/*
 * FreeRTOS TLS Echo Server V1.1.1
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://aws.amazon.com/freertos
 * http://www.FreeRTOS.org
 */

package main

import (
	"crypto/rand"
	"crypto/tls"
	"crypto/x509"
	"io"
	"io/ioutil"
	"log"
	"net"
	"time"
)

//************** CONFIG SECTION *************//
//Folder were certs are put
const sCertPath string = "certs/"
const sServerCert string = "server.pem"
const sServerKey string = "server.key"
const sEchoPort string = "9000"
const xReadTimeoutSeconds = 300

func main() {

	// load certificates
	xServerCert, xStatus := tls.LoadX509KeyPair(sCertPath+sServerCert, sCertPath+sServerKey)
	if xStatus != nil {
		log.Printf("Error %s while loading server certificates", xStatus)
		return
	}

	xServerCA, xStatus := ioutil.ReadFile(sCertPath + sServerCert)
	xServerCAPool := x509.NewCertPool()
	xServerCAPool.AppendCertsFromPEM(xServerCA)

	//Configure TLS

	xTLSconfig := tls.Config{Certificates: []tls.Certificate{xServerCert},
		MinVersion: tls.VersionTLS12,
		RootCAs:    xServerCAPool,
		ClientAuth: tls.RequireAnyClientCert,
	}
	xTLSconfig.Rand = rand.Reader

	sService := ":" + sEchoPort
	xEchoServer, xStatus := tls.Listen("tcp", sService, &xTLSconfig)
	if xStatus != nil {
		log.Printf("Error %s while trying to listen", xStatus)
	}
	log.Print("Listening to port " + sEchoPort)

	defer xEchoServer.Close()

	for {

		xConnection, xStatus := xEchoServer.Accept()
		if xStatus != nil {
			log.Printf("Error %s while trying to connect", xStatus)
		} else {
			go echoServerThread(xConnection)
		}
	}
}

func echoServerThread(xConnection net.Conn) {
	defer xConnection.Close()

	xDataBuffer := make([]byte, 4096)

	for {
		xConnection.SetReadDeadline(time.Now().Add(xReadTimeoutSeconds * time.Second))
		xNbBytes, xStatus := xConnection.Read(xDataBuffer)
		if xStatus != nil {
			//EOF mean end of connection
			if xStatus != io.EOF {
				//If not EOF then it is an error
			}
			break
		}

		xNbBytes, xStatus = xConnection.Write(xDataBuffer[:xNbBytes])
		if xStatus != nil {
			log.Printf("Error %s while sending data", xStatus)
			break
		}
	}
}
