PeteUDPServer

// UDP server that use non-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")

// Port numbers of server that will be used for communication with clients
#define SERVER_PORT1 15011
#define SERVER_PORT2 15012

// Size of buffer that will be used for sending and receiving messages to clients
#define BUFFER_SIZE 512

int main()
{
    // Server addresses
    sockaddr_in serverAddress1;
    sockaddr_in serverAddress2;

    // 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 serverAddress1 and serverAddress2 structures used by bind function
    memset((char*)&serverAddress1, 0, sizeof(serverAddress1));
    serverAddress1.sin_family = AF_INET;            // set server address protocol family
    serverAddress1.sin_addr.s_addr = INADDR_ANY;    // use all available addresses of server
    serverAddress1.sin_port = htons(SERVER_PORT1);  // 15001 port

    memset((char*)&serverAddress2, 0, sizeof(serverAddress2));
    serverAddress2.sin_family = AF_INET;                            // set server address protocol family
    serverAddress2.sin_addr.s_addr = inet_addr("127.0.0.1");        // loop address
    serverAddress2.sin_port = htons(SERVER_PORT2);                  // 15002 port

    // Create first socket
    SOCKET serverSocket1 = socket(AF_INET,      // IPv4 address famly
        SOCK_DGRAM,   // datagram socket
        IPPROTO_UDP); // UDP

    // Check if socket creation succeeded
    if (serverSocket1 == INVALID_SOCKET)
    {
        printf("Creating socket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // Create second socket
    SOCKET serverSocket2 = socket(AF_INET,      // IPv4 address famly
        SOCK_DGRAM,   // datagram socket
        IPPROTO_UDP); // UDP

    // Check if socket creation succeeded
    if (serverSocket2 == 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 first socket
    int iResult = bind(serverSocket1,(SOCKADDR *)&serverAddress1, sizeof(serverAddress1));

    // Check if socket is succesfully binded to server address data
    if (iResult == SOCKET_ERROR)
    {
        printf("Socket bind failed with error: %d\n", WSAGetLastError());
        closesocket(serverSocket1);
        WSACleanup();
        return 1;
    }

    // Bind server address structure (type, port number and local address) to second socket
    iResult = bind(serverSocket2,(SOCKADDR *)&serverAddress2, sizeof(serverAddress2));

    // Check if socket is succesfully binded to server address data
    if (iResult == SOCKET_ERROR)
    {
        printf("Socket bind failed with error: %d\n", WSAGetLastError());
        closesocket(serverSocket2);
        WSACleanup();
        return 1;
    }

    // Setting non-blocking mode to both sockets
    unsigned long mode = 1;
    if(ioctlsocket(serverSocket1, FIONBIO, &mode) != 0 || ioctlsocket(serverSocket2, FIONBIO, &mode) != 0)
    {
        printf("ioctlsocket failed with error %d\n", WSAGetLastError());
        closesocket(serverSocket1);
        closesocket(serverSocket2);
        WSACleanup();
        return 1;
    }

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

    // Main server loop
    while (true)
    {
        // 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);

        // Declare and initialize set of socket descriptor for buffer reading
        fd_set readfds;
        FD_ZERO(&readfds);

        // Add socket to set readfds
        FD_SET(serverSocket1, &readfds);
        FD_SET(serverSocket2, &readfds);

        // Declare and initialize set of socket descriptor for exceptions
        fd_set exceptfds;
        FD_ZERO(&exceptfds);

        // Add socket to set exceptfds
        FD_SET(serverSocket1, &exceptfds);
        FD_SET(serverSocket2, &exceptfds);

        // Wait new messages to arrive in one of the sockets in readfds set and wait for possible exception on sockets in exceptfds set
        int sResult = select(0, &readfds , NULL , &exceptfds , NULL);

        // Check whether the error occurred
        if (sResult == SOCKET_ERROR)
        {
            printf("select failed with error: %d\n", WSAGetLastError());
            break;
        }

        // If result is positive, that is indicator that packet has arrived to one or more socket or there is exception on some socket
        // Result number corresonds to number of sockets that have an event
        else if (sResult > 0)
        {
            unsigned long portNumber = 0;

            // We will check if packet is arrived to one of our sockets (if two or more sockets are used, we have to check each socket)
            if(FD_ISSET(serverSocket1, &readfds))
            {
                // Receive client message
                iResult = recvfrom(serverSocket1,           // Socket with port 15001
                    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
                portNumber = SERVER_PORT1;
                if(iResult != SOCKET_ERROR)
                {
                    // Set end of string
                    dataBuffer[iResult] = '\0';


                    printf("Server received message on %d port. Client sent: %s.\n", portNumber,dataBuffer);
                }
                else
                {
                    printf("recvfrom failed with error: %d\n", WSAGetLastError());
                    continue;
                }
            }
            if(FD_ISSET(serverSocket2, &readfds))
            {
                // Receive client message
                iResult = recvfrom(serverSocket2,           // Socket with port 15002
                    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
                portNumber = SERVER_PORT2;
                if(iResult != SOCKET_ERROR)
                {
                    // Set end of string
                    dataBuffer[iResult] = '\0';


                    printf("Server received message on %d port. Client sent: %s.\n", portNumber,dataBuffer);
                }
                else
                {
                    printf("recvfrom failed with error: %d\n", WSAGetLastError());
                    continue;
                }
            }
            // We will check if an exception occurred on one of our sockets. Close server application if error occured
            if(FD_ISSET(serverSocket1, &exceptfds))
            {
                break;
            }
            if(FD_ISSET(serverSocket2, &exceptfds))
            {
                break;
            }
            // neither of two socket is in these two sets (some error has occurred)
            else
            {
                continue;
            }

            // Check if message is succesfully received

        }
    }

    // Close server application
    if (SOCKET_ERROR == closesocket(serverSocket1) || SOCKET_ERROR == closesocket(serverSocket2))
    {
        printf("closesocket failed with error: %ld\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

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

    // Close Winsock library
    WSACleanup();
    return 0;
}