From 2d18eb668687da5a3056994496f44daafac315f9 Mon Sep 17 00:00:00 2001
From: Val Packett <val@packett.cool>
Date: Fri, 22 Mar 2024 15:35:34 -0300
Subject: [PATCH] udp: fix msghdr creation on musl libc

Right now building for musl also requires updating glommio to a git
version.
---
 .../src/workers/socket/uring/recv_helper.rs   | 34 ++++++++-----------
 .../src/workers/socket/uring/send_buffers.rs  | 12 ++-----
 2 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/crates/udp/src/workers/socket/uring/recv_helper.rs b/crates/udp/src/workers/socket/uring/recv_helper.rs
index 0aef6d9..7e7ca64 100644
--- a/crates/udp/src/workers/socket/uring/recv_helper.rs
+++ b/crates/udp/src/workers/socket/uring/recv_helper.rs
@@ -1,6 +1,6 @@
 use std::{
+    mem::MaybeUninit,
     net::{Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
-    ptr::null_mut,
 };
 
 use aquatic_common::CanonicalSocketAddr;
@@ -39,15 +39,13 @@ impl RecvHelper {
             sin_zero: [0; 8],
         }));
 
-        let msghdr_v4 = Box::into_raw(Box::new(libc::msghdr {
-            msg_name: name_v4 as *mut libc::c_void,
-            msg_namelen: core::mem::size_of::<libc::sockaddr_in>() as u32,
-            msg_iov: null_mut(),
-            msg_iovlen: 0,
-            msg_control: null_mut(),
-            msg_controllen: 0,
-            msg_flags: 0,
-        }));
+        // XXX: on musl libc, msghdr contains private padding fields
+        let msghdr_v4 = unsafe {
+            let mut hdr = MaybeUninit::<libc::msghdr>::zeroed().assume_init();
+            hdr.msg_name = name_v4 as *mut libc::c_void;
+            hdr.msg_namelen = core::mem::size_of::<libc::sockaddr_in>() as u32;
+            Box::into_raw(Box::new(hdr))
+        };
 
         let name_v6 = Box::into_raw(Box::new(libc::sockaddr_in6 {
             sin6_family: 0,
@@ -57,15 +55,13 @@ impl RecvHelper {
             sin6_scope_id: 0,
         }));
 
-        let msghdr_v6 = Box::into_raw(Box::new(libc::msghdr {
-            msg_name: name_v6 as *mut libc::c_void,
-            msg_namelen: core::mem::size_of::<libc::sockaddr_in6>() as u32,
-            msg_iov: null_mut(),
-            msg_iovlen: 0,
-            msg_control: null_mut(),
-            msg_controllen: 0,
-            msg_flags: 0,
-        }));
+        // XXX: on musl libc, msghdr contains private padding fields
+        let msghdr_v6 = unsafe {
+            let mut hdr = MaybeUninit::<libc::msghdr>::zeroed().assume_init();
+            hdr.msg_name = name_v6 as *mut libc::c_void;
+            hdr.msg_namelen = core::mem::size_of::<libc::sockaddr_in6>() as u32;
+            Box::into_raw(Box::new(hdr))
+        };
 
         Self {
             socket_is_ipv4: config.network.address.is_ipv4(),
diff --git a/crates/udp/src/workers/socket/uring/send_buffers.rs b/crates/udp/src/workers/socket/uring/send_buffers.rs
index 902e251..b2b1772 100644
--- a/crates/udp/src/workers/socket/uring/send_buffers.rs
+++ b/crates/udp/src/workers/socket/uring/send_buffers.rs
@@ -1,6 +1,7 @@
 use std::{
     io::Cursor,
     iter::repeat_with,
+    mem::MaybeUninit,
     net::SocketAddr,
     ptr::{addr_of_mut, null_mut},
 };
@@ -135,21 +136,14 @@ impl SendBuffer {
                 iov_base: null_mut(),
                 iov_len: 0,
             },
-            msghdr: libc::msghdr {
-                msg_name: null_mut(),
-                msg_namelen: 0,
-                msg_iov: null_mut(),
-                msg_iovlen: 1,
-                msg_control: null_mut(),
-                msg_controllen: 0,
-                msg_flags: 0,
-            },
+            msghdr: unsafe { MaybeUninit::<libc::msghdr>::zeroed().assume_init() },
         });
 
         instance.iovec.iov_base = addr_of_mut!(instance.bytes) as *mut libc::c_void;
         instance.iovec.iov_len = instance.bytes.len();
 
         instance.msghdr.msg_iov = addr_of_mut!(instance.iovec);
+        instance.msghdr.msg_iovlen = 1;
 
         if socket_is_ipv4 {
             instance.msghdr.msg_name = addr_of_mut!(instance.name_v4) as *mut libc::c_void;