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//! The BSD sockets API requires us to read the `ss_family` field before we can
//! interpret the rest of a `sockaddr` produced by the kernel.
#![allow(unsafe_code)]
use crate::backend::c;
use crate::io;
#[cfg(target_os = "linux")]
use crate::net::xdp::{SockaddrXdpFlags, SocketAddrXdp};
use crate::net::{Ipv4Addr, Ipv6Addr, SocketAddrAny, SocketAddrUnix, SocketAddrV4, SocketAddrV6};
use core::mem::size_of;
use core::slice;
// This must match the header of `sockaddr`.
#[repr(C)]
struct sockaddr_header {
ss_family: u16,
}
/// Read the `ss_family` field from a socket address returned from the OS.
///
/// # Safety
///
/// `storage` must point to a valid socket address returned from the OS.
#[inline]
unsafe fn read_ss_family(storage: *const c::sockaddr) -> u16 {
// Assert that we know the layout of `sockaddr`.
let _ = c::sockaddr {
__storage: c::sockaddr_storage {
__bindgen_anon_1: linux_raw_sys::net::__kernel_sockaddr_storage__bindgen_ty_1 {
__bindgen_anon_1:
linux_raw_sys::net::__kernel_sockaddr_storage__bindgen_ty_1__bindgen_ty_1 {
ss_family: 0_u16,
__data: [0; 126_usize],
},
},
},
};
(*storage.cast::<sockaddr_header>()).ss_family
}
/// Set the `ss_family` field of a socket address to `AF_UNSPEC`, so that we
/// can test for `AF_UNSPEC` to test whether it was stored to.
#[inline]
pub(crate) unsafe fn initialize_family_to_unspec(storage: *mut c::sockaddr) {
(*storage.cast::<sockaddr_header>()).ss_family = c::AF_UNSPEC as _;
}
/// Read a socket address encoded in a platform-specific format.
///
/// # Safety
///
/// `storage` must point to valid socket address storage.
pub(crate) unsafe fn read_sockaddr(
storage: *const c::sockaddr,
len: usize,
) -> io::Result<SocketAddrAny> {
let offsetof_sun_path = super::addr::offsetof_sun_path();
if len < size_of::<c::sa_family_t>() {
return Err(io::Errno::INVAL);
}
match read_ss_family(storage).into() {
c::AF_INET => {
if len < size_of::<c::sockaddr_in>() {
return Err(io::Errno::INVAL);
}
let decode = &*storage.cast::<c::sockaddr_in>();
Ok(SocketAddrAny::V4(SocketAddrV4::new(
Ipv4Addr::from(u32::from_be(decode.sin_addr.s_addr)),
u16::from_be(decode.sin_port),
)))
}
c::AF_INET6 => {
if len < size_of::<c::sockaddr_in6>() {
return Err(io::Errno::INVAL);
}
let decode = &*storage.cast::<c::sockaddr_in6>();
Ok(SocketAddrAny::V6(SocketAddrV6::new(
Ipv6Addr::from(decode.sin6_addr.in6_u.u6_addr8),
u16::from_be(decode.sin6_port),
u32::from_be(decode.sin6_flowinfo),
decode.sin6_scope_id,
)))
}
c::AF_UNIX => {
if len < offsetof_sun_path {
return Err(io::Errno::INVAL);
}
if len == offsetof_sun_path {
Ok(SocketAddrAny::Unix(SocketAddrUnix::new(&[][..])?))
} else {
let decode = &*storage.cast::<c::sockaddr_un>();
// On Linux check for Linux's [abstract namespace].
//
if decode.sun_path[0] == 0 {
let bytes = &decode.sun_path[1..len - offsetof_sun_path];
// SAFETY: Convert `&[c_char]` to `&[u8]`.
let bytes = slice::from_raw_parts(bytes.as_ptr().cast::<u8>(), bytes.len());
return SocketAddrUnix::new_abstract_name(bytes).map(SocketAddrAny::Unix);
}
// Otherwise we expect a NUL-terminated filesystem path.
let bytes = &decode.sun_path[..len - 1 - offsetof_sun_path];
// SAFETY: Convert `&[c_char]` to `&[u8]`.
let bytes = slice::from_raw_parts(bytes.as_ptr().cast::<u8>(), bytes.len());
assert_eq!(decode.sun_path[len - 1 - offsetof_sun_path], 0);
Ok(SocketAddrAny::Unix(SocketAddrUnix::new(bytes)?))
}
}
#[cfg(target_os = "linux")]
c::AF_XDP => {
if len < size_of::<c::sockaddr_xdp>() {
return Err(io::Errno::INVAL);
}
let decode = &*storage.cast::<c::sockaddr_xdp>();
Ok(SocketAddrAny::Xdp(SocketAddrXdp::new(
SockaddrXdpFlags::from_bits_retain(decode.sxdp_flags),
u32::from_be(decode.sxdp_ifindex),
u32::from_be(decode.sxdp_queue_id),
u32::from_be(decode.sxdp_shared_umem_fd),
)))
}
_ => Err(io::Errno::NOTSUP),
}
}
/// Read an optional socket address returned from the OS.
///
/// # Safety
///
/// `storage` must point to a valid socket address returned from the OS.
pub(crate) unsafe fn maybe_read_sockaddr_os(
storage: *const c::sockaddr,
len: usize,
) -> Option<SocketAddrAny> {
if len == 0 {
None
} else {
Some(read_sockaddr_os(storage, len))
}
}
/// Read a socket address returned from the OS.
///
/// # Safety
///
/// `storage` must point to a valid socket address returned from the OS.
pub(crate) unsafe fn read_sockaddr_os(storage: *const c::sockaddr, len: usize) -> SocketAddrAny {
let offsetof_sun_path = super::addr::offsetof_sun_path();
assert!(len >= size_of::<c::sa_family_t>());
match read_ss_family(storage).into() {
c::AF_INET => {
assert!(len >= size_of::<c::sockaddr_in>());
let decode = &*storage.cast::<c::sockaddr_in>();
SocketAddrAny::V4(SocketAddrV4::new(
Ipv4Addr::from(u32::from_be(decode.sin_addr.s_addr)),
u16::from_be(decode.sin_port),
))
}
c::AF_INET6 => {
assert!(len >= size_of::<c::sockaddr_in6>());
let decode = &*storage.cast::<c::sockaddr_in6>();
SocketAddrAny::V6(SocketAddrV6::new(
Ipv6Addr::from(decode.sin6_addr.in6_u.u6_addr8),
u16::from_be(decode.sin6_port),
u32::from_be(decode.sin6_flowinfo),
decode.sin6_scope_id,
))
}
c::AF_UNIX => {
assert!(len >= offsetof_sun_path);
if len == offsetof_sun_path {
SocketAddrAny::Unix(SocketAddrUnix::new(&[][..]).unwrap())
} else {
let decode = &*storage.cast::<c::sockaddr_un>();
// On Linux check for Linux's [abstract namespace].
//
if decode.sun_path[0] == 0 {
let bytes = &decode.sun_path[1..len - offsetof_sun_path];
// SAFETY: Convert `&[c_char]` to `&[u8]`.
let bytes = slice::from_raw_parts(bytes.as_ptr().cast::<u8>(), bytes.len());
return SocketAddrAny::Unix(SocketAddrUnix::new_abstract_name(bytes).unwrap());
}
// Otherwise we expect a NUL-terminated filesystem path.
assert_eq!(decode.sun_path[len - 1 - offsetof_sun_path], 0);
let bytes = &decode.sun_path[..len - 1 - offsetof_sun_path];
// SAFETY: Convert `&[c_char]` to `&[u8]`.
let bytes = slice::from_raw_parts(bytes.as_ptr().cast::<u8>(), bytes.len());
SocketAddrAny::Unix(SocketAddrUnix::new(bytes).unwrap())
}
}
#[cfg(target_os = "linux")]
c::AF_XDP => {
assert!(len >= size_of::<c::sockaddr_xdp>());
let decode = &*storage.cast::<c::sockaddr_xdp>();
SocketAddrAny::Xdp(SocketAddrXdp::new(
SockaddrXdpFlags::from_bits_retain(decode.sxdp_flags),
u32::from_be(decode.sxdp_ifindex),
u32::from_be(decode.sxdp_queue_id),
u32::from_be(decode.sxdp_shared_umem_fd),
))
}
other => unimplemented!("{:?}", other),
}
}