refactor: DNS

dns/transport/tls.go

@@ -0,0 +1,115 @@
+package transport
+
+import (
+	"context"
+	"sync"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/tls"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/dns"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing/common"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/x/list"
+
+	mDNS "github.com/miekg/dns"
+)
+
+var _ adapter.DNSTransport = (*TLSTransport)(nil)
+
+func RegisterTLS(registry *dns.TransportRegistry) {
+	dns.RegisterTransport[option.RemoteTLSDNSServerOptions](registry, C.DNSTypeTLS, NewTLS)
+}
+
+type TLSTransport struct {
+	dns.TransportAdapter
+	logger      logger.ContextLogger
+	dialer      N.Dialer
+	serverAddr  M.Socksaddr
+	tlsConfig   tls.Config
+	access      sync.Mutex
+	connections list.List[*tlsDNSConn]
+}
+
+type tlsDNSConn struct {
+	tls.Conn
+	queryId uint16
+}
+
+func NewTLS(ctx context.Context, logger log.ContextLogger, tag string, options option.RemoteTLSDNSServerOptions) (adapter.DNSTransport, error) {
+	transportDialer, err := dns.NewRemoteDialer(ctx, options.RemoteDNSServerOptions)
+	if err != nil {
+		return nil, err
+	}
+	tlsOptions := common.PtrValueOrDefault(options.TLS)
+	tlsOptions.Enabled = true
+	tlsConfig, err := tls.NewClient(ctx, options.Server, tlsOptions)
+	if err != nil {
+		return nil, err
+	}
+	serverAddr := options.ServerOptions.Build()
+	if serverAddr.Port == 0 {
+		serverAddr.Port = 853
+	}
+	return &TLSTransport{
+		TransportAdapter: dns.NewTransportAdapterWithRemoteOptions(C.DNSTypeTLS, tag, options.RemoteDNSServerOptions),
+		logger:           logger,
+		dialer:           transportDialer,
+		serverAddr:       serverAddr,
+		tlsConfig:        tlsConfig,
+	}, nil
+}
+
+func (t *TLSTransport) Reset() {
+	t.access.Lock()
+	defer t.access.Unlock()
+	for connection := t.connections.Front(); connection != nil; connection = connection.Next() {
+		connection.Value.Close()
+	}
+	t.connections.Init()
+}
+
+func (t *TLSTransport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
+	t.access.Lock()
+	conn := t.connections.PopFront()
+	t.access.Unlock()
+	if conn != nil {
+		response, err := t.exchange(message, conn)
+		if err == nil {
+			return response, nil
+		}
+	}
+	tcpConn, err := t.dialer.DialContext(ctx, N.NetworkTCP, t.serverAddr)
+	if err != nil {
+		return nil, err
+	}
+	tlsConn, err := tls.ClientHandshake(ctx, tcpConn, t.tlsConfig)
+	if err != nil {
+		tcpConn.Close()
+		return nil, err
+	}
+	return t.exchange(message, &tlsDNSConn{Conn: tlsConn})
+}
+
+func (t *TLSTransport) exchange(message *mDNS.Msg, conn *tlsDNSConn) (*mDNS.Msg, error) {
+	conn.queryId++
+	err := WriteMessage(conn, conn.queryId, message)
+	if err != nil {
+		conn.Close()
+		return nil, E.Cause(err, "write request")
+	}
+	response, err := ReadMessage(conn)
+	if err != nil {
+		conn.Close()
+		return nil, E.Cause(err, "read response")
+	}
+	t.access.Lock()
+	t.connections.PushBack(conn)
+	t.access.Unlock()
+	return response, nil
+}