mirror of
https://github.com/octoleo/syncthing.git
synced 2024-12-24 03:45:32 +00:00
130 lines
3.4 KiB
Go
130 lines
3.4 KiB
Go
// Copyright 2013, Cong Ding. All rights reserved.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//
|
|
// Author: Cong Ding <dinggnu@gmail.com>
|
|
|
|
package stun
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"encoding/binary"
|
|
"errors"
|
|
)
|
|
|
|
type packet struct {
|
|
types uint16
|
|
length uint16
|
|
transID []byte // 4 bytes magic cookie + 12 bytes transaction id
|
|
attributes []attribute
|
|
}
|
|
|
|
func newPacket() (*packet, error) {
|
|
v := new(packet)
|
|
v.transID = make([]byte, 16)
|
|
binary.BigEndian.PutUint32(v.transID[:4], magicCookie)
|
|
_, err := rand.Read(v.transID[4:])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
v.attributes = make([]attribute, 0, 10)
|
|
v.length = 0
|
|
return v, nil
|
|
}
|
|
|
|
func newPacketFromBytes(packetBytes []byte) (*packet, error) {
|
|
if len(packetBytes) < 24 {
|
|
return nil, errors.New("Received data length too short.")
|
|
}
|
|
pkt := new(packet)
|
|
pkt.types = binary.BigEndian.Uint16(packetBytes[0:2])
|
|
pkt.length = binary.BigEndian.Uint16(packetBytes[2:4])
|
|
pkt.transID = packetBytes[4:20]
|
|
pkt.attributes = make([]attribute, 0, 10)
|
|
for pos := uint16(20); pos < uint16(len(packetBytes)); {
|
|
types := binary.BigEndian.Uint16(packetBytes[pos : pos+2])
|
|
length := binary.BigEndian.Uint16(packetBytes[pos+2 : pos+4])
|
|
if pos+4+length > uint16(len(packetBytes)) {
|
|
return nil, errors.New("Received data format mismatch.")
|
|
}
|
|
value := packetBytes[pos+4 : pos+4+length]
|
|
attribute := newAttribute(types, value)
|
|
pkt.addAttribute(*attribute)
|
|
pos += align(length) + 4
|
|
}
|
|
return pkt, nil
|
|
}
|
|
|
|
func (v *packet) addAttribute(a attribute) {
|
|
v.attributes = append(v.attributes, a)
|
|
v.length += align(a.length) + 4
|
|
}
|
|
|
|
func (v *packet) bytes() []byte {
|
|
packetBytes := make([]byte, 4)
|
|
binary.BigEndian.PutUint16(packetBytes[0:2], v.types)
|
|
binary.BigEndian.PutUint16(packetBytes[2:4], v.length)
|
|
packetBytes = append(packetBytes, v.transID...)
|
|
for _, a := range v.attributes {
|
|
buf := make([]byte, 2)
|
|
binary.BigEndian.PutUint16(buf, a.types)
|
|
packetBytes = append(packetBytes, buf...)
|
|
binary.BigEndian.PutUint16(buf, a.length)
|
|
packetBytes = append(packetBytes, buf...)
|
|
packetBytes = append(packetBytes, a.value...)
|
|
}
|
|
return packetBytes
|
|
}
|
|
|
|
func (v *packet) getSourceAddr() *Host {
|
|
return v.getRawAddr(attributeSourceAddress)
|
|
}
|
|
|
|
func (v *packet) getMappedAddr() *Host {
|
|
return v.getRawAddr(attributeMappedAddress)
|
|
}
|
|
|
|
func (v *packet) getChangedAddr() *Host {
|
|
return v.getRawAddr(attributeChangedAddress)
|
|
}
|
|
|
|
func (v *packet) getOtherAddr() *Host {
|
|
return v.getRawAddr(attributeOtherAddress)
|
|
}
|
|
|
|
func (v *packet) getRawAddr(attribute uint16) *Host {
|
|
for _, a := range v.attributes {
|
|
if a.types == attribute {
|
|
return a.rawAddr()
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (v *packet) getXorMappedAddr() *Host {
|
|
addr := v.getXorAddr(attributeXorMappedAddress)
|
|
if addr == nil {
|
|
addr = v.getXorAddr(attributeXorMappedAddressExp)
|
|
}
|
|
return addr
|
|
}
|
|
|
|
func (v *packet) getXorAddr(attribute uint16) *Host {
|
|
for _, a := range v.attributes {
|
|
if a.types == attribute {
|
|
return a.xorAddr(v.transID)
|
|
}
|
|
}
|
|
return nil
|
|
}
|