Create your own Web Server using C#

The Code (2)

We also need to identify the Mime type, using the file extension supplied by the user

public string GetMimeType(string sRequestedFile)
{


    StreamReader sr;
    String sLine = "";
    String sMimeType = "";
    String sFileExt = "";
    String sMimeExt = "";

    // Convert to lowercase
    sRequestedFile = sRequestedFile.ToLower();

    int iStartPos = sRequestedFile.IndexOf(".");

    sFileExt = sRequestedFile.Substring(iStartPos);

    try
    {
        //Open the Vdirs.dat to find out the list virtual directories
        sr = new StreamReader("data\\Mime.Dat");

        while ((sLine = sr.ReadLine()) != null)
        {

            sLine.Trim();

            if (sLine.Length > 0)
            {
                //find the separator
                iStartPos = sLine.IndexOf(";");

                // Convert to lower case
                sLine = sLine.ToLower();

                sMimeExt = sLine.Substring(0,iStartPos);
                sMimeType = sLine.Substring(iStartPos + 1);

                if (sMimeExt == sFileExt)
                    break;
            }
        }
    }
    catch (Exception e)
    {
        Console.WriteLine("An Exception Occurred : " + e.ToString());
    }

    if (sMimeExt == sFileExt)
        return sMimeType; 
    else
        return "";
}

Now we will write the function, to build and sends header information to the browser (client)

public void SendHeader(string sHttpVersion, string sMIMEHeader,
    int iTotBytes, string sStatusCode, ref Socket mySocket)
{

    String sBuffer = "";
    
    // if Mime type is not provided set default to text/html
    if (sMIMEHeader.Length == 0 )
    {
        sMIMEHeader = "text/html";  // Default Mime Type is text/html
    }

    sBuffer = sBuffer + sHttpVersion + sStatusCode + "\r\n";
    sBuffer = sBuffer + "Server: cx1193719-b\r\n";
    sBuffer = sBuffer + "Content-Type: " + sMIMEHeader + "\r\n";
    sBuffer = sBuffer + "Accept-Ranges: bytes\r\n";
    sBuffer = sBuffer + "Content-Length: " + iTotBytes + "\r\n\r\n";
    
    Byte[] bSendData = Encoding.ASCII.GetBytes(sBuffer); 

    SendToBrowser( bSendData, ref mySocket);

    Console.WriteLine("Total Bytes : " + iTotBytes.ToString());

}

The SendToBrowser function sends information to the browser. This is an overloaded function.


public void SendToBrowser(String sData, ref Socket mySocket)
{
    SendToBrowser (Encoding.ASCII.GetBytes(sData), ref mySocket);
}


public void SendToBrowser(Byte[] bSendData, ref Socket mySocket)
{
    int numBytes = 0;
    try
    {
        if (mySocket.Connected)
        {
            if (( numBytes = mySocket.Send(bSendData,
                     bSendData.Length,0)) == -1)
                Console.WriteLine("Socket Error cannot Send Packet");
            else
            {
                Console.WriteLine("No. of bytes send {0}" , numBytes);
            }
        }
        else
            Console.WriteLine("Connection Dropped....");
    }
    catch (Exception  e)
    {
        Console.WriteLine("Error Occurred : {0} ", e );
    }
}

We now have all the building blocks ready, now we will delve into the key function of our application.


public void StartListen()
{

    int iStartPos = 0;
    String sRequest;
    String sDirName;
    String sRequestedFile;
    String sErrorMessage;
    String sLocalDir;
    String sMyWebServerRoot = "C:\\MyWebServerRoot\\";
    String sPhysicalFilePath = "";
    String sFormattedMessage = "";
    String sResponse = "";


    while(true)
    {
        //Accept a new connection
        Socket mySocket = myListener.AcceptSocket() ;

        Console.WriteLine ("Socket Type " +     mySocket.SocketType ); 
        if(mySocket.Connected)
        {
            Console.WriteLine("\nClient Connected!!\n==================\n
             CLient IP {0}\n", mySocket.RemoteEndPoint) ;


            //make a byte array and receive data from the client 
            Byte[] bReceive = new Byte[1024] ;
            int i = mySocket.Receive(bReceive,bReceive.Length,0) ;


            //Convert Byte to String
            string sBuffer = Encoding.ASCII.GetString(bReceive);


            //At present we will only deal with GET type
            if (sBuffer.Substring(0,3) != "GET" )
            {
                Console.WriteLine("Only Get Method is supported..");
                mySocket.Close();
                return;
            }


            // Look for HTTP request
            iStartPos = sBuffer.IndexOf("HTTP",1);


            // Get the HTTP text and version e.g. it will return "HTTP/1.1"
            string sHttpVersion = sBuffer.Substring(iStartPos,8);


            // Extract the Requested Type and Requested file/directory
            sRequest = sBuffer.Substring(0,iStartPos - 1);


            //Replace backslash with Forward Slash, if Any
            sRequest.Replace("\\","/");


            //If file name is not supplied add forward slash to indicate 
            //that it is a directory and then we will look for the 
            //default file name..
            if ((sRequest.IndexOf(".") <1) && (!sRequest.EndsWith("/")))
            {
                sRequest = sRequest + "/"; 
            }
            //Extract the requested file name
            iStartPos = sRequest.LastIndexOf("/") + 1;
            sRequestedFile = sRequest.Substring(iStartPos);


            //Extract The directory Name
               sDirName = sRequest.Substring(sRequest.IndexOf("/"), 
                       sRequest.LastIndexOf("/")-3);

The code is self-explanatory. It receives the request, converts it into string from bytes then look for the request type, extracts the HTTP Version, file and directory information.

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About the author

Imtiaz Alam United States

Imtiaz Alam is a Senior Developer, currently residing in Phoenix, Arizona. He has more than five years of development experience in developing Mirosoft based Solution.

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