nex-go/client.go

package nex

import (
	"crypto/rc4"
	"fmt"
	"net"
	"time"
)

// Client represents a connected or non-connected PRUDP client
type Client struct {
	address                   *net.UDPAddr
	server                    *Server
	cipher                    *rc4.Cipher
	decipher                  *rc4.Cipher
	prudpProtocolMinorVersion int
	supportedFunctions        int
	signatureKey              []byte
	signatureBase             int
	serverConnectionSignature []byte
	clientConnectionSignature []byte
	sessionKey                []byte
	sequenceIDIn              *Counter
	sequenceIDOut             *Counter
	pid                       uint32
	stationURLs               []string
	connectionID              uint32
	pingCheckTimer            *time.Timer
	pingKickTimer             *time.Timer
	connected                 bool
}

// Reset resets the Client to default values
func (client *Client) Reset() error {
	client.sequenceIDIn = NewCounter(0)
	client.sequenceIDOut = NewCounter(0)

	client.UpdateAccessKey(client.Server().AccessKey())
	err := client.UpdateRC4Key([]byte("CD&ML"))
	if err != nil {
		return fmt.Errorf("Failed to update client RC4 key. %s", err.Error())
	}

	if client.Server().PRUDPVersion() == 0 {
		client.SetServerConnectionSignature(make([]byte, 4))
		client.SetClientConnectionSignature(make([]byte, 4))
	} else {
		client.SetServerConnectionSignature([]byte{})
		client.SetClientConnectionSignature([]byte{})
	}

	client.SetConnected(false)

	return nil
}

// Address returns the clients UDP address
func (client *Client) Address() *net.UDPAddr {
	return client.address
}

// Server returns the server the client is currently connected to
func (client *Client) Server() *Server {
	return client.server
}

// PRUDPProtocolMinorVersion returns the client PRUDP minor version
func (client *Client) PRUDPProtocolMinorVersion() int {
	return client.prudpProtocolMinorVersion
}

// SetPRUDPProtocolMinorVersion sets the client PRUDP minor
func (client *Client) SetPRUDPProtocolMinorVersion(prudpProtocolMinorVersion int) {
	client.prudpProtocolMinorVersion = prudpProtocolMinorVersion
}

// SupportedFunctions returns the supported PRUDP functions by the client
func (client *Client) SupportedFunctions() int {
	return client.supportedFunctions
}

// SetSupportedFunctions sets the supported PRUDP functions by the client
func (client *Client) SetSupportedFunctions(supportedFunctions int) {
	client.supportedFunctions = supportedFunctions
}

// UpdateRC4Key sets the client RC4 stream key
func (client *Client) UpdateRC4Key(key []byte) error {
	cipher, err := rc4.NewCipher(key)
	if err != nil {
		return fmt.Errorf("Failed to create RC4 cipher. %s", err.Error())
	}

	client.cipher = cipher

	decipher, err := rc4.NewCipher(key)
	if err != nil {
		return fmt.Errorf("Failed to create RC4 decipher. %s", err.Error())
	}

	client.decipher = decipher

	return nil
}

// Cipher returns the RC4 cipher stream for out-bound packets
func (client *Client) Cipher() *rc4.Cipher {
	return client.cipher
}

// Decipher returns the RC4 cipher stream for in-bound packets
func (client *Client) Decipher() *rc4.Cipher {
	return client.decipher
}

// UpdateAccessKey sets the client signature base and signature key
func (client *Client) UpdateAccessKey(accessKey string) {
	client.signatureBase = sum([]byte(accessKey))
	client.signatureKey = MD5Hash([]byte(accessKey))
}

// SignatureBase returns the v0 checksum signature base
func (client *Client) SignatureBase() int {
	return client.signatureBase
}

// SignatureKey returns signature key
func (client *Client) SignatureKey() []byte {
	return client.signatureKey
}

// SetServerConnectionSignature sets the clients server-side connection signature
func (client *Client) SetServerConnectionSignature(serverConnectionSignature []byte) {
	client.serverConnectionSignature = serverConnectionSignature
}

// ServerConnectionSignature returns the clients server-side connection signature
func (client *Client) ServerConnectionSignature() []byte {
	return client.serverConnectionSignature
}

// SetClientConnectionSignature sets the clients client-side connection signature
func (client *Client) SetClientConnectionSignature(clientConnectionSignature []byte) {
	client.clientConnectionSignature = clientConnectionSignature
}

// ClientConnectionSignature returns the clients client-side connection signature
func (client *Client) ClientConnectionSignature() []byte {
	return client.clientConnectionSignature
}

// SequenceIDCounterOut returns the clients packet SequenceID counter for out-going packets
func (client *Client) SequenceIDCounterOut() *Counter {
	return client.sequenceIDOut
}

// SequenceIDCounterIn returns the clients packet SequenceID counter for incoming packets
func (client *Client) SequenceIDCounterIn() *Counter {
	return client.sequenceIDIn
}

// SetSessionKey sets the clients session key
func (client *Client) SetSessionKey(sessionKey []byte) {
	client.sessionKey = sessionKey
}

// SessionKey returns the clients session key
func (client *Client) SessionKey() []byte {
	return client.sessionKey
}

// SetPID sets the clients NEX PID
func (client *Client) SetPID(pid uint32) {
	client.pid = pid
}

// PID returns the clients NEX PID
func (client *Client) PID() uint32 {
	return client.pid
}

// SetStationURLs sets the clients Station URLs
func (client *Client) SetStationURLs(stationURLs []string) {
	client.stationURLs = stationURLs
}

// StationURLs returns the clients Station URLs
func (client *Client) StationURLs() []string {
	return client.stationURLs
}

// SetConnectionID sets the clients Connection ID
func (client *Client) SetConnectionID(connectionID uint32) {
	client.connectionID = connectionID
}

// ConnectionID returns the clients Connection ID
func (client *Client) ConnectionID() uint32 {
	return client.connectionID
}

// SetConnected sets the clients connection status
func (client *Client) SetConnected(connected bool) {
	client.connected = connected
}

// IncreasePingTimeoutTime adds a number of seconds to the check timer
func (client *Client) IncreasePingTimeoutTime(seconds int) {
	//Stop the kick timer if we get something back
	if client.pingKickTimer != nil {
		client.pingKickTimer.Stop()
	}
	//and reset the check timer
	if client.pingCheckTimer != nil {
		client.pingCheckTimer.Reset(time.Second * time.Duration(seconds))
	}
}

// StartTimeoutTimer begins the packet timeout timer
func (client *Client) StartTimeoutTimer() {
	//if we haven't gotten a ping *from* the client, send them one to check all is well
	client.pingCheckTimer = time.AfterFunc(time.Second*time.Duration(client.server.PingTimeout()), func() {
		client.server.SendPing(client)
		//if we *still* get nothing, they're gone
		client.pingKickTimer = time.AfterFunc(time.Second*time.Duration(client.server.PingTimeout()), func() {
			client.server.TimeoutKick(client)
		})
	})
}

// NewClient returns a new PRUDP client
func NewClient(address *net.UDPAddr, server *Server) *Client {
	client := &Client{
		address: address,
		server:  server,
	}

	err := client.Reset()
	if err != nil {
		// TODO - Should this return the error too?
		logger.Error(err.Error())
		return nil
	}

	return client
}