getservbyport

// WS2_32.dll
#include <windows.h>

SERVENT* getservbyport(
    INT port,
    LPCSTR proto   // optional
);

<DllImport("WS2_32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function getservbyport(
    port As Integer,   ' INT
    <MarshalAs(UnmanagedType.LPStr)> proto As String   ' LPCSTR optional
) As IntPtr
End Function

' port : INT
' proto : LPCSTR optional
Declare PtrSafe Function getservbyport Lib "ws2_32" ( _
    ByVal port As Long, _
    ByVal proto As String) As LongPtr
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

getservbyport = ctypes.windll.ws2_32.getservbyport
getservbyport.restype = ctypes.c_void_p
getservbyport.argtypes = [
    ctypes.c_int,  # port : INT
    wintypes.LPCSTR,  # proto : LPCSTR optional
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('WS2_32.dll')
getservbyport = Fiddle::Function.new(
  lib['getservbyport'],
  [
    Fiddle::TYPE_INT,  # port : INT
    Fiddle::TYPE_VOIDP,  # proto : LPCSTR optional
  ],
  Fiddle::TYPE_VOIDP)

#[link(name = "ws2_32")]
extern "system" {
    fn getservbyport(
        port: i32,  // INT
        proto: *const u8  // LPCSTR optional
    ) -> *mut SERVENT;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("WS2_32.dll", SetLastError = true)]
public static extern IntPtr getservbyport(int port, [MarshalAs(UnmanagedType.LPStr)] string proto);
"@
$api = Add-Type -MemberDefinition $sig -Name 'WS2_32_getservbyport' -Namespace Win32 -PassThru
# $api::getservbyport(port, proto)

#uselib "WS2_32.dll"
#func global getservbyport "getservbyport" sptr, sptr
; getservbyport port, proto   ; 戻り値は stat
; port : INT -> "sptr"
; proto : LPCSTR optional -> "sptr"
; ※HSP3.7は #func のため戻り値はシステム変数 stat に格納されます。

#uselib "WS2_32.dll"
#cfunc global getservbyport "getservbyport" int, str
; res = getservbyport(port, proto)
; port : INT -> "int"
; proto : LPCSTR optional -> "str"

; SERVENT* getservbyport(INT port, LPCSTR proto)
#uselib "WS2_32.dll"
#cfunc global getservbyport "getservbyport" int, str
; res = getservbyport(port, proto)
; port : INT -> "int"
; proto : LPCSTR optional -> "str"

import (
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	ws2_32 = windows.NewLazySystemDLL("WS2_32.dll")
	procgetservbyport = ws2_32.NewProc("getservbyport")
)

// port (INT), proto (LPCSTR optional)
r1, _, err := procgetservbyport.Call(
	uintptr(port),
	uintptr(unsafe.Pointer(windows.BytePtrFromString(proto))),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // SERVENT*

function getservbyport(
  port: Integer;   // INT
  proto: PAnsiChar   // LPCSTR optional
): Pointer; stdcall;
  external 'WS2_32.dll' name 'getservbyport';

result := DllCall("WS2_32\getservbyport"
    , "Int", port   ; INT
    , "AStr", proto   ; LPCSTR optional
    , "Ptr")   ; return: SERVENT*

●getservbyport(port, proto) = DLL("WS2_32.dll", "void* getservbyport(int, char*)")
# 呼び出し: getservbyport(port, proto)
# port : INT -> "int"
# proto : LPCSTR optional -> "char*"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。