server.go

package main

import (
	"context"
	"fmt"
	"gopkg.in/yaml.v3"
	"log"
	"net"
	command_line "node/command-line"
	ObjectStorage "node/object-storage"
	ProcessConnection "node/process-connection"
	. "node/types"
	"node/utilities"
	"os"
	"strconv"
	"sync"
)

/**
 * @file Server.go - Server for the blockchain
 * @brief Distributed Systems - Blockchain, each instance of this program is a node in the blockchain
 * @author Xavier Perret
 * @date 28/10/2022
 * @version 1.3
 */

func listenForConnections(serverConfig Config, objectStorage Blob, addressToListenOn string, amIRoot bool) {
	port := strconv.FormatInt(int64(serverConfig.Port), 10)
	completeAddress := addressToListenOn + ":" + port

	server, err := net.Listen("tcp", completeAddress)
	if err != nil {
		fmt.Println("Error while creating the server :", err)
		os.Exit(1)
	}

	fmt.Println("Server is ready to accept connections")
	fmt.Println("listening on ", completeAddress)

	var mu sync.Mutex
	for {
		// Listening for connections
		conn, err := server.Accept()
		if err != nil {
			fmt.Println("Error accepting: ", err.Error())
		} else {
			go ProcessConnection.ProcessClient(conn, server, objectStorage, serverConfig, amIRoot, &mu)
		}
	}
}

func main() {
	ctx := context.Background()
	argsLen := len(os.Args)
	isThereEnoughArgs := argsLen <= 1
	if isThereEnoughArgs {
		fmt.Println("First argument should be the path of the config file '--path=<config.yaml>'")
		os.Exit(1)
	}

	// init configuration
	args := os.Args[1:]
	fmt.Println("Program started with arguments", args)
	fmt.Println("config file path is ", args[0][7:])

	buf, err := os.ReadFile(args[0][7:])
	if err != nil {
		fmt.Println("Error while reading the config file", err)
		fmt.Println("Exiting...")
		os.Exit(1)
	}

	var serverConfig Config
	err = yaml.Unmarshal(buf, &serverConfig)
	if err != nil {
		os.Exit(1)
	}

	utilities.PrintConfig(serverConfig)

	amIRoot := argsLen == 3
	if amIRoot {
		if os.Args[3] == "--root" {
			amIRoot = true
		}
	}
	if !amIRoot {
		fmt.Println("Third argument is not --root meaning this node is not meant to be directly stimulated by the client")
	}

	azureCreds := ObjectStorage.InitAzureCredentials("hepiadistributedsystems")
	blobName := "blob-number-" + strconv.Itoa(serverConfig.ID)
	objectStorage := ObjectStorage.InitializeBlobFromObjectStorageCreds(blobName, azureCreds)

	addressToListenOn := "0.0.0.0"
	go listenForConnections(serverConfig, objectStorage, addressToListenOn, amIRoot)
	command_line.ServerUserInputLoop(serverConfig, true, objectStorage)

	_, err = objectStorage.BlockBlobClient.Delete(ctx, nil)
	if err != nil {
		fmt.Println("Error while deleting the blob", err)
		fmt.Println("This previous error is normal if the blob was already deleted or wasn't created")
	}

	// Delete the container
	fmt.Println("Deleting the container " + objectStorage.BlobName)
	_, err = objectStorage.ContainerClient.Delete(ctx, nil)

	if err != nil {
		log.Fatalf("Failure: %+v", err)
	}
}