Add support for external subnets

Author: Nieuwejaar

.github/buildomat/common.sh

@@ -1,9 +1,19 @@
 #!/bin/bash
 
+# The tofino2 has 20 stages, and the current sidecar.p4 needs all 20 of them.
+# Specifying the number of stages isn't strictly necessary, but it allows us to
+# track when we exceed the current ceiling. The underlying intention is to grow
+# deliberately and thoughtfully, given the limited space on the ASIC.
+#
+# Note: this now seems silly since we have maxed out the number of stages, but
+# we want to leave this check and note in place should we ever find a way to
+# reduce our footprint below 20 stages.
+TOFINO_STAGES=20
+
 # These describe which version of the SDE to download and where to find it
-SDE_COMMIT=eb08b0b0e55792bbba206202603da0fd791ea555
-SDE_PKG_SHA256=fbaea9ccd7ece70cdc20207e2f9b4750243468c6fe95c6a1fae9734201307db7
-SDE_DEB_SHA256=14050fd9a08b8b0b2ec7c827fa06a51516369a81bcf616d16699302b58d8ea9a
+SDE_COMMIT=e61fe02c3c1c384b2e212c90177fcea76a31fd4e
+SDE_PKG_SHA256=8a87a9b0bed3c5440a173a7a41361bdeb5e7a848882da6b4aa48c8fb0043f3bd
+SDE_DEB_SHA256=a292e2dd5311647c4852bb41f2532dd1fdf30325b6d04cccb7e85b873e521d5f
 
 [ `uname -s` == "SunOS" ] && SERIES=illumos
 [ `uname -s` == "SunOS" ] || SERIES=linux

.github/buildomat/jobs/image.sh

@@ -101,11 +101,7 @@ pfexec chown "$UID" /out
 
 banner "P4 Codegen"
 # Add gcc-12 so the p4 compiler can find cpp
-# The tofino2 has 20 stages, but the current sidecar.p4 will fit into 19.  We
-# add the "--stages 19" here to detect if/when the program grows beyond that
-# limit.  It's not necessarily a problem if we grow, but given the limited space
-# on the ASIC, we want to grow deliberatately and thoughtfully.
-PATH=/opt/gcc-12/bin:$PATH cargo xtask codegen --stages 19
+PATH=/opt/gcc-12/bin:$PATH cargo xtask codegen --stages $TOFINO_STAGES
 
 # Preserve all the diagnostics spit out by the compiler
 mkdir -p /out/p4c-diags

.github/buildomat/jobs/packet-test.sh

@@ -77,7 +77,7 @@ export SDE=/opt/oxide/tofino_sde
 
 banner "Build"
 cargo build --features=tofino_asic --bin dpd --bin swadm
-cargo xtask codegen --stages 19
+cargo xtask codegen --stages $TOFINO_STAGES
 
 banner "Test"
 sudo -E ./tools/veth_setup.sh

asic/src/softnpu/table.rs

@@ -2,7 +2,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/
 //
-// Copyright 2025 Oxide Computer Company
+// Copyright 2026 Oxide Computer Company
 
 use slog::{error, trace};
 use softnpu_lib::{ManagementRequest, TableAdd, TableRemove};
@@ -31,6 +31,8 @@ const LOCAL_V6: &str = "ingress.local.local_v6";
 const LOCAL_V4: &str = "ingress.local.local_v4";
 const NAT_V4: &str = "ingress.nat.nat_v4";
 const NAT_V6: &str = "ingress.nat.nat_v6";
+const ATTACHED_SUBNET_V4: &str = "ingress.attached.attached_subnet_v4";
+const ATTACHED_SUBNET_V6: &str = "ingress.attached.attached_subnet_v6";
 const _NAT_ICMP_V6: &str = "ingress.nat.nat_icmp_v6";
 const _NAT_ICMP_V4: &str = "ingress.nat.nat_icmp_v4";
 const RESOLVER_V4: &str = "ingress.resolver.resolver_v4";
@@ -54,12 +56,16 @@ const ARP: &str = "pipe.Ingress.l3_router.Router4.Arp.tbl";
 const DPD_MAC_REWRITE: &str = "pipe.Ingress.mac_rewrite.mac_rewrite";
 const NAT_INGRESS4: &str = "pipe.Ingress.nat_ingress.ingress_ipv4";
 const NAT_INGRESS6: &str = "pipe.Ingress.nat_ingress.ingress_ipv6";
+const ATTACHED_SUBNET_INGRESS4: &str =
+    "pipe.Ingress.attached_subnet_ingress.attached_subnets_v4";
+const ATTACHED_SUBNET_INGRESS6: &str =
+    "pipe.Ingress.attached_subnet_ingress.attached_subnets_v6";
 
 // All tables are defined to be 1024 entries deep
 const TABLE_SIZE: usize = 4096;
 
 impl TableOps<Handle> for Table {
-    fn new(_hdl: &Handle, name: &str) -> AsicResult<Table> {
+    fn new(hdl: &Handle, name: &str) -> AsicResult<Table> {
         // TODO just mapping sidecar.p4 things onto simplified sidecar-lite.p4
         // things to get started.
         let (id, dpd_id) = match name {
@@ -84,8 +90,16 @@ impl TableOps<Handle> for Table {
             }
             NAT_INGRESS4 => (Some(NAT_V4.into()), Some(NAT_INGRESS4.into())),
             NAT_INGRESS6 => (Some(NAT_V6.into()), Some(NAT_INGRESS6.into())),
+            ATTACHED_SUBNET_INGRESS4 => (
+                Some(ATTACHED_SUBNET_V4.into()),
+                Some(ATTACHED_SUBNET_INGRESS4.into()),
+            ),
+            ATTACHED_SUBNET_INGRESS6 => (
+                Some(ATTACHED_SUBNET_V6.into()),
+                Some(ATTACHED_SUBNET_INGRESS6.into()),
+            ),
             x => {
-                println!("TABLE NOT HANDLED {x}");
+                error!(hdl.log, "TABLE NOT HANDLED {x}");
                 (None, None)
             }
         };
@@ -382,7 +396,9 @@ impl TableOps<Handle> for Table {
                 ("rewrite", params)
             }
             (NAT_INGRESS4, "forward_ipv4_to")
-            | (NAT_INGRESS6, "forward_ipv6_to") => {
+            | (NAT_INGRESS6, "forward_ipv6_to")
+            | (ATTACHED_SUBNET_INGRESS4, "forward_to_v4")
+            | (ATTACHED_SUBNET_INGRESS6, "forward_to_v6") => {
                 let mut target = Vec::new();
                 let mut vni = Vec::new();
                 let mut mac = Vec::new();
@@ -463,7 +479,7 @@ impl TableOps<Handle> for Table {
                 ("forward_to_sled", params)
             }
             (tbl, x) => {
-                println!("ACTION NOT HANDLED {tbl} {x}");
+                error!(hdl.log, "ACTION NOT HANDLED {tbl} {x}");
                 return Ok(());
             }
         };
@@ -610,7 +626,7 @@ fn keyset_data(match_data: Vec<MatchEntryField>, table: &str) -> Vec<u8> {
             MatchEntryValue::Lpm(x) => {
                 let mut data: Vec<u8> = Vec::new();
                 match table {
-                    ROUTER_V4_IDX => {
+                    ROUTER_V4_IDX | ATTACHED_SUBNET_V4 => {
                         // prefix for longest prefix match operation
                         // "dst_addr" => hdr.ipv4.dst: lpm => bit<32>
                         serialize_value_type_be(&x.prefix, &mut data);

common/src/attached_subnet.rs

@@ -0,0 +1,26 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/
+//
+// Copyright 2026 Oxide Computer Company
+
+use oxnet::IpNet;
+use std::fmt;
+
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+use crate::network::InstanceTarget;
+
+/** represents an external subnet mapping */
+#[derive(Debug, Copy, Clone, PartialEq, Deserialize, Serialize, JsonSchema)]
+pub struct AttachedSubnetEntry {
+    pub subnet: IpNet,
+    pub tgt: InstanceTarget,
+}
+
+impl fmt::Display for AttachedSubnetEntry {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}->{}", self.subnet, self.tgt)
+    }
+}

common/src/lib.rs

@@ -2,7 +2,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/
 //
-// Copyright 2025 Oxide Computer Company
+// Copyright 2026 Oxide Computer Company
 
 use std::collections::BTreeSet;
 use std::convert::TryFrom;
@@ -11,6 +11,7 @@ use std::sync::Once;
 use std::time::Duration;
 use std::time::Instant;
 
+pub mod attached_subnet;
 pub mod counters;
 pub mod logging;
 pub mod nat;

common/src/nat.rs

@@ -2,97 +2,14 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/
 //
-// Copyright 2025 Oxide Computer Company
+// Copyright 2026 Oxide Computer Company
 
-use std::fmt;
 use std::net::{Ipv4Addr, Ipv6Addr};
 
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 
-use crate::network::MacAddr;
-
-/// A Geneve Virtual Network Identifier.
-///
-/// A Geneve VNI is a 24-bit value used to identify virtual networks
-/// encapsulated using the Generic Network Virtualization Encapsulation (Geneve)
-/// protocol (RFC 8926).
-#[derive(
-    Clone,
-    Copy,
-    Debug,
-    Deserialize,
-    Eq,
-    Hash,
-    JsonSchema,
-    PartialEq,
-    PartialOrd,
-    Ord,
-    Serialize,
-)]
-#[serde(try_from = "u32")]
-pub struct Vni(u32);
-
-impl Vni {
-    const MAX_VNI: u32 = 0x00FF_FFFF;
-    const ERR_MSG: &'static str = "VNI out of 24-bit range";
-
-    /// Construct a new VNI, validating that it's a valid 24-bit value.
-    pub const fn new(vni: u32) -> Option<Self> {
-        // bool.then_some is not const, unforunately
-        if vni <= Self::MAX_VNI {
-            Some(Self(vni))
-        } else {
-            None
-        }
-    }
-
-    /// Return the VNI as a u32.
-    pub const fn as_u32(&self) -> u32 {
-        self.0
-    }
-}
-
-impl core::convert::TryFrom<u32> for Vni {
-    type Error = &'static str;
-
-    fn try_from(vni: u32) -> Result<Self, Self::Error> {
-        Self::new(vni).ok_or(Self::ERR_MSG)
-    }
-}
-
-impl core::str::FromStr for Vni {
-    type Err = &'static str;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s.parse::<u32>().map(Vni::new) {
-            Err(_) | Ok(None) => Err(Self::ERR_MSG),
-            Ok(Some(vni)) => Ok(vni),
-        }
-    }
-}
-
-impl fmt::Display for Vni {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.0)
-    }
-}
-
-/** represents an internal NAT target */
-#[derive(
-    Debug, Copy, Clone, Deserialize, Serialize, JsonSchema, Eq, PartialEq,
-)]
-pub struct NatTarget {
-    pub internal_ip: Ipv6Addr,
-    pub inner_mac: MacAddr,
-    pub vni: Vni,
-}
-
-impl fmt::Display for NatTarget {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}/{}/{}", self.internal_ip, self.inner_mac, self.vni)
-    }
-}
+use crate::network::NatTarget;
 
 /** represents an IPv6 NAT reservation */
 #[derive(Debug, Copy, Clone, Deserialize, Serialize, JsonSchema)]
@@ -130,7 +47,7 @@ impl PartialEq for Ipv4Nat {
 
 #[cfg(test)]
 mod tests {
-    use super::Vni;
+    use crate::network::Vni;
 
     #[test]
     fn test_vni() {