Cross-Platform System Call Executor (x86, x64, ARM) in Delphi

SysCallExecutor.pas

unit SysCallExecutor;

interface

uses
  Windows, SysUtils;

type
  TSysCallExecutor = class
  private
    function GetSysCallNumber(const FunctionName: string): Cardinal;
    function GetProcAddressEx(const ModuleName, FunctionName: string): Pointer;
  public
    function ExecuteSysCall(SysCallNumber: Cardinal; Parameters: array of Pointer): Integer;
    function ExecuteFunctionByName(const FunctionName: string; Parameters: array of Pointer): Integer;
  end;

implementation

function TSysCallExecutor.GetProcAddressEx(const ModuleName, FunctionName: string): Pointer;
var
  ModuleHandle: HMODULE;
begin
  ModuleHandle := GetModuleHandle(PChar(ModuleName));
  if ModuleHandle = 0 then
    raise Exception.CreateFmt('Module not found: %s', [ModuleName]);

  Result := GetProcAddress(ModuleHandle, PChar(FunctionName));
  if not Assigned(Result) then
    raise Exception.CreateFmt('Function not found: %s in module %s', [FunctionName, ModuleName]);
end;

function TSysCallExecutor.GetSysCallNumber(const FunctionName: string): Cardinal;
var
  NtFunction: Pointer;
begin
  NtFunction := GetProcAddressEx('ntdll.dll', FunctionName);
  if not Assigned(NtFunction) then
    raise Exception.CreateFmt('Failed to locate function: %s', [FunctionName]);

  Result := PCardinal(Cardinal(NtFunction) + 1)^; // Syscall number is located at +1 offset
end;

function TSysCallExecutor.ExecuteSysCall(SysCallNumber: Cardinal; Parameters: array of Pointer): Integer;
{$IFDEF WIN32}
asm
  // Save state
  pushad
  pushfd

  // Load syscall number
  mov eax, SysCallNumber

  // Load parameters into registers
  mov ecx, Parameters

  // Execute syscall
  int $2E // System call interrupt for 32-bit systems

  // Store result in EAX
  mov @Result, eax

  // Restore state
  popfd
  popad
end;
{$ELSEIF Defined(WIN64)}
asm
  // x64 uses the syscall instruction
  mov r10, rcx         // First parameter in rcx
  mov eax, SysCallNumber
  syscall              // Invoke syscall
  mov @Result, eax     // Return value in eax
end;
{$ELSEIF Defined(ARM)}
asm
  // ARM architecture uses SVC (Supervisor Call) for syscalls
  mov w8, SysCallNumber // Load syscall number into w8 (ARM convention)
  svc #0                // Supervisor call
  mov @Result, w0       // Store the result from x0 (ARM convention)
end;
{$ELSE}
  {$ERROR Unsupported architecture}
{$ENDIF}

function TSysCallExecutor.ExecuteFunctionByName(const FunctionName: string; Parameters: array of Pointer): Integer;
var
  SysCallNumber: Cardinal;
begin
  SysCallNumber := GetSysCallNumber(FunctionName);
  Result := ExecuteSysCall(SysCallNumber, Parameters);
end;

end.

program LowLevelHttp;

{$APPTYPE CONSOLE}

uses
  SysCallExecutor, Windows, SysUtils;

procedure PerformHttpPostAndGet;
var
  Executor: TSysCallExecutor;
  SocketHandle: THandle;
  ServerAddr: TSockAddrIn;
  IoStatusBlock: IO_STATUS_BLOCK;
  Request: string;
  Response: array[0..4095] of AnsiChar;
  Result: Integer;
  BytesReceived: Cardinal;
begin
  Executor := TSysCallExecutor.Create;
  try
    // Step 1: Create a socket using NtCreateFile
    Result := Executor.ExecuteFunctionByName(
      'NtCreateFile',
      [@SocketHandle,
       Pointer($80100000), // FILE_GENERIC_WRITE | FILE_GENERIC_READ
       nil,                // ObjectAttributes
       @IoStatusBlock,
       nil,                // Allocation size
       Pointer(0),         // File attributes
       Pointer(3),         // Share access: FILE_SHARE_READ
       Pointer(1),         // Create disposition: FILE_OPEN
       Pointer(0),         // Create options
       nil,                // EaBuffer
       Pointer(0)          // EaLength
      ]);
    if Result <> 0 then
      raise Exception.CreateFmt('Failed to create socket: %d', [Result]);

    Writeln('Socket created.');

    // Step 2: Connect to the server
    FillChar(ServerAddr, SizeOf(ServerAddr), 0);
    ServerAddr.sin_family := AF_INET;
    ServerAddr.sin_port := htons(80); // HTTP port
    ServerAddr.sin_addr.S_addr := inet_addr('93.184.216.34'); // example.com

    Result := Executor.ExecuteFunctionByName(
      'NtDeviceIoControlFile',
      [SocketHandle,
       nil,                // Event
       nil,                // ApcRoutine
       nil,                // ApcContext
       @IoStatusBlock,
       Pointer(IOCTL_CONNECT), // IOCTL_CONNECT placeholder
       @ServerAddr,
       Pointer(SizeOf(ServerAddr)),
       nil,
       Pointer(0)
      ]);
    if Result <> 0 then
      raise Exception.CreateFmt('Failed to connect: %d', [Result]);

    Writeln('Connected to server.');

    // Step 3: Perform HTTP POST to upload data
    Request :=
      'POST /upload HTTP/1.1' + #13#10 +
      'Host: example.com' + #13#10 +
      'Content-Type: text/plain' + #13#10 +
      'Content-Length: 11' + #13#10 +
      #13#10 +
      'Hello World';

    Result := Executor.ExecuteFunctionByName(
      'NtDeviceIoControlFile',
      [SocketHandle,
       nil,                // Event
       nil,                // ApcRoutine
       nil,                // ApcContext
       @IoStatusBlock,
       Pointer(IOCTL_SEND), // IOCTL_SEND placeholder
       @Request[1],
       Pointer(Length(Request)),
       nil,
       Pointer(0)
      ]);
    if Result <> 0 then
      raise Exception.CreateFmt('Failed to send POST request: %d', [Result]);

    Writeln('POST request sent.');

    // Step 4: Perform HTTP GET to retrieve uploaded data
    Request :=
      'GET /upload HTTP/1.1' + #13#10 +
      'Host: example.com' + #13#10 +
      #13#10;

    Result := Executor.ExecuteFunctionByName(
      'NtDeviceIoControlFile',
      [SocketHandle,
       nil,                // Event
       nil,                // ApcRoutine
       nil,                // ApcContext
       @IoStatusBlock,
       Pointer(IOCTL_SEND), // IOCTL_SEND placeholder
       @Request[1],
       Pointer(Length(Request)),
       nil,
       Pointer(0)
      ]);
    if Result <> 0 then
      raise Exception.CreateFmt('Failed to send GET request: %d', [Result]);

    Writeln('GET request sent.');

    // Step 5: Receive the response
    FillChar(Response, SizeOf(Response), 0);
    Result := Executor.ExecuteFunctionByName(
      'NtDeviceIoControlFile',
      [SocketHandle,
       nil,                // Event
       nil,                // ApcRoutine
       nil,                // ApcContext
       @IoStatusBlock,
       Pointer(IOCTL_RECEIVE), // IOCTL_RECEIVE placeholder
       @Response,
       Pointer(SizeOf(Response)),
       nil,
       Pointer(0)
      ]);
    if Result = 0 then
    begin
      BytesReceived := IoStatusBlock.Information;
      Writeln('Response received:');
      Writeln(Copy(Response, 1, BytesReceived));
    end
    else
      Writeln('Failed to receive response: ', Result);

  finally
    Executor.Free;
  end;
end;

begin
  PerformHttpPostAndGet;
end.