feat(tailscale): Add TailscaleListener and TailscaleConn

Needs testing on a native windows machine

Signed-off-by: quexeky <git@quexeky.dev>

src-tauri/tailscale/src/lib.rs

@@ -2,18 +2,20 @@
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
 
-use std::os::raw::{c_int, c_char};
 use std::ffi::{CStr, CString};
+use std::io::{Read, Write};
+#[cfg(not(target_os = "windows"))]
+use std::os::fd::{AsRawFd, RawFd};
+#[cfg(target_os = "windows")]
+use std::os::windows::io::{AsRawHandle, RawHandle};
+use std::os::raw::{c_char, c_int};
 mod bindings;
 
 type GoInt = i64;
 
-
 use bindings::*;
 use libc;
 
-
-
 #[derive(Debug)]
 pub enum TailscaleError {
     ApiError(c_int, String),
@@ -43,7 +45,6 @@ impl From<std::io::Error> for TailscaleError {
     }
 }
 
-
 // Helper function to get error message from the server handle
 // This helper is needed because TsnetErrmsg requires the server handle (sd)
 fn get_tsnet_errmsg(sd: c_int) -> String {
@@ -51,16 +52,16 @@ fn get_tsnet_errmsg(sd: c_int) -> String {
     let message = unsafe { TsnetErrmsg(sd, buf.as_mut_ptr() as *mut c_char, buf.len()) };
 
     if message == 0 {
-        // Success, buf contains the null-terminated string
         let c_str = unsafe { CStr::from_ptr(buf.as_ptr() as *const c_char) };
         c_str.to_string_lossy().into_owned()
     } else {
-        // If errmsg itself failed
-        format!("(Failed to get error message, TsnetErrmsg returned {})", message)
+        format!(
+            "(Failed to get error message, TsnetErrmsg returned {})",
+            message
+        )
     }
 }
 
-
 fn parse_tsnet_result(sd: c_int, ret: c_int) -> Result<(), TailscaleError> {
     match ret {
         0 => Ok(()),
@@ -73,9 +74,25 @@ fn parse_tsnet_result(sd: c_int, ret: c_int) -> Result<(), TailscaleError> {
     }
 }
 
-
 pub struct Tailscale(c_int);
 
+// A TailscaleListener is a socket on the tailnet listening for connections.
+//
+// It is much like allocating a system socket(2) and calling listen(2).
+// Accept connections with tailscale_accept and close the listener  with close.
+//
+// Under the hood, a tailscale_listener is one half of a socketpair itself,
+// used to move the connection fd from Go to C. This means you can use epoll
+// or its equivalent on a tailscale_listener to know if there is a connection
+// read to accept.
+pub struct TailscaleListener(c_int);
+
+// A TailscaleConn is a connection to an address on the tailnet.
+//
+// It is a pipe(2) on which you can use read(2), write(2), and close(2).
+// For extra control over the connection, see the tailscale_conn_* functions.
+pub struct TailscaleConn(c_int);
+
 // NEEDS REVIEW. CANNOT BE BADLY DONE
 impl Drop for Tailscale {
     fn drop(&mut self) {
@@ -86,6 +103,26 @@ impl Drop for Tailscale {
     }
 }
 
+impl Drop for TailscaleListener {
+    fn drop(&mut self) {
+        // TailscaleListener is treated like a file descriptor.
+        let ret = unsafe { libc::close(self.0) };
+         if ret != 0 && ret != libc::EBADF {
+             eprintln!("Error closing Tailscale listener {}: {}", self.0, ret);
+        }
+    }
+}
+
+impl Drop for TailscaleConn {
+    fn drop(&mut self) {
+        // TailscaleConn is treated like a file descriptor (pipe).
+        let ret = unsafe { libc::close(self.0) };
+         if ret != 0 && ret != libc::EBADF {
+             eprintln!("Error closing Tailscale connection {}: {}", self.0, ret);
+        }
+    }
+}
+
 impl Tailscale {
     pub fn new() -> Self {
         Tailscale(unsafe { TsnetNewServer() })
@@ -148,7 +185,7 @@ impl Tailscale {
             0 => {
                 let c_str = unsafe { CStr::from_ptr(buf.as_ptr() as *const c_char) };
                 c_str.to_str().map_err(TailscaleError::from) // Convert Utf8Error
-            },
+            }
             code if code == libc::EBADF => Err(TailscaleError::BadFileDescriptor),
             code if code == libc::ERANGE => Err(TailscaleError::BufferTooSmall),
             _ => {
@@ -164,7 +201,7 @@ impl Tailscale {
         proxy_buf: &mut [u8],
         local_buf: &mut [u8],
     ) -> Result<(), TailscaleError> {
-         // C header says proxy_cred_out and local_api_cred_out must hold 33 bytes.
+        // C header says proxy_out and local_out must hold 33 bytes.
         if proxy_buf.len() < 33 || local_buf.len() < 33 {
             return Err(TailscaleError::BufferTooSmall); // Custom check based on docs
         }
@@ -181,14 +218,59 @@ impl Tailscale {
 
         parse_tsnet_result(self.0, ret)
     }
+    pub fn dial(&self, network: &str, addr: &str) -> Result<TailscaleConn, TailscaleError> {
+        let c_network = CString::new(network)?;
+        let c_addr = CString::new(addr)?;
+        let mut conn_out: c_int = -1;
+        let ret = unsafe {
+            TsnetDial(
+                self.0,
+                c_network.as_ptr() as *mut c_char,
+                c_addr.as_ptr() as *mut c_char,
+                &mut conn_out,
+            )
+        };
+
+        parse_tsnet_result(self.0, ret)?;
+
+        if ret == 0 && conn_out != -1 {
+            Ok(TailscaleConn(conn_out))
+        } else if ret == 0 {
+            Err(TailscaleError::InvalidHandle)
+        } else {
+            unreachable!();
+        }
+    }
+    pub fn listen(&self, network: &str, addr: &str) -> Result<TailscaleListener, TailscaleError> {
+        let c_network = CString::new(network)?;
+        let c_addr = CString::new(addr)?;
+        let mut listener_out: c_int = -1; // Use c_int for the output pointer
+        let ret = unsafe {
+            TsnetListen(
+                self.0,
+                c_network.as_ptr() as *mut c_char,
+                c_addr.as_ptr() as *mut c_char,
+                &mut listener_out,
+            )
+        };
+
+        parse_tsnet_result(self.0, ret)?;
+
+        if ret == 0 && listener_out != -1 {
+            Ok(TailscaleListener(listener_out))
+        } else if ret == 0 {
+            Err(TailscaleError::InvalidHandle)
+        } else {
+            unreachable!();
+        }
+    }
 
-    /// Configures Funnel to route requests from the public web to a local plaintext HTTP/1 server.
     pub fn enable_funnel_to_localhost_plaintext_http1(
         &self,
         localhost_port: i32,
     ) -> Result<(), TailscaleError> {
-         let ret = unsafe { TsnetEnableFunnelToLocalhostPlaintextHttp1(self.0, localhost_port as c_int) };
-         // Returns 0 on success or -1 on error.
+        let ret =
+            unsafe { TsnetEnableFunnelToLocalhostPlaintextHttp1(self.0, localhost_port as c_int) };
         parse_tsnet_result(self.0, ret)
     }
 
@@ -202,7 +284,65 @@ impl Tailscale {
             code if code == libc::EBADF => Err(TailscaleError::BadFileDescriptor),
             code if code == libc::ERANGE => Err(TailscaleError::BufferTooSmall),
             // TsnetErrmsg should ideally not return other codes, but handle defensively
-             _ => Err(TailscaleError::ApiError(ret, format!("TsnetErrmsg returned unknown code {}", ret))),
+            _ => Err(TailscaleError::ApiError(
+                ret,
+                format!("TsnetErrmsg returned unknown code {}", ret),
+            )),
         }
     }
 }
+
+#[cfg(not(target_os = "windows"))]
+// Requires the connection handle to behave like a raw file descriptor.
+impl AsRawFd for TailscaleConn {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0
+    }
+}
+#[cfg(target_os = "windows")]
+impl AsRawHandle for TailscaleConn {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.0
+    }
+}
+
+impl Read for TailscaleConn {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        #[cfg(not(target_os = "windows"))]
+        let fd = self.as_raw_fd();
+        #[cfg(target_os = "windows")]
+        let fd = self.as_raw_handle();
+        // Safety: Calling libc::read on a valid file descriptor.
+        // The caller must ensure the handle is valid for reading (it is after successful dial/accept).
+        let n = unsafe {
+            libc::read(fd, buf.as_mut_ptr() as *mut libc::c_void, buf.len())
+        };
+        if n < 0 {
+            Err(std::io::Error::last_os_error())
+        } else {
+            Ok(n as usize)
+        }
+    }
+}
+
+impl Write for TailscaleConn {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        
+        let fd = self.as_raw_fd();
+        // Safety: Calling libc::write on a valid file descriptor.
+        // The caller must ensure the handle is valid for writing (it is after successful dial/accept).
+        let n = unsafe {
+            libc::write(fd, buf.as_ptr() as *const libc::c_void, buf.len())
+        };
+        if n < 0 {
+            Err(std::io::Error::last_os_error())
+        } else {
+            Ok(n as usize)
+        }
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        // For a pipe/socket, flush is often a no-op after write.
+        Ok(())
+    }
+}