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// Package stun contains ICE specific STUN code
package stun
import (
"errors"
"fmt"
"net"
"time"
"github.com/pion/stun"
)
var (
errGetXorMappedAddrResponse = errors.New("failed to get XOR-MAPPED-ADDRESS response")
errMismatchUsername = errors.New("username mismatch")
)
// GetXORMappedAddr initiates a stun requests to serverAddr using conn, reads the response and returns
// the XORMappedAddress returned by the STUN server.
func GetXORMappedAddr(conn net.PacketConn, serverAddr net.Addr, timeout time.Duration) (*stun.XORMappedAddress, error) {
if timeout > 0 {
if err := conn.SetReadDeadline(time.Now().Add(timeout)); err != nil {
return nil, err
}
// Reset timeout after completion
defer conn.SetReadDeadline(time.Time{}) //nolint:errcheck
}
req, err := stun.Build(stun.BindingRequest, stun.TransactionID)
if err != nil {
return nil, err
}
if _, err = conn.WriteTo(req.Raw, serverAddr); err != nil {
return nil, err
}
const maxMessageSize = 1280
buf := make([]byte, maxMessageSize)
n, _, err := conn.ReadFrom(buf)
if err != nil {
return nil, err
}
res := &stun.Message{Raw: buf[:n]}
if err = res.Decode(); err != nil {
return nil, err
}
var addr stun.XORMappedAddress
if err = addr.GetFrom(res); err != nil {
return nil, fmt.Errorf("%w: %v", errGetXorMappedAddrResponse, err)
}
return &addr, nil
}
// AssertUsername checks that the given STUN message m has a USERNAME attribute with a given value
func AssertUsername(m *stun.Message, expectedUsername string) error {
var username stun.Username
if err := username.GetFrom(m); err != nil {
return err
} else if string(username) != expectedUsername {
return fmt.Errorf("%w expected(%x) actual(%x)", errMismatchUsername, expectedUsername, string(username))
}
return nil
}
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