sockaddr/
lib.rs

1// Copyright 2023 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Crate providing utilities for coercing between types of sockaddr structs.
6
7#![warn(missing_docs)]
8
9use std::num::NonZeroU64;
10
11/// Socket addresses that can be converted to `libc::sockaddr_ll`.
12pub trait TryToSockaddrLl {
13    /// Converts `self` to a `libc::sockaddr_ll`, returning `None` if `self`'s
14    /// underlying socket address type is not `libc::sockaddr_ll`.
15    fn try_to_sockaddr_ll(&self) -> Option<libc::sockaddr_ll>;
16}
17
18impl TryToSockaddrLl for socket2::SockAddr {
19    fn try_to_sockaddr_ll(&self) -> Option<libc::sockaddr_ll> {
20        if self.family()
21            != libc::sa_family_t::try_from(libc::AF_PACKET)
22                .expect("libc::AF_PACKET should fit in libc::sa_family_t")
23        {
24            return None;
25        }
26
27        let mut sockaddr_ll = libc::sockaddr_ll {
28            sll_family: 0,
29            sll_protocol: 0,
30            sll_ifindex: 0,
31            sll_hatype: 0,
32            sll_pkttype: 0,
33            sll_halen: 0,
34            sll_addr: [0; 8],
35        };
36
37        let len = usize::try_from(self.len()).expect("socklen_t should fit in usize");
38        // We assert `>=` rather than `==` because if `self` came from a getsockname() call, its
39        // length only includes the portion of `sll_addr` that is actually used (according to
40        // `sll_halen`) rather than all 8 bytes.
41        assert!(std::mem::size_of::<libc::sockaddr_ll>() >= len);
42
43        // SAFETY: we've checked that len <= size_of<sockaddr_ll>().
44        unsafe {
45            let sockaddr: *const libc::sockaddr = self.as_ptr();
46            let sockaddr_ll: *mut libc::sockaddr_ll = &mut sockaddr_ll;
47            std::ptr::copy_nonoverlapping(sockaddr.cast::<u8>(), sockaddr_ll.cast::<u8>(), len);
48        }
49
50        Some(sockaddr_ll)
51    }
52}
53
54/// Socket addresses that can be converted to `socket2::SockAddr`.
55pub trait IntoSockAddr {
56    /// Converts `self` to a `socket2::SockAddr`.
57    fn into_sockaddr(self) -> socket2::SockAddr;
58}
59
60impl IntoSockAddr for libc::sockaddr_ll {
61    fn into_sockaddr(self) -> socket2::SockAddr {
62        if libc::c_int::from(self.sll_family) != libc::AF_PACKET {
63            panic!("sll_family != AF_PACKET, got {:?}", self.sll_family);
64        }
65        let sockaddr_ll_len = libc::socklen_t::try_from(std::mem::size_of::<libc::sockaddr_ll>())
66            .expect("size of sockaddr_ll should always fit in socklen_t");
67
68        // SAFETY: We ensure that the address family (`AF_PACKET`) and length (`sockaddr_ll_len`)
69        // match the type of storage address (`sockaddr_ll`).
70        // TODO(https://fxbug.dev/42055728): Move this unsafe code upstream into `socket2`.
71        let ((), sock_addr) = unsafe {
72            socket2::SockAddr::try_init(|sockaddr_storage, len_ptr| {
73                (sockaddr_storage as *mut libc::sockaddr_ll).write(self);
74                len_ptr.write(sockaddr_ll_len);
75                Ok(())
76            })
77        }
78        .expect(
79            "initialize socket address should always succeed because \
80                 our init fn always returns Ok(())",
81        );
82        sock_addr
83    }
84}
85
86/// Socket address for an Ethernet packet socket.
87pub struct EthernetSockaddr {
88    /// The interface identifier, or `None` for no interface.
89    pub interface_id: Option<NonZeroU64>,
90    /// The link address.
91    pub addr: net_types::ethernet::Mac,
92    /// The Ethernet frame type.
93    pub protocol: packet_formats::ethernet::EtherType,
94}
95
96impl From<EthernetSockaddr> for libc::sockaddr_ll {
97    fn from(value: EthernetSockaddr) -> Self {
98        let EthernetSockaddr { interface_id, addr, protocol } = value;
99
100        let mut sll_addr = [0; 8];
101        let addr_bytes = addr.bytes();
102        sll_addr[..addr_bytes.len()].copy_from_slice(&addr_bytes);
103
104        let ethertype = u16::from(protocol);
105        libc::sockaddr_ll {
106            sll_family: libc::AF_PACKET
107                .try_into()
108                .expect("libc::AF_PACKET should fit in sll_family field"),
109            sll_ifindex: interface_id
110                .map_or(0, NonZeroU64::get)
111                .try_into()
112                .expect("interface_id should fit in sll_ifindex field"),
113            // Network order is big endian.
114            sll_protocol: ethertype.to_be(),
115            sll_halen: addr_bytes
116                .len()
117                .try_into()
118                .expect("hardware address length should fit in sll_halen field"),
119            sll_addr,
120            sll_hatype: 0,  // unused by sendto() or bind()
121            sll_pkttype: 0, // unused by sendto() or bind()
122        }
123    }
124}
125
126/// Socket address for a Pure IP packet socket.
127pub struct PureIpSockaddr {
128    /// The interface identifier, or `None` for no interface.
129    pub interface_id: Option<NonZeroU64>,
130    /// The IP version.
131    pub protocol: net_types::ip::IpVersion,
132}
133
134impl From<PureIpSockaddr> for libc::sockaddr_ll {
135    fn from(value: PureIpSockaddr) -> Self {
136        let PureIpSockaddr { interface_id, protocol } = value;
137        libc::sockaddr_ll {
138            sll_family: libc::AF_PACKET
139                .try_into()
140                .expect("libc::AF_PACKET should fit in sll_family field"),
141            sll_ifindex: interface_id
142                .map_or(0, NonZeroU64::get)
143                .try_into()
144                .expect("interface_id should fit in sll_ifindex field"),
145            sll_protocol: sockaddr_ll_ip_protocol(protocol),
146            // Pure IP devices don't have a hardware address.
147            sll_halen: 0,
148            sll_addr: [0, 0, 0, 0, 0, 0, 0, 0],
149            sll_hatype: 0,  // unused by sendto() or bind()
150            sll_pkttype: 0, // unused by sendto() or bind()
151        }
152    }
153}
154
155/// Returns the protocol, in network byte order, for the given `IpVersion`.
156pub fn sockaddr_ll_ip_protocol(ip_version: net_types::ip::IpVersion) -> u16 {
157    let protocol = match ip_version {
158        net_types::ip::IpVersion::V4 => libc::ETH_P_IP,
159        net_types::ip::IpVersion::V6 => libc::ETH_P_IPV6,
160    };
161    // Network order is big endian.
162    u16::try_from(protocol).expect("protocol should fit in a u16 field").to_be()
163}
164
165#[cfg(test)]
166mod test {
167    use super::*;
168    use proptest::prelude::*;
169
170    #[derive(proptest_derive::Arbitrary, Debug)]
171    struct SockaddrLl {
172        sll_family: u16,
173        sll_protocol: u16,
174        sll_ifindex: i32,
175        sll_hatype: u16,
176        sll_pkttype: u8,
177        sll_halen: u8,
178        sll_addr: [u8; 8],
179    }
180
181    impl From<SockaddrLl> for libc::sockaddr_ll {
182        fn from(
183            SockaddrLl {
184                sll_family,
185                sll_protocol,
186                sll_ifindex,
187                sll_hatype,
188                sll_pkttype,
189                sll_halen,
190                sll_addr,
191            }: SockaddrLl,
192        ) -> Self {
193            libc::sockaddr_ll {
194                sll_family,
195                sll_protocol,
196                sll_ifindex,
197                sll_hatype,
198                sll_pkttype,
199                sll_halen,
200                sll_addr,
201            }
202        }
203    }
204
205    proptest! {
206        #![proptest_config(ProptestConfig {
207            failure_persistence: Some(
208                Box::<proptest::test_runner::MapFailurePersistence>::default()
209            ),
210            ..ProptestConfig::default()
211        })]
212
213        #[test]
214        fn roundtrip(addr in any::<SockaddrLl>().prop_map(|addr| SockaddrLl {
215            sll_family: u16::try_from(libc::AF_PACKET).unwrap(),
216            ..addr
217        })) {
218            let sockaddr_ll_start = libc::sockaddr_ll::from(addr);
219            let sockaddr = sockaddr_ll_start.into_sockaddr();
220            let sockaddr_ll_end = sockaddr.try_to_sockaddr_ll().unwrap();
221            prop_assert_eq!(sockaddr_ll_start, sockaddr_ll_end);
222        }
223    }
224
225    #[test]
226    fn not_sockaddr_ll_returns_none() {
227        let sockaddr = socket2::SockAddr::from(net_declare::std_socket_addr!("192.168.0.1:8080"));
228        assert_eq!(sockaddr.try_to_sockaddr_ll(), None);
229    }
230}
sockaddr/lib.rs

sockaddr/
lib.rs
