Postavka_Klient_UDP

// UDP client that uses 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_IP_ADDRESS "127.0.0.1"       // IPv4 address of server
#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 client


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

    // Size of server address structure
    int sockAddrLen = sizeof(serverAddress);

    // Buffer that will be used for sending and receiving messages to client
    char dataBuffer[BUFFER_SIZE];

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

    // Initialize windows sockets for this process
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);

    // Check if library is succesfully initialized
    if (iResult != 0)
    {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    // Initialize memory for address structure
    memset((char*)&serverAddress, 0, sizeof(serverAddress));

    // Initialize address structure of server
    serverAddress.sin_family = AF_INET;                             // IPv4 address famly
    serverAddress.sin_addr.s_addr = inet_addr(SERVER_IP_ADDRESS);   // Set server IP address using string
    serverAddress.sin_port = htons(SERVER_PORT);                    // Set server port

    // Create a socket
    SOCKET clientSocket = socket(AF_INET,      // IPv4 address famly
        SOCK_DGRAM,                            // Datagram socket
        IPPROTO_UDP);                          // UDP protocol

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

    printf("Enter message to send:\n");

    // Read string from user into outgoing buffer
    gets_s(dataBuffer, BUFFER_SIZE);

    // Send message to server
    iResult = sendto(clientSocket,      // Own socket
        dataBuffer,                     // Text of message
        strlen(dataBuffer),             // Message size
        0,                              // No flags
        (SOCKADDR*)&serverAddress,      // Address structure of server (type, IP address and port)
        sizeof(serverAddress));         // Size of sockadr_in structure

    // Check if message is succesfully sent. If not, close client application
    if (iResult == SOCKET_ERROR)
    {
        printf("sendto failed with error: %d\n", WSAGetLastError());
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }

    // Only for demonstration purpose
    printf("Press any key to exit: ");
    _getch();

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

    // Close Winsock library
    WSACleanup();

    // Client has succesfully sent a message
    return 0;
}