rustix 0.38.44

Safe Rust bindings to POSIX/Unix/Linux/Winsock-like syscalls
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221

//! 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].
                //
                // [abstract namespace]: https://man7.org/linux/man-pages/man7/unix.7.html
                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].
                //
                // [abstract namespace]: https://man7.org/linux/man-pages/man7/unix.7.html
                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),
    }
}