feat(platform): add support for FreeBSD interface statistics

src/platform/freebsd.rs

@@ -0,0 +1,125 @@
+// SPDX-FileCopyrightText: 2026-Present Nils Andreas Svee mailto:contact@lochnair.net (github @Lochnair)
+//
+// SPDX-License-Identifier: MPL-2.0
+
+use std::ffi::CString;
+use std::io;
+use std::mem::{MaybeUninit, size_of};
+use std::ptr;
+
+use log::warn;
+
+use super::noop::NoopTrafficControl;
+use crate::platform::{InterfaceStats, InterfaceStatsProvider};
+
+#[derive(Debug, thiserror::Error)]
+pub(crate) enum FreeBsdInterfaceStatsError {
+    #[error("interface name contains a NUL byte")]
+    InterfaceNameContainsNul(#[source] std::ffi::NulError),
+
+    #[error("interface `{interface}` was not found")]
+    InterfaceNotFound {
+        interface: String,
+        #[source]
+        source: io::Error,
+    },
+
+    #[error("failed to query statistics for interface `{interface}`")]
+    Sysctl {
+        interface: String,
+        #[source]
+        source: io::Error,
+    },
+
+    #[error(
+        "unexpected interface-statistics response size for `{interface}`: \
+         expected {expected} bytes, received {actual}"
+    )]
+    UnexpectedResponseSize {
+        interface: String,
+        expected: usize,
+        actual: usize,
+    },
+}
+
+#[derive(Debug, Default)]
+pub(crate) struct FreeBsdInterfaceStats;
+
+impl InterfaceStatsProvider for FreeBsdInterfaceStats {
+    type Error = FreeBsdInterfaceStatsError;
+
+    fn read_stats(&mut self, interface: &str) -> Result<InterfaceStats, Self::Error> {
+        let interface_name = CString::new(interface)
+            .map_err(FreeBsdInterfaceStatsError::InterfaceNameContainsNul)?;
+        let interface_index = unsafe { libc::if_nametoindex(interface_name.as_ptr()) };
+        if interface_index == 0 {
+            return Err(FreeBsdInterfaceStatsError::InterfaceNotFound {
+                interface: interface.to_string(),
+                source: io::Error::last_os_error(),
+            });
+        }
+
+        let mib = [
+            libc::CTL_NET,
+            libc::PF_LINK,
+            libc::NETLINK_GENERIC,
+            libc::IFMIB_IFDATA,
+            interface_index as libc::c_int,
+            libc::IFDATA_GENERAL,
+        ];
+
+        let mut ifmd = MaybeUninit::<libc::ifmibdata>::uninit();
+        let mut returned_len = size_of::<libc::ifmibdata>();
+
+        let result = unsafe {
+            libc::sysctl(
+                mib.as_ptr(),
+                mib.len() as libc::c_uint,
+                ifmd.as_mut_ptr().cast::<libc::c_void>(),
+                &mut returned_len,
+                ptr::null(),
+                0,
+            )
+        };
+
+        if result == -1 {
+            return Err(FreeBsdInterfaceStatsError::Sysctl {
+                interface: interface.to_string(),
+                source: io::Error::last_os_error(),
+            });
+        }
+
+        let expected_len = size_of::<libc::ifmibdata>();
+        if returned_len != expected_len {
+            return Err(FreeBsdInterfaceStatsError::UnexpectedResponseSize {
+                interface: interface.to_string(),
+                expected: expected_len,
+                actual: returned_len,
+            });
+        }
+
+        let ifmd = unsafe { ifmd.assume_init() };
+
+        Ok(InterfaceStats {
+            rx_bytes: ifmd.ifmd_data.ifi_ibytes,
+            tx_bytes: ifmd.ifmd_data.ifi_obytes,
+        })
+    }
+}
+
+pub(crate) type PlatformInterfaceStats = FreeBsdInterfaceStats;
+pub(crate) type PlatformTrafficControl = NoopTrafficControl;
+
+pub(crate) fn interface_stats_provider() -> PlatformInterfaceStats {
+    FreeBsdInterfaceStats
+}
+
+pub(crate) fn traffic_control_backend() -> PlatformTrafficControl {
+    NoopTrafficControl
+}
+
+pub(crate) fn warn_platform_limitations() {
+    warn!(
+        "Traffic control is unavailable on FreeBSD; requested rate changes will be calculated but not applied."
+    );
+}