github.com/maenmax/kairep@v0.0.0-20210218001208-55bf3df36788/src/golang.org/x/crypto/openpgp/packet/userattribute.go (about)

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package packet
     6  
     7  import (
     8  	"bytes"
     9  	"image"
    10  	"image/jpeg"
    11  	"io"
    12  	"io/ioutil"
    13  )
    14  
    15  const UserAttrImageSubpacket = 1
    16  
    17  // UserAttribute is capable of storing other types of data about a user
    18  // beyond name, email and a text comment. In practice, user attributes are typically used
    19  // to store a signed thumbnail photo JPEG image of the user.
    20  // See RFC 4880, section 5.12.
    21  type UserAttribute struct {
    22  	Contents []*OpaqueSubpacket
    23  }
    24  
    25  // NewUserAttributePhoto creates a user attribute packet
    26  // containing the given images.
    27  func NewUserAttributePhoto(photos ...image.Image) (uat *UserAttribute, err error) {
    28  	uat = new(UserAttribute)
    29  	for _, photo := range photos {
    30  		var buf bytes.Buffer
    31  		// RFC 4880, Section 5.12.1.
    32  		data := []byte{
    33  			0x10, 0x00, // Little-endian image header length (16 bytes)
    34  			0x01,       // Image header version 1
    35  			0x01,       // JPEG
    36  			0, 0, 0, 0, // 12 reserved octets, must be all zero.
    37  			0, 0, 0, 0,
    38  			0, 0, 0, 0}
    39  		if _, err = buf.Write(data); err != nil {
    40  			return
    41  		}
    42  		if err = jpeg.Encode(&buf, photo, nil); err != nil {
    43  			return
    44  		}
    45  		uat.Contents = append(uat.Contents, &OpaqueSubpacket{
    46  			SubType:  UserAttrImageSubpacket,
    47  			Contents: buf.Bytes()})
    48  	}
    49  	return
    50  }
    51  
    52  // NewUserAttribute creates a new user attribute packet containing the given subpackets.
    53  func NewUserAttribute(contents ...*OpaqueSubpacket) *UserAttribute {
    54  	return &UserAttribute{Contents: contents}
    55  }
    56  
    57  func (uat *UserAttribute) parse(r io.Reader) (err error) {
    58  	// RFC 4880, section 5.13
    59  	b, err := ioutil.ReadAll(r)
    60  	if err != nil {
    61  		return
    62  	}
    63  	uat.Contents, err = OpaqueSubpackets(b)
    64  	return
    65  }
    66  
    67  // Serialize marshals the user attribute to w in the form of an OpenPGP packet, including
    68  // header.
    69  func (uat *UserAttribute) Serialize(w io.Writer) (err error) {
    70  	var buf bytes.Buffer
    71  	for _, sp := range uat.Contents {
    72  		sp.Serialize(&buf)
    73  	}
    74  	if err = serializeHeader(w, packetTypeUserAttribute, buf.Len()); err != nil {
    75  		return err
    76  	}
    77  	_, err = w.Write(buf.Bytes())
    78  	return
    79  }
    80  
    81  // ImageData returns zero or more byte slices, each containing
    82  // JPEG File Interchange Format (JFIF), for each photo in the
    83  // the user attribute packet.
    84  func (uat *UserAttribute) ImageData() (imageData [][]byte) {
    85  	for _, sp := range uat.Contents {
    86  		if sp.SubType == UserAttrImageSubpacket && len(sp.Contents) > 16 {
    87  			imageData = append(imageData, sp.Contents[16:])
    88  		}
    89  	}
    90  	return
    91  }