From 573409fb641e465c8d77056447b2c9974091062e Mon Sep 17 00:00:00 2001
From: OlivierHecart <olivier@zettascale.tech>
Date: Fri, 10 Jan 2025 18:08:17 +0100
Subject: [PATCH] Scan network interfaces once at startup (#1704)

* Retrieve network interfaces once in a lazy_static

* Fix non unix build
---
 commons/zenoh-util/src/net/mod.rs | 32 ++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/commons/zenoh-util/src/net/mod.rs b/commons/zenoh-util/src/net/mod.rs
index 65577ac61d..777dc886c6 100644
--- a/commons/zenoh-util/src/net/mod.rs
+++ b/commons/zenoh-util/src/net/mod.rs
@@ -13,6 +13,10 @@
 //
 use std::net::{IpAddr, Ipv6Addr};
 
+#[cfg(unix)]
+use lazy_static::lazy_static;
+#[cfg(unix)]
+use pnet_datalink::NetworkInterface;
 use tokio::net::{TcpSocket, UdpSocket};
 use zenoh_core::zconfigurable;
 #[cfg(unix)]
@@ -24,6 +28,11 @@ zconfigurable! {
     static ref WINDOWS_GET_ADAPTERS_ADDRESSES_MAX_RETRIES: u32 = 3;
 }
 
+#[cfg(unix)]
+lazy_static! {
+    static ref IFACES: Vec<NetworkInterface> = pnet_datalink::interfaces();
+}
+
 #[cfg(windows)]
 unsafe fn get_adapters_addresses(af_spec: i32) -> ZResult<Vec<u8>> {
     use winapi::um::iptypes::IP_ADAPTER_ADDRESSES_LH;
@@ -59,7 +68,7 @@ unsafe fn get_adapters_addresses(af_spec: i32) -> ZResult<Vec<u8>> {
 pub fn get_interface(name: &str) -> ZResult<Option<IpAddr>> {
     #[cfg(unix)]
     {
-        for iface in pnet_datalink::interfaces() {
+        for iface in IFACES.iter() {
             if iface.name == name {
                 for ifaddr in &iface.ips {
                     if ifaddr.is_ipv4() {
@@ -122,7 +131,7 @@ pub fn get_interface(name: &str) -> ZResult<Option<IpAddr>> {
 pub fn get_multicast_interfaces() -> Vec<IpAddr> {
     #[cfg(unix)]
     {
-        pnet_datalink::interfaces()
+        IFACES
             .iter()
             .filter_map(|iface| {
                 if iface.is_up() && iface.is_running() && iface.is_multicast() {
@@ -146,8 +155,8 @@ pub fn get_multicast_interfaces() -> Vec<IpAddr> {
 pub fn get_local_addresses(interface: Option<&str>) -> ZResult<Vec<IpAddr>> {
     #[cfg(unix)]
     {
-        Ok(pnet_datalink::interfaces()
-            .into_iter()
+        Ok(IFACES
+            .iter()
             .filter(|iface| {
                 if let Some(interface) = interface.as_ref() {
                     if iface.name != *interface {
@@ -156,7 +165,7 @@ pub fn get_local_addresses(interface: Option<&str>) -> ZResult<Vec<IpAddr>> {
                 }
                 iface.is_up() && iface.is_running()
             })
-            .flat_map(|iface| iface.ips)
+            .flat_map(|iface| iface.ips.clone())
             .map(|ipnet| ipnet.ip())
             .collect())
     }
@@ -196,7 +205,7 @@ pub fn get_local_addresses(interface: Option<&str>) -> ZResult<Vec<IpAddr>> {
 pub fn get_unicast_addresses_of_multicast_interfaces() -> Vec<IpAddr> {
     #[cfg(unix)]
     {
-        pnet_datalink::interfaces()
+        IFACES
             .iter()
             .filter(|iface| iface.is_up() && iface.is_running() && iface.is_multicast())
             .flat_map(|iface| {
@@ -219,10 +228,7 @@ pub fn get_unicast_addresses_of_multicast_interfaces() -> Vec<IpAddr> {
 pub fn get_unicast_addresses_of_interface(name: &str) -> ZResult<Vec<IpAddr>> {
     #[cfg(unix)]
     {
-        match pnet_datalink::interfaces()
-            .into_iter()
-            .find(|iface| iface.name == name)
-        {
+        match IFACES.iter().find(|iface| iface.name == name) {
             Some(iface) => {
                 if !iface.is_up() {
                     bail!("Interface {name} is not up");
@@ -276,7 +282,7 @@ pub fn get_unicast_addresses_of_interface(name: &str) -> ZResult<Vec<IpAddr>> {
 pub fn get_index_of_interface(addr: IpAddr) -> ZResult<u32> {
     #[cfg(unix)]
     {
-        pnet_datalink::interfaces()
+        IFACES
             .iter()
             .find(|iface| iface.ips.iter().any(|ipnet| ipnet.ip() == addr))
             .map(|iface| iface.index)
@@ -313,12 +319,12 @@ pub fn get_interface_names_by_addr(addr: IpAddr) -> ZResult<Vec<String>> {
     #[cfg(unix)]
     {
         if addr.is_unspecified() {
-            Ok(pnet_datalink::interfaces()
+            Ok(IFACES
                 .iter()
                 .map(|iface| iface.name.clone())
                 .collect::<Vec<String>>())
         } else {
-            Ok(pnet_datalink::interfaces()
+            Ok(IFACES
                 .iter()
                 .filter(|iface| iface.ips.iter().any(|ipnet| ipnet.ip() == addr))
                 .map(|iface| iface.name.clone())