From a6a21981cf651b2b55a8849bd50e7bff6724165c Mon Sep 17 00:00:00 2001
From: Marc Odermatt <marcoder@ethz.ch>
Date: Fri, 26 Jul 2024 09:01:02 +0200
Subject: [PATCH] FABRID detachable extensions

---
 private/path/combinator/fabrid_accumulator.go | 80 +++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 private/path/combinator/fabrid_accumulator.go

diff --git a/private/path/combinator/fabrid_accumulator.go b/private/path/combinator/fabrid_accumulator.go
new file mode 100644
index 0000000000..35f735bda9
--- /dev/null
+++ b/private/path/combinator/fabrid_accumulator.go
@@ -0,0 +1,80 @@
+// Copyright 2018 ETH Zurich, Anapaya Systems
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package combinator
+
+import (
+	"time"
+
+	"github.com/scionproto/scion/pkg/addr"
+	"github.com/scionproto/scion/pkg/experimental/fabrid"
+	fabrid_ext "github.com/scionproto/scion/pkg/segment/extensions/fabrid"
+	"github.com/scionproto/scion/pkg/snet"
+)
+
+// We go through the list of ASEntries and store for each IA a pointer to the FABRID
+// Map found in the ASEntries' extensions.  If there is already a map stored, check the info time,
+// and replace with the newer FABRID maps. This results in a map[IA]FabridMapEntry, which can be
+// used to find the policies that are available for each of the interface pairs on the path.
+type FabridMapEntry struct {
+	Map *fabrid_ext.Detached
+	Ts  time.Time
+	// The Digest of the Fabrid Maps, this can be empty.
+	Digest []byte
+}
+
+func GetFabridInfoForIntfs(ia addr.IA, ig, eg uint16, maps map[addr.IA]FabridMapEntry,
+	allowIpPolicies bool) *snet.FabridInfo {
+	policies := make([]*fabrid.Policy, 0)
+	fabridMap, exist := maps[ia]
+	if !exist {
+		return &snet.FabridInfo{
+			Enabled:  false,
+			Policies: policies,
+			Digest:   []byte{},
+			Detached: false,
+		}
+	} else if fabridMap.Map == nil {
+		return &snet.FabridInfo{
+			Enabled:  true,
+			Policies: policies,
+			Digest:   fabridMap.Digest,
+			Detached: len(fabridMap.Digest) > 0,
+		}
+	}
+	for k, v := range fabridMap.Map.SupportedIndicesMap {
+		if !k.Matches(ig, eg, allowIpPolicies) {
+			continue
+		}
+		for _, policy := range v {
+			val, ok := fabridMap.Map.IndexIdentiferMap[policy]
+			if !ok {
+				continue
+			}
+			policies = append(policies, &fabrid.Policy{
+				IsLocal:    val.IsLocal,
+				Identifier: val.Identifier,
+				Index:      fabrid.PolicyID(policy),
+			})
+
+		}
+	}
+
+	return &snet.FabridInfo{
+		Enabled:  true,
+		Policies: policies,
+		Digest:   fabridMap.Digest,
+		Detached: false,
+	}
+}