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attestation.go
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attestation.go
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// Copyright © 2020 Attestant Limited.
// 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 phase0
import (
"bytes"
"encoding/hex"
"encoding/json"
"fmt"
"strings"
"github.com/goccy/go-yaml"
"github.com/pkg/errors"
bitfield "github.com/prysmaticlabs/go-bitfield"
)
// Attestation is the Ethereum 2 attestation structure.
type Attestation struct {
AggregationBits bitfield.Bitlist `ssz-max:"2048"`
Data *AttestationData
Signature BLSSignature `ssz-size:"96"`
}
// attestationJSON is a raw representation of the struct.
type attestationJSON struct {
AggregationBits string `json:"aggregation_bits"`
Data *AttestationData `json:"data"`
Signature string `json:"signature"`
}
// attestationYAML is a raw representation of the struct.
type attestationYAML struct {
AggregationBits string `yaml:"aggregation_bits"`
Data *AttestationData `yaml:"data"`
Signature string `yaml:"signature"`
}
// MarshalJSON implements json.Marshaler.
func (a *Attestation) MarshalJSON() ([]byte, error) {
return json.Marshal(&attestationJSON{
AggregationBits: fmt.Sprintf("%#x", []byte(a.AggregationBits)),
Data: a.Data,
Signature: fmt.Sprintf("%#x", a.Signature),
})
}
// UnmarshalJSON implements json.Unmarshaler.
func (a *Attestation) UnmarshalJSON(input []byte) error {
var attestationJSON attestationJSON
err := json.Unmarshal(input, &attestationJSON)
if err != nil {
return errors.Wrap(err, "invalid JSON")
}
return a.unpack(&attestationJSON)
}
func (a *Attestation) unpack(attestationJSON *attestationJSON) error {
var err error
if attestationJSON.AggregationBits == "" {
return errors.New("aggregation bits missing")
}
if a.AggregationBits, err = hex.DecodeString(strings.TrimPrefix(attestationJSON.AggregationBits, "0x")); err != nil {
return errors.Wrap(err, "invalid value for beacon block root")
}
a.Data = attestationJSON.Data
if a.Data == nil {
return errors.New("data missing")
}
if attestationJSON.Signature == "" {
return errors.New("signature missing")
}
signature, err := hex.DecodeString(strings.TrimPrefix(attestationJSON.Signature, "0x"))
if err != nil {
return errors.Wrap(err, "invalid value for signature")
}
if len(signature) != SignatureLength {
return errors.New("incorrect length for signature")
}
copy(a.Signature[:], signature)
return nil
}
// MarshalYAML implements yaml.Marshaler.
func (a *Attestation) MarshalYAML() ([]byte, error) {
yamlBytes, err := yaml.MarshalWithOptions(&attestationYAML{
AggregationBits: fmt.Sprintf("%#x", []byte(a.AggregationBits)),
Data: a.Data,
Signature: fmt.Sprintf("%#x", a.Signature),
}, yaml.Flow(true))
if err != nil {
return nil, err
}
return bytes.ReplaceAll(yamlBytes, []byte(`"`), []byte(`'`)), nil
}
// UnmarshalYAML implements yaml.Unmarshaler.
func (a *Attestation) UnmarshalYAML(input []byte) error {
// We unmarshal to the JSON struct to save on duplicate code.
var attestationJSON attestationJSON
if err := yaml.Unmarshal(input, &attestationJSON); err != nil {
return err
}
return a.unpack(&attestationJSON)
}
// String returns a string version of the structure.
func (a *Attestation) String() string {
data, err := yaml.Marshal(a)
if err != nil {
return fmt.Sprintf("ERR: %v", err)
}
return string(data)
}