Fix overflow in DHCPv6 client remaining seconds calculation

This fixes an issue where overflows (e.g. due to time mismatches between
router and manager) cause the DHCPv6 client display logic to crash. Now,
0 is displayed instead.

1 files changed, 7 insertions, 9 deletions

diff --git a/src-tauri/src/main.rs b/src-tauri/src/main.rs
index da58602..5bb2103 100644
--- a/src-tauri/src/main.rs
+++ b/src-tauri/src/main.rs
@@ -151,13 +151,11 @@ impl Dhcpv6Status {
 impl From<Dhcpv6Lease> for Dhcpv6Status {
     fn from(lease: Dhcpv6Lease) -> Self {
         let validity = if lease.is_valid() { "✅" } else { "❌" };
+        let localnow = Local::now();
+        let ts = DateTime::<Local>::from(lease.timestamp);
 
         Self {
-            timestamp: format!(
-                "{} {}",
-                validity,
-                DateTime::<Local>::from(lease.timestamp).format("%d.%m.%Y %H:%M:%S UTC%Z")
-            ),
+            timestamp: format!("{} {}", validity, ts.format("%d.%m.%Y %H:%M:%S UTC%Z")),
             srvaddr: if lease.server
                 == SocketAddr::V6(SocketAddrV6::new(Ipv6Addr::UNSPECIFIED, 0, 0, 0))
             {
@@ -173,7 +171,7 @@ impl From<Dhcpv6Lease> for Dhcpv6Status {
             } else {
                 let remaining_secs = std::cmp::max(
                     (Duration::from_secs(lease.t1.into())
-                        - lease.timestamp.elapsed().unwrap_or(Duration::ZERO))
+                        .saturating_sub(lease.timestamp.elapsed().unwrap_or(Duration::ZERO)))
                     .as_secs(),
                     0,
                 );
@@ -189,7 +187,7 @@ impl From<Dhcpv6Lease> for Dhcpv6Status {
             } else {
                 let remaining_secs = std::cmp::max(
                     (Duration::from_secs(lease.t2.into())
-                        - lease.timestamp.elapsed().unwrap_or(Duration::ZERO))
+                        .saturating_sub(lease.timestamp.elapsed().unwrap_or(Duration::ZERO)))
                     .as_secs(),
                     0,
                 );
@@ -207,7 +205,7 @@ impl From<Dhcpv6Lease> for Dhcpv6Status {
             } else {
                 let remaining_secs = std::cmp::max(
                     (Duration::from_secs(lease.preflft.into())
-                        - lease.timestamp.elapsed().unwrap_or(Duration::ZERO))
+                        .saturating_sub(lease.timestamp.elapsed().unwrap_or(Duration::ZERO)))
                     .as_secs(),
                     0,
                 );
@@ -223,7 +221,7 @@ impl From<Dhcpv6Lease> for Dhcpv6Status {
             } else {
                 let remaining_secs = std::cmp::max(
                     (Duration::from_secs(lease.validlft.into())
-                        - lease.timestamp.elapsed().unwrap_or(Duration::ZERO))
+                        .saturating_sub(lease.timestamp.elapsed().unwrap_or(Duration::ZERO)))
                     .as_secs(),
                     0,
                 );