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use std::{
ffi::{c_int, c_uchar},
mem, ptr,
};
use windows_sys::Win32::Networking::WinSock;
use super::{CMsgHdr, MsgHdr};
#[derive(Copy, Clone)]
#[repr(align(8))] // Conservative bound for align_of<WinSock::CMSGHDR>
pub(crate) struct Aligned<T>(pub(crate) T);
/// Helpers for [`WinSock::WSAMSG`]
// https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/Networking/WinSock/struct.WSAMSG.html
impl MsgHdr for WinSock::WSAMSG {
type ControlMessage = WinSock::CMSGHDR;
fn cmsg_first_hdr(&self) -> *mut Self::ControlMessage {
if self.Control.len as usize >= mem::size_of::<WinSock::CMSGHDR>() {
self.Control.buf as *mut WinSock::CMSGHDR
} else {
ptr::null_mut::<WinSock::CMSGHDR>()
}
}
fn cmsg_nxt_hdr(&self, cmsg: &Self::ControlMessage) -> *mut Self::ControlMessage {
let next =
(cmsg as *const _ as usize + cmsghdr_align(cmsg.cmsg_len)) as *mut WinSock::CMSGHDR;
let max = self.Control.buf as usize + self.Control.len as usize;
if unsafe { next.offset(1) } as usize > max {
ptr::null_mut()
} else {
next
}
}
fn set_control_len(&mut self, len: usize) {
self.Control.len = len as _;
}
fn control_len(&self) -> usize {
self.Control.len as _
}
}
/// Helpers for [`WinSock::CMSGHDR`]
// https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/Networking/WinSock/struct.CMSGHDR.html
impl CMsgHdr for WinSock::CMSGHDR {
fn cmsg_len(length: usize) -> usize {
cmsgdata_align(mem::size_of::<Self>()) + length
}
fn cmsg_space(length: usize) -> usize {
cmsgdata_align(mem::size_of::<Self>() + cmsghdr_align(length))
}
fn cmsg_data(&self) -> *mut c_uchar {
(self as *const _ as usize + cmsgdata_align(mem::size_of::<Self>())) as *mut c_uchar
}
fn set(&mut self, level: c_int, ty: c_int, len: usize) {
self.cmsg_level = level as _;
self.cmsg_type = ty as _;
self.cmsg_len = len as _;
}
fn len(&self) -> usize {
self.cmsg_len as _
}
}
// Helpers functions for `WinSock::WSAMSG` and `WinSock::CMSGHDR` are based on C macros from
fn cmsghdr_align(length: usize) -> usize {
(length + mem::align_of::<WinSock::CMSGHDR>() - 1) & !(mem::align_of::<WinSock::CMSGHDR>() - 1)
}
fn cmsgdata_align(length: usize) -> usize {
(length + mem::align_of::<usize>() - 1) & !(mem::align_of::<usize>() - 1)
}