tea/vendor/github.com/ProtonMail/go-crypto/openpgp/internal/encoding/oid.go

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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package encoding
import (
"io"
"github.com/ProtonMail/go-crypto/openpgp/errors"
)
// OID is used to store a variable-length field with a one-octet size
// prefix. See https://tools.ietf.org/html/rfc6637#section-9.
type OID struct {
bytes []byte
}
const (
// maxOID is the maximum number of bytes in a OID.
maxOID = 254
// reservedOIDLength1 and reservedOIDLength2 are OID lengths that the RFC
// specifies are reserved.
reservedOIDLength1 = 0
reservedOIDLength2 = 0xff
)
// NewOID returns a OID initialized with bytes.
func NewOID(bytes []byte) *OID {
switch len(bytes) {
case reservedOIDLength1, reservedOIDLength2:
panic("encoding: NewOID argument length is reserved")
default:
if len(bytes) > maxOID {
panic("encoding: NewOID argment too large")
}
}
return &OID{
bytes: bytes,
}
}
// Bytes returns the decoded data.
func (o *OID) Bytes() []byte {
return o.bytes
}
// BitLength is the size in bits of the decoded data.
func (o *OID) BitLength() uint16 {
return uint16(len(o.bytes) * 8)
}
// EncodedBytes returns the encoded data.
func (o *OID) EncodedBytes() []byte {
return append([]byte{byte(len(o.bytes))}, o.bytes...)
}
// EncodedLength is the size in bytes of the encoded data.
func (o *OID) EncodedLength() uint16 {
return uint16(1 + len(o.bytes))
}
// ReadFrom reads into b the next OID from r.
func (o *OID) ReadFrom(r io.Reader) (int64, error) {
var buf [1]byte
n, err := io.ReadFull(r, buf[:])
if err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return int64(n), err
}
switch buf[0] {
case reservedOIDLength1, reservedOIDLength2:
return int64(n), errors.UnsupportedError("reserved for future extensions")
}
o.bytes = make([]byte, buf[0])
nn, err := io.ReadFull(r, o.bytes)
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return int64(n) + int64(nn), err
}