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Xray-core/transport/internet/headers/dns/dns.go

58 lines
1.4 KiB

package dns
import (
"context"
"encoding/binary"
"github.com/miekg/dns"
"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/dice"
)
type DNS struct {
header []byte
}
func (d DNS) Size() int32 {
return int32(len(d.header))
}
// Serialize implements PacketHeader.
func (d DNS) Serialize(b []byte) {
copy(b, d.header)
binary.BigEndian.PutUint16(b[0:], dice.RollUint16()) // random transaction ID
}
// NewDNS returns a new DNS instance based on given config.
func NewDNS(ctx context.Context, config interface{}) (interface{}, error) {
var header []byte
header = binary.BigEndian.AppendUint16(header, 0x0000) // Transaction ID
header = binary.BigEndian.AppendUint16(header, 0x0100) // Flags: Standard query
header = binary.BigEndian.AppendUint16(header, 0x0001) // Questions
header = binary.BigEndian.AppendUint16(header, 0x0000) // Answer RRs
header = binary.BigEndian.AppendUint16(header, 0x0000) // Authority RRs
header = binary.BigEndian.AppendUint16(header, 0x0000) // Additional RRs
buf := make([]byte, 0x100)
off1, err := dns.PackDomainName(dns.Fqdn(config.(*Config).Domain), buf, 0, nil, false)
if err != nil {
return nil, err
}
header = append(header, buf[:off1]...)
header = binary.BigEndian.AppendUint16(header, 0x0001) // Type: A
header = binary.BigEndian.AppendUint16(header, 0x0001) // Class: IN
return DNS{
header: header,
}, nil
}
func init() {
common.Must(common.RegisterConfig((*Config)(nil), NewDNS))
}