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authoritative.go
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authoritative.go
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// Copyright 2020 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 hiddenpath
import (
"context"
"github.com/scionproto/scion/pkg/addr"
"github.com/scionproto/scion/pkg/private/serrors"
seg "github.com/scionproto/scion/pkg/segment"
)
// SegmentRequest is a request for hidden segments.
type SegmentRequest struct {
// GroupIDs are the hidden path group IDs for which the segments are
// requested.
GroupIDs []GroupID
// DstIA is the destination ISD-AS of the segments that are requested.
DstIA addr.IA
// Peer is ISD-AS of the requesting peer.
Peer addr.IA
}
// AuthoritativeServer serves segments from the database.
type AuthoritativeServer struct {
// Groups is the current set of groups.
Groups map[GroupID]*Group
// DB is used to read hidden segments.
DB Store
// LocalIA is the ISD-AS this server is run in.
LocalIA addr.IA
}
// Segments returns the segments for the request or errors out if there was an
// error.
func (s AuthoritativeServer) Segments(ctx context.Context,
req SegmentRequest) ([]*seg.Meta, error) {
if len(req.GroupIDs) == 0 {
return nil, serrors.New("no group IDs provided")
}
for _, id := range req.GroupIDs {
group, ok := s.Groups[id]
if !ok {
return nil, serrors.New("request for unknown group", "group_id", id)
}
if !canRead(req.Peer, group) {
return nil, serrors.New("not allowed to read group", "group_id", id)
}
if !isAuthoritative(s.LocalIA, group) {
return nil, serrors.New("not authoritative for group", "group_id", id)
}
}
segs, err := s.DB.Get(ctx, req.DstIA, req.GroupIDs)
if err != nil {
return nil, err
}
return segs, nil
}
func canRead(peer addr.IA, group *Group) bool {
owner := group.Owner.Equal(peer)
_, registry := group.Registries[peer]
_, writer := group.Writers[peer]
_, reader := group.Readers[peer]
return owner || registry || writer || reader
}
func isAuthoritative(localIA addr.IA, group *Group) bool {
_, auth := group.Registries[localIA]
return auth
}