Introduce load_wireguard_kernel_module() for FreeBSD

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "defguard_wireguard_rs"
-version = "0.6.0"
+version = "0.6.1"
 edition = "2021"
 rust-version = "1.80"
 description = "A unified multi-platform high-level API for managing WireGuard interfaces"

src/bsd/ifconfig.rs

@@ -3,8 +3,6 @@ use std::{
     os::fd::AsRawFd,
 };
 
-#[cfg(target_os = "freebsd")]
-use libc::{c_char, kld_load};
 use libc::{IFF_UP, IF_NAMESIZE};
 use nix::{ioctl_readwrite, ioctl_write_ptr, sys::socket::AddressFamily};
 
@@ -75,21 +73,6 @@ pub struct IfReq {
 impl IfReq {
     #[must_use]
     pub(super) fn new(if_name: &str) -> Self {
-        // First, try to load a kernel module for this type of network interface.
-        // Omit digits at the end of interface name, e.g. "wg0" -> "if_wg".
-        #[cfg(target_os = "freebsd")]
-        {
-            let index = if_name
-                .find(|c: char| c.is_ascii_digit())
-                .unwrap_or(if_name.len());
-            let mod_name = format!("if_{}", &if_name[0..index]);
-            unsafe {
-                // Ignore the return value for the time being.
-                // Do the cast because `c_char` differs across platforms.
-                kld_load(mod_name.as_ptr() as *const c_char);
-            }
-        }
-
         Self {
             ifr_name: make_ifr_name(if_name),
             ifr_ifru: SockAddrIn::default(),

src/bsd/mod.rs

@@ -81,6 +81,8 @@ pub enum IoError {
     NetworkInterface,
     #[error("Not enough bytes to unpack")]
     Unpack,
+    #[error("Failed to load kernel module")]
+    KernelModule,
 }
 
 impl From<IoError> for WireguardInterfaceError {
@@ -301,6 +303,17 @@ pub fn delete_peer(if_name: &str, public_key: &Key) -> Result<(), IoError> {
     wg_data.write_data()
 }
 
+#[cfg(target_os = "freebsd")]
+pub fn load_wireguard_kernel_module() -> Result<(), IoError> {
+    // Ignore the return value for the time being.
+    let retval = unsafe { libc::kld_load(c"if_wg".as_ptr()) };
+    if retval == 0 {
+        Ok(())
+    } else {
+        Err(IoError::KernelModule)
+    }
+}
+
 pub fn create_interface(if_name: &str) -> Result<(), IoError> {
     let mut ifreq = IfReq::new(if_name);
     ifreq.create()?;

src/wgapi_freebsd.rs

@@ -14,6 +14,7 @@ use crate::{
 impl WireguardInterfaceApi for WGApi<Kernel> {
     /// Creates a WireGuard network interface.
     fn create_interface(&self) -> Result<(), WireguardInterfaceError> {
+        bsd::load_wireguard_kernel_module();
         debug!("Creating interface {}", &self.ifname);
         bsd::create_interface(&self.ifname)?;
         debug!("Interface {} created successfully", &self.ifname);