recvfrom

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

INT recvfrom(
    SOCKET s,
    LPSTR buf,
    INT len,
    INT flags,
    SOCKADDR* from,   // optional
    INT* fromlen   // optional
);

<DllImport("WS2_32.dll", SetLastError:=True, ExactSpelling:=True)>
Public Shared Function recvfrom(
    s As UIntPtr,   ' SOCKET
    <MarshalAs(UnmanagedType.LPStr)> buf As System.Text.StringBuilder,   ' LPSTR out
    len As Integer,   ' INT
    flags As Integer,   ' INT
    [from] As IntPtr,   ' SOCKADDR* optional, out
    fromlen As IntPtr   ' INT* optional, in/out
) As Integer
End Function

' s : SOCKET
' buf : LPSTR out
' len : INT
' flags : INT
' from : SOCKADDR* optional, out
' fromlen : INT* optional, in/out
Declare PtrSafe Function recvfrom Lib "ws2_32" ( _
    ByVal s As LongPtr, _
    ByVal buf As String, _
    ByVal len As Long, _
    ByVal flags As Long, _
    ByVal from As LongPtr, _
    ByVal fromlen As LongPtr) As Long
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

recvfrom = ctypes.windll.ws2_32.recvfrom
recvfrom.restype = ctypes.c_int
recvfrom.argtypes = [
    ctypes.c_size_t,  # s : SOCKET
    wintypes.LPSTR,  # buf : LPSTR out
    ctypes.c_int,  # len : INT
    ctypes.c_int,  # flags : INT
    ctypes.c_void_p,  # from : SOCKADDR* optional, out
    ctypes.POINTER(ctypes.c_int),  # fromlen : INT* optional, in/out
]
# GetLastError: use ctypes.GetLastError() (or ctypes.WinDLL(use_last_error=True))

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('WS2_32.dll')
recvfrom = Fiddle::Function.new(
  lib['recvfrom'],
  [
    Fiddle::TYPE_UINTPTR_T,  # s : SOCKET
    Fiddle::TYPE_VOIDP,  # buf : LPSTR out
    Fiddle::TYPE_INT,  # len : INT
    Fiddle::TYPE_INT,  # flags : INT
    Fiddle::TYPE_VOIDP,  # from : SOCKADDR* optional, out
    Fiddle::TYPE_VOIDP,  # fromlen : INT* optional, in/out
  ],
  Fiddle::TYPE_INT)

#[link(name = "ws2_32")]
extern "system" {
    fn recvfrom(
        s: usize,  // SOCKET
        buf: *mut u8,  // LPSTR out
        len: i32,  // INT
        flags: i32,  // INT
        from: *mut SOCKADDR,  // SOCKADDR* optional, out
        fromlen: *mut i32  // INT* optional, in/out
    ) -> i32;
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("WS2_32.dll", SetLastError = true)]
public static extern int recvfrom(UIntPtr s, [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder buf, int len, int flags, IntPtr from, IntPtr fromlen);
"@
$api = Add-Type -MemberDefinition $sig -Name 'WS2_32_recvfrom' -Namespace Win32 -PassThru
# $api::recvfrom(s, buf, len, flags, from, fromlen)

#uselib "WS2_32.dll"
#func global recvfrom "recvfrom" sptr, sptr, sptr, sptr, sptr, sptr
; recvfrom s, varptr(buf), len, flags, varptr(from), varptr(fromlen)   ; 戻り値は stat
; s : SOCKET -> "sptr"
; buf : LPSTR out -> "sptr"
; len : INT -> "sptr"
; flags : INT -> "sptr"
; from : SOCKADDR* optional, out -> "sptr"
; fromlen : INT* optional, in/out -> "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 recvfrom "recvfrom" sptr, var, int, int, var, var
; res = recvfrom(s, buf, len, flags, from, fromlen)
; s : SOCKET -> "sptr"
; buf : LPSTR out -> "var"
; len : INT -> "int"
; flags : INT -> "int"
; from : SOCKADDR* optional, out -> "var"
; fromlen : INT* optional, in/out -> "var"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

; INT recvfrom(SOCKET s, LPSTR buf, INT len, INT flags, SOCKADDR* from, INT* fromlen)
#uselib "WS2_32.dll"
#cfunc global recvfrom "recvfrom" intptr, var, int, int, var, var
; res = recvfrom(s, buf, len, flags, from, fromlen)
; s : SOCKET -> "intptr"
; buf : LPSTR out -> "var"
; len : INT -> "int"
; flags : INT -> "int"
; from : SOCKADDR* optional, out -> "var"
; fromlen : INT* optional, in/out -> "var"
; ※出力/バッファ引数は var 方式(変数を直接渡す)。varptr 方式にも切替可。

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

var (
	ws2_32 = windows.NewLazySystemDLL("WS2_32.dll")
	procrecvfrom = ws2_32.NewProc("recvfrom")
)

// s (SOCKET), buf (LPSTR out), len (INT), flags (INT), from (SOCKADDR* optional, out), fromlen (INT* optional, in/out)
r1, _, err := procrecvfrom.Call(
	uintptr(s),
	uintptr(buf),
	uintptr(len),
	uintptr(flags),
	uintptr(from),
	uintptr(fromlen),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // INT

function recvfrom(
  s: NativeUInt;   // SOCKET
  buf: PAnsiChar;   // LPSTR out
  len: Integer;   // INT
  flags: Integer;   // INT
  from: Pointer;   // SOCKADDR* optional, out
  fromlen: Pointer   // INT* optional, in/out
): Integer; stdcall;
  external 'WS2_32.dll' name 'recvfrom';

result := DllCall("WS2_32\recvfrom"
    , "UPtr", s   ; SOCKET
    , "Ptr", buf   ; LPSTR out
    , "Int", len   ; INT
    , "Int", flags   ; INT
    , "Ptr", from   ; SOCKADDR* optional, out
    , "Ptr", fromlen   ; INT* optional, in/out
    , "Int")   ; return: INT

●recvfrom(s, buf, len, flags, from, fromlen) = DLL("WS2_32.dll", "int recvfrom(int, char*, int, int, void*, void*)")
# 呼び出し: recvfrom(s, buf, len, flags, from, fromlen)
# s : SOCKET -> "int"
# buf : LPSTR out -> "char*"
# len : INT -> "int"
# flags : INT -> "int"
# from : SOCKADDR* optional, out -> "void*"
# fromlen : INT* optional, in/out -> "void*"
# 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)。