KlientUDPResen

// 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"
#define SERVER_PORT 15001
#define BUFFER_SIZE 512


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

    // Size of sockaddr_in structure
    int sockAddrSize = sizeof(serverAddress);

    // Buffer we will use to store message
    char dataBuffer[BUFFER_SIZE];

    // Port on server that will be used for communication with client
    unsigned short serverPort = SERVER_PORT;

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

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

    // Initialize serverAddress structure
    memset((char*)&serverAddress, 0, sockAddrSize);
    serverAddress.sin_family = AF_INET;
    serverAddress.sin_addr.s_addr = inet_addr(SERVER_IP_ADDRESS);
    serverAddress.sin_port = htons(serverPort);

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

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

    char previous_message[BUFFER_SIZE];

    while (true)
    {
        // Read string from user into outgoing buffer
        printf("Enter message to send: ");
        gets_s(dataBuffer, BUFFER_SIZE);

        // Check if client closing command is entered
        if (!strcmp(dataBuffer, "stop client"))
        {
            break;
        }

        // Send message to server
        iResult = sendto(clientSocket,
            dataBuffer,
            strlen(dataBuffer),
            0,
            (SOCKADDR*)&serverAddress,
            sockAddrSize);

        // Check result of send function
        if (iResult == SOCKET_ERROR)
        {
            printf("sendto failed with error: %d\n", WSAGetLastError());
            closesocket(clientSocket);
            WSACleanup();
            return 1;
        }


        // Check if 'server close command' is issued. Client is also closing, after server is closed.
        //compare current and previous message
        if (!strcmp(previous_message, dataBuffer))
        {
            printf("Two identical messages were sent consecutively. Server is being closed.\n");
            break;
        }
        //store current message for next comparison
        strcpy(previous_message, dataBuffer);



        // Receive server message
        iResult = recvfrom(clientSocket,
            dataBuffer,
            BUFFER_SIZE,
            0,
            (SOCKADDR*)&serverAddress,
            &sockAddrSize);

        if (iResult == SOCKET_ERROR)
        {
            printf("recvfrom failed with error: %d\n", WSAGetLastError());
            continue;
        }

        // Set end of string
        dataBuffer[iResult] = '\0';
        // Log message from server
        printf("Message from server: %s.\n\n", dataBuffer);

    }

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

    WSACleanup();

    return 0;
}