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package stun
import (
"errors"
"fmt"
)
// Attributes is list of message attributes.
type Attributes []RawAttribute
// Get returns first attribute from list by the type.
// If attribute is present the RawAttribute is returned and the
// boolean is true. Otherwise the returned RawAttribute will be
// empty and boolean will be false.
func (a Attributes) Get(t AttrType) (RawAttribute, bool) {
for _, candidate := range a {
if candidate.Type == t {
return candidate, true
}
}
return RawAttribute{}, false
}
// AttrType is attribute type.
type AttrType uint16
// Required returns true if type is from comprehension-required range (0x0000-0x7FFF).
func (t AttrType) Required() bool {
return t <= 0x7FFF
}
// Optional returns true if type is from comprehension-optional range (0x8000-0xFFFF).
func (t AttrType) Optional() bool {
return t >= 0x8000
}
// Attributes from comprehension-required range (0x0000-0x7FFF).
const (
AttrMappedAddress AttrType = 0x0001 // MAPPED-ADDRESS
AttrUsername AttrType = 0x0006 // USERNAME
AttrMessageIntegrity AttrType = 0x0008 // MESSAGE-INTEGRITY
AttrErrorCode AttrType = 0x0009 // ERROR-CODE
AttrUnknownAttributes AttrType = 0x000A // UNKNOWN-ATTRIBUTES
AttrRealm AttrType = 0x0014 // REALM
AttrNonce AttrType = 0x0015 // NONCE
AttrXORMappedAddress AttrType = 0x0020 // XOR-MAPPED-ADDRESS
)
// Attributes from comprehension-optional range (0x8000-0xFFFF).
const (
AttrSoftware AttrType = 0x8022 // SOFTWARE
AttrAlternateServer AttrType = 0x8023 // ALTERNATE-SERVER
AttrFingerprint AttrType = 0x8028 // FINGERPRINT
)
// Attributes from RFC 5245 ICE.
const (
AttrPriority AttrType = 0x0024 // PRIORITY
AttrUseCandidate AttrType = 0x0025 // USE-CANDIDATE
AttrICEControlled AttrType = 0x8029 // ICE-CONTROLLED
AttrICEControlling AttrType = 0x802A // ICE-CONTROLLING
)
// Attributes from RFC 5766 TURN.
const (
AttrChannelNumber AttrType = 0x000C // CHANNEL-NUMBER
AttrLifetime AttrType = 0x000D // LIFETIME
AttrXORPeerAddress AttrType = 0x0012 // XOR-PEER-ADDRESS
AttrData AttrType = 0x0013 // DATA
AttrXORRelayedAddress AttrType = 0x0016 // XOR-RELAYED-ADDRESS
AttrEvenPort AttrType = 0x0018 // EVEN-PORT
AttrRequestedTransport AttrType = 0x0019 // REQUESTED-TRANSPORT
AttrDontFragment AttrType = 0x001A // DONT-FRAGMENT
AttrReservationToken AttrType = 0x0022 // RESERVATION-TOKEN
)
// Attributes from RFC 5780 NAT Behavior Discovery
const (
AttrOtherAddress AttrType = 0x802C // OTHER-ADDRESS
AttrChangeRequest AttrType = 0x0003 // CHANGE-REQUEST
)
// Attributes from RFC 6062 TURN Extensions for TCP Allocations.
const (
AttrConnectionID AttrType = 0x002a // CONNECTION-ID
)
// Attributes from RFC 6156 TURN IPv6.
const (
AttrRequestedAddressFamily AttrType = 0x0017 // REQUESTED-ADDRESS-FAMILY
)
// Attributes from An Origin Attribute for the STUN Protocol.
const (
AttrOrigin AttrType = 0x802F
)
// Value returns uint16 representation of attribute type.
func (t AttrType) Value() uint16 {
return uint16(t)
}
var attrNames = map[AttrType]string{
AttrMappedAddress: "MAPPED-ADDRESS",
AttrUsername: "USERNAME",
AttrErrorCode: "ERROR-CODE",
AttrMessageIntegrity: "MESSAGE-INTEGRITY",
AttrUnknownAttributes: "UNKNOWN-ATTRIBUTES",
AttrRealm: "REALM",
AttrNonce: "NONCE",
AttrXORMappedAddress: "XOR-MAPPED-ADDRESS",
AttrSoftware: "SOFTWARE",
AttrAlternateServer: "ALTERNATE-SERVER",
AttrOtherAddress: "OTHER-ADDRESS",
AttrChangeRequest: "CHANGE-REQUEST",
AttrFingerprint: "FINGERPRINT",
AttrPriority: "PRIORITY",
AttrUseCandidate: "USE-CANDIDATE",
AttrICEControlled: "ICE-CONTROLLED",
AttrICEControlling: "ICE-CONTROLLING",
AttrChannelNumber: "CHANNEL-NUMBER",
AttrLifetime: "LIFETIME",
AttrXORPeerAddress: "XOR-PEER-ADDRESS",
AttrData: "DATA",
AttrXORRelayedAddress: "XOR-RELAYED-ADDRESS",
AttrEvenPort: "EVEN-PORT",
AttrRequestedTransport: "REQUESTED-TRANSPORT",
AttrDontFragment: "DONT-FRAGMENT",
AttrReservationToken: "RESERVATION-TOKEN",
AttrConnectionID: "CONNECTION-ID",
AttrRequestedAddressFamily: "REQUESTED-ADDRESS-FAMILY",
AttrOrigin: "ORIGIN",
}
func (t AttrType) String() string {
s, ok := attrNames[t]
if !ok {
// Just return hex representation of unknown attribute type.
return fmt.Sprintf("0x%x", uint16(t))
}
return s
}
// RawAttribute is a Type-Length-Value (TLV) object that
// can be added to a STUN message. Attributes are divided into two
// types: comprehension-required and comprehension-optional. STUN
// agents can safely ignore comprehension-optional attributes they
// don't understand, but cannot successfully process a message if it
// contains comprehension-required attributes that are not
// understood.
type RawAttribute struct {
Type AttrType
Length uint16 // ignored while encoding
Value []byte
}
// AddTo implements Setter, adding attribute as a.Type with a.Value and ignoring
// the Length field.
func (a RawAttribute) AddTo(m *Message) error {
m.Add(a.Type, a.Value)
return nil
}
// Equal returns true if a == b.
func (a RawAttribute) Equal(b RawAttribute) bool {
if a.Type != b.Type {
return false
}
if a.Length != b.Length {
return false
}
if len(b.Value) != len(a.Value) {
return false
}
for i, v := range a.Value {
if b.Value[i] != v {
return false
}
}
return true
}
func (a RawAttribute) String() string {
return fmt.Sprintf("%s: 0x%x", a.Type, a.Value)
}
// ErrAttributeNotFound means that attribute with provided attribute
// type does not exist in message.
var ErrAttributeNotFound = errors.New("attribute not found")
// Get returns byte slice that represents attribute value,
// if there is no attribute with such type,
// ErrAttributeNotFound is returned.
func (m *Message) Get(t AttrType) ([]byte, error) {
v, ok := m.Attributes.Get(t)
if !ok {
return nil, ErrAttributeNotFound
}
return v.Value, nil
}
// STUN aligns attributes on 32-bit boundaries, attributes whose content
// is not a multiple of 4 bytes are padded with 1, 2, or 3 bytes of
// padding so that its value contains a multiple of 4 bytes. The
// padding bits are ignored, and may be any value.
//
// https://tools.ietf.org/html/rfc5389#section-15
const padding = 4
func nearestPaddedValueLength(l int) int {
n := padding * (l / padding)
if n < l {
n += padding
}
return n
}
// This method converts uint16 vlue to AttrType. If it finds an old attribute
// type value, it also translates it to the new value to enable backward
// compatibility. (See: https://github.com/pion/stun/issues/21)
func compatAttrType(val uint16) AttrType {
if val == 0x8020 {
return AttrXORMappedAddress // new: 0x0020
}
return AttrType(val)
}
