Misc internal optimizations

* Make ipv4addr_to_libc const
* Use mem::transmute in ipv4addr_to_libc and ipv6addr_to_libc

Fixes #1687
Fixes #1688

1 files changed, 10 insertions, 11 deletions

diff --git a/src/sys/socket/addr.rs b/src/sys/socket/addr.rs
index 4a16eea9..c7b5f29e 100644
--- a/src/sys/socket/addr.rs
+++ b/src/sys/socket/addr.rs
@@ -40,23 +40,22 @@ use std::{fmt, mem, net, ptr, slice};
 
 /// Convert a std::net::Ipv4Addr into the libc form.
 #[cfg(feature = "net")]
-pub(crate) fn ipv4addr_to_libc(addr: net::Ipv4Addr) -> libc::in_addr {
-    let octets = addr.octets();
-    libc::in_addr {
-        s_addr: u32::to_be(
-            ((octets[0] as u32) << 24)
-                | ((octets[1] as u32) << 16)
-                | ((octets[2] as u32) << 8)
-                | (octets[3] as u32),
-        ),
+pub(crate) const fn ipv4addr_to_libc(addr: net::Ipv4Addr) -> libc::in_addr {
+    static_assertions::assert_eq_size!(net::Ipv4Addr, libc::in_addr);
+    // Safe because both types have the same memory layout, and no fancy Drop
+    // impls.
+    unsafe {
+        mem::transmute(addr)
     }
 }
 
 /// Convert a std::net::Ipv6Addr into the libc form.
 #[cfg(feature = "net")]
 pub(crate) const fn ipv6addr_to_libc(addr: &net::Ipv6Addr) -> libc::in6_addr {
-    libc::in6_addr {
-        s6_addr: addr.octets(),
+    static_assertions::assert_eq_size!(net::Ipv6Addr, libc::in6_addr);
+    // Safe because both are Newtype wrappers around the same libc type
+    unsafe {
+        mem::transmute(*addr)
     }
 }