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 +1,56 @@
+#![allow(unsafe_code)]
+
+#[cfg(feature = "alloc")]
+use crate::alloc::string::String;
+use crate::backend::io::syscalls::ioctl;
+use crate::fd::AsFd;
+use crate::io;
+use crate::net::netdevice::open_socket;
+#[cfg(feature = "alloc")]
+use libc::SIOCGIFNAME;
+use libc::{__c_anonymous_ifr_ifru, c_char, ifreq, IFNAMSIZ, SIOCGIFINDEX};
+
+#[cfg(target_os = "linux")]
+pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
+    let if_name_bytes = if_name.as_bytes();
+    if if_name_bytes.len() >= IFNAMSIZ as usize {
+        return Err(io::Errno::NODEV);
+    }
+
+    let mut ifreq = ifreq {
+        ifr_name: [0; 16],
+        ifr_ifru: __c_anonymous_ifr_ifru { ifru_ifindex: 0 },
+    };
+
+    let mut if_name_c_char_iter = if_name_bytes.iter().map(|byte| *byte as c_char);
+    ifreq.ifr_name[..if_name_bytes.len()].fill_with(|| if_name_c_char_iter.next().unwrap());
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX as _, &mut ifreq as *mut ifreq as _) }?;
+    let index = unsafe { ifreq.ifr_ifru.ifru_ifindex };
+    Ok(index as u32)
+}
+
+#[cfg(all(target_os = "linux", feature = "alloc"))]
+pub(crate) fn index_to_name(index: u32) -> io::Result<String> {
+    let mut ifreq = ifreq {
+        ifr_name: [0; 16],
+        ifr_ifru: __c_anonymous_ifr_ifru {
+            ifru_ifindex: index as _,
+        },
+    };
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFNAME as _, &mut ifreq as *mut ifreq as _) }?;
+
+    if let Some(nul_byte) = ifreq.ifr_name.iter().position(|char| *char == 0) {
+        let name: String = ifreq.ifr_name[..nul_byte]
+            .iter()
+            .map(|v| *v as u8 as char)
+            .collect();
+
+        Ok(name)
+    } else {
+        Err(io::Errno::INVAL)
+    }
+}

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 +1,58 @@
+#![allow(unsafe_code)]
+
+#[cfg(feature = "alloc")]
+use crate::alloc::string::String;
+use crate::backend::io::syscalls::ioctl;
+use crate::fd::AsFd;
+use crate::io;
+use crate::net::netdevice::open_socket;
+use linux_raw_sys::ioctl::SIOCGIFINDEX;
+#[cfg(feature = "alloc")]
+use linux_raw_sys::ioctl::SIOCGIFNAME;
+use linux_raw_sys::net::{ifreq, ifreq__bindgen_ty_1, ifreq__bindgen_ty_2, IFNAMSIZ};
+
+#[cfg(target_os = "linux")]
+pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
+    let if_name_bytes = if_name.as_bytes();
+    if if_name_bytes.len() >= IFNAMSIZ as usize {
+        return Err(io::Errno::NODEV);
+    }
+
+    let mut ifreq = ifreq {
+        ifr_ifrn: ifreq__bindgen_ty_1 { ifrn_name: [0; 16] },
+        ifr_ifru: ifreq__bindgen_ty_2 { ifru_ivalue: 0 },
+    };
+    unsafe { ifreq.ifr_ifrn.ifrn_name[..if_name_bytes.len()].copy_from_slice(if_name_bytes) };
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX, &mut ifreq as *mut ifreq as _) }?;
+    let index = unsafe { ifreq.ifr_ifru.ifru_ivalue };
+    Ok(index as u32)
+}
+
+#[cfg(all(target_os = "linux", feature = "alloc"))]
+pub(crate) fn index_to_name(index: u32) -> io::Result<String> {
+    let mut ifreq = ifreq {
+        ifr_ifrn: ifreq__bindgen_ty_1 { ifrn_name: [0; 16] },
+        ifr_ifru: ifreq__bindgen_ty_2 {
+            ifru_ivalue: index as _,
+        },
+    };
+
+    let fd = open_socket()?;
+    unsafe { ioctl(fd.as_fd(), SIOCGIFNAME, &mut ifreq as *mut ifreq as _) }?;
+
+    if let Some(nul_byte) = unsafe { ifreq.ifr_ifrn.ifrn_name }
+        .iter()
+        .position(|char| *char == 0)
+    {
+        let name = unsafe { ifreq.ifr_ifrn.ifrn_name }[..nul_byte]
+            .iter()
+            .map(|v| *v as char)
+            .collect();
+
+        Ok(name)
+    } else {
+        Err(io::Errno::INVAL)
+    }
+}

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 +1,84 @@
+//! Low-level Linux network device access
+//!
+//! # References
+//! - [Linux]
+//!
+//! [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
+
+#[cfg(feature = "alloc")]
+use crate::alloc::string::String;
+use crate::fd::OwnedFd;
+use crate::io;
+use crate::io::Errno;
+use crate::net::{socket, AddressFamily, SocketType};
+
+/// 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, 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 name_to_index(if_name: &str) -> io::Result<u32> {
+    crate::backend::net::netdevice::name_to_index(if_name)
+}
+
+/// `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(all(target_os = "linux", feature = "alloc"))]
+pub fn index_to_name(index: u32) -> io::Result<String> {
+    crate::backend::net::netdevice::index_to_name(index)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::backend::net::netdevice::{index_to_name, name_to_index};
+
+    #[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(loopback_index), name_to_index("lo"));
+    }
+
+    #[test]
+    #[cfg(all(target_os = "linux", feature = "alloc"))]
+    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("lo".to_owned()), index_to_name(loopback_index));
+    }
+}