Don't assume representation of Ipv*Addr types

Also, remove two uses of unsafe :)

Author: est31

quinn/src/platform/unix.rs

@@ -2,7 +2,7 @@ use std::{
     io,
     io::IoSliceMut,
     mem::{self, MaybeUninit},
-    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
+    net::{IpAddr, Ipv4Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
     os::unix::io::AsRawFd,
     ptr,
     task::{Context, Poll},
@@ -332,6 +332,12 @@ pub fn caps() -> UdpCapabilities {
 
 const CMSG_LEN: usize = 80;
 
+fn in_addr(addr: &Ipv4Addr) -> libc::in_addr {
+    libc::in_addr {
+        s_addr: u32::from_ne_bytes(addr.octets()),
+    }
+}
+
 fn prepare_msg(
     transmit: &Transmit,
     hdr: &mut libc::msghdr,
@@ -375,18 +381,16 @@ fn prepare_msg(
                 IpAddr::V4(v4) => {
                     let pktinfo = libc::in_pktinfo {
                         ipi_ifindex: 0,
-                        ipi_spec_dst: unsafe {
-                            *(v4 as *const Ipv4Addr as *const () as *const libc::in_addr)
-                        },
+                        ipi_spec_dst: in_addr(v4),
                         ipi_addr: libc::in_addr { s_addr: 0 },
                     };
                     encoder.push(libc::IPPROTO_IP, libc::IP_PKTINFO, pktinfo);
                 }
                 IpAddr::V6(v6) => {
                     let pktinfo = libc::in6_pktinfo {
                         ipi6_ifindex: 0,
-                        ipi6_addr: unsafe {
-                            *(v6 as *const Ipv6Addr as *const () as *const libc::in6_addr)
+                        ipi6_addr: libc::in6_addr {
+                            s6_addr: v6.octets(),
                         },
                     };
                     encoder.push(libc::IPPROTO_IPV6, libc::IPV6_PKTINFO, pktinfo);