yats.git

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/**
 * Yats - yats
 *
 * This file is licensed under the Affero General Public License version 3 or
 * later. See the COPYING file.
 *
 * @author Paolo Lulli <kevwe.com>
 * @copyright Paolo Lulli 2024
 */

package tcp

import (
	"crypto/tls"
	"fmt"
	"log"
	"net"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"
	"yats-server/config"
	"yats-server/tlv"
)

type tcpserver struct {
	wg         sync.WaitGroup
	listener   net.Listener
	shutdown   chan struct{}
	connection chan net.Conn
}

func createServer(cfg config.Configuration) (*tcpserver, error) {

	var listener net.Listener
	var err error

	if cfg.TlsActive == "true" {
		cert, err := tls.LoadX509KeyPair(cfg.TlsCertificate, cfg.TlsKeyFile)
		if err != nil {
			log.Fatalf("server: loadkeys: %s", err)
		}
		tlsconfig := tls.Config{Certificates: []tls.Certificate{cert}, InsecureSkipVerify: false}
		//listener, err := tls.Dial("tcp", cfg.TcpAddress, &tlsconfig)

		listener, err = tls.Listen("tcp", cfg.TcpAddress, &tlsconfig)
	} else {
		listener, err = net.Listen("tcp", cfg.TcpAddress)
	}
	if err != nil {
		return nil, fmt.Errorf("failed to listen on address %s: %w", cfg.TcpAddress, err)
	}

	return &tcpserver{
		listener:   listener,
		shutdown:   make(chan struct{}),
		connection: make(chan net.Conn),
	}, nil
}

func (s *tcpserver) acceptConnections() {
	defer s.wg.Done()

	for {
		select {
		case <-s.shutdown:
			return
		default:
			conn, err := s.listener.Accept()
			if err != nil {
				continue
			}
			s.connection <- conn
		}
	}
}

func (s *tcpserver) handleConnections() {
	defer s.wg.Done()

	for {
		select {
		case <-s.shutdown:
			return
		case conn := <-s.connection:
			go s.handleConnection(conn)
		}
	}
}

func (s *tcpserver) handleConnection(conn net.Conn) {
	defer conn.Close()

	tlscon, ok := conn.(*tls.Conn)
	if ok {
		state := tlscon.ConnectionState()
		log.Println("Server: client public key is:")
		clientCN := state.PeerCertificates[0].Subject.CommonName
		fmt.Printf("clientCN: %s\n", clientCN)
	}

	// Read incoming data
	buf := make([]byte, 1024)
	_, err := conn.Read(buf)
	if err != nil {
		fmt.Println(err)
		return
	}

	fmt.Printf("Received: %s", buf)
	decodeTlv, bytes, err := tlv.DecodeTlv(buf)
	if err == nil {
		fmt.Printf("Decoded: tlv: %s with value: %x", decodeTlv, bytes)
	}
}

func (s *tcpserver) Start() {
	s.wg.Add(2)
	go s.acceptConnections()
	go s.handleConnections()
}

func (s *tcpserver) Stop() {
	close(s.shutdown)
	s.listener.Close()

	done := make(chan struct{})
	go func() {
		s.wg.Wait()
		close(done)
	}()

	select {
	case <-done:
		return
	case <-time.After(time.Second):
		fmt.Println("Timed out waiting for connections to finish.")
		return
	}
}

func RunTcpServer(cfg config.Configuration) {
	s, err := createServer(cfg)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	s.Start()

	// Wait for a SIGINT or SIGTERM signal to gracefully shut down the tcpserver
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	<-sigChan

	fmt.Println("Shutting down tcpserver...")
	s.Stop()
	fmt.Println("tcpserver stopped.")
}