Xray-core/common/mux/frame.go

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package mux
import (
"encoding/binary"
"io"
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"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/bitmask"
"github.com/xtls/xray-core/common/buf"
"github.com/xtls/xray-core/common/net"
"github.com/xtls/xray-core/common/protocol"
"github.com/xtls/xray-core/common/serial"
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)
type SessionStatus byte
const (
SessionStatusNew SessionStatus = 0x01
SessionStatusKeep SessionStatus = 0x02
SessionStatusEnd SessionStatus = 0x03
SessionStatusKeepAlive SessionStatus = 0x04
)
const (
OptionData bitmask.Byte = 0x01
OptionError bitmask.Byte = 0x02
)
type TargetNetwork byte
const (
TargetNetworkTCP TargetNetwork = 0x01
TargetNetworkUDP TargetNetwork = 0x02
)
var addrParser = protocol.NewAddressParser(
protocol.AddressFamilyByte(byte(protocol.AddressTypeIPv4), net.AddressFamilyIPv4),
protocol.AddressFamilyByte(byte(protocol.AddressTypeDomain), net.AddressFamilyDomain),
protocol.AddressFamilyByte(byte(protocol.AddressTypeIPv6), net.AddressFamilyIPv6),
protocol.PortThenAddress(),
)
/*
Frame format
2 bytes - length
2 bytes - session id
1 bytes - status
1 bytes - option
1 byte - network
2 bytes - port
n bytes - address
*/
type FrameMetadata struct {
Target net.Destination
SessionID uint16
Option bitmask.Byte
SessionStatus SessionStatus
}
func (f FrameMetadata) WriteTo(b *buf.Buffer) error {
lenBytes := b.Extend(2)
len0 := b.Len()
sessionBytes := b.Extend(2)
binary.BigEndian.PutUint16(sessionBytes, f.SessionID)
common.Must(b.WriteByte(byte(f.SessionStatus)))
common.Must(b.WriteByte(byte(f.Option)))
if f.SessionStatus == SessionStatusNew {
switch f.Target.Network {
case net.Network_TCP:
common.Must(b.WriteByte(byte(TargetNetworkTCP)))
case net.Network_UDP:
common.Must(b.WriteByte(byte(TargetNetworkUDP)))
}
if err := addrParser.WriteAddressPort(b, f.Target.Address, f.Target.Port); err != nil {
return err
}
} else if b.UDP != nil {
b.WriteByte(byte(TargetNetworkUDP))
addrParser.WriteAddressPort(b, b.UDP.Address, b.UDP.Port)
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}
len1 := b.Len()
binary.BigEndian.PutUint16(lenBytes, uint16(len1-len0))
return nil
}
// Unmarshal reads FrameMetadata from the given reader.
func (f *FrameMetadata) Unmarshal(reader io.Reader) error {
metaLen, err := serial.ReadUint16(reader)
if err != nil {
return err
}
if metaLen > 512 {
return newError("invalid metalen ", metaLen).AtError()
}
b := buf.New()
defer b.Release()
if _, err := b.ReadFullFrom(reader, int32(metaLen)); err != nil {
return err
}
return f.UnmarshalFromBuffer(b)
}
// UnmarshalFromBuffer reads a FrameMetadata from the given buffer.
// Visible for testing only.
func (f *FrameMetadata) UnmarshalFromBuffer(b *buf.Buffer) error {
if b.Len() < 4 {
return newError("insufficient buffer: ", b.Len())
}
f.SessionID = binary.BigEndian.Uint16(b.BytesTo(2))
f.SessionStatus = SessionStatus(b.Byte(2))
f.Option = bitmask.Byte(b.Byte(3))
f.Target.Network = net.Network_Unknown
if f.SessionStatus == SessionStatusNew || (f.SessionStatus == SessionStatusKeep && b.Len() != 4) {
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if b.Len() < 8 {
return newError("insufficient buffer: ", b.Len())
}
network := TargetNetwork(b.Byte(4))
b.Advance(5)
addr, port, err := addrParser.ReadAddressPort(nil, b)
if err != nil {
return newError("failed to parse address and port").Base(err)
}
switch network {
case TargetNetworkTCP:
f.Target = net.TCPDestination(addr, port)
case TargetNetworkUDP:
f.Target = net.UDPDestination(addr, port)
default:
return newError("unknown network type: ", network)
}
}
return nil
}