1];
defaultGateway := NetPage.Values[2];
prefferredDNSServer := NetPage.Values[3];
Command :=
'netsh interface ip set address "Wi-Fi" static ' +
ipAddress + ' ' + subnetMask + ' ' + defaultGateway + ' ' + prefferredDNSServer;
Exec('cmd.exe', '/C ' + Command, '', SW_SHOW, ewWaitUntilTerminated, ResultCode)
end;
end;
Though, in general, you should do any changes to the target system, until the user confirms the installation by clicking "Install" on the "Ready to Install" page.
While you can use CurPageID = wpReady for that, a more idiomatic approach is using CurStepChanged(ssInstall) (or ssPostInstall):
procedure CurStepChanged(CurStep: TSetupStep);
var
ipAddress, subnetMask, defaultGateway, prefferredDNSServer: String;
ResultCode: Integer;
Command: string;
begin
if CurStep = ssInstall then
begin
ipAddress := NetPage.Values[0];
subnetMask := NetPage.Values[1];
defaultGateway := NetPage.Values[2];
prefferredDNSServer := NetPage.Values[3];
Command :=
'netsh interface ip set address "Wi-Fi" static ' +
ipAddress + ' ' + subnetMask + ' ' + defaultGateway + ' ' + prefferredDNSServer;
Exec('cmd.exe', '/C ' + Command, '', SW_SHOW, ewWaitUntilTerminated, ResultCode)
end;
end;