Source: opaque.go in package golang.org/x/crypto/openpgp/packet


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.

Packet type

Reason why the packet was parsed opaquely

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
}

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