bugfix(controller): WAN at 2048 (#3310)

Author: bgm-malbeclabs

controlplane/controller/internal/controller/fixtures/interfaces.txt

@@ -154,12 +154,12 @@ interface Switch1/1/4
    isis network point-to-point
 !
 interface Switch1/1/5
-   mtu 2048
+   mtu 1500
    no switchport
    ip address 172.16.0.14/31
 !
 interface Switch1/1/6
-   mtu 2048
+   mtu 1500
    no switchport
    ip address 172.16.0.16/31
 !

controlplane/controller/internal/controller/render_test.go

@@ -521,7 +521,7 @@ func TestRenderConfig(t *testing.T) {
 						{
 							Name:          "Switch1/1/5",
 							Ip:            netip.MustParsePrefix("172.16.0.14/31"),
-							Mtu:           2048,
+							Mtu:           1500,
 							InterfaceType: InterfaceTypePhysical,
 							Metric:        20000,
 							IsLink:        true,
@@ -531,7 +531,7 @@ func TestRenderConfig(t *testing.T) {
 						{
 							Name:          "Switch1/1/6",
 							Ip:            netip.MustParsePrefix("172.16.0.16/31"),
-							Mtu:           2048,
+							Mtu:           1500,
 							InterfaceType: InterfaceTypePhysical,
 							Metric:        25000,
 							IsLink:        true,

controlplane/controller/internal/controller/server.go

@@ -392,9 +392,6 @@ func (c *Controller) updateStateCache(ctx context.Context) error {
 			}
 
 			d.Interfaces[i].Metric = uint32(microseconds)
-			if link.Mtu > 0 && (iface.IsCYOA || iface.IsDIA) {
-				d.Interfaces[i].Mtu = uint16(link.Mtu)
-			}
 			d.Interfaces[i].IsLink = true
 			d.Interfaces[i].LinkStatus = link.Status
 			linkMetrics.WithLabelValues(device.Code, iface.Name, d.PubKey).Set(float64(d.Interfaces[i].Metric))

controlplane/controller/internal/controller/templates/tunnel.tmpl

@@ -88,11 +88,7 @@ system control-plane
 interface {{ .Name }}
    {{- if .IsPhysical }}
       {{- if or .IsCYOA .IsDIA }}
-         {{- if .Mtu }}
-   mtu {{ .Mtu }}
-         {{- else }}
    mtu 1500
-         {{- end }}
       {{- else }}
    mtu 2048
       {{- end }}

smartcontract/programs/doublezero-serviceability/src/processors/device/interface/create.rs

@@ -140,6 +140,24 @@ pub fn process_create_device_interface(
         return Err(DoubleZeroError::CyoaRequiresPhysical.into());
     }
 
+    // Validate MTU based on interface type
+    let is_cyoa_or_dia =
+        value.interface_cyoa != InterfaceCYOA::None || value.interface_dia != InterfaceDIA::None;
+    if interface_type == InterfaceType::Loopback {
+        if value.mtu != 0 {
+            return Err(DoubleZeroError::InvalidMtu.into());
+        }
+    } else if is_cyoa_or_dia {
+        if value.mtu != 1500 {
+            return Err(DoubleZeroError::InvalidMtu.into());
+        }
+    } else {
+        // WAN/DZX physical interfaces must be 2048
+        if value.mtu != 2048 {
+            return Err(DoubleZeroError::InvalidMtu.into());
+        }
+    }
+
     // ip_net can only be set on CYOA, DIA, or user-tunnel-endpoint interfaces
     if value.ip_net.is_some()
         && value.interface_cyoa == InterfaceCYOA::None

smartcontract/programs/doublezero-serviceability/src/processors/device/interface/update.rs

@@ -226,6 +226,21 @@ pub fn process_update_device_interface(
         iface.node_segment_idx = node_segment_idx;
     }
 
+    // Validate MTU against final interface state
+    let is_cyoa_or_dia =
+        iface.interface_cyoa != InterfaceCYOA::None || iface.interface_dia != InterfaceDIA::None;
+    if iface.interface_type == InterfaceType::Loopback {
+        if iface.mtu != 0 {
+            return Err(DoubleZeroError::InvalidMtu.into());
+        }
+    } else if is_cyoa_or_dia {
+        if iface.mtu != 1500 {
+            return Err(DoubleZeroError::InvalidMtu.into());
+        }
+    } else if iface.mtu != 2048 {
+        return Err(DoubleZeroError::InvalidMtu.into());
+    }
+
     // CYOA interfaces must have an ip_net — prevent setting CYOA without ip_net
     // or clearing ip_net from a CYOA interface via update
     if iface.interface_cyoa != InterfaceCYOA::None && iface.ip_net == NetworkV4::default() {

smartcontract/programs/doublezero-serviceability/src/processors/link/create.rs

@@ -150,6 +150,11 @@ pub fn process_create_link(
         return Err(DoubleZeroError::InvalidContributor.into());
     }
 
+    // WAN/DZX links must have MTU 2048
+    if value.mtu != 2048 {
+        return Err(DoubleZeroError::InvalidMtu.into());
+    }
+
     let side_a_iface = side_a_dev
         .interfaces
         .iter()

smartcontract/programs/doublezero-serviceability/src/processors/link/update.rs

@@ -164,6 +164,9 @@ pub fn process_update_link(
             link.bandwidth = bandwidth;
         }
         if let Some(mtu) = value.mtu {
+            if mtu != 2048 {
+                return Err(DoubleZeroError::InvalidMtu.into());
+            }
             link.mtu = mtu;
         }
         if let Some(delay_ns) = value.delay_ns {

smartcontract/programs/doublezero-serviceability/tests/delete_cyoa_interface_test.rs

@@ -410,7 +410,7 @@ async fn test_update_cyoa_interface_with_invalid_sibling() {
         program_id,
         DoubleZeroInstruction::UpdateDeviceInterface(DeviceInterfaceUpdateArgs {
             name: "ethernet1".to_string(),
-            mtu: Some(9000),
+            mtu: Some(1500),
             ..Default::default()
         }),
         vec![
@@ -434,7 +434,7 @@ async fn test_update_cyoa_interface_with_invalid_sibling() {
         .unwrap();
 
     let updated_iface = device.find_interface("Ethernet1").unwrap().1;
-    assert_eq!(updated_iface.mtu, 9000, "MTU should be updated to 9000");
+    assert_eq!(updated_iface.mtu, 1500, "MTU should be updated to 1500");
     assert_eq!(
         updated_iface.ip_net,
         "63.243.225.62/30".parse().unwrap(),

smartcontract/programs/doublezero-serviceability/tests/global_test.rs

@@ -403,7 +403,7 @@ async fn test_doublezero_program() {
         ip_net: None,
         bandwidth: 0,
         cir: 0,
-        mtu: 1500,
+        mtu: 2048,
         routing_mode: RoutingMode::Static,
         vlan_id: 0,
         user_tunnel_endpoint: false,
@@ -592,7 +592,7 @@ async fn test_doublezero_program() {
         cir: 0,
         ip_net: None,
 
-        mtu: 1500,
+        mtu: 2048,
         routing_mode: RoutingMode::Static,
         vlan_id: 0,
         user_tunnel_endpoint: false,
@@ -643,7 +643,7 @@ async fn test_doublezero_program() {
         code: tunnel_la_ny_code.clone(),
         link_type: LinkLinkType::WAN,
         bandwidth: 15_000_000_000,
-        mtu: 4900,
+        mtu: 2048,
         delay_ns: 1000000,
         jitter_ns: 100000,
         side_a_iface_name: "Ethernet0".to_string(),