Add name_to_index() & index_to_name()

Author: arctic-alpaca

src/backend/libc/net/mod.rs

@@ -8,6 +8,8 @@ pub(crate) mod ext;
     target_os = "wasi"
 )))]
 pub(crate) mod msghdr;
+#[cfg(target_os = "linux")]
+pub(crate) mod netdevice;
 pub(crate) mod read_sockaddr;
 pub(crate) mod send_recv;
 #[cfg(not(any(target_os = "redox", target_os = "wasi")))]

src/backend/libc/net/netdevice.rs

@@ -0,0 +1,62 @@
+#![allow(unsafe_code)]
+
+use crate::backend::io::syscalls::ioctl;
+use crate::io;
+use crate::net::netdevice::open_socket;
+use libc::{c_char, ifreq, IFNAMSIZ, SIOCGIFINDEX, SIOCGIFNAME};
+use std::ffi::{CStr, CString};
+use std::mem::MaybeUninit;
+use std::os::fd::AsFd;
+use std::ptr::{addr_of, addr_of_mut};
+
+#[cfg(target_os = "linux")]
+pub(crate) fn index_to_name(if_name: String) -> io::Result<u32> {
+    if if_name.len() >= IFNAMSIZ as usize {
+        return Err(io::Errno::NODEV);
+    }
+    let mut ifrn_name = [0; IFNAMSIZ as usize];
+    let c_string_name = CString::new(if_name).map_err(|_cstr_err| io::Errno::INVAL)?;
+    // Convert from CString to c_char array.
+    c_string_name
+        .as_bytes_with_nul()
+        .iter()
+        .map(|byte| *byte as c_char)
+        .enumerate()
+        .for_each(|(i, c_char_byte)| ifrn_name[i] = c_char_byte);
+
+    let mut uninit_ifreq = MaybeUninit::<ifreq>::uninit();
+    let uninit_ifreq_ptr = uninit_ifreq.as_mut_ptr();
+    unsafe {
+        addr_of_mut!((*uninit_ifreq_ptr).ifr_name).write(ifrn_name);
+    }
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX as _, uninit_ifreq_ptr as _) }?;
+    let index = unsafe { *addr_of!((*uninit_ifreq_ptr).ifr_ifru.ifru_ifindex) };
+    Ok(index as u32)
+}
+
+#[cfg(target_os = "linux")]
+pub(crate) fn name_to_index(index: u32) -> io::Result<String> {
+    let mut uninit_ifreq = MaybeUninit::<ifreq>::uninit();
+    let uninit_ifreq_ptr = uninit_ifreq.as_mut_ptr();
+    unsafe {
+        addr_of_mut!((*uninit_ifreq_ptr).ifr_ifru.ifru_ifindex).write(index as _);
+    }
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFNAME as _, uninit_ifreq_ptr as _) }?;
+
+    let ifr_name = unsafe { *addr_of!((*uninit_ifreq_ptr).ifr_name) };
+    let mut result_name = [0; IFNAMSIZ as usize];
+    // Convert from c_char array to u8 array.
+    ifr_name
+        .iter()
+        .map(|v| *v as u8)
+        .enumerate()
+        .for_each(|(i, u8_byte)| result_name[i] = u8_byte);
+
+    let name = CStr::from_bytes_until_nul(&result_name).map_err(|_cstr_err| io::Errno::INVAL)?;
+
+    Ok(name.to_string_lossy().to_string())
+}

src/backend/linux_raw/net/mod.rs

@@ -1,5 +1,7 @@
 pub(crate) mod addr;
 pub(crate) mod msghdr;
+#[cfg(target_os = "linux")]
+pub(crate) mod netdevice;
 pub(crate) mod read_sockaddr;
 pub(crate) mod send_recv;
 pub(crate) mod sockopt;

src/backend/linux_raw/net/netdevice.rs

@@ -0,0 +1,63 @@
+#![allow(unsafe_code)]
+
+use crate::backend::io::syscalls::ioctl;
+use crate::io;
+use crate::net::netdevice::open_socket;
+use linux_raw_sys::ctypes::c_char;
+use linux_raw_sys::ioctl::{SIOCGIFINDEX, SIOCGIFNAME};
+use linux_raw_sys::net::{ifreq, IFNAMSIZ};
+use std::ffi::{CStr, CString};
+use std::mem::MaybeUninit;
+use std::os::fd::AsFd;
+use std::ptr::{addr_of, addr_of_mut};
+
+#[cfg(target_os = "linux")]
+pub(crate) fn index_to_name(if_name: String) -> io::Result<u32> {
+    if if_name.len() >= IFNAMSIZ as usize {
+        return Err(io::Errno::NODEV);
+    }
+    let mut ifrn_name = [0; IFNAMSIZ as usize];
+    let c_string_name = CString::new(if_name).map_err(|_cstr_err| io::Errno::INVAL)?;
+    // Convert from CString to c_char array.
+    c_string_name
+        .as_bytes_with_nul()
+        .iter()
+        .map(|byte| *byte as c_char)
+        .enumerate()
+        .for_each(|(i, c_char_byte)| ifrn_name[i] = c_char_byte);
+
+    let mut uninit_ifreq = MaybeUninit::<ifreq>::uninit();
+    let uninit_ifreq_ptr = uninit_ifreq.as_mut_ptr();
+    unsafe {
+        addr_of_mut!((*uninit_ifreq_ptr).ifr_ifrn.ifrn_name).write(ifrn_name);
+    }
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX, uninit_ifreq_ptr as _) }?;
+    let index = unsafe { *addr_of!((*uninit_ifreq_ptr).ifr_ifru.ifru_ivalue) };
+    Ok(index as u32)
+}
+
+#[cfg(target_os = "linux")]
+pub(crate) fn name_to_index(index: u32) -> io::Result<String> {
+    let mut uninit_ifreq = MaybeUninit::<ifreq>::uninit();
+    let uninit_ifreq_ptr = uninit_ifreq.as_mut_ptr();
+    unsafe {
+        addr_of_mut!((*uninit_ifreq_ptr).ifr_ifru.ifru_ivalue).write(index as _);
+    }
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFNAME, uninit_ifreq_ptr as _) }?;
+
+    let ifrn_name = unsafe { *addr_of!((*uninit_ifreq_ptr).ifr_ifrn.ifrn_name) };
+    let mut result_name = [0; IFNAMSIZ as usize];
+    // Convert from c_char array to u8 array.
+    ifrn_name
+        .iter()
+        .map(|v| *v as u8)
+        .enumerate()
+        .for_each(|(i, u8_byte)| result_name[i] = u8_byte);
+
+    let name = CStr::from_bytes_until_nul(&result_name).map_err(|_cstr_err| io::Errno::INVAL)?;
+    Ok(name.to_string_lossy().to_string())
+}

src/net/mod.rs

@@ -16,6 +16,8 @@ mod types;
 #[cfg(windows)]
 mod wsa;
 
+#[cfg(target_os = "linux")]
+pub mod netdevice;
 pub mod sockopt;
 
 pub use crate::maybe_polyfill::net::{

src/net/netdevice.rs

@@ -0,0 +1,82 @@
+//! Low-level Linux network device access
+//!
+//! # References
+//! - [Linux]
+//!
+//! [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
+
+use crate::io;
+use crate::io::Errno;
+use crate::net::{socket, AddressFamily, SocketType};
+use std::os::fd::OwnedFd;
+
+/// Creates a socket used to communicate with the kernel in the ioctl calls.
+#[cfg(target_os = "linux")]
+pub(crate) fn open_socket() -> io::Result<OwnedFd> {
+    if let Ok(fd) = socket(AddressFamily::UNIX, SocketType::DGRAM, None) {
+        Ok(fd)
+    } else if let Ok(fd) = socket(AddressFamily::INET, SocketType::DGRAM, None) {
+        Ok(fd)
+    } else if let Ok(fd) = socket(AddressFamily::INET6, SocketType::DGRAM, None) {
+        Ok(fd)
+    } else {
+        Err(Errno::NOENT)
+    }
+}
+
+/// `ioctl(fd, SIOCGIFNAME, ifreq)`—Returns the interface name for a given index.
+///
+/// # References
+///  - [Linux]
+///
+/// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
+#[inline]
+#[doc(alias = "SIOCGIFNAME")]
+#[cfg(target_os = "linux")]
+pub fn name_to_index(index: u32) -> io::Result<String> {
+    crate::backend::net::netdevice::name_to_index(index)
+}
+
+/// `ioctl(fd, SIOCGIFINDEX, ifreq)`—Returns the interface index for a given name.
+///
+/// # References
+///  - [Linux]
+///
+/// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
+#[inline]
+#[doc(alias = "SIOCGIFINDEX")]
+#[cfg(target_os = "linux")]
+pub fn index_to_name(if_name: String) -> io::Result<u32> {
+    crate::backend::net::netdevice::index_to_name(if_name)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::backend::net::netdevice::{index_to_name, name_to_index};
+
+    #[test]
+    #[cfg(target_os = "linux")]
+    fn test_index_to_name() {
+        let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
+            .unwrap()
+            .as_str()
+            .split_at(1)
+            .0
+            .parse::<u32>()
+            .unwrap();
+        assert_eq!(Ok(loopback_index), index_to_name("lo".to_owned()));
+    }
+
+    #[test]
+    #[cfg(target_os = "linux")]
+    fn test_name_to_index() {
+        let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
+            .unwrap()
+            .as_str()
+            .split_at(1)
+            .0
+            .parse::<u32>()
+            .unwrap();
+        assert_eq!(Ok("lo".to_owned()), name_to_index(loopback_index));
+    }
+}