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// Copyright 2012 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 packet
import (
"bytes"
"io"
"io/ioutil"
"golang.org/x/crypto/openpgp/errors"
)
// OpaquePacket represents an OpenPGP packet as raw, unparsed data. This is
// useful for splitting and storing the original packet contents separately,
// handling unsupported packet types or accessing parts of the packet not yet
// implemented by this package.
type OpaquePacket struct {
// Packet type
Tag uint8
// Reason why the packet was parsed opaquely
Reason error
// Binary contents of the packet data
Contents []byte
}
func (op *OpaquePacket) parse(r io.Reader) (err error) {
op.Contents, err = ioutil.ReadAll(r)
return
}
// Serialize marshals the packet to a writer in its original form, including
// the packet header.
func (op *OpaquePacket) Serialize(w io.Writer) (err error) {
err = serializeHeader(w, packetType(op.Tag), len(op.Contents))
if err == nil {
_, err = w.Write(op.Contents)
}
return
}
// Parse attempts to parse the opaque contents into a structure supported by
// this package. If the packet is not known then the result will be another
// OpaquePacket.
func (op *OpaquePacket) Parse() (p Packet, err error) {
hdr := bytes.NewBuffer(nil)
err = serializeHeader(hdr, packetType(op.Tag), len(op.Contents))
if err != nil {
op.Reason = err
return op, err
}
p, err = Read(io.MultiReader(hdr, bytes.NewBuffer(op.Contents)))
if err != nil {
op.Reason = err
p = op
}
return
}
// OpaqueReader reads OpaquePackets from an io.Reader.
type OpaqueReader struct {
r io.Reader
}
func NewOpaqueReader(r io.Reader) *OpaqueReader {
return &OpaqueReader{r: r}
}
// Read the next OpaquePacket.
func (or *OpaqueReader) Next() (op *OpaquePacket, err error) {
tag, _, contents, err := readHeader(or.r)
if err != nil {
return
}
op = &OpaquePacket{Tag: uint8(tag), Reason: err}
err = op.parse(contents)
if err != nil {
consumeAll(contents)
}
return
}
// OpaqueSubpacket represents an unparsed OpenPGP subpacket,
// as found in signature and user attribute packets.
type OpaqueSubpacket struct {
SubType uint8
Contents []byte
}
// OpaqueSubpackets extracts opaque, unparsed OpenPGP subpackets from
// their byte representation.
func OpaqueSubpackets(contents []byte) (result []*OpaqueSubpacket, err error) {
var (
subHeaderLen int
subPacket *OpaqueSubpacket
)
for len(contents) > 0 {
subHeaderLen, subPacket, err = nextSubpacket(contents)
if err != nil {
break
}
result = append(result, subPacket)
contents = contents[subHeaderLen+len(subPacket.Contents):]
}
return
}
func nextSubpacket(contents []byte) (subHeaderLen int, subPacket *OpaqueSubpacket, err error) {
// RFC 4880, section 5.2.3.1
var subLen uint32
if len(contents) < 1 {
goto Truncated
}
subPacket = &OpaqueSubpacket{}
switch {
case contents[0] < 192:
subHeaderLen = 2 // 1 length byte, 1 subtype byte
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[0])
contents = contents[1:]
case contents[0] < 255:
subHeaderLen = 3 // 2 length bytes, 1 subtype
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[0]-192)<<8 + uint32(contents[1]) + 192
contents = contents[2:]
default:
subHeaderLen = 6 // 5 length bytes, 1 subtype
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[1])<<24 |
uint32(contents[2])<<16 |
uint32(contents[3])<<8 |
uint32(contents[4])
contents = contents[5:]
}
if subLen > uint32(len(contents)) || subLen == 0 {
goto Truncated
}
subPacket.SubType = contents[0]
subPacket.Contents = contents[1:subLen]
return
Truncated:
err = errors.StructuralError("subpacket truncated")
return
}
func (osp *OpaqueSubpacket) Serialize(w io.Writer) (err error) {
buf := make([]byte, 6)
n := serializeSubpacketLength(buf, len(osp.Contents)+1)
buf[n] = osp.SubType
if _, err = w.Write(buf[:n+1]); err != nil {
return
}
_, err = w.Write(osp.Contents)
return
}
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