mirror of
https://github.com/octoleo/syncthing.git
synced 2024-12-23 11:28:59 +00:00
107 lines
3.5 KiB
Go
107 lines
3.5 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 (
|
|
"encoding/binary"
|
|
"hash/crc32"
|
|
"net"
|
|
)
|
|
|
|
type attribute struct {
|
|
types uint16
|
|
length uint16
|
|
value []byte
|
|
}
|
|
|
|
func newAttribute(types uint16, value []byte) *attribute {
|
|
att := new(attribute)
|
|
att.types = types
|
|
att.value = padding(value)
|
|
att.length = uint16(len(att.value))
|
|
return att
|
|
}
|
|
|
|
func newFingerprintAttribute(packet *packet) *attribute {
|
|
crc := crc32.ChecksumIEEE(packet.bytes()) ^ fingerprint
|
|
buf := make([]byte, 4)
|
|
binary.BigEndian.PutUint32(buf, crc)
|
|
return newAttribute(attributeFingerprint, buf)
|
|
}
|
|
|
|
func newSoftwareAttribute(name string) *attribute {
|
|
return newAttribute(attributeSoftware, []byte(name))
|
|
}
|
|
|
|
func newChangeReqAttribute(changeIP bool, changePort bool) *attribute {
|
|
value := make([]byte, 4)
|
|
if changeIP {
|
|
value[3] |= 0x04
|
|
}
|
|
if changePort {
|
|
value[3] |= 0x02
|
|
}
|
|
return newAttribute(attributeChangeRequest, value)
|
|
}
|
|
|
|
// 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
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
// |x x x x x x x x| Family | X-Port |
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
// | X-Address (Variable)
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
//
|
|
// Figure 6: Format of XOR-MAPPED-ADDRESS Attribute
|
|
func (v *attribute) xorAddr(transID []byte) *Host {
|
|
xorIP := make([]byte, 16)
|
|
for i := 0; i < len(v.value)-4; i++ {
|
|
xorIP[i] = v.value[i+4] ^ transID[i]
|
|
}
|
|
family := uint16(v.value[1])
|
|
port := binary.BigEndian.Uint16(v.value[2:4])
|
|
// Truncate if IPv4, otherwise net.IP sometimes renders it as an IPv6 address.
|
|
if family == attributeFamilyIPv4 {
|
|
xorIP = xorIP[:4]
|
|
}
|
|
x := binary.BigEndian.Uint16(transID[:2])
|
|
return &Host{family, net.IP(xorIP).String(), port ^ x}
|
|
}
|
|
|
|
// 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
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
// |0 0 0 0 0 0 0 0| Family | Port |
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
// | |
|
|
// | Address (32 bits or 128 bits) |
|
|
// | |
|
|
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
//
|
|
// Figure 5: Format of MAPPED-ADDRESS Attribute
|
|
func (v *attribute) rawAddr() *Host {
|
|
host := new(Host)
|
|
host.family = uint16(v.value[1])
|
|
host.port = binary.BigEndian.Uint16(v.value[2:4])
|
|
// Truncate if IPv4, otherwise net.IP sometimes renders it as an IPv6 address.
|
|
if host.family == attributeFamilyIPv4 {
|
|
v.value = v.value[:8]
|
|
}
|
|
host.ip = net.IP(v.value[4:]).String()
|
|
return host
|
|
}
|