Added if_nametoindex (and necessary module based on Cs net/if.h)

src/lib.rs

@@ -31,6 +31,9 @@ pub mod mount;
 #[cfg(any(target_os = "linux"))]
 pub mod mqueue;
 
+#[cfg(any(target_os = "linux"))]
+pub mod net;
+
 #[cfg(any(target_os = "linux", target_os = "android"))]
 pub mod sched;
 

src/net/if_.rs

@@ -0,0 +1,34 @@
+//! Network interface name resolution.
+//!
+//! Uses Linux and/or POSIX functions to resolve interface names like "eth0"
+//! or "socan1" into device numbers.
+
+use libc;
+use libc::c_uint;
+use std::ffi::{CString, NulError};
+use ::{Result, Error};
+
+/// Resolve an interface into a interface number.
+pub fn if_nametoindex(name: &str) -> Result<c_uint> {
+    let name = match CString::new(name) {
+        Err(e) => match e { NulError(..) => {
+            // A NulError indicates that a '\0' was found inside the string,
+            // making it impossible to create valid C-String. To avoid having
+            // to create a new error type for this rather rare case,
+            // nix::Error's invalid_argument() constructor is used.
+            //
+            // We match the NulError individually here to ensure to avoid
+            // accidentally returning invalid_argument() for errors other than
+            // NulError (which currently don't exist).
+            return Err(Error::invalid_argument());
+        }},
+        Ok(s) => s
+    };
+
+    let if_index;
+    unsafe {
+        if_index = libc::if_nametoindex(name.as_ptr());
+    }
+
+    if if_index == 0 { Err(Error::last()) } else { Ok(if_index) }
+}

src/net/mod.rs

@@ -0,0 +1,3 @@
+// To avoid clashing with the keyword "if", we use "if_" as the module name.
+// The original header is called "net/if.h".
+pub mod if_;