/
attribute.go
438 lines (376 loc) · 9.09 KB
/
attribute.go
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package stun
import (
"bytes"
"crypto/hmac"
"crypto/sha1"
"fmt"
"hash/crc32"
"net"
"strconv"
)
// Attribute represents a STUN attribute.
type Attr interface {
Type() uint16
Marshal(p []byte) []byte
Unmarshal(b []byte) error
}
// IP address family
const (
IPv4 = 0x01
IPv6 = 0x02
)
// IP address family
const (
ChangeIP uint64 = 0x04
ChangePort = 0x02
)
func newAttr(typ uint16) Attr {
switch typ {
case AttrMappedAddress, AttrXorPeerAddress, AttrXorRelayedAddress,
AttrXorMappedAddress, AttrAlternateServer, AttrResponseOrigin, AttrOtherAddress,
AttrResponseAddress, AttrSourceAddress, AttrChangedAddress, AttrReflectedFrom:
return &addr{typ: typ}
case AttrRequestedAddressFamily, AttrRequestedTransport:
return &number{typ: typ, size: 4, pad: 24}
case AttrChannelNumber, AttrResponsePort:
return &number{typ: typ, size: 4, pad: 16}
case AttrLifetime, AttrConnectionID, AttrCacheTimeout,
AttrBandwidth, AttrTimerVal,
AttrTransactionTransmitCounter,
AttrEcnCheck, AttrChangeRequest, AttrPriority:
return &number{typ: typ, size: 4}
case AttrIceControlled, AttrIceControlling:
return &number{typ: typ, size: 8}
case AttrUsername, AttrRealm, AttrNonce, AttrSoftware, AttrPassword, AttrThirdPartyAuthorization,
AttrData, AttrAccessToken, AttrReservationToken, AttrMobilityTicket, AttrPadding, AttrUnknownAttributes:
return &raw{typ: typ}
case AttrMessageIntegrity:
return &integrity{}
case AttrErrorCode:
return &Error{}
case AttrEvenPort:
return &number{typ: typ, size: 1}
case AttrDontFragment, AttrUseCandidate:
return flag(typ)
case AttrFingerprint:
return &fingerprint{}
}
return nil
}
func AttrName(typ uint16) string {
if r, ok := attrNames[typ]; ok {
return r
}
return "0x" + strconv.FormatUint(uint64(typ), 16)
}
func Int(typ uint16, v uint64) Attr {
switch typ {
case AttrRequestedAddressFamily, AttrRequestedTransport:
return &number{typ, 4, 24, v}
case AttrChannelNumber, AttrResponsePort:
return &number{typ, 4, 16, v}
case AttrIceControlled, AttrIceControlling:
return &number{typ, 8, 0, v}
case AttrEvenPort:
return &number{typ, 1, 0, v}
default:
return &number{typ, 4, 0, v}
}
}
type number struct {
typ uint16
size, pad uint8
v uint64
}
func (a *number) Type() uint16 { return a.typ }
func (a *number) Marshal(p []byte) []byte {
r, b := grow(p, int(a.size))
switch a.size {
case 1:
b[0] = byte(a.v)
case 4:
be.PutUint32(b, uint32(a.v<<a.pad))
case 8:
be.PutUint64(b, a.v<<a.pad)
}
return r
}
func (a *number) Unmarshal(b []byte) error {
if len(b) < int(a.size) {
return errFormat
}
switch a.size {
case 1:
a.v = uint64(b[0])
case 4:
a.v = uint64(be.Uint32(b) >> a.pad)
case 8:
a.v = be.Uint64(b) >> a.pad
}
return nil
}
func (a *number) String() string {
return "0x" + strconv.FormatUint(a.v, 16)
}
func Flag(v uint16) Attr {
return flag(v)
}
type flag uint16
func (attr flag) Type() uint16 { return uint16(attr) }
func (flag) Marshal(p []byte) []byte { return p }
func (flag) Unmarshal(b []byte) error { return nil }
// Error represents the ERROR-CODE attribute.
type Error struct {
Code int
Reason string
}
func NewError(code int) *Error {
return &Error{code, ErrorText(code)}
}
func (*Error) Type() uint16 { return AttrErrorCode }
func (e *Error) Marshal(p []byte) []byte {
r, b := grow(p, 4+len(e.Reason))
b[0] = 0
b[1] = 0
b[2] = byte(e.Code / 100)
b[3] = byte(e.Code % 100)
copy(b[4:], e.Reason)
return r
}
func (e *Error) Unmarshal(b []byte) error {
if len(b) < 4 {
return errFormat
}
e.Code = int(b[2])*100 + int(b[3])
e.Reason = getString(b[4:])
return nil
}
func (e *Error) Error() string { return e.String() }
func (e *Error) String() string { return fmt.Sprintf("%d %s", e.Code, e.Reason) }
// ErrorText returns a text for the STUN error code. It returns the empty string if the code is unknown.
func ErrorText(code int) string { return errorText[code] }
func getString(b []byte) string {
for i := len(b); i >= 0; i-- {
if b[i-1] > 0 {
return string(b[:i])
}
}
return ""
}
func Addr(typ uint16, v net.Addr) Attr {
ip, port := SockAddr(v)
return &addr{typ, ip, port}
}
func SockAddr(v net.Addr) (net.IP, int) {
switch a := v.(type) {
case *net.UDPAddr:
return a.IP, a.Port
case *net.TCPAddr:
return a.IP, a.Port
case *net.IPAddr:
return a.IP, 0
default:
return net.IPv4zero, 0
}
}
func sameAddr(a, b net.Addr) bool {
aip, aport := SockAddr(a)
bip, bport := SockAddr(b)
return aip.Equal(bip) && aport == bport
}
func NewAddr(network string, ip net.IP, port int) net.Addr {
switch network {
case "udp", "udp4", "udp6":
return &net.UDPAddr{IP: ip, Port: port}
case "tcp", "tcp4", "tcp6":
return &net.TCPAddr{IP: ip, Port: port}
}
return &net.IPAddr{IP: ip}
}
func IP(typ uint16, ip net.IP) Attr { return &addr{typ, ip, 0} }
type addr struct {
typ uint16
IP net.IP
Port int
}
func (addr *addr) Type() uint16 { return addr.typ }
func (addr *addr) Addr(network string) net.Addr {
return NewAddr(network, addr.IP, addr.Port)
}
func (addr *addr) Xored() bool {
switch addr.typ {
case AttrXorMappedAddress, AttrXorPeerAddress, AttrXorRelayedAddress:
return true
default:
return false
}
}
func (addr *addr) Marshal(p []byte) []byte {
return addr.MarshalAddr(p, nil)
}
func (addr *addr) MarshalAddr(p, tx []byte) []byte {
fam, ip := IPv4, addr.IP.To4()
if ip == nil {
fam, ip = IPv6, addr.IP
}
r, b := grow(p, 4+len(ip))
b[0] = 0
b[1] = byte(fam)
if addr.Xored() && tx != nil {
be.PutUint16(b[2:], uint16(addr.Port)^0x2112)
b = b[4:]
for i, it := range ip {
b[i] = it ^ tx[i]
}
} else {
be.PutUint16(b[2:], uint16(addr.Port))
copy(b[4:], ip)
}
return r
}
func (addr *addr) Unmarshal(b []byte) error {
return addr.UnmarshalAddr(b, nil)
}
func (addr *addr) UnmarshalAddr(b, tx []byte) error {
if len(b) < 4 {
return errFormat
}
n, port := net.IPv4len, int(be.Uint16(b[2:]))
if b[1] == IPv6 {
n = net.IPv6len
}
if b = b[4:]; len(b) < n {
return errFormat
}
addr.IP = make(net.IP, n)
if addr.Xored() && tx != nil {
for i, it := range b {
addr.IP[i] = it ^ tx[i]
}
addr.Port = port ^ 0x2112
} else {
copy(addr.IP, b)
addr.Port = port
}
return nil
}
func (addr *addr) Equal(a *addr) bool {
return addr == a || (addr != nil && a != nil && addr.IP.Equal(a.IP) && addr.Port == a.Port)
}
func (addr *addr) String() string {
if addr.Port == 0 {
return addr.IP.String()
}
return net.JoinHostPort(addr.IP.String(), strconv.Itoa(addr.Port))
}
func Bytes(typ uint16, v []byte) Attr { return &raw{typ, v} }
type raw struct {
typ uint16
data []byte
}
func (attr *raw) Type() uint16 { return attr.typ }
func (attr *raw) Marshal(p []byte) []byte { return append(p, attr.data...) }
func (attr *raw) Unmarshal(p []byte) error {
attr.data = p
return nil
}
func (attr *raw) String() string { return string(attr.data) }
func String(typ uint16, v string) Attr {
return &str{typ, v}
}
type str struct {
typ uint16
data string
}
func (attr *str) Type() uint16 { return attr.typ }
func (attr *str) Marshal(p []byte) []byte { return append(p, attr.data...) }
func (attr *str) Unmarshal(p []byte) error {
attr.data = string(p)
return nil
}
func (attr *str) String() string { return attr.data }
func MessageIntegrity(key []byte) Attr {
return &integrity{key: key}
}
type integrity struct {
key, sum, raw []byte
}
func (*integrity) Type() uint16 {
return AttrMessageIntegrity
}
func (attr *integrity) Marshal(p []byte) []byte {
return append(p, attr.sum...)
}
func (attr *integrity) Unmarshal(b []byte) error {
if len(b) < 20 {
return errFormat
}
attr.sum = b
return nil
}
func (attr *integrity) MarshalSum(p, raw []byte) []byte {
n := len(raw) - 4
be.PutUint16(raw[2:], uint16(n+4))
return attr.Sum(attr.key, raw[:n], p)
}
func (attr *integrity) UnmarshalSum(p, raw []byte) error {
attr.raw = raw
return attr.Unmarshal(p)
}
func (attr *integrity) Sum(key, data, p []byte) []byte {
h := hmac.New(sha1.New, key)
h.Write(data)
return h.Sum(p)
}
func (attr *integrity) Check(key []byte) bool {
r := attr.raw
if len(r) < 44 {
return r == nil
}
be.PutUint16(r[2:], uint16(len(r)-20))
h := attr.Sum(key, r[:len(r)-24], nil)
return bytes.Equal(h, attr.sum)
}
var Fingerprint Attr = &fingerprint{}
type fingerprint struct {
sum uint32
raw []byte
}
func (*fingerprint) Type() uint16 {
return AttrFingerprint
}
func (attr *fingerprint) Marshal(p []byte) []byte {
r, b := grow(p, 4)
be.PutUint32(b, attr.sum)
return r
}
func (attr *fingerprint) Unmarshal(b []byte) error {
if len(b) < 4 {
return errFormat
}
attr.sum = be.Uint32(b)
return nil
}
func (attr *fingerprint) MarshalSum(p, raw []byte) []byte {
n := len(raw) - 4
be.PutUint16(raw[2:], uint16(n-12))
v := attr.Sum(raw[:n])
r, b := grow(p, 4)
be.PutUint32(b, v)
return r
}
func (attr *fingerprint) UnmarshalSum(p, raw []byte) error {
attr.raw = raw
return attr.Unmarshal(p)
}
func (attr *fingerprint) Sum(p []byte) uint32 {
return crc32.ChecksumIEEE(p) ^ 0x5354554e
}
func (attr *fingerprint) Check() bool {
r := attr.raw
if len(r) < 28 {
return r == nil
}
be.PutUint16(r[2:], uint16(len(r)-20))
return attr.Sum(r[:len(r)-8]) == attr.sum
}