std: replace the `FromInner` implementation for addresses with private conversion functions

Having these implementation available crate-wide means that platforms not using sockets for their networking code have to stub out the libc definitions required to support them. This PR moves the conversions to private helper functions that are only available where actually needed.

I also fixed the signature of the function converting from a C socket address to a Rust one: taking a reference to a `sockaddr_storage` resulted in unsound usage inside  `LookupHost::next`, which could create a reference to a structure smaller than `sockaddr_storage`. Thus I've replaced the argument type with a pointer and made the function `unsafe`.

5 files changed, 31 insertions, 30 deletions

diff --git a/library/std/src/sys/net/connection/socket/hermit.rs b/library/std/src/sys/net/connection/socket/hermit.rs
index 42179dcc915..e393342ced9 100644
--- a/library/std/src/sys/net/connection/socket/hermit.rs
+++ b/library/std/src/sys/net/connection/socket/hermit.rs
@@ -2,13 +2,13 @@
 
 use core::ffi::c_int;
 
-pub(crate) use hermit_abi as netc;
+pub(super) use hermit_abi as netc;
 
+use super::{getsockopt, setsockopt, socket_addr_from_c, socket_addr_to_c};
 use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::hermit::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, RawFd};
 use crate::sys::fd::FileDesc;
-use crate::sys::net::{getsockopt, setsockopt, sockaddr_to_addr};
 use crate::sys::time::Instant;
 pub use crate::sys::{cvt, cvt_r};
 use crate::sys_common::{AsInner, FromInner, IntoInner};
@@ -55,7 +55,7 @@ impl Socket {
     }
 
     pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
-        let (addr, len) = addr.into_inner();
+        let (addr, len) = socket_addr_to_c(addr);
         cvt_r(|| unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
         Ok(())
     }
@@ -63,7 +63,7 @@ impl Socket {
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {
-            let (addr, len) = addr.into_inner();
+            let (addr, len) = socket_addr_to_c(addr);
             cvt(netc::connect(self.as_raw_fd(), addr.as_ptr(), len))
         };
         self.set_nonblocking(false)?;
@@ -195,7 +195,7 @@ impl Socket {
                 &mut addrlen,
             )
         })?;
-        Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
+        Ok((n as usize, unsafe { socket_addr_from_c(&storage, addrlen as usize)? }))
     }
 
     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
diff --git a/library/std/src/sys/net/connection/socket/solid.rs b/library/std/src/sys/net/connection/socket/solid.rs
index f85ecbb883e..906bef267b6 100644
--- a/library/std/src/sys/net/connection/socket/solid.rs
+++ b/library/std/src/sys/net/connection/socket/solid.rs
@@ -1,17 +1,17 @@
 use libc::{c_int, c_void, size_t};
 
 use self::netc::{MSG_PEEK, sockaddr, socklen_t};
+use super::{getsockopt, setsockopt, socket_addr_from_c, socket_addr_to_c};
 use crate::ffi::CStr;
 use crate::io::{self, BorrowedBuf, BorrowedCursor, ErrorKind, IoSlice, IoSliceMut};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::solid::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd};
 use crate::sys::abi;
-use crate::sys::net::{getsockopt, setsockopt, sockaddr_to_addr};
 use crate::sys_common::{FromInner, IntoInner};
 use crate::time::Duration;
 use crate::{cmp, mem, ptr, str};
 
-pub mod netc {
+pub(super) mod netc {
     pub use crate::sys::abi::sockets::*;
 }
 
@@ -131,7 +131,7 @@ impl Socket {
     }
 
     pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
-        let (addr, len) = addr.into_inner();
+        let (addr, len) = socket_addr_to_c(addr);
         cvt(unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
         Ok(())
     }
@@ -256,7 +256,7 @@ impl Socket {
                 &mut addrlen,
             )
         })?;
-        Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
+        Ok((n as usize, unsafe { socket_addr_from_c(&storage, addrlen as usize)? }))
     }
 
     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
diff --git a/library/std/src/sys/net/connection/socket/unix.rs b/library/std/src/sys/net/connection/socket/unix.rs
index da631605527..34ab26bc117 100644
--- a/library/std/src/sys/net/connection/socket/unix.rs
+++ b/library/std/src/sys/net/connection/socket/unix.rs
@@ -5,7 +5,7 @@ use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
 use crate::sys::fd::FileDesc;
-use crate::sys::net::{getsockopt, setsockopt, sockaddr_to_addr};
+use crate::sys::net::{getsockopt, setsockopt};
 use crate::sys::pal::IsMinusOne;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::{Duration, Instant};
@@ -19,8 +19,9 @@ cfg_if::cfg_if! {
     }
 }
 
-pub(crate) use libc as netc;
+pub(super) use libc as netc;
 
+use super::{socket_addr_from_c, socket_addr_to_c};
 pub use crate::sys::{cvt, cvt_r};
 
 #[expect(non_camel_case_types)]
@@ -150,7 +151,7 @@ impl Socket {
     }
 
     pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
-        let (addr, len) = addr.into_inner();
+        let (addr, len) = socket_addr_to_c(addr);
         loop {
             let result = unsafe { libc::connect(self.as_raw_fd(), addr.as_ptr(), len) };
             if result.is_minus_one() {
@@ -168,7 +169,7 @@ impl Socket {
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {
-            let (addr, len) = addr.into_inner();
+            let (addr, len) = socket_addr_to_c(addr);
             cvt(libc::connect(self.as_raw_fd(), addr.as_ptr(), len))
         };
         self.set_nonblocking(false)?;
@@ -334,7 +335,7 @@ impl Socket {
                 &mut addrlen,
             )
         })?;
-        Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
+        Ok((n as usize, unsafe { socket_addr_from_c(&storage, addrlen as usize)? }))
     }
 
     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
diff --git a/library/std/src/sys/net/connection/socket/wasip2.rs b/library/std/src/sys/net/connection/socket/wasip2.rs
index 9d1c05a473e..c5034e73dd7 100644
--- a/library/std/src/sys/net/connection/socket/wasip2.rs
+++ b/library/std/src/sys/net/connection/socket/wasip2.rs
@@ -1,19 +1,18 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
+pub(super) use libc as netc;
 use libc::{c_int, c_void, size_t};
 
+use super::{getsockopt, setsockopt, socket_addr_from_c, socket_addr_to_c};
 use crate::ffi::CStr;
 use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
-use crate::sys::net::{getsockopt, setsockopt, sockaddr_to_addr};
 use crate::sys::unsupported;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::{Duration, Instant};
 use crate::{cmp, mem, str};
 
-pub extern crate libc as netc;
-
 #[allow(non_camel_case_types)]
 pub type wrlen_t = size_t;
 
@@ -89,7 +88,7 @@ impl Socket {
     }
 
     pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
-        let (addr, len) = addr.into_inner();
+        let (addr, len) = socket_addr_to_c(addr);
         cvt_r(|| unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
         Ok(())
     }
@@ -224,7 +223,7 @@ impl Socket {
                 &mut addrlen,
             )
         })?;
-        Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
+        Ok((n as usize, unsafe { socket_addr_from_c(&storage, addrlen as usize)? }))
     }
 
     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
diff --git a/library/std/src/sys/net/connection/socket/windows.rs b/library/std/src/sys/net/connection/socket/windows.rs
index 80cf37eaf05..428f142dabe 100644
--- a/library/std/src/sys/net/connection/socket/windows.rs
+++ b/library/std/src/sys/net/connection/socket/windows.rs
@@ -2,6 +2,7 @@
 
 use core::ffi::{c_int, c_long, c_ulong, c_ushort};
 
+use super::{getsockopt, setsockopt, socket_addr_from_c, socket_addr_to_c};
 use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut, Read};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::windows::io::{
@@ -16,7 +17,7 @@ use crate::{cmp, mem, ptr, sys};
 #[allow(non_camel_case_types)]
 pub type wrlen_t = i32;
 
-pub mod netc {
+pub(super) mod netc {
     //! BSD socket compatibility shim
     //!
     //! Some Windows API types are not quite what's expected by our cross-platform
@@ -225,7 +226,7 @@ impl Socket {
     }
 
     pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
-        let (addr, len) = addr.into_inner();
+        let (addr, len) = socket_addr_to_c(addr);
         let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
         cvt(result).map(drop)
     }
@@ -401,12 +402,12 @@ impl Socket {
                 let error = unsafe { c::WSAGetLastError() };
 
                 if error == c::WSAESHUTDOWN {
-                    Ok((0, super::sockaddr_to_addr(&storage, addrlen as usize)?))
+                    Ok((0, unsafe { socket_addr_from_c(&storage, addrlen as usize)? }))
                 } else {
                     Err(io::Error::from_raw_os_error(error))
                 }
             }
-            _ => Ok((result as usize, super::sockaddr_to_addr(&storage, addrlen as usize)?)),
+            _ => Ok((result as usize, unsafe { socket_addr_from_c(&storage, addrlen as usize)? })),
         }
     }
 
@@ -451,11 +452,11 @@ impl Socket {
             }
             None => 0,
         };
-        super::setsockopt(self, c::SOL_SOCKET, kind, timeout)
+        setsockopt(self, c::SOL_SOCKET, kind, timeout)
     }
 
     pub fn timeout(&self, kind: c_int) -> io::Result<Option<Duration>> {
-        let raw: u32 = super::getsockopt(self, c::SOL_SOCKET, kind)?;
+        let raw: u32 = getsockopt(self, c::SOL_SOCKET, kind)?;
         if raw == 0 {
             Ok(None)
         } else {
@@ -488,26 +489,26 @@ impl Socket {
             l_linger: linger.unwrap_or_default().as_secs() as c_ushort,
         };
 
-        super::setsockopt(self, c::SOL_SOCKET, c::SO_LINGER, linger)
+        setsockopt(self, c::SOL_SOCKET, c::SO_LINGER, linger)
     }
 
     pub fn linger(&self) -> io::Result<Option<Duration>> {
-        let val: c::LINGER = super::getsockopt(self, c::SOL_SOCKET, c::SO_LINGER)?;
+        let val: c::LINGER = getsockopt(self, c::SOL_SOCKET, c::SO_LINGER)?;
 
         Ok((val.l_onoff != 0).then(|| Duration::from_secs(val.l_linger as u64)))
     }
 
     pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
-        super::setsockopt(self, c::IPPROTO_TCP, c::TCP_NODELAY, nodelay as c::BOOL)
+        setsockopt(self, c::IPPROTO_TCP, c::TCP_NODELAY, nodelay as c::BOOL)
     }
 
     pub fn nodelay(&self) -> io::Result<bool> {
-        let raw: c::BOOL = super::getsockopt(self, c::IPPROTO_TCP, c::TCP_NODELAY)?;
+        let raw: c::BOOL = getsockopt(self, c::IPPROTO_TCP, c::TCP_NODELAY)?;
         Ok(raw != 0)
     }
 
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
-        let raw: c_int = super::getsockopt(self, c::SOL_SOCKET, c::SO_ERROR)?;
+        let raw: c_int = getsockopt(self, c::SOL_SOCKET, c::SO_ERROR)?;
         if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }
     }