Cx

/**


        printf("Do you wish to upload or download a file? Enter [u/d] for up or down respectively, followed by the full filename, including the extension. Alternatively press $ to terminate the program");
        >> server is given this info
        parse string, call relevant build function if sending -> sends rdy2rec if receiver & calls relevant accept frame for when data is being sent back
        fileopen read when sending
        gets(request);  // read in the string

        for client sender {
        generate byte count for payload
        first n bytes are byte count so insert those
        give in first token of string (u)
        give name of file being sent/received
        }

        for server sender {
        generate byte count for payload
        first n bytes are byte count so insert those
        give error/success code
        }
        for both sender
        TESTARRAY[LASTCHAROFHEADER] = '#';  // replace null terminator with CR
        method of loading file into TBS

        for client receiver {
        read count so knows how much data to expect
        see if there was an error
        file open to write with user supplied name
        if no error, pipe payload into file
        }

        for server receiver {
        read count so knows how much data to expect
        read filename
        file open to write with client supplied name
        pipe payload into file
        }

        file close


        why doesnt client give error codes to the server too?













**/

#include <stdio.h>
#include <winsock2.h>
#include <ws2tcpip.h>

void printError(void);  // function to display error messages

int main()
{
    WSADATA wsaData;  // create structure to hold winsock data
    int retVal, nRx, nIn, j;
    int endLine = 0, stop = 0;  // flags to control loops
    char serverIP[20];      // IP address of server
    int serverPort;         // port used by server
    char request[100];      // array to hold user input
    char reply[100];        // array to hold received bytes

    // Initialise winsock, version 2.2, giving pointer to data structure
    retVal = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (retVal != 0)  // check for error
    {
        printf("*** WSAStartup failed: %d\n", retVal);
        printError();
        return 1;
    }
    else printf("WSAStartup succeeded\n" );

    // Create a handle for a socket, to be used by the client
    SOCKET clientSocket = INVALID_SOCKET;  // handle called clientSocket

    // Create the socket, and assign it to the handle
    // AF_INET means IP version 4,
    // SOCK_STREAM means socket works with streams of bytes,
    // IPPROTO_TCP means TCP transport protocol.
    clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (clientSocket == INVALID_SOCKET)  // check for error
    {
        printf("*** Failed to create socket\n");
        printError();
        stop = 1;
    }
    else printf("Socket created\n" );

    // Get the details of the server from the user
    printf("Enter IP address of server: ");
    scanf("%20s", serverIP);  // get IP address as string

    printf("Enter port number: ");
    scanf("%d", &serverPort);     // get port number as integer

    gets(request);  // flush the endline from the input buffer

    // Build a structure to identify the service required
    // This has to contain the IP address and port of the server
    struct sockaddr_in service;  // IP address and port structure
    service.sin_family = AF_INET;  // specify IP version 4 family
    service.sin_addr.s_addr = inet_addr(serverIP);  // set IP address
    // function inet_addr() converts IP address string to 32-bit number
    service.sin_port = htons(serverPort);  // set port number
    // function htons() converts 16-bit integer to network format

    // Try to connect to the service required
    printf("Trying to connect to %s on port %d\n", serverIP, serverPort);
    retVal = connect(clientSocket, (SOCKADDR *) &service, sizeof(service));
    if( retVal != 0)  // check for error
    {
        printf("*** Error connecting\n");
        printError();
        stop = 1;  // make sure we do not go into the while loop
    }
    else printf("Connected!\n");

    // Main loop to send messages and receive responses
    // This example assumes client will send first
    while (stop == 0)
    {
        // Get user request and send it to the server


        printf("Do you wish to upload or download a file? Enter [u/d] for up or down respectively, followed by the full filename, including the extension. Alternatively press $ to terminate the program");
        gets(request);  // read in the string
        // gets() reads until enter (CR), but does not put CR in string
        nIn = strlen(request);  //find the length

        /** for downloading **/

        /** generate byte count for payload **/
        /** first n bytes are byte count so insert those **/

        /** give in first token of string (u or d) **/
        /** give name of file being [up/down]loaded **/

        /**TESTARRAY**/[/**LASTCHAROFHEADER**/] = '#';  // replace null terminator with CR
        /**TESTARRAT**/[/**FIRSTPAYLOADCHARACTER**/] = /** method of loading file into TBS **/


        if (request[0] == '$') stop = 1;  // set stop flag if $ entered

        if (stop == 1) printf("Closing connection as requested...\n");
        else  // send the message and try to receive a reply
        {
            // send() arguments: socket handle, array of bytes to send,
            // number of bytes to send, and last argument of 0.
           /** change this retVal = send(clientSocket, request, nIn+2, 0);  // send nIn+2 bytes **/
            // retVal will be number of bytes sent, or error indicator

            if( retVal == SOCKET_ERROR) // check for error
            {
                printf("*** Error sending\n");
                printError();
            }
            else printf("Sent %d bytes, waiting for reply...\n", retVal);

            endLine = 0;
            do  // loop to receive entire reply, terminated by LF
            {
                // Try to receive some bytes
                // recv() arguments: socket handle, array to hold rx bytes,
                // maximum number of bytes to receive, last argument 0.
                nRx = recv(clientSocket, reply, 100, 0);
                // nRx will be number of bytes received, or error indicator

                if( nRx == SOCKET_ERROR)  // check for error
                {
                    printf("Problem receiving\n");
                    //printError();
                    stop = 1;  // exit the loop if problem
                }
                else if (nRx == 0)  // connection closed
                {
                    printf("Connection closed by server\n");
                    stop = 1;
                }
                else if (nRx > 0)  // we got some data
                {
                    for (j = 0; j < nRx; j++)
                    {
                        printf("%c", reply[j]);  // print each character
                        if (reply[j] == 10) endLine = 1;  // found LF
                    }
                }
            }
            while ((endLine == 0) && (stop == 0));
            // continue until endline or error or connection closed
            // if it was endline, the outer loop should continue

        } // end else (not stop)

    }  // end while stop == 0
    // When this loop exits, it is time to tidy up and end the program

    // Shut down the sending side of the TCP connection first
    retVal = shutdown(clientSocket, SD_SEND);
    if( retVal != 0)  // check for error
    {
        printf("*** Error shutting down sending\n");
        printError();
    }

    // Then close the socket
    retVal = closesocket(clientSocket);
    if( retVal != 0)  // check for error
    {
        printf("*** Error closing socket\n");
        printError();
    }
    else printf("Socket closed\n");

    // Finally clean up the winsock system
    retVal = WSACleanup();
    printf("WSACleanup returned %d\n",retVal);

    // Prompt for user input, so window stays open when run outside CodeBlocks
    printf("\nPress return to exit:");
    gets(request);
    return 0;
}

/* Function to print informative error messages
   when something goes wrong...  */
void printError(void)
{
    char lastError[1024];
    int errCode;

    errCode = WSAGetLastError();  // get the error code for the last error
    FormatMessage(
        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        errCode,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        lastError,
        1024,
        NULL);  // convert error code to error message
    printf("WSA Error Code %d = %s\n", errCode, lastError);
}