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signed.go
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signed.go
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// Copyright 2017 ETH Zurich
//
// 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 ctrl
import (
"context"
"fmt"
"github.com/scionproto/scion/go/lib/common"
"github.com/scionproto/scion/go/proto"
)
const LenSize = 4
var _ common.Payload = (*SignedPld)(nil)
var _ proto.Cerealizable = (*SignedPld)(nil)
type SignedPld struct {
Blob common.RawBytes
Sign *proto.SignS
pld *Pld
}
func NewSignedPld(cpld *Pld, signer Signer) (*SignedPld, error) {
// Make a copy of signer, so the caller can re-use it.
var err error
spld := &SignedPld{}
if spld.Blob, err = proto.PackRoot(cpld); err != nil {
return nil, err
}
sign, err := signer.Sign(spld.Blob)
if err != nil {
return nil, err
}
spld.Sign = sign
return spld, nil
}
func NewSignedPldFromRaw(b common.RawBytes) (*SignedPld, error) {
sp := &SignedPld{}
if len(b) < 4 {
return nil, common.NewBasicError("Ctrl payload length field too short", nil,
"minimum", 4, "actual", len(b))
}
n := common.Order.Uint32(b)
if int(n)+4 != len(b) {
return nil, common.NewBasicError("Invalid ctrl payload length", nil,
"expected", n+4, "actual", len(b))
}
return sp, proto.ParseFromRaw(sp, b[4:])
}
// UnsafePld extracts the control payload without verifying the payload.
func (sp *SignedPld) UnsafePld() (*Pld, error) {
var err error
if sp.pld == nil {
sp.pld, err = NewPldFromRaw(sp.Blob)
}
return sp.pld, err
}
// GetVerifiedPld extracts the control payload and verifies it. If
// verification fails, an error is returned instead.
func (sp *SignedPld) GetVerifiedPld(ctx context.Context, verifier Verifier) (*Pld, error) {
return verifier.VerifyPld(ctx, sp)
}
func (sp *SignedPld) Len() int {
return -1
}
func (sp *SignedPld) Copy() (common.Payload, error) {
return &SignedPld{Blob: append(common.RawBytes(nil), sp.Blob...), Sign: sp.Sign.Copy()}, nil
}
func (sp *SignedPld) WritePld(b common.RawBytes) (int, error) {
n, err := proto.WriteRoot(sp, b[4:])
common.Order.PutUint32(b, uint32(n))
return n + 4, err
}
func (sp *SignedPld) PackPld() (common.RawBytes, error) {
b, err := proto.PackRoot(sp)
if err != nil {
return nil, err
}
// Make a larger buffer, to allow pre-pending of the length field.
full := make(common.RawBytes, LenSize+len(b))
// Write length field
common.Order.PutUint32(full, uint32(len(b)))
// Copy the encoded proto into the full buffer
copy(full[LenSize:], b)
return full, err
}
func (sp *SignedPld) ProtoId() proto.ProtoIdType {
return proto.SignedCtrlPld_TypeID
}
func (sp *SignedPld) String() string {
return fmt.Sprintf("SignedCtrlPld: %s %s", sp.Blob, sp.Sign)
}