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serialize.go
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serialize.go
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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.
package macaroon
import (
"context"
"encoding/binary"
"errors"
)
type fieldType int
const (
fieldEOS fieldType = 0
fieldLocation fieldType = 1
fieldIdentifier fieldType = 2
fieldVerificationID fieldType = 4
fieldSignature fieldType = 6
)
const (
version byte = 2
)
type packet struct {
fieldType fieldType
data []byte
}
// Serialize converts macaroon to binary format
func (m *Macaroon) Serialize() (data []byte) {
ctx := context.TODO()
defer mon.Task()(&ctx)(nil)
// Start data from version int
data = append(data, version)
// Serilize Identity
data = serializePacket(data, packet{
fieldType: fieldIdentifier,
data: m.head,
})
data = append(data, 0)
// Serialize caveats
for _, cav := range m.caveats {
data = serializePacket(data, packet{
fieldType: fieldIdentifier,
data: cav,
})
data = append(data, 0)
}
data = append(data, 0)
// Serialize tail
data = serializePacket(data, packet{
fieldType: fieldSignature,
data: m.tail,
})
return data
}
// serializePacket converts packet to binary
func serializePacket(data []byte, p packet) []byte {
data = appendVarint(data, int(p.fieldType))
data = appendVarint(data, len(p.data))
data = append(data, p.data...)
return data
}
func appendVarint(data []byte, x int) []byte {
var buf [binary.MaxVarintLen32]byte
n := binary.PutUvarint(buf[:], uint64(x))
return append(data, buf[:n]...)
}
// ParseMacaroon converts binary to macaroon
func ParseMacaroon(data []byte) (_ *Macaroon, err error) {
ctx := context.TODO()
defer mon.Task()(&ctx)(&err)
if len(data) < 2 {
return nil, errors.New("empty macaroon")
}
if data[0] != version {
return nil, errors.New("invalid macaroon version")
}
// skip version
data = data[1:]
// Parse Location
data, section, err := parseSection(data)
if err != nil {
return nil, err
}
if len(section) > 0 && section[0].fieldType == fieldLocation {
section = section[1:]
}
if len(section) != 1 || section[0].fieldType != fieldIdentifier {
return nil, errors.New("invalid macaroon header")
}
mac := Macaroon{}
mac.head = section[0].data
for {
rest, section, err := parseSection(data)
if err != nil {
return nil, err
}
data = rest
if len(section) == 0 {
break
}
if len(section) > 0 && section[0].fieldType == fieldLocation {
section = section[1:]
}
if len(section) == 0 || section[0].fieldType != fieldIdentifier {
return nil, errors.New("no Identifier in caveat")
}
cav := append([]byte(nil), section[0].data...)
section = section[1:]
if len(section) == 0 {
// First party caveat.
//if cav.Location != "" {
// return nil, errors.New("location not allowed in first party caveat")
//}
mac.caveats = append(mac.caveats, cav)
continue
}
if len(section) != 1 {
return nil, errors.New("extra fields found in caveat")
}
if section[0].fieldType != fieldVerificationID {
return nil, errors.New("invalid field found in caveat")
}
//cav.VerificationId = section[0].data
mac.caveats = append(mac.caveats, cav)
}
_, sig, err := parsePacket(data)
if err != nil {
return nil, err
}
if sig.fieldType != fieldSignature {
return nil, errors.New("unexpected field found instead of signature")
}
if len(sig.data) != 32 {
return nil, errors.New("signature has unexpected length")
}
mac.tail = make([]byte, 32)
copy(mac.tail, sig.data)
//return data, nil
// Parse Identity
// Parse caveats
// Parse tail
return &mac, nil
}
// parseSection returns data leftover and packet array
func parseSection(data []byte) ([]byte, []packet, error) {
prevFieldType := fieldType(-1)
var packets []packet
for {
if len(data) == 0 {
return nil, nil, errors.New("section extends past end of buffer")
}
rest, p, err := parsePacket(data)
if err != nil {
return nil, nil, err
}
if p.fieldType == fieldEOS {
return rest, packets, nil
}
if p.fieldType <= prevFieldType {
return nil, nil, errors.New("fields out of order")
}
packets = append(packets, p)
prevFieldType = p.fieldType
data = rest
}
}
// parsePacket returns data leftover and packet
func parsePacket(data []byte) ([]byte, packet, error) {
data, ft, err := parseVarint(data)
if err != nil {
return nil, packet{}, err
}
p := packet{fieldType: fieldType(ft)}
if p.fieldType == fieldEOS {
return data, p, nil
}
data, packLen, err := parseVarint(data)
if err != nil {
return nil, packet{}, err
}
if packLen > len(data) {
return nil, packet{}, errors.New("out of bounds")
}
if packLen == 0 {
p.data = nil
return data, p, nil
}
p.data = data[0:packLen]
return data[packLen:], p, nil
}
func parseVarint(data []byte) ([]byte, int, error) {
value, n := binary.Uvarint(data)
if n <= 0 || value > 0x7fffffff {
return nil, 0, errors.New("varint error")
}
return data[n:], int(value), nil
}