Add new admin panel, failover, dns fallback, providers, limiters. Update XHTTP

protocol/failover/protocol.go

@@ -0,0 +1,97 @@
+package failover
+
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/gofrs/uuid/v5"
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+)
+
+const (
+	Version    = 0
+	BufferSize = 10
+)
+
+const (
+	CommandTCP       = 1
+	CommandReconnect = 2
+)
+
+const (
+	StatusOK uint8 = iota + 1
+	StatusSessionNotFound
+)
+
+var (
+	SessionClosed   = E.New("session closed")
+	SessionNotFound = E.New("session not found")
+	SessionExpired  = E.New("session expired")
+	SessionBroken   = E.New("session broken")
+)
+
+var Destination = M.Socksaddr{
+	Fqdn: "sp.failover.sing-box.arpa",
+	Port: 444,
+}
+
+var AddressSerializer = M.NewSerializer(
+	M.AddressFamilyByte(0x01, M.AddressFamilyIPv4),
+	M.AddressFamilyByte(0x03, M.AddressFamilyIPv6),
+	M.AddressFamilyByte(0x02, M.AddressFamilyFqdn),
+	M.PortThenAddress(),
+)
+
+type Request struct {
+	UUID        uuid.UUID
+	Command     byte
+	Destination M.Socksaddr
+}
+
+func ReadRequest(reader io.Reader) (*Request, error) {
+	var request Request
+	var version uint8
+	err := binary.Read(reader, binary.BigEndian, &version)
+	if err != nil {
+		return nil, err
+	}
+	if version != Version {
+		return nil, E.New("unknown version: ", version)
+	}
+	_, err = io.ReadFull(reader, request.UUID[:])
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Read(reader, binary.BigEndian, &request.Command)
+	if err != nil {
+		return nil, err
+	}
+	request.Destination, err = AddressSerializer.ReadAddrPort(reader)
+	if err != nil {
+		return nil, err
+	}
+	return &request, nil
+}
+
+func WriteRequest(writer io.Writer, request *Request) error {
+	var requestLen int
+	requestLen += 1  // version
+	requestLen += 1  // command
+	requestLen += 16 // UUID
+	requestLen += AddressSerializer.AddrPortLen(request.Destination)
+	buffer := buf.NewSize(requestLen)
+	defer buffer.Release()
+	common.Must(
+		buffer.WriteByte(Version),
+		common.Error(buffer.Write(request.UUID[:])),
+		buffer.WriteByte(request.Command),
+	)
+	err := AddressSerializer.WriteAddrPort(buffer, request.Destination)
+	if err != nil {
+		return err
+	}
+	return common.Error(writer.Write(buffer.Bytes()))
+}