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package proto
import "github.com/pion/stun"
// EvenPort represents EVEN-PORT attribute.
//
// This attribute allows the client to request that the port in the
// relayed transport address be even, and (optionally) that the server
// reserve the next-higher port number.
//
// RFC 5766 Section 14.6
type EvenPort struct {
// ReservePort means that the server is requested to reserve
// the next-higher port number (on the same IP address)
// for a subsequent allocation.
ReservePort bool
}
func (p EvenPort) String() string {
if p.ReservePort {
return "reserve: true"
}
return "reserve: false"
}
const (
evenPortSize = 1
firstBitSet = (1 << 8) - 1 // 0b100000000
)
// AddTo adds EVEN-PORT to message.
func (p EvenPort) AddTo(m *stun.Message) error {
v := make([]byte, evenPortSize)
if p.ReservePort {
// Set first bit to 1.
v[0] = firstBitSet
}
m.Add(stun.AttrEvenPort, v)
return nil
}
// GetFrom decodes EVEN-PORT from message.
func (p *EvenPort) GetFrom(m *stun.Message) error {
v, err := m.Get(stun.AttrEvenPort)
if err != nil {
return err
}
if err = stun.CheckSize(stun.AttrEvenPort, len(v), evenPortSize); err != nil {
return err
}
if v[0]&firstBitSet > 0 {
p.ReservePort = true
}
return nil
}
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