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// Copyright 2013 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"
"image"
"image/jpeg"
"io"
"io/ioutil"
)
const UserAttrImageSubpacket = 1
// UserAttribute is capable of storing other types of data about a user
// beyond name, email and a text comment. In practice, user attributes are typically used
// to store a signed thumbnail photo JPEG image of the user.
// See RFC 4880, section 5.12.
type UserAttribute struct {
Contents []*OpaqueSubpacket
}
// NewUserAttributePhoto creates a user attribute packet
// containing the given images.
func NewUserAttributePhoto(photos ...image.Image) (uat *UserAttribute, err error) {
uat = new(UserAttribute)
for _, photo := range photos {
var buf bytes.Buffer
// RFC 4880, Section 5.12.1.
data := []byte{
0x10, 0x00, // Little-endian image header length (16 bytes)
0x01, // Image header version 1
0x01, // JPEG
0, 0, 0, 0, // 12 reserved octets, must be all zero.
0, 0, 0, 0,
0, 0, 0, 0}
if _, err = buf.Write(data); err != nil {
return
}
if err = jpeg.Encode(&buf, photo, nil); err != nil {
return
}
uat.Contents = append(uat.Contents, &OpaqueSubpacket{
SubType: UserAttrImageSubpacket,
Contents: buf.Bytes()})
}
return
}
// NewUserAttribute creates a new user attribute packet containing the given subpackets.
func NewUserAttribute(contents ...*OpaqueSubpacket) *UserAttribute {
return &UserAttribute{Contents: contents}
}
func (uat *UserAttribute) parse(r io.Reader) (err error) {
// RFC 4880, section 5.13
b, err := ioutil.ReadAll(r)
if err != nil {
return
}
uat.Contents, err = OpaqueSubpackets(b)
return
}
// Serialize marshals the user attribute to w in the form of an OpenPGP packet, including
// header.
func (uat *UserAttribute) Serialize(w io.Writer) (err error) {
var buf bytes.Buffer
for _, sp := range uat.Contents {
sp.Serialize(&buf)
}
if err = serializeHeader(w, packetTypeUserAttribute, buf.Len()); err != nil {
return err
}
_, err = w.Write(buf.Bytes())
return
}
// ImageData returns zero or more byte slices, each containing
// JPEG File Interchange Format (JFIF), for each photo in the
// the user attribute packet.
func (uat *UserAttribute) ImageData() (imageData [][]byte) {
for _, sp := range uat.Contents {
if sp.SubType == UserAttrImageSubpacket && len(sp.Contents) > 16 {
imageData = append(imageData, sp.Contents[16:])
}
}
return
}
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