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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package stun
import (
"fmt"
"io"
"net"
"strconv"
)
// MappedAddress represents MAPPED-ADDRESS attribute.
//
// This attribute is used only by servers for achieving backwards
// compatibility with RFC 3489 clients.
//
// RFC 5389 Section 15.1
type MappedAddress struct {
IP net.IP
Port int
}
// AlternateServer represents ALTERNATE-SERVER attribute.
//
// RFC 5389 Section 15.11
type AlternateServer struct {
IP net.IP
Port int
}
// ResponseOrigin represents RESPONSE-ORIGIN attribute.
//
// RFC 5780 Section 7.3
type ResponseOrigin struct {
IP net.IP
Port int
}
// OtherAddress represents OTHER-ADDRESS attribute.
//
// RFC 5780 Section 7.4
type OtherAddress struct {
IP net.IP
Port int
}
// AddTo adds ALTERNATE-SERVER attribute to message.
func (s *AlternateServer) AddTo(m *Message) error {
a := (*MappedAddress)(s)
return a.AddToAs(m, AttrAlternateServer)
}
// GetFrom decodes ALTERNATE-SERVER from message.
func (s *AlternateServer) GetFrom(m *Message) error {
a := (*MappedAddress)(s)
return a.GetFromAs(m, AttrAlternateServer)
}
func (a MappedAddress) String() string {
return net.JoinHostPort(a.IP.String(), strconv.Itoa(a.Port))
}
// GetFromAs decodes MAPPED-ADDRESS value in message m as an attribute of type t.
func (a *MappedAddress) GetFromAs(m *Message, t AttrType) error {
v, err := m.Get(t)
if err != nil {
return err
}
if len(v) <= 4 {
return io.ErrUnexpectedEOF
}
family := bin.Uint16(v[0:2])
if family != familyIPv6 && family != familyIPv4 {
return newDecodeErr("xor-mapped address", "family",
fmt.Sprintf("bad value %d", family),
)
}
ipLen := net.IPv4len
if family == familyIPv6 {
ipLen = net.IPv6len
}
// Ensuring len(a.IP) == ipLen and reusing a.IP.
if len(a.IP) < ipLen {
a.IP = a.IP[:cap(a.IP)]
for len(a.IP) < ipLen {
a.IP = append(a.IP, 0)
}
}
a.IP = a.IP[:ipLen]
for i := range a.IP {
a.IP[i] = 0
}
a.Port = int(bin.Uint16(v[2:4]))
copy(a.IP, v[4:])
return nil
}
// AddToAs adds MAPPED-ADDRESS value to m as t attribute.
func (a *MappedAddress) AddToAs(m *Message, t AttrType) error {
var (
family = familyIPv4
ip = a.IP
)
if len(a.IP) == net.IPv6len {
if isIPv4(ip) {
ip = ip[12:16] // like in ip.To4()
} else {
family = familyIPv6
}
} else if len(ip) != net.IPv4len {
return ErrBadIPLength
}
value := make([]byte, 128)
value[0] = 0 // first 8 bits are zeroes
bin.PutUint16(value[0:2], family)
bin.PutUint16(value[2:4], uint16(a.Port))
copy(value[4:], ip)
m.Add(t, value[:4+len(ip)])
return nil
}
// AddTo adds MAPPED-ADDRESS to message.
func (a *MappedAddress) AddTo(m *Message) error {
return a.AddToAs(m, AttrMappedAddress)
}
// GetFrom decodes MAPPED-ADDRESS from message.
func (a *MappedAddress) GetFrom(m *Message) error {
return a.GetFromAs(m, AttrMappedAddress)
}
// AddTo adds OTHER-ADDRESS attribute to message.
func (o *OtherAddress) AddTo(m *Message) error {
a := (*MappedAddress)(o)
return a.AddToAs(m, AttrOtherAddress)
}
// GetFrom decodes OTHER-ADDRESS from message.
func (o *OtherAddress) GetFrom(m *Message) error {
a := (*MappedAddress)(o)
return a.GetFromAs(m, AttrOtherAddress)
}
func (o OtherAddress) String() string {
return net.JoinHostPort(o.IP.String(), strconv.Itoa(o.Port))
}
// AddTo adds RESPONSE-ORIGIN attribute to message.
func (o *ResponseOrigin) AddTo(m *Message) error {
a := (*MappedAddress)(o)
return a.AddToAs(m, AttrResponseOrigin)
}
// GetFrom decodes RESPONSE-ORIGIN from message.
func (o *ResponseOrigin) GetFrom(m *Message) error {
a := (*MappedAddress)(o)
return a.GetFromAs(m, AttrResponseOrigin)
}
func (o ResponseOrigin) String() string {
return net.JoinHostPort(o.IP.String(), strconv.Itoa(o.Port))
}
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