From 5f28321e7365a851fc64cb74b9b0a6a3cadd1ebe Mon Sep 17 00:00:00 2001
From: Yury Yarashevich <yura.yaroshevich@gmail.com>
Date: Wed, 31 Jul 2024 23:13:58 +0200
Subject: [PATCH] Fix SocketAddr to libc::sockaddr conversion.

---
 CHANGELOG.md                                  |  1 +
 .../src/network_reachability.rs               | 66 ++++++++++++++++---
 2 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1887f92..8895fd1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ Line wrap the file at 100 chars.                                              Th
 
 
 ## [Unreleased]
+- Fix `std::net::SocketAddr` conversion to `libc::sockaddr`
 
 ## [0.6.0] - 2024-01-31
 ### Changed
diff --git a/system-configuration/src/network_reachability.rs b/system-configuration/src/network_reachability.rs
index 2770ee3..d52e868 100644
--- a/system-configuration/src/network_reachability.rs
+++ b/system-configuration/src/network_reachability.rs
@@ -344,24 +344,35 @@ impl<T: Fn(ReachabilityFlags) + Sync + Send> NetworkReachabilityCallbackContext<
 /// libc::sockaddr_in6, depending on the passed in standard library SocketAddr.
 fn to_c_sockaddr(addr: SocketAddr) -> Box<libc::sockaddr> {
     let ptr = match addr {
+        // See reference conversion from socket2:
+        // https://github.com/rust-lang/socket2/blob/3a938932829ea6ee3025d2d7a86c7b095c76e6c3/src/sockaddr.rs#L277-L287
+        // https://github.com/rust-lang/socket2/blob/3a938932829ea6ee3025d2d7a86c7b095c76e6c3/src/sys/unix.rs#L1356-L1363
         SocketAddr::V4(addr) => Box::into_raw(Box::new(libc::sockaddr_in {
             sin_len: std::mem::size_of::<libc::sockaddr_in>() as u8,
-            sin_family: libc::AF_INET as u8,
-            sin_port: addr.port(),
-            sin_addr: libc::in_addr {
-                s_addr: u32::from(*addr.ip()),
+            sin_family: libc::AF_INET as libc::sa_family_t,
+            sin_port: addr.port().to_be(),
+            sin_addr: {
+                // `s_addr` is stored as BE on all machines, and the array is in BE order.
+                // So the native endian conversion method is used so that it's never
+                // swapped.
+                libc::in_addr {
+                    s_addr: u32::from_ne_bytes(addr.ip().octets()),
+                }
             },
-            sin_zero: [0i8; 8],
+            sin_zero: Default::default(),
         })) as *mut c_void,
+        // See reference conversion from socket2:
+        // https://github.com/rust-lang/socket2/blob/3a938932829ea6ee3025d2d7a86c7b095c76e6c3/src/sockaddr.rs#L314-L331
+        // https://github.com/rust-lang/socket2/blob/3a938932829ea6ee3025d2d7a86c7b095c76e6c3/src/sys/unix.rs#L1369-L1373
         SocketAddr::V6(addr) => Box::into_raw(Box::new(libc::sockaddr_in6 {
             sin6_len: std::mem::size_of::<libc::sockaddr_in6>() as u8,
-            sin6_family: libc::AF_INET6 as u8,
-            sin6_port: addr.port(),
-            sin6_flowinfo: 0,
+            sin6_family: libc::AF_INET6 as libc::sa_family_t,
+            sin6_port: addr.port().to_be(),
+            sin6_flowinfo: addr.flowinfo(),
             sin6_addr: libc::in6_addr {
                 s6_addr: addr.ip().octets(),
             },
-            sin6_scope_id: 0,
+            sin6_scope_id: addr.scope_id(),
         })) as *mut c_void,
     };
 
@@ -373,7 +384,10 @@ mod test {
     use super::*;
 
     use core_foundation::runloop::{kCFRunLoopCommonModes, CFRunLoop};
-    use std::ffi::CString;
+    use std::{
+        ffi::CString,
+        net::{Ipv4Addr, Ipv6Addr},
+    };
 
     #[test]
     fn test_network_reachability_from_addr() {
@@ -434,6 +448,38 @@ mod test {
         }
     }
 
+    #[test]
+    fn test_sockaddr_local_to_dns_google_pair_reachability() {
+        let sockaddrs = [
+            "[2001:4860:4860::8844]:443".parse::<SocketAddr>().unwrap(),
+            "8.8.4.4:443".parse().unwrap(),
+        ];
+        for remote_addr in sockaddrs {
+            match std::net::TcpStream::connect(remote_addr) {
+                Err(_) => {
+                    let local_addr = if remote_addr.is_ipv4() {
+                        SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 0)
+                    } else {
+                        SocketAddr::new(Ipv6Addr::UNSPECIFIED.into(), 0)
+                    };
+                    let reachability =
+                        SCNetworkReachability::from_addr_pair(local_addr, remote_addr);
+                    let reachability_flags = reachability.reachability().unwrap();
+                    // Verify that not established tcp connection path is reported as not reachable.
+                    assert!(!reachability_flags.contains(ReachabilityFlags::REACHABLE));
+                }
+                Ok(tcp) => {
+                    let local = tcp.local_addr().unwrap();
+                    let remote = tcp.peer_addr().unwrap();
+                    let reachability = SCNetworkReachability::from_addr_pair(local, remote);
+                    let reachability_flags = reachability.reachability().unwrap();
+                    // Verify established tcp connection path is reported as reachable.
+                    assert!(reachability_flags.contains(ReachabilityFlags::REACHABLE));
+                }
+            }
+        }
+    }
+
     #[test]
     fn test_reachability_ref_from_host() {
         let valid_inputs = vec!["example.com", "host-in-local-network", "en0"];