package inbound import ( "context" "encoding/binary" "io" "net" "github.com/sagernet/sing-box/adapter" "github.com/sagernet/sing-box/log" "github.com/sagernet/sing/common" "github.com/sagernet/sing/common/buf" N "github.com/sagernet/sing/common/network" "golang.org/x/net/dns/dnsmessage" ) func NewDNSConnection(ctx context.Context, router adapter.Router, logger log.ContextLogger, conn net.Conn, metadata adapter.InboundContext) error { ctx = adapter.WithContext(ctx, &metadata) _buffer := buf.StackNewSize(1024) defer common.KeepAlive(_buffer) buffer := common.Dup(_buffer) defer buffer.Release() for { var queryLength uint16 err := binary.Read(conn, binary.BigEndian, &queryLength) if err != nil { return err } if queryLength > 1024 { return io.ErrShortBuffer } buffer.FullReset() _, err = buffer.ReadFullFrom(conn, int(queryLength)) if err != nil { return err } var message dnsmessage.Message err = message.Unpack(buffer.Bytes()) if err != nil { return err } if len(message.Questions) > 0 { question := message.Questions[0] metadata.Domain = string(question.Name.Data[:question.Name.Length-1]) logger.DebugContext(ctx, "inbound dns query ", formatDNSQuestion(question), " from ", metadata.Source) } go func() error { response, err := router.Exchange(ctx, &message) if err != nil { return err } _responseBuffer := buf.StackNewSize(1024) defer common.KeepAlive(_responseBuffer) responseBuffer := common.Dup(_responseBuffer) defer responseBuffer.Release() responseBuffer.Resize(2, 0) n, err := response.AppendPack(responseBuffer.Index(0)) if err != nil { return err } responseBuffer.Truncate(len(n)) binary.BigEndian.PutUint16(responseBuffer.ExtendHeader(2), uint16(len(n))) _, err = conn.Write(responseBuffer.Bytes()) return err }() } } func NewDNSPacketConnection(ctx context.Context, router adapter.Router, logger log.ContextLogger, conn N.PacketConn, metadata adapter.InboundContext) error { ctx = adapter.WithContext(ctx, &metadata) _buffer := buf.StackNewSize(1024) defer common.KeepAlive(_buffer) buffer := common.Dup(_buffer) defer buffer.Release() for { buffer.FullReset() destination, err := conn.ReadPacket(buffer) if err != nil { return err } var message dnsmessage.Message err = message.Unpack(buffer.Bytes()) if err != nil { return err } if len(message.Questions) > 0 { question := message.Questions[0] metadata.Domain = string(question.Name.Data[:question.Name.Length-1]) logger.DebugContext(ctx, "inbound dns query ", formatDNSQuestion(question), " from ", metadata.Source) } go func() error { response, err := router.Exchange(ctx, &message) if err != nil { return err } _responseBuffer := buf.StackNewSize(1024) defer common.KeepAlive(_responseBuffer) responseBuffer := common.Dup(_responseBuffer) defer responseBuffer.Release() n, err := response.AppendPack(responseBuffer.Index(0)) if err != nil { return err } responseBuffer.Truncate(len(n)) err = conn.WritePacket(responseBuffer, destination) return err }() } } func formatDNSQuestion(question dnsmessage.Question) string { return string(question.Name.Data[:question.Name.Length-1]) + " " + question.Type.String()[4:] + " " + question.Class.String()[5:] }