From 5023b6b0c328c0fb7286bbfb3325fec1a371b615 Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josh@tailscale.com>
Date: Thu, 8 Jul 2021 13:58:06 -0700
Subject: [PATCH] make ipv4/ipv6 code parallel

and thus more clearly correct
weirdly, since it is using unsafe
---
 net/uring/io_uring_linux.go | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/uring/io_uring_linux.go b/net/uring/io_uring_linux.go
index 183d334d9..e5f1e3b69 100644
--- a/net/uring/io_uring_linux.go
+++ b/net/uring/io_uring_linux.go
@@ -5,7 +5,6 @@ package uring
 import "C"
 
 import (
-	"encoding/binary"
 	"errors"
 	"fmt"
 	"net"
@@ -289,9 +288,9 @@ func (u *UDPConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	copy(rbuf, p)
 
 	if u.is4 {
-		// TODO: are the following two lines of code correct?
-		ipu32 := binary.BigEndian.Uint32(udpAddr.IP)
-		r.sa.sin_addr.s_addr = C.uint32_t(endian.Hton32(ipu32))
+		dst := (*[4]byte)((unsafe.Pointer)(&r.sa.sin_addr.s_addr))
+		src := (*[4]byte)((unsafe.Pointer)(&udpAddr.IP[0]))
+		*dst = *src
 		r.sa.sin_port = C.uint16_t(endian.Hton16(uint16(udpAddr.Port)))
 		r.sa.sin_family = C.AF_INET
 	} else {