checkpoint

tun/src/unix/mod.rs

@@ -1,11 +1,13 @@
+use std::mem::size_of;
 use std::{
     io::{Error, Read},
+    mem,
     os::fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd},
 };
 
-use tracing::instrument;
+use tracing::{debug, error, instrument};
 
-use super::TunOptions;
+use super::{syscall, TunOptions};
 
 mod queue;
 
@@ -17,9 +19,13 @@ mod imp;
 #[path = "linux/mod.rs"]
 mod imp;
 
+use crate::os_imp::imp::sys;
+use crate::os_imp::imp::sys::resolve_ctl_info;
 use fehler::throws;
 pub use imp::TunInterface;
+use libc::{getpeername, sockaddr_ctl, sockaddr_storage, socklen_t, AF_SYSTEM, AF_SYS_CONTROL};
 pub use queue::TunQueue;
+use socket2::SockAddr;
 
 impl AsRawFd for TunInterface {
     fn as_raw_fd(&self) -> RawFd {
@@ -47,8 +53,8 @@ impl TunInterface {
         // there might be a more efficient way to implement this
         let tmp_buf = &mut [0u8; 1500];
         let len = self.socket.read(tmp_buf)?;
-        buf[..len-4].copy_from_slice(&tmp_buf[4..len]);
-        len-4
+        buf[..len - 4].copy_from_slice(&tmp_buf[4..len]);
+        len - 4
     }
 
     #[throws]
@@ -76,3 +82,35 @@ pub fn string_to_ifname(name: &str) -> [libc::c_char; libc::IFNAMSIZ] {
     buf[..len].copy_from_slice(unsafe { &*(name.as_bytes() as *const _ as *const [libc::c_char]) });
     buf
 }
+
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+pub fn retrieve() -> Option<TunInterface> {
+    (3..100)
+        .filter_map(|i| {
+            let result = unsafe {
+                let mut addr = sockaddr_ctl {
+                    sc_len: size_of::<sockaddr_ctl>() as u8,
+                    sc_family: 0,
+                    ss_sysaddr: 0,
+                    sc_id: 0,
+                    sc_unit: 0,
+                    sc_reserved: Default::default(),
+                };
+                let mut len = mem::size_of::<sockaddr_ctl>() as libc::socklen_t;
+                let res = syscall!(getpeername(i, &mut addr as *mut _ as *mut _, len as *mut _));
+                tracing::debug!("getpeername{}: {:?}", i, res);
+                if res.is_err() {
+                    return None;
+                }
+                if addr.sc_family == sys::AF_SYSTEM as u8
+                    && addr.ss_sysaddr == sys::AF_SYS_CONTROL as u16
+                {
+                    Some(TunInterface::from_raw_fd(i))
+                } else {
+                    None
+                }
+            };
+            result
+        })
+        .next()
+}