core

type ClientConfig struct {
	Cipher ShadowCipher
}

type EIHHash [16]byte // Extensible Identity Headers hash

type KeySizeError int

type MetaCipher struct {
	Name      string
	KeySize   int
	SaltSize  int
	NonceSize int
	TagSize   int
}

type ServerConfig struct {
	Cipher ShadowCipher
	Users  []UserConfig
}

type SessionHash string

type ShadowCipher interface {
	TCPConnCipher
	UDPConnCipher
	SaltSize() int
	KeySize() int
	NonceSize() int
	TagSize() int
	Encrypter(key, salt []byte) (cipher.AEAD, error)
	Decrypter(key, salt []byte) (cipher.AEAD, error)
	// Start from SIP023, the cipher can hold multiple keys for clients
	// For server, user configuration should bind to implementation, ShadowCipher just save the main key
	Keys() [][]byte
	Key() []byte      // return last key
	FirstKey() []byte // return first key
}

type TCPClient struct {
	// contains filtered or unexported fields
}

type TCPConfig struct {
	Users []UserConfig
}

type TCPConn interface {
	net.Conn

	InitServer() error                                                  // for server side
	InitClient(target socks.Addr, padding, initialPayload []byte) error // for client side
	Target() socks.Addr

	ClientFirstWrite() error // send headers, for fast opening
}

type TCPConnCipher interface {
	TCPConn(net.Conn, TCPConfig, int) TCPConn
}

type TCPServer struct {
	// contains filtered or unexported fields
}

type UDPClient struct {
	// contains filtered or unexported fields
}

type UDPConfig struct {
	Users []UserConfig
}

type UDPConnCipher interface {
	NewUDPSessionManager(timeout time.Duration, config UDPConfig, windowSize, role int) UDPSessionManager
}

type UDPServer struct {
	// contains filtered or unexported fields
}

type UDPSession interface {
	// Target returns the destination address for this session
	Target() socks.Addr

	ClientAddr() netip.AddrPort

	// LastUsed returns when this session was last used
	LastUsed() time.Time

	// update LastUsed
	Touch()

	SessionID() uint64

	// unique id for identifying session
	Hash() SessionHash
}

type UDPSessionManager interface {
	// This function should complete following things:
	// 1. Decrypt data and send to target
	// 2. Validate session
	ServerHandleInbound(encrypted []byte, clientAddr netip.AddrPort) (UDPSession, []byte, error)

	// This function should return data from target, so it's maybe a block function.
	ServerHandleOutbound(plaintext []byte, session UDPSession) ([]byte, error)

	ClientHandleInbound(payload []byte, target socks.Addr, clientAddr netip.AddrPort) (UDPSession, []byte, error)

	// This function should return data from target, so it's maybe a block function.
	ClientHandleOutbound(encrypted []byte, session UDPSession) ([]byte, error)
}

type UserConfig struct {
	Name     string
	Password string
}