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//
// Copyright (c) 2017 anygone contributors (see AUTHORS file)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * Neither the name of anygone nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
package satp
import (
"bytes"
"encoding/binary"
"errors"
)
// 0 1 2 3
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | sequence number | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
// | sender ID | MUX | |
// +#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+ |
// | | payload type | | |
// | +-------------------------------+ | |
// | | .... payload ... | |
// | | +-------------------------------+ |
// | | | padding (OPT) | pad count(OPT)| |
// +#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+#+-+
// | : authentication tag (RECOMMENDED) : |
// | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
// | |
// +- Encrypted Portion Authenticated Portion ---+
type PlainPacket struct {
Type uint16
Payload []byte
}
func NewPlainPacket(PayloadType uint16) (pp *PlainPacket) {
pp = &PlainPacket{}
pp.Type = PayloadType
return
}
func (pp *PlainPacket) MarshalBinary() (data []byte, err error) {
buf := &bytes.Buffer{}
if err = binary.Write(buf, binary.BigEndian, pp.Type); err != nil {
return
}
buf.Write(pp.Payload) // returned error is always nil
return buf.Bytes(), nil
}
func (pp *PlainPacket) UnmarshalBinary(data []byte) (err error) {
buf := bytes.NewReader(data)
if err = binary.Read(buf, binary.BigEndian, &(pp.Type)); err != nil {
return
}
if buf.Len() > 0 {
pp.Payload = make([]byte, buf.Len())
buf.Read(pp.Payload)
}
return
}
type EncryptedPacket struct {
SequenceNumber uint32
SenderID uint16
Mux uint16
Payload []byte
AuthTag []byte
}
func NewEncryptedPacket(AuthTagLength uint) (ep *EncryptedPacket) {
ep = &EncryptedPacket{}
if AuthTagLength > 0 {
ep.AuthTag = make([]byte, AuthTagLength)
}
return
}
func (ep *EncryptedPacket) MarshalBinary() (data []byte, err error) {
buf := &bytes.Buffer{}
if err = binary.Write(buf, binary.BigEndian, ep.SequenceNumber); err != nil {
return
}
if err = binary.Write(buf, binary.BigEndian, ep.SenderID); err != nil {
return
}
if err = binary.Write(buf, binary.BigEndian, ep.Mux); err != nil {
return
}
if len(ep.Payload) >= 2 { // Payload must at least have a payload type which is a uint16 -> 2 bytes
buf.Write(ep.Payload) // returned error is always nil
} else {
return nil, errors.New("Unable to marshal packet: payload is empty/too short")
}
if len(ep.AuthTag) > 0 {
buf.Write(ep.AuthTag) // returned error is always nil
}
return buf.Bytes(), nil
}
func (ep *EncryptedPacket) UnmarshalBinary(data []byte) (err error) {
buf := bytes.NewReader(data)
if err = binary.Read(buf, binary.BigEndian, &(ep.SequenceNumber)); err != nil {
return
}
if err = binary.Read(buf, binary.BigEndian, &(ep.SenderID)); err != nil {
return
}
if err = binary.Read(buf, binary.BigEndian, &(ep.Mux)); err != nil {
return
}
if (buf.Len() - len(ep.AuthTag)) < 2 { // 2 bytes payload type + length of AuthTag must be left on buffer
return errors.New("Unable to unmarshal packet: too short")
}
ep.Payload = make([]byte, buf.Len()-len(ep.AuthTag))
buf.Read(ep.Payload)
buf.Read(ep.AuthTag)
return
}
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