ServerUDPPostavka1

// UDP server that use blocking sockets
#define _WINSOCK_DEPRECATED_NO_WARNINGS

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
#include "conio.h"

#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")

#define SERVER_PORT 15000   // Port number of server that will be used for communication with clients
#define BUFFER_SIZE 512     // Size of buffer that will be used for sending and receiving messages to clients

int main()
{
    // Server address
    sockaddr_in serverAddress;

    // Buffer we will use to send and receive clients' messages
    char dataBuffer[BUFFER_SIZE];

    // WSADATA data structure that is to receive details of the Windows Sockets implementation
    WSADATA wsaData;

    // Initialize windows sockets library for this process
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        printf("WSAStartup failed with error: %d\n", WSAGetLastError());
        return 1;
    }

    // Initialize serverAddress structure used by bind function
    memset((char*)&serverAddress, 0, sizeof(serverAddress));
    serverAddress.sin_family = AF_INET;             // set server address protocol family
    serverAddress.sin_addr.s_addr = INADDR_ANY;     // use all available addresses of server
    serverAddress.sin_port = htons(SERVER_PORT);

    // Create a socket
    SOCKET serverSocket = socket(AF_INET,      // IPv4 address famly
        SOCK_DGRAM,                            // datagram socket
        IPPROTO_UDP);                          // UDP

    // Check if socket creation succeeded
    if (serverSocket == INVALID_SOCKET)
    {
        printf("Creating socket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // Bind server address structure (type, port number and local address) to socket
    int iResult = bind(serverSocket, (SOCKADDR*)&serverAddress, sizeof(serverAddress));

    // Check if socket is succesfully binded to server datas
    if (iResult == SOCKET_ERROR)
    {
        printf("Socket bind failed with error: %d\n", WSAGetLastError());
        closesocket(serverSocket);
        WSACleanup();
        return 1;
    }

    printf("Simple UDP server started and waiting client messages.\n");

    // Main server loop
    while (1)
    {
        // Declare and initialize client address that will be set from recvfrom
        sockaddr_in clientAddress;
        memset(&clientAddress, 0, sizeof(clientAddress));

        // Set whole buffer to zero
        memset(dataBuffer, 0, BUFFER_SIZE);

        // size of client address
        int sockAddrLen = sizeof(clientAddress);

        // Receive client message
        iResult = recvfrom(serverSocket,    // Own socket
            dataBuffer,                     // Buffer that will be used for receiving message
            BUFFER_SIZE,                    // Maximal size of buffer
            0,                              // No flags
            (SOCKADDR*)&clientAddress,      // Client information from received message (ip address and port)
            &sockAddrLen);                  // Size of sockadd_in structure

        // Check if message is succesfully received
        if (iResult == SOCKET_ERROR)
        {
            printf("recvfrom failed with error: %d\n", WSAGetLastError());
            continue;
        }

        // Set end of string
        dataBuffer[iResult] = '\0';

        char ipAddress[16]; // 15 spaces for decimal notation (for example: "192.168.100.200") + '\0'

        // Copy client ip to local char[]
        strcpy_s(ipAddress, sizeof(ipAddress), inet_ntoa(clientAddress.sin_addr));

        // Convert port number from network byte order to host byte order
        unsigned short clientPort = ntohs(clientAddress.sin_port);

        printf("Client connected from ip: %s, port: %d, sent: %s.\n", ipAddress, clientPort, dataBuffer);

        // Possible server-shutdown logic could be put here
    }

    // Close server application
    iResult = closesocket(serverSocket);
    if (iResult == SOCKET_ERROR)
    {
        printf("closesocket failed with error: %ld\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    printf("Server successfully shut down.\n");

    // Close Winsock library
    WSACleanup();

    return 0;
}